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<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/comparing-whole-number-place-values</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x40b497d9.jpg</video:thumbnail_loc><video:title>Comparing whole number place values</video:title><video:description>Sal compares whole numbers written in expanded form, written form, and number form.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3Xcae0OGavk.mp4/3Xcae0OGavk.mp4</video:content_loc><video:duration>91</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/comparing-multi-digit-numbers-word-problems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x48d6cc8f4f0840e4.jpg</video:thumbnail_loc><video:title>Comparing multi-digit whole numbers word problems</video:title><video:description>Sal solves word problems that involve comparing multi-digit whole numbers.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PqyS66_mE24.mp4/PqyS66_mE24.mp4</video:content_loc><video:duration>352</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/rounding-whole-numbers-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/2600660.jpg</video:thumbnail_loc><video:title>Rounding whole numbers to nearest hundred</video:title><video:description>Sal rounds 24,259 to the nearest hundred.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_qzs1zozTBo.mp4/_qzs1zozTBo.mp4</video:content_loc><video:duration>263</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/rounding-whole-numbers-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/2600661.jpg</video:thumbnail_loc><video:title>Rounding whole numbers to nearest thousand</video:title><video:description>Sal rounds 423,275 to the nearest thousand.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/fh8gkPW_6g4.mp4/fh8gkPW_6g4.mp4</video:content_loc><video:duration>148</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/rounding-to-nearest-ten-hundred-and-thousand</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2f58281c05cca46c.jpg</video:thumbnail_loc><video:title>Rounding whole numbers word problems</video:title><video:description>Sal solves word problems by rounding whole numbers to the nearest ten, hundred, or thousand.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Gg-GD5QfbB4.mp4/Gg-GD5QfbB4.mp4</video:content_loc><video:duration>202</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/rounding-whole-numbers-missing-digit</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xaa79450a.jpg</video:thumbnail_loc><video:title>Rounding whole numbers: missing digit</video:title><video:description>Lindsay finds the missing digit in an estimation problem by using a number line.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Hixy7TX-Nwo.mp4/Hixy7TX-Nwo.mp4</video:content_loc><video:duration>353</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/adding-multi-digit-numbers-with-place-value</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfe5a4a1f7a48fc5c.jpg</video:thumbnail_loc><video:title>Relate place value to standard algorithm for multi-digit addition</video:title><video:description>Transition from a place value chart to standard algorithm when adding multi-digit numbers.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DqaHhReVpZI.mp4/DqaHhReVpZI.mp4</video:content_loc><video:duration>382</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/adding-multi-digit-numbers-with-regrouping</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe7ae47a2d1df7023.jpg</video:thumbnail_loc><video:title>Adding multi-digit numbers: 48,029+233,930</video:title><video:description>Add 48,029+233,930 using the standard algorithm.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TVtdqRNJmiw.mp4/TVtdqRNJmiw.mp4</video:content_loc><video:duration>138</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/regrouping-borrowing-twice-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbedc5cb2.jpg</video:thumbnail_loc><video:title>Multi-digit subtraction with regrouping twice</video:title><video:description>Sal using regrouping to subtact 9601-8023.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OJ-wajo6oa4.mp4/OJ-wajo6oa4.mp4</video:content_loc><video:duration>306</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/understanding-place-value-when-subtracting</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x90ad6246dbd32e70.jpg</video:thumbnail_loc><video:title>Relate place value to standard algorithm for multi-digit subtraction</video:title><video:description>Transition from a place value chart to standard algorithm when subtracting multi-digit numbers.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/XAPhD7EDQUk.mp4/XAPhD7EDQUk.mp4</video:content_loc><video:duration>398</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/subtracting-multi-digit-numbers-with-regrouping</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8f58991ebfadaeed.jpg</video:thumbnail_loc><video:title>Multi-digit subtraction: 389,002-76,151</video:title><video:description>Subtract 389,002-76,151 using the standard algorithm.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/buyK1y4rV3E.mp4/buyK1y4rV3E.mp4</video:content_loc><video:duration>201</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/metric-distance</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x58cdb0a7.jpg</video:thumbnail_loc><video:title>Metric system: units of distance</video:title><video:description>Sal discusses metric units of length or distance such as millimeter, centimeter, meter, and kilometer.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/I3kQJvR7ZIg.mp4/I3kQJvR7ZIg.mp4</video:content_loc><video:duration>416</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/metric-units-of-volume</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9bd087b9.jpg</video:thumbnail_loc><video:title>Metric system: units of volume</video:title><video:description>Learn about metric units of volume or capacity such as milliliter and liter.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LhMEqsL_M5o.mp4/LhMEqsL_M5o.mp4</video:content_loc><video:duration>254</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/converting-weight</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x13181fc4.jpg</video:thumbnail_loc><video:title>How to convert kg to mg and T to oz</video:title><video:description>Sal converts kilograms to milligrams and tons to ounces.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1oFv56vSvvA.mp4/1oFv56vSvvA.mp4</video:content_loc><video:duration>264</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/liters-to-milliliters-examples</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3025a20d31aa23f7.jpg</video:thumbnail_loc><video:title>Convert liters to milliliters</video:title><video:description>Sal converts between liters and milliliters.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OfTTjQW0CBw.mp4/OfTTjQW0CBw.mp4</video:content_loc><video:duration>127</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/converting-metric-distance</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x53e22e6d.jpg</video:thumbnail_loc><video:title>Converting metric units of length</video:title><video:description>Learn convert kilometers, meters, and centimeters.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9iulv2QvKwo.mp4/9iulv2QvKwo.mp4</video:content_loc><video:duration>157</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/metric-system-unit-conversion-examples</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4e848a7034350a0b.jpg</video:thumbnail_loc><video:title>Multi-step unit conversion examples (metric)</video:title><video:description>Sal solves multi-step unit conversion examples with metric units of measure.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ODJzxGj_zvU.mp4/ODJzxGj_zvU.mp4</video:content_loc><video:duration>323</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/multiplication-and-division-word-problems-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2187d181.jpg</video:thumbnail_loc><video:title>Comparing with multiplication: magic</video:title><video:description>Sal solves a multiplication comparison word problem with Harry Potter characters.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9CZfG3r5JBE.mp4/9CZfG3r5JBE.mp4</video:content_loc><video:duration>70</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/comparisons-subtraction-division</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9c85eb98.jpg</video:thumbnail_loc><video:title>Comparing with multiplication and addition: money</video:title><video:description>Sal solves 2 multiplication comparison word problems.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ZS157czfx4E.mp4/ZS157czfx4E.mp4</video:content_loc><video:duration>395</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/comparing-area</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x927667dd.jpg</video:thumbnail_loc><video:title>Comparing areas word problem</video:title><video:description>Sal compares the area of two posters using their side-lengths.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/D2Ks5SKU6GM.mp4/D2Ks5SKU6GM.mp4</video:content_loc><video:duration>141</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/multiplying-10s</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6b483ff6.jpg</video:thumbnail_loc><video:title>Multiplying 10s</video:title><video:description>Lindsay multiplies multiples of 10 by other multiples of 10, such as 30x50.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/uHHnwafYivk.mp4/uHHnwafYivk.mp4</video:content_loc><video:duration>308</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/multiplying-1-digit-numbers-by-10-100-and-1000</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x618e0032.jpg</video:thumbnail_loc><video:title>Multiplying 1-digit numbers by 10, 100, and 1000</video:title><video:description>Lindsay finds a pattern from multiplying 1-digit numbers by 10, 100, and 1000.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/SG4gX-VGzog.mp4/SG4gX-VGzog.mp4</video:content_loc><video:duration>377</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/multiplying-1-digit-numbers-by-multiples-of-10</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc4250c8b.jpg</video:thumbnail_loc><video:title>Multiplying 1-digit numbers by multiples of 10, 100, and 1000</video:title><video:description>Lindsay finds a pattern from multiplying 1-digit numbers by multiples of 10, 100, and 1000.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tHQOAvbyRL0.mp4/tHQOAvbyRL0.mp4</video:content_loc><video:duration>484</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/more-ways-to-think-about-multiplying</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc0a0f006.jpg</video:thumbnail_loc><video:title>Using area model and properties to multiply</video:title><video:description>Sal uses place value, the distributive property, associative property, and an area model to show more ways to multiply.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/NWJinKmWzx8.mp4/NWJinKmWzx8.mp4</video:content_loc><video:duration>391</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/4-by-1-multiplication-with-grid</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xde6ebdd7.jpg</video:thumbnail_loc><video:title>Multiplying with area model: 6 x 7981</video:title><video:description>Sal uses an area model to multiply 6x7981.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/UvAOynxGfIU.mp4/UvAOynxGfIU.mp4</video:content_loc><video:duration>214</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/estimating-with-multiplication</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x09c0495345f64016.jpg</video:thumbnail_loc><video:title>Estimating with multiplication</video:title><video:description>Sal estimates to find reasonable products to 1-digit by 2, 3, and 4-digit multiplication expressions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/eXJb76JUvko.mp4/eXJb76JUvko.mp4</video:content_loc><video:duration>189</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/multiplying-2-digits-by-1-digit-with-partial-products</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x99032ee123e55595.jpg</video:thumbnail_loc><video:title>Multiplying 2-digits by 1-digit with partial products</video:title><video:description>We can multiply larger numbers by multiplying by the tens and ones separately, then adding the products together. Multiplying with partial products is one way we use the distributive property.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/RSx20wLxctc.mp4/RSx20wLxctc.mp4</video:content_loc><video:duration>274</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/multiplying-using-area-models-and-the-standard-algorithm</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc8c8cab6547bf583.jpg</video:thumbnail_loc><video:title>Relate multiplication with area models to the standard algorithm</video:title><video:description>Learn the concept of multi-digit multiplication. Watch and learn how to break down the process into understandable steps, using two different methods.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/fQ1zZYWjvwc.mp4/fQ1zZYWjvwc.mp4</video:content_loc><video:duration>417</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/3-digit-times-1-digit-example-no-carrying</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x509df20f.jpg</video:thumbnail_loc><video:title>Multiplying 3-digit by 1-digit</video:title><video:description>Learn to multiply a 3-digit number by a 1-digit number without regrouping. In this video, we will multiply 4x201.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4BtXvopHXI8.mp4/4BtXvopHXI8.mp4</video:content_loc><video:duration>114</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/3-digit-times-1-digit-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4d3274dc.jpg</video:thumbnail_loc><video:title>Multiplying 3-digit by 1-digit (regrouping)</video:title><video:description>Learn to multiply a 3-digit number by a 1-digit number using regrouping. In this video, we will multiply 7x253.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TqRReFvbpXA.mp4/TqRReFvbpXA.mp4</video:content_loc><video:duration>135</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/estimating-2-digit-multiplication-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x541ec875243fd608.jpg</video:thumbnail_loc><video:title>Estimating 2-digit multiplication</video:title><video:description>Sal estimates to find reasonable products to 2-digit multiplication expressions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/FCFYGpY-MM0.mp4/FCFYGpY-MM0.mp4</video:content_loc><video:duration>164</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/area-model-for-multiplication</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x58e24008.jpg</video:thumbnail_loc><video:title>Multiplying with area model: 16 x 27</video:title><video:description>Sal uses an area model to multiply 16x27.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vbGwcvXgDlg.mp4/vbGwcvXgDlg.mp4</video:content_loc><video:duration>527</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/understanding-multiplication-through-area-models</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x29584c60.jpg</video:thumbnail_loc><video:title>Multiplying with area model: 78 x 65</video:title><video:description>Sal uses an area model to multiply 78x65.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/p0jCw2sqZgs.mp4/p0jCw2sqZgs.mp4</video:content_loc><video:duration>298</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/multiplying-two-2-digit-numbers-using-partial-products</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x36b3930d835242db.jpg</video:thumbnail_loc><video:title>Multiplying two 2-digit numbers using partial products</video:title><video:description>26 times 37 is the same as 20 times 37 plus 6 times 37. The distributive property allows us to find each part of the product, like 3 tens times 2 tens, then add them all to get the whole product.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/O2ifHv-3dZA.mp4/O2ifHv-3dZA.mp4</video:content_loc><video:duration>266</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/introduction-to-remainders</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2e6c5e31.jpg</video:thumbnail_loc><video:title>Intro to remainders</video:title><video:description>Sal shows how a remainder is what&apos;s left over in a division problem.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/BIGX05Mp5nw.mp4/BIGX05Mp5nw.mp4</video:content_loc><video:duration>143</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/quotients-that-are-multiples-of-10</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe7f435e0.jpg</video:thumbnail_loc><video:title>Quotients that are multiples of 10</video:title><video:description>Lindsay breaks down division problems using multiples of 10.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/UzXoxglkr98.mp4/UzXoxglkr98.mp4</video:content_loc><video:duration>373</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/division-using-understanding-of-place-value</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x11ff35e2.jpg</video:thumbnail_loc><video:title>Division using place value</video:title><video:description>Sal uses an understanding of place value to divide 5600÷8 and 846÷2.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xUjRwepN7dk.mp4/xUjRwepN7dk.mp4</video:content_loc><video:duration>484</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/area-models-to-visualize-division-using-place-value</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa6e15515.jpg</video:thumbnail_loc><video:title>Division with area models</video:title><video:description>Sal uses area models to divide 268÷2 and 856÷8.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/FKJjqEdfB9Y.mp4/FKJjqEdfB9Y.mp4</video:content_loc><video:duration>498</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/multi-step-word-problems-with-whole-numbers-exercise-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x06f7f404.jpg</video:thumbnail_loc><video:title>Division word problem: field goals</video:title><video:description>Sal solves a division word problem.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/anlOhNHlqwg.mp4/anlOhNHlqwg.mp4</video:content_loc><video:duration>179</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/multi-step-word-problems-with-whole-numbers-exercise-t2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xad8542bb.jpg</video:thumbnail_loc><video:title>Multiplication word problem: pizza</video:title><video:description>Sal solves a multiplication word problem.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/cTveNRjWQYo.mp4/cTveNRjWQYo.mp4</video:content_loc><video:duration>158</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/understanding-factor-pairs</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0775563f039594d4.jpg</video:thumbnail_loc><video:title>Understanding factor pairs</video:title><video:description>Use multiplication and an understanding of area to identify factor pairs for 6 and 16.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/KcKOM7Degu0.mp4/KcKOM7Degu0.mp4</video:content_loc><video:duration>249</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/finding-factors-of-a-number</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/2600703.jpg</video:thumbnail_loc><video:title>Finding factors of a number</video:title><video:description>Sal finds the factors of 120.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vcn2ruTOwFo.mp4/vcn2ruTOwFo.mp4</video:content_loc><video:duration>593</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/reasoning-about-factors-and-multiples</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6cf07b5dab8b8803.jpg</video:thumbnail_loc><video:title>Reasoning about factors and multiples</video:title><video:description>Use the equation 3x5=15 to understand the relationship between factors and multiples.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/g805f4HlV1Y.mp4/g805f4HlV1Y.mp4</video:content_loc><video:duration>98</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/finding-factors-and-multiples</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb863d3f2.jpg</video:thumbnail_loc><video:title>Finding factors and multiples</video:title><video:description>Sal uses divisibility rules to determine if numbers are factors of 154 and then finds multiples of 14.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5xe-6GPR_qQ.mp4/5xe-6GPR_qQ.mp4</video:content_loc><video:duration>240</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/identifying-multiples</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1a766ffd661cae5e.jpg</video:thumbnail_loc><video:title>Identifying multiples</video:title><video:description>Use skip counting and division to identify multiples of 9.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/U5L_aaQ6pYQ.mp4/U5L_aaQ6pYQ.mp4</video:content_loc><video:duration>240</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/figuring-out-days-of-the-week</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x429c2c78.jpg</video:thumbnail_loc><video:title>Factors and multiples: days of the week</video:title><video:description>Sal uses factors and multiples to figure out days of the week.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/S7CLLRHe8ik.mp4/S7CLLRHe8ik.mp4</video:content_loc><video:duration>322</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/prime-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/85595310.jpg</video:thumbnail_loc><video:title>Prime numbers</video:title><video:description>Prime numbers are numbers that have only 2 factors: 1 and themselves. For example, the first 5 prime numbers are 2, 3, 5, 7, and 11. By contrast, numbers with more than 2 factors are call composite numbers.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/mIStB5X4U8M.mp4/mIStB5X4U8M.mp4</video:content_loc><video:duration>493</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/recognizing-prime-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/158925083.jpg</video:thumbnail_loc><video:title>Recognizing prime and composite numbers</video:title><video:description>Can you recognize the prime numbers in this group of numbers? Which are prime, composite, or neither?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3h4UK62Qrbo.mp4/3h4UK62Qrbo.mp4</video:content_loc><video:duration>280</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/math-patterns-example-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8ad2e2cc.jpg</video:thumbnail_loc><video:title>Math patterns: table</video:title><video:description>Sal explains a pattern with the number of seats at a table.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/KSrnZMAfwTM.mp4/KSrnZMAfwTM.mp4</video:content_loc><video:duration>218</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/math-patterns-example-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe158b503.jpg</video:thumbnail_loc><video:title>Math patterns: toothpicks</video:title><video:description>Sal explores a pattern of creating figures with toothpicks.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/mFftY8Y_pyY.mp4/mFftY8Y_pyY.mp4</video:content_loc><video:duration>341</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/long-division-without-remainder</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xebe85e0b.jpg</video:thumbnail_loc><video:title>Intro to long division (no remainders)</video:title><video:description>Watch an introduction to long division with the problem 96÷4.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/KFzcwWTEDDI.mp4/KFzcwWTEDDI.mp4</video:content_loc><video:duration>195</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/division-3-more-long-division-and-remainder-examples</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23848.jpg</video:thumbnail_loc><video:title>Long division with remainders: 2292÷4</video:title><video:description>Learn the long division process for multi-digit numbers, including examples with remainders. The video emphasizes the importance of practice and understanding multiplication tables to tackle any division problem using long division techniques.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/NcADzGz3bSI.mp4/NcADzGz3bSI.mp4</video:content_loc><video:duration>607</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/long-division-with-remainder-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1a34ebb5.jpg</video:thumbnail_loc><video:title>Long division with remainders: 3771÷8</video:title><video:description>To divide 3,771 by 8 using long division, start by dividing the first two digits, 37, by 8. This results in a quotient of 4. Next, bring down the next digit, 7, and divide 57 by 8, which goes 7 times. Finally, bring down the last digit, 1, and divide 11 by 8. This yields a quotient of 1 and a remainder of 3.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/MbpmP1esh-Q.mp4/MbpmP1esh-Q.mp4</video:content_loc><video:duration>161</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/multiplying-2-digit-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7ea237eb.jpg</video:thumbnail_loc><video:title>Multiplying 2-digit numbers</video:title><video:description>Learn to multiply two-digit numbers. In this video, we will multiply 36 times 27.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DaQlieZH1kk.mp4/DaQlieZH1kk.mp4</video:content_loc><video:duration>247</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/language-and-notation-of-basic-geometry</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/611259516.jpg</video:thumbnail_loc><video:title>Terms &amp; labels in geometry</video:title><video:description>Explore geometry fundamentals, including points, line segments, rays, and lines. Understand dimensions and how these elements form shapes and patterns. Learn key geometric terms like colinear points, midpoints, and vertices, and enhance your knowledge of geometry. Improve your skills and discover the world of shapes and space.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/il0EJrY64qE.mp4/il0EJrY64qE.mp4</video:content_loc><video:duration>778</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/lines-line-segments-and-rays</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/211177355.jpg</video:thumbnail_loc><video:title>Lines, line segments, &amp; rays</video:title><video:description>Learn the difference between lines, line segments, and rays.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/JcqCf762y9w.mp4/JcqCf762y9w.mp4</video:content_loc><video:duration>218</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/angle-basics</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/263439065.jpg</video:thumbnail_loc><video:title>Angles: introduction</video:title><video:description>Two rays that share the same endpoint form an angle. Learn about angles and the parts of an angle, like the vertex.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/H-de6Tkxej8.mp4/H-de6Tkxej8.mp4</video:content_loc><video:duration>409</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/naming-angles</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x66f2a779.jpg</video:thumbnail_loc><video:title>Naming angles</video:title><video:description>Sal names angles based on their vertex and endpoints.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6vRgqB0PSXE.mp4/6vRgqB0PSXE.mp4</video:content_loc><video:duration>71</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/recognizing-angles-examples</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1781a3d6.jpg</video:thumbnail_loc><video:title>Recognizing angles</video:title><video:description>Sal identifies acute, obtuse, and right angles in diagrams and pictures.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/B0R3MJOrST0.mp4/B0R3MJOrST0.mp4</video:content_loc><video:duration>135</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/acute-right-and-obtuse-angles</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/60129393.jpg</video:thumbnail_loc><video:title>Acute, right, &amp; obtuse angles</video:title><video:description>Acute angles measure less than 90 degrees. Right angles measure 90 degrees. Obtuse angles measure more than 90 degrees. Learn about angles types and see examples of each.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ALhv3Rlydig.mp4/ALhv3Rlydig.mp4</video:content_loc><video:duration>332</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/drawing-acute-right-and-obtuse-angles</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x93c8f042.jpg</video:thumbnail_loc><video:title>Drawing acute, right and obtuse angles</video:title><video:description>Learn how to draw acute, right, and obtuse angles with given points.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4ZyTVTGVPgE.mp4/4ZyTVTGVPgE.mp4</video:content_loc><video:duration>160</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/parallel-and-perpendicular-lines-intro</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe3c54f14.jpg</video:thumbnail_loc><video:title>Parallel &amp; perpendicular lines intro</video:title><video:description>Parallel lines never intersect, and perpendicular lines intersect at a 90 degree angle. Learn how to identify parallel and perpendicular lines.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/V0xounKGEXs.mp4/V0xounKGEXs.mp4</video:content_loc><video:duration>128</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/identifying-parallel-and-perpendicular-lines</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/372432667.jpg</video:thumbnail_loc><video:title>Parallel &amp; perpendicular lines</video:title><video:description>Parallel lines are lines that never intersect, and they form the same angle when they cross another line. Perpendicular lines intersect at a 90-degree angle, forming a square corner. We can identify these lines using angles and symbols in diagrams.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/aq_XL6FrmGs.mp4/aq_XL6FrmGs.mp4</video:content_loc><video:duration>215</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/drawing-lines-exercise-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfcdfb0ea.jpg</video:thumbnail_loc><video:title>Drawing parallel line segments</video:title><video:description>Sal draws parallel line segments with given points.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DkZnevdbf0A.mp4/DkZnevdbf0A.mp4</video:content_loc><video:duration>115</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/angle-measurement-and-circle-arcs</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x15cb233f.jpg</video:thumbnail_loc><video:title>Angle measurement &amp; circle arcs</video:title><video:description>Learn to measure angles as part of a circle.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/D-EIh7NJvtQ.mp4/D-EIh7NJvtQ.mp4</video:content_loc><video:duration>457</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/measuring-angles-circular-protractor</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc20e9a03.jpg</video:thumbnail_loc><video:title>Measuring angles with a circular protractor</video:title><video:description>Lindsay measures angles with a circular protractor.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Ttji2_wBSEo.mp4/Ttji2_wBSEo.mp4</video:content_loc><video:duration>109</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/angles-in-circles-word-problem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7d0b3648.jpg</video:thumbnail_loc><video:title>Angles in circles word problem</video:title><video:description>Lindsay solves a word problems about angles as part of a circle.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_jRXtJz3CYc.mp4/_jRXtJz3CYc.mp4</video:content_loc><video:duration>199</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/angle-sense-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd505def0.jpg</video:thumbnail_loc><video:title>Identifying an angle</video:title><video:description>Sal matches pictures of angles to their degrees.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2mzuFKCuDg4.mp4/2mzuFKCuDg4.mp4</video:content_loc><video:duration>123</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/measuring-angles-in-degrees</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/263439060.jpg</video:thumbnail_loc><video:title>Measuring angles in degrees</video:title><video:description>Learn how to measure an angle with a protractor.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/92aLiyeQj0w.mp4/92aLiyeQj0w.mp4</video:content_loc><video:duration>502</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/using-a-protractor</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/263439062.jpg</video:thumbnail_loc><video:title>Measuring angles using a protractor</video:title><video:description>Learn to use a virtual protractor to measure angles.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/dw41PMWek6U.mp4/dw41PMWek6U.mp4</video:content_loc><video:duration>205</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/measuring-angles</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/211177356.jpg</video:thumbnail_loc><video:title>Measuring angles using a protractor 2</video:title><video:description>Sal measures several angles with a protractor.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/wJ37GJyViU8.mp4/wJ37GJyViU8.mp4</video:content_loc><video:duration>245</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/constructing-angles</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb6f10aaa.jpg</video:thumbnail_loc><video:title>Constructing angles</video:title><video:description>Sal uses a protractor to create 10° and 155° angles.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/QmfoIvgIVlE.mp4/QmfoIvgIVlE.mp4</video:content_loc><video:duration>161</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/decomposing-angles</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6c2451f9.jpg</video:thumbnail_loc><video:title>Decomposing an angle</video:title><video:description>Sal finds the measure of angles by adding or subtracting.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/M7NVKImDqGg.mp4/M7NVKImDqGg.mp4</video:content_loc><video:duration>103</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/decomposing-angles-add</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe1272e01.jpg</video:thumbnail_loc><video:title>Decomposing angles</video:title><video:description>Lindsay finds the measures of angles using addition.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/uMj46crbLaw.mp4/uMj46crbLaw.mp4</video:content_loc><video:duration>185</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/axis-of-symmetry</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x78b40eae.jpg</video:thumbnail_loc><video:title>Intro to reflective symmetry</video:title><video:description>Introduction to the concept of an &quot;axis of symmetry&quot;</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LrTn4cvsewk.mp4/LrTn4cvsewk.mp4</video:content_loc><video:duration>167</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/identifying-symmetrical-figures</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1f16d320.jpg</video:thumbnail_loc><video:title>Identifying symmetrical figures</video:title><video:description>Lindsay identifies lines of symmetry on three shapes.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/59s_CQjTD6w.mp4/59s_CQjTD6w.mp4</video:content_loc><video:duration>333</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/scalene-isosceles-equilateral-from-angle</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7eb84d3e.jpg</video:thumbnail_loc><video:title>Classifying triangles by angles</video:title><video:description>You say you can&apos;t categorize a triangle because you don&apos;t know the length of the sides. Guess what? If you know the size of the angles you can!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/sZMezOCZr40.mp4/sZMezOCZr40.mp4</video:content_loc><video:duration>330</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/scalene-isosceles-equilateral-acute-right-obtuse</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdb593bbc.jpg</video:thumbnail_loc><video:title>Classifying triangles</video:title><video:description>The video explores how triangles are classified based on their sides and angles. It introduces the terms scalene, isosceles, and equilateral for side lengths, and acute, right, and obtuse for angles. It emphasizes that triangles can be categorized in multiple ways based on these characteristics.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/D5lZ3thuEeA.mp4/D5lZ3thuEeA.mp4</video:content_loc><video:duration>360</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/recog-triangles-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3fd4b56d.jpg</video:thumbnail_loc><video:title>Worked example: Classifying triangles</video:title><video:description>Work through sample problems categorizing triangles as scalene, isosceles, equilateral, acute, right, or obtuse.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/NRS2ZJVVzOI.mp4/NRS2ZJVVzOI.mp4</video:content_loc><video:duration>143</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/classifying-shapes-examples</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe37249c4.jpg</video:thumbnail_loc><video:title>Classifying shapes by line and angles types</video:title><video:description>Sal categorizes shapes based on their sides and angles.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PiQxA9O7Rd8.mp4/PiQxA9O7Rd8.mp4</video:content_loc><video:duration>135</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/quadrilateral-properties</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/370305272.jpg</video:thumbnail_loc><video:title>Quadrilateral properties</video:title><video:description>Learn about the properties of quadrilaterals, parallelograms, trapezoids, rhombuses, rectangles, and squares.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5CeBlu260Rw.mp4/5CeBlu260Rw.mp4</video:content_loc><video:duration>307</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/classifying-shapes-by-lines-and-angles</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd20b343f.jpg</video:thumbnail_loc><video:title>Classifying shapes by lines and angles</video:title><video:description>Lindsay classifies a shape based on hints about its sides and angles.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xO4n3LfmVag.mp4/xO4n3LfmVag.mp4</video:content_loc><video:duration>217</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/decomposing-a-mixed-number</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5939f38d.jpg</video:thumbnail_loc><video:title>Decomposing a mixed number</video:title><video:description>Sal uses fraction models to decompose 2 1/4.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/erZe85NrsK0.mp4/erZe85NrsK0.mp4</video:content_loc><video:duration>300</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/equivalent-amount-of-pizza</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x22c750f5.jpg</video:thumbnail_loc><video:title>Equivalent fractions</video:title><video:description>Learn how equivalent fractions represent the same amount, even with different numerators and denominators. We uses a pizza example to show how 1/2, 2/4, and 4/8 are equivalent, as they all represent the same portion.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/N1X0vf5PUz4.mp4/N1X0vf5PUz4.mp4</video:content_loc><video:duration>258</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/visualizing-equivalent-fractions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x885328b8.jpg</video:thumbnail_loc><video:title>Visualizing equivalent fractions</video:title><video:description>Sal uses fraction models to show equivalent fractions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Bt60JVZRVCI.mp4/Bt60JVZRVCI.mp4</video:content_loc><video:duration>225</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/more-equivalent-fractions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa40a399e.jpg</video:thumbnail_loc><video:title>More on equivalent fractions</video:title><video:description>Sal uses fraction models and multiplication to find equivalent fractions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/yZqVJtDO7gc.mp4/yZqVJtDO7gc.mp4</video:content_loc><video:duration>294</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/finding-common-denominators</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/158925087.jpg</video:thumbnail_loc><video:title>Finding common denominators</video:title><video:description>Learn all about finding common denominators in fractions. Watch how to use the least common multiple of the denominators to rewrite fractions, making them easier to compare or add.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lxjmR4pYIVU.mp4/lxjmR4pYIVU.mp4</video:content_loc><video:duration>282</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/common-denominators-35-and-72</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf9ec9a64.jpg</video:thumbnail_loc><video:title>Common denominators: 3/5 and 7/2</video:title><video:description>Learn how to rewrite fractions with different denominators as equivalent fractions with a common denominator. Watch how to visually represent this process and apply it to solve problems.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0EwwoDVJVPQ.mp4/0EwwoDVJVPQ.mp4</video:content_loc><video:duration>255</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/comparing-fractions-visually-with-a-bar</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4e435a2c.jpg</video:thumbnail_loc><video:title>Comparing fractions: tape diagram</video:title><video:description>Sal compares fractions with unlike denominators by drawing bars</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ory05j2jgBM.mp4/ory05j2jgBM.mp4</video:content_loc><video:duration>155</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/comparing-fractions-on-a-number-line</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb915b4f5.jpg</video:thumbnail_loc><video:title>Comparing fractions: number line</video:title><video:description>Sal compares fractions on a number line</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7vWzd-ZV6-Q.mp4/7vWzd-ZV6-Q.mp4</video:content_loc><video:duration>175</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/comparing-fractions-visually-with-pies</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa9de51d5.jpg</video:thumbnail_loc><video:title>Comparing fractions: fraction models</video:title><video:description>Sal compares fractions visually with pies</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/uCtXyhepAmQ.mp4/uCtXyhepAmQ.mp4</video:content_loc><video:duration>152</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/comparing-fractions-with-different-denominators</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe9caeb3f.jpg</video:thumbnail_loc><video:title>Comparing fractions 1 (unlike denominators)</video:title><video:description>Sal compares fractions by finding a common denominator.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/zRjLZROI7wc.mp4/zRjLZROI7wc.mp4</video:content_loc><video:duration>256</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/comparing-fractions-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/153770147.jpg</video:thumbnail_loc><video:title>Comparing fractions 2 (unlike denominators)</video:title><video:description>Sal compares fractions by finding a common denominator.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2dbasvm3iG0.mp4/2dbasvm3iG0.mp4</video:content_loc><video:duration>428</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/adding-fractions-with-like-denominators</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/2600768.jpg</video:thumbnail_loc><video:title>Adding fractions with like denominators</video:title><video:description>Sal adds 3/15+7/15.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/EJjnEau6aeI.mp4/EJjnEau6aeI.mp4</video:content_loc><video:duration>198</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/subtracting-fractions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/2600773.jpg</video:thumbnail_loc><video:title>Subtracting fractions with like denominators</video:title><video:description>Sal subtracts 8/18-5/18.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/UbUdyE1_b9g.mp4/UbUdyE1_b9g.mp4</video:content_loc><video:duration>146</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/fraction-word-problems-1-exercise</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9b1143b5.jpg</video:thumbnail_loc><video:title>Fraction word problem: pizza</video:title><video:description>Sal uses fraction models to figure out what fraction of a pizza is left.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/u2hLYcmI5y4.mp4/u2hLYcmI5y4.mp4</video:content_loc><video:duration>319</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/subtracting-fractions-word-problem-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa613e211.jpg</video:thumbnail_loc><video:title>Fraction word problem: piano</video:title><video:description>Sal solves a fraction word problem about practicing piano. The fractions have common denominators.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0njioQqIxKY.mp4/0njioQqIxKY.mp4</video:content_loc><video:duration>184</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/adding-fractions-word-problem-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xcd390cf1.jpg</video:thumbnail_loc><video:title>Fraction word problem: lizard</video:title><video:description>Sal solves a fraction word problem about the length of a lizard. The fractions have common denominators.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gPbN26bYyN8.mp4/gPbN26bYyN8.mp4</video:content_loc><video:duration>149</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/adding-fractions-word-problem-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0913bd5c.jpg</video:thumbnail_loc><video:title>Fraction word problem: spider eyes</video:title><video:description>Sal solves a fraction word problem about spider eyes. The fractions have common denominators.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5r2FYszC_sU.mp4/5r2FYszC_sU.mp4</video:content_loc><video:duration>105</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/multiplying-fractions-and-whole-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3769a3bc.jpg</video:thumbnail_loc><video:title>Multiplying unit fractions and whole numbers</video:title><video:description>Learn how to multiply a whole number by a fraction, using both visual and computational methods. Multiplying 1/2 by 5 can be understood as adding five 1/2&apos;s together, resulting in 5/2.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4PlkCiEXBQI.mp4/4PlkCiEXBQI.mp4</video:content_loc><video:duration>188</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/changing-a-mixed-number-to-an-improper-fraction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/2600700.jpg</video:thumbnail_loc><video:title>Writing mixed numbers as improper fractions</video:title><video:description>Sal rewrites 5 1/4 as an improper fraction.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xkg7370cpjs.mp4/xkg7370cpjs.mp4</video:content_loc><video:duration>403</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/changing-an-improper-fraction-to-a-mixed-number</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/2600701.jpg</video:thumbnail_loc><video:title>Writing improper fractions as mixed numbers</video:title><video:description>Sal rewrite 7/4 as a mixed number.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8JyPzTeA_8w.mp4/8JyPzTeA_8w.mp4</video:content_loc><video:duration>242</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/making-line-plots-with-fractional-data</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4a27cfbc236d6423.jpg</video:thumbnail_loc><video:title>Making line plots with fractional data</video:title><video:description>The video is all about creating line plots to represent data sets. It emphasizes the importance of using fractions of a unit (like 1/2, 1/4, 1/8) to accurately depict measurements. It also shows how line plots can help solve problems involving addition and subtraction of fractions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/NG51xCPse5Y.mp4/NG51xCPse5Y.mp4</video:content_loc><video:duration>195</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/interpreting-line-plots</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbb328a6d44f13d41.jpg</video:thumbnail_loc><video:title>Interpreting line plots with fractions</video:title><video:description>The weights on this line plot are to the nearest 1/8 pound, because there are 8 equal spaces between whole numbers. Each dot represents the weight of one baby. Let&apos;s find the difference between the two heaviest babies.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/78zFg2F3HsI.mp4/78zFg2F3HsI.mp4</video:content_loc><video:duration>165</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/interpreting-data-in-line-plots</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1e343920.jpg</video:thumbnail_loc><video:title>Reading a line plot with fractions</video:title><video:description>Explore the concept of interpreting data on line plots, particularly focusing on how to read and understand line plots that display measurements in fractions. Understand the importance of comparing data points and calculating differences between them.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4smVBLi3DxU.mp4/4smVBLi3DxU.mp4</video:content_loc><video:duration>213</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/adding-mixed-numbers-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfa82ffcf.jpg</video:thumbnail_loc><video:title>Intro to adding mixed numbers</video:title><video:description>Sal adds 2 mixed numbers with common (like) denominators.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pxX07gUbIQQ.mp4/pxX07gUbIQQ.mp4</video:content_loc><video:duration>241</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/subtracting-mixed-numbers-with-like-denominators</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x551b7da0.jpg</video:thumbnail_loc><video:title>Intro to subtracting mixed numbers</video:title><video:description>Sal subtracts 2 mixed numbers with common (like) denominators.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/zm3TXDZrifU.mp4/zm3TXDZrifU.mp4</video:content_loc><video:duration>289</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/word-problem-subtracting-fractions-with-like-denominators</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x99617da1b54c4cc3.jpg</video:thumbnail_loc><video:title>Subtracting mixed numbers with like denominators word problem</video:title><video:description>Sal solves a word problem involving mixed number subtraction by using a visual model.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9aD5Z_EMxos.mp4/9aD5Z_EMxos.mp4</video:content_loc><video:duration>189</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/concept-whole-fraction-mult</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x848c25e5.jpg</video:thumbnail_loc><video:title>Multiplying fractions and whole numbers visually</video:title><video:description>Learn the concept of multiplying fractions and whole numbers. Watch how to visually represent this process and practice understanding the relationship between fractions and whole numbers in multiplication.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/XaJQse2u5TQ.mp4/XaJQse2u5TQ.mp4</video:content_loc><video:duration>246</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/fraction-whole-multiplication-concept</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8320c937.jpg</video:thumbnail_loc><video:title>Equivalent fraction and whole number multiplication problems</video:title><video:description>Sal relates mixed numbers to whole number/fraction multiplication problem.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ZlhrXO1-osA.mp4/ZlhrXO1-osA.mp4</video:content_loc><video:duration>164</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/multiplying-fractions-word-problem-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x487557ed.jpg</video:thumbnail_loc><video:title>Multiplying fractions word problem: movies</video:title><video:description>Sal solves a multiplication fraction word problem about movies.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Yq9W6B7XnmU.mp4/Yq9W6B7XnmU.mp4</video:content_loc><video:duration>222</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/multiplying-fractions-word-problem-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8737839e.jpg</video:thumbnail_loc><video:title>Multiplying fractions word problem: milk</video:title><video:description>Sal solves a multiplication fraction word problem about milk.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/GvgJ2_7P9SA.mp4/GvgJ2_7P9SA.mp4</video:content_loc><video:duration>139</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/multiplying-fractions-by-whole-numbers-word-problem-math-4th-grade-khan-academy</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2c824088.jpg</video:thumbnail_loc><video:title>Multiplying fractions by whole numbers word problem</video:title><video:description>Lindsay solves a word problem that involves multiplying a fraction by a whole number.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6PMQdHCtUtA.mp4/6PMQdHCtUtA.mp4</video:content_loc><video:duration>141</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/examples-relating-decimals-and-fractions-in-words</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x25085dfdfb13c401.jpg</video:thumbnail_loc><video:title>Relating decimals and fractions in words</video:title><video:description>Sal relates equivalent decimals and fractions written in word form.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5TwOaUrniaI.mp4/5TwOaUrniaI.mp4</video:content_loc><video:duration>191</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/introduction-to-decimals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x07ef47f9.jpg</video:thumbnail_loc><video:title>Decimal place value</video:title><video:description>Sal introduces decimal numbers and understanding place value to the right of the decimal.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/BItpeFXC4vA.mp4/BItpeFXC4vA.mp4</video:content_loc><video:duration>386</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/decimals-as-words</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa6903bbe.jpg</video:thumbnail_loc><video:title>Decimals as words</video:title><video:description>Sal writes 0.17 and 40.03 in words. He also writes twenty-four hundredths using numbers.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qSPwUDmpnJ4.mp4/qSPwUDmpnJ4.mp4</video:content_loc><video:duration>338</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/graphing-tenths-from-0-to-1-math-4th-grade-khan-academy</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x83474085.jpg</video:thumbnail_loc><video:title>Graphing tenths from 0 to 1</video:title><video:description>Lindsay graphs 0.6 on a number line.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7oUBK0cNxV8.mp4/7oUBK0cNxV8.mp4</video:content_loc><video:duration>91</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/identifying-tenths-on-a-number-line-math-4th-grade-khan-academy</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5eacb0ab.jpg</video:thumbnail_loc><video:title>Identifying tenths on a number line</video:title><video:description>Lindsay identifies a point graphed on a number line.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qb0QSP7Sfz4.mp4/qb0QSP7Sfz4.mp4</video:content_loc><video:duration>112</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/rewriting-fractions-as-decimals-math-4th-grade-khan-academy</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x647578e2.jpg</video:thumbnail_loc><video:title>Rewriting fractions as decimals</video:title><video:description>Lindsay rewrites two fractions as decimals. The fractions have denominators of 10 and 100.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4LvGU1a9Z5Q.mp4/4LvGU1a9Z5Q.mp4</video:content_loc><video:duration>238</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/visually-converting-from-tenths-to-hundredths</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x01630e18.jpg</video:thumbnail_loc><video:title>Visually converting tenths and hundredths</video:title><video:description>Sal rewrites 8/10 with a denominator of 100.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/zEd67cLFnuQ.mp4/zEd67cLFnuQ.mp4</video:content_loc><video:duration>260</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/decompose-hundredths-on-number-line</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2effd053.jpg</video:thumbnail_loc><video:title>Decomposing hundredths on number line</video:title><video:description>Sal decomposes 26/100 into tenths and hundredths using a number line.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/k4bqucu56Ig.mp4/k4bqucu56Ig.mp4</video:content_loc><video:duration>106</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/graphing-hundredths-from-0-to-01-math-4th-grade-khan-academy</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x67fe7215.jpg</video:thumbnail_loc><video:title>Graphing hundredths from 0 to 0.1</video:title><video:description>Lindsay graphs 0.04 on a number line.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/SrL8abwGKyA.mp4/SrL8abwGKyA.mp4</video:content_loc><video:duration>159</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/identifying-hundredths-on-a-number-line-math-4th-grade-khan-academy</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x39416065.jpg</video:thumbnail_loc><video:title>Identifying hundredths on a number line</video:title><video:description>Lindsay identifies decimals graphed on a number line.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/bFjaZ_8pi3c.mp4/bFjaZ_8pi3c.mp4</video:content_loc><video:duration>171</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/decimals-on-a-number-line-2-examples</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x77c3a934.jpg</video:thumbnail_loc><video:title>Plotting decimal numbers on a number line</video:title><video:description>Sal finds decimals with hundredths on a number line.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gWqYXa7r_V0.mp4/gWqYXa7r_V0.mp4</video:content_loc><video:duration>248</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/fraction-decimal-intuition-examples</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x24a0750c.jpg</video:thumbnail_loc><video:title>Writing a number as a fraction and decimal</video:title><video:description>Sal shows the connection between decimals and fractions using a grid diagram and number lines.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/NfU7cmajLAY.mp4/NfU7cmajLAY.mp4</video:content_loc><video:duration>277</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/place-value-for-decimals-greater-than-one</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x155513a9.jpg</video:thumbnail_loc><video:title>Decimal place value with regrouping</video:title><video:description>Sal discusses decimal numbers that are greater than 1.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-BYomxn8Rss.mp4/-BYomxn8Rss.mp4</video:content_loc><video:duration>415</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/examples-writing-decimals-and-fractions-greater-than-1-shown-on-grids</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x784640bb38759977.jpg</video:thumbnail_loc><video:title>Writing decimals and fractions greater than 1 shown on grids</video:title><video:description>Sal writes decimal numbers and fractions greater than 1 shown on grids. Decimals are limited to tenths and hundredths.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ek0zu14IP7g.mp4/ek0zu14IP7g.mp4</video:content_loc><video:duration>182</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/writing-decimals-and-fractions-from-number-lines</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3051d55d5e8d5157.jpg</video:thumbnail_loc><video:title>Writing decimals and fractions shown on number lines</video:title><video:description>Sal writes decimal numbers and fractions greater than 1 shown on number lines. Decimals are limited to tenths and hundredths.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/68mrr430De0.mp4/68mrr430De0.mp4</video:content_loc><video:duration>163</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/comparing-decimals-visually-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8f4a7db6.jpg</video:thumbnail_loc><video:title>Comparing decimals visually</video:title><video:description>Sal compares 0.17 and 0.2 using grid diagrams.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ftEVCrKfIVM.mp4/ftEVCrKfIVM.mp4</video:content_loc><video:duration>220</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/comparing-numbers-represented-in-different-ways</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7b0897be.jpg</video:thumbnail_loc><video:title>Comparing numbers represented different ways</video:title><video:description>Examples of Khan Academy practice problems where you compare decimals, fractions, and number diagrams.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/YM4lE4q0fSk.mp4/YM4lE4q0fSk.mp4</video:content_loc><video:duration>460</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/decimals-on-a-number-line</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/158925082.jpg</video:thumbnail_loc><video:title>Comparing decimal numbers on a number line</video:title><video:description>Sal compares decimals on a number line.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LpLnmuAyNWg.mp4/LpLnmuAyNWg.mp4</video:content_loc><video:duration>99</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/comparing-decimals-with-hundredths</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x818728a2.jpg</video:thumbnail_loc><video:title>Comparing decimals (tenths and hundredths)</video:title><video:description>Sal compares decimals like 0.7 and 0.09 with greater and less than symbols.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/EX9CdUAMpgE.mp4/EX9CdUAMpgE.mp4</video:content_loc><video:duration>209</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/4th-engage-ny/v/comparing-decimals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1807.jpg</video:thumbnail_loc><video:title>Comparing decimals 3</video:title><video:description>Sal compares decimals like 45.675 and 45.645 with greater and less than symbols.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/HCC96awA-FM.mp4/HCC96awA-FM.mp4</video:content_loc><video:duration>89</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/converting-decimals-to-fractions-1-ex-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/915208238.jpg</video:thumbnail_loc><video:title>Rewriting decimals as fractions: 0.15</video:title><video:description>Decimals can be written in fraction form. To convert a decimal to a fraction, place the decimal number over its place value. For example, in 0.6, the six is in the tenths place, so we place 6 over 10 to create the equivalent fraction, 6/10. If needed, simplify the fraction.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DR2DYe7PI74.mp4/DR2DYe7PI74.mp4</video:content_loc><video:duration>116</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/converting-decimals-to-fractions-1-ex-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/914994686.jpg</video:thumbnail_loc><video:title>Rewriting decimals as fractions: 0.8</video:title><video:description>Sal converts 0.8 to a fraction.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9P80OLC6wKY.mp4/9P80OLC6wKY.mp4</video:content_loc><video:duration>53</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/converting-decimals-to-fractions-1-ex-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/915122530.jpg</video:thumbnail_loc><video:title>Rewriting decimals as fractions: 0.36</video:title><video:description>Sal converts 0.36 to a fraction.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OS1g4PDdNdM.mp4/OS1g4PDdNdM.mp4</video:content_loc><video:duration>74</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/adding-fractions-with-10-and-100-as-denominators</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x05f0312b.jpg</video:thumbnail_loc><video:title>Adding fractions (denominators 10 &amp; 100)</video:title><video:description>Sal adds 3/10+7/100 by finding a common denominator.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/YZD5ifHZILE.mp4/YZD5ifHZILE.mp4</video:content_loc><video:duration>265</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/adding-tenths-to-hundredths</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x48b4dd1b5fbb427f.jpg</video:thumbnail_loc><video:title>Adding fractions: 7/10+13/100</video:title><video:description>Sal uses visual models to add 7/10 and 13/100.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/D5yQESfE4Bw.mp4/D5yQESfE4Bw.mp4</video:content_loc><video:duration>187</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/converting-us-fluid-volume</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8db1ea4b.jpg</video:thumbnail_loc><video:title>Converting US customary units of volume</video:title><video:description>Sal converts between gallons, quarts, pints, cups, and fluid ounces.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9UVgO8zS474.mp4/9UVgO8zS474.mp4</video:content_loc><video:duration>157</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/feet-to-inches-exercise-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe364a4f7.jpg</video:thumbnail_loc><video:title>Converting feet to inches</video:title><video:description>Learn to convert feet to inches.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/zsI4g5XSlbw.mp4/zsI4g5XSlbw.mp4</video:content_loc><video:duration>51</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/time-unit-conversion</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xacafa3ce.jpg</video:thumbnail_loc><video:title>Converting units of time</video:title><video:description>Learn to convert hours, minutes, and seconds.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-r7JwuSdj5M.mp4/-r7JwuSdj5M.mp4</video:content_loc><video:duration>202</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/change-from-buying-apples</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xaee188ce.jpg</video:thumbnail_loc><video:title>Word problem: making change</video:title><video:description>Sal solves how much change Charles will get after his purchase.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_YXF7WDpWpg.mp4/_YXF7WDpWpg.mp4</video:content_loc><video:duration>194</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/currency-conversion-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5ad67dda.jpg</video:thumbnail_loc><video:title>Currency conversion word problem</video:title><video:description>Sal converts between American dollars and Chinese yuan.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/XcRX-mkjeiM.mp4/XcRX-mkjeiM.mp4</video:content_loc><video:duration>54</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/unit-sense-exercise-example-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5c798014.jpg</video:thumbnail_loc><video:title>Choose pounds or ounces to measure weight</video:title><video:description>Sal discusses US customary units of mass or weight such as ounce, pound, and ton.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/V1LloSp4PV4.mp4/V1LloSp4PV4.mp4</video:content_loc><video:duration>75</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/us-customary-weight</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x81f65552.jpg</video:thumbnail_loc><video:title>U.S. customary units: weight</video:title><video:description>Sal discusses US customary units of mass or weight such as ounces, pounds, and tons.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Dj1rbIP8PHM.mp4/Dj1rbIP8PHM.mp4</video:content_loc><video:duration>220</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/us-customary-distance</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc43fda34.jpg</video:thumbnail_loc><video:title>U.S. customary units: distance</video:title><video:description>Sal discusses US customary units of length or distance such as inch, foot, and yard.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/M9bisHkXbKc.mp4/M9bisHkXbKc.mp4</video:content_loc><video:duration>311</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/us-customary-fluid-volume</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb277b208.jpg</video:thumbnail_loc><video:title>U.S. customary units: fluid volume</video:title><video:description>Sal discusses US customary units of volume or capacity such as teaspoon, fluid ounce, cup, pint, quart, and gallon.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/eqKnx5Yk508.mp4/eqKnx5Yk508.mp4</video:content_loc><video:duration>441</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/multi-step-unit-conversion-examples</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x446e081e3471afcb.jpg</video:thumbnail_loc><video:title>Multi-step unit conversion examples (U.S. Customary)</video:title><video:description>Sal solves multi-step unit conversion example using U.S. Customary units of measure.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5QFwaG5oM_A.mp4/5QFwaG5oM_A.mp4</video:content_loc><video:duration>337</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/time-word-problem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3f5d6857.jpg</video:thumbnail_loc><video:title>Time word problem: Susan&apos;s break</video:title><video:description>Dive into the concept of converting units of time, specifically minutes into hours. Understand the importance the relationship between these units and demonstrates how to apply this knowledge to solve real-world problems involving time intervals.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/UhMM68fq9FA.mp4/UhMM68fq9FA.mp4</video:content_loc><video:duration>218</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/rounding-to-the-nearest-10</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd886d7e1.jpg</video:thumbnail_loc><video:title>Rounding to nearest 10</video:title><video:description>This video teaches rounding numbers to the nearest 10 using number lines. It demonstrates rounding with examples like 36, 34, 35, 26, and 12, and provides a rule for rounding when the ones place is 5 or greater. This helps students practice estimation in real-life situations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/w2M5CzTFYfI.mp4/w2M5CzTFYfI.mp4</video:content_loc><video:duration>382</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/rounding-to-the-nearest-100</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xace78db7.jpg</video:thumbnail_loc><video:title>Rounding to nearest 100</video:title><video:description>Learners can use a number line to round three digit numbers to the nearest hundred. We learn that the midpoint on the number line helps determine if the number rounds up or round down. In this video, it all comes down to the tens place!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/19yOv4P2ccw.mp4/19yOv4P2ccw.mp4</video:content_loc><video:duration>296</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/the-idea-of-division</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdba36435.jpg</video:thumbnail_loc><video:title>The idea of division</video:title><video:description>Sal uses an array and understanding of multiplication to divide.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/QI6x0KNxiCs.mp4/QI6x0KNxiCs.mp4</video:content_loc><video:duration>481</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/quadrilateral-overview</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/339557900.jpg</video:thumbnail_loc><video:title>Intro to quadrilateral</video:title><video:description>There are many different types of quadrilaterals. A quadrilateral is defined as a two-dimensional shape with four sides, four vertices, and four angles. There are two main types: concave and convex. There are also various subcategories of convex quadrilaterals, such as trapezoids, parallelograms, rectangles, rhombi, and squares.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Ka82QC4QvGA.mp4/Ka82QC4QvGA.mp4</video:content_loc><video:duration>504</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/quadrilateral-types-exercise</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x819465b4.jpg</video:thumbnail_loc><video:title>Quadrilateral types</video:title><video:description>Learn to identify quadrilaterals such as kites, trapezoids, parallelograms, rhombuses, rectangles, and squares by side length, presence of parallel sides, and angle type.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/wPZIa3SjPF0.mp4/wPZIa3SjPF0.mp4</video:content_loc><video:duration>169</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/classifying-shapes</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x32882801.jpg</video:thumbnail_loc><video:title>Classifying quadrilaterals</video:title><video:description>There are many different relationships between the types of quadrilaterals. Parallelograms have two sets of parallel sides, rhombuses are parallelograms with equal side lengths, and squares are rhombuses with right angles. Though there is overlap, not all quadrilaterals fit into each category.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1pHhMX0_4Bw.mp4/1pHhMX0_4Bw.mp4</video:content_loc><video:duration>148</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/4th-grade-illustrative-mathematics/v/solving-word-problems-involving-factors-and-multiples</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7dc30e3b70022372.jpg</video:thumbnail_loc><video:title>Solving word problems involving factors and multiples</video:title><video:description>Learn how to solve word problems that involve factors and multiples within 100.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/r7rFBk4uBlU.mp4/r7rFBk4uBlU.mp4</video:content_loc><video:duration>212</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/equivalent-fractions-with-models</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe04b6d954e97827c.jpg</video:thumbnail_loc><video:title>Equivalent fractions with models</video:title><video:description>Sal uses fraction models and tape diagrams to help identify equivalent fractions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vTjgaVmJ8fk.mp4/vTjgaVmJ8fk.mp4</video:content_loc><video:duration>336</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/equivalent-fractions-on-number-lines</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x088ac06e90f8e10f.jpg</video:thumbnail_loc><video:title>Equivalent fractions on number lines</video:title><video:description>Sal uses a number line to help identify equivalent fractions with different denominators.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/bBkUqkI2TSw.mp4/bBkUqkI2TSw.mp4</video:content_loc><video:duration>274</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/comparing-fractions-word-problems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7f990c0c901888f3.jpg</video:thumbnail_loc><video:title>Comparing fractions word problems</video:title><video:description>Sal practices comparing fractions using real-world contexts.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/NEjIVR9kAFE.mp4/NEjIVR9kAFE.mp4</video:content_loc><video:duration>307</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/common-denominators-14-and-56</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbb7dcccd.jpg</video:thumbnail_loc><video:title>Common denominators: 1/4 and 5/6</video:title><video:description>Learn how to find common denominators for fractions with different numerators and denominators by identifying multiples of the original denominators. It demonstrates the process using 1/4 and 5/6, showing that 12 and 24 can be common denominators.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/T8U7hCmUdpo.mp4/T8U7hCmUdpo.mp4</video:content_loc><video:duration>499</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/order-fractions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x65f66810.jpg</video:thumbnail_loc><video:title>Ordering fractions</video:title><video:description>Lindsay orders 7/10, 1/3, and 5/6 using common denominators.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ONsI-yIbsBg.mp4/ONsI-yIbsBg.mp4</video:content_loc><video:duration>359</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/4th-grade-illustrative-mathematics/v/multiplying-a-unit-fraction-and-a-whole-number-with-fraction-models</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5dbe6ca69e524f0b.jpg</video:thumbnail_loc><video:title>Multiplying a unit fraction and a whole number with fraction models</video:title><video:description>Worked examples on using a tape diagram to determine the product of a whole number and a unit fraction.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9FmYFzSEqOI.mp4/9FmYFzSEqOI.mp4</video:content_loc><video:duration>229</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/4th-grade-illustrative-mathematics/v/subtracting-a-fraction-from-a-whole-number</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xee80e94ce41793a9.jpg</video:thumbnail_loc><video:title>Subtracting a fraction from a whole number</video:title><video:description>Learn two strategies for how to subtract a fraction from a whole number.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PZtc8BBiMnE.mp4/PZtc8BBiMnE.mp4</video:content_loc><video:duration>154</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/4th-grade-illustrative-mathematics/v/subtracting-a-mixed-number-from-a-whole-number</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x736c40f0a2fd3882.jpg</video:thumbnail_loc><video:title>Subtracting a mixed number from a whole number</video:title><video:description>Worked example showing how to subtract a mixed number from a whole number.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9W9HeeD3Dog.mp4/9W9HeeD3Dog.mp4</video:content_loc><video:duration>136</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/adding-mixed-numbers-with-like-denominators</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xedb21f38298b8e8d.jpg</video:thumbnail_loc><video:title>Adding mixed numbers with like denominators</video:title><video:description>Sal practices adding mixed numbers with common (like) denominators.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/t32jFmpE-ec.mp4/t32jFmpE-ec.mp4</video:content_loc><video:duration>173</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/mixed-number-subtraction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x64c1922925855264.jpg</video:thumbnail_loc><video:title>Subtracting mixed numbers with like denominators</video:title><video:description>Sal practices subtracting mixed numbers with common (like) denominators.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/QJZ6mBW8xTU.mp4/QJZ6mBW8xTU.mp4</video:content_loc><video:duration>138</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/mixed-number-addition-with-regrouping</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x833785ba0b451037.jpg</video:thumbnail_loc><video:title>Mixed number addition with regrouping</video:title><video:description>Sal practices adding mixed numbers with common (like) denominators. Items require regrouping.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tNaKlG_GJGQ.mp4/tNaKlG_GJGQ.mp4</video:content_loc><video:duration>220</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/subtract-mixed-numbers-with-regrouping</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6e3ce4abf9bb9bcb.jpg</video:thumbnail_loc><video:title>Subtracting mixed numbers with regrouping</video:title><video:description>Sal practices subtracting mixed numbers with common (like) denominators. Items require regrouping (borrowing).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TQEg9dMIWFU.mp4/TQEg9dMIWFU.mp4</video:content_loc><video:duration>180</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/decomposing-hudredths-into-tenths-and-hundredths</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbe6334e8.jpg</video:thumbnail_loc><video:title>Decomposing hundredths</video:title><video:description>Sal decomposes 47/100 into tenths and hundredths.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/kAm9x3uWF9I.mp4/kAm9x3uWF9I.mp4</video:content_loc><video:duration>250</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/fraction-multiplcation-on-the-number-line</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5e8a62f5b4be1859.jpg</video:thumbnail_loc><video:title>Fraction multiplication on the number line</video:title><video:description>Sal uses number lines to help solve multiplication equations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ltKaGC8jfd4.mp4/ltKaGC8jfd4.mp4</video:content_loc><video:duration>181</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/multiply-mixed-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd7b2de40bb5fa61c.jpg</video:thumbnail_loc><video:title>Multiplying mixed numbers by whole numbers</video:title><video:description>Sal uses repeated addition to help multiply a whole number by a mixed number.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hjbSbHr3Fhk.mp4/hjbSbHr3Fhk.mp4</video:content_loc><video:duration>144</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/4th-grade-illustrative-mathematics/v/ordering-decimals-visually-least-to-greatest</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x90947b37936447c8.jpg</video:thumbnail_loc><video:title>Ordering decimals visually: least to greatest</video:title><video:description>Let&apos;s order decimals shown with tenths and hundredths grids from least to greatest.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/uvtHTOt17io.mp4/uvtHTOt17io.mp4</video:content_loc><video:duration>149</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/4th-grade-illustrative-mathematics/v/ordering-decimals-visually-greatest-to-least</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4c954ea03b06f818.jpg</video:thumbnail_loc><video:title>Ordering decimals visually: greatest to least</video:title><video:description>Let&apos;s order decimals shown with tenths and hundredths grids from greatest to least.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/WlW3l-hM6OA.mp4/WlW3l-hM6OA.mp4</video:content_loc><video:duration>256</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/4th-grade-illustrative-mathematics/v/locating-large-numbers-on-a-number-line</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbc90c35356dd281b.jpg</video:thumbnail_loc><video:title>Locating large numbers on a number line</video:title><video:description>Learn how to locate multi-digit numbers on a number line.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/zgNQlR9fJeI.mp4/zgNQlR9fJeI.mp4</video:content_loc><video:duration>198</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/4th-grade-illustrative-mathematics/v/ordering-multi-digit-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc55471a58c2b851c.jpg</video:thumbnail_loc><video:title>Ordering multi digit numbers</video:title><video:description>Practice using place value to order multi digit number from least to greatest.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/K52kqv87zEg.mp4/K52kqv87zEg.mp4</video:content_loc><video:duration>91</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/4th-grade-illustrative-mathematics/v/finding-the-nearest-multiple-of-1000-10000-and-100000</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x98f58633cf81b6f5.jpg</video:thumbnail_loc><video:title>Finding the nearest multiple of 1,000, 10,000 and 100,000</video:title><video:description>Learn how to find the nearest multiple of 1,000, 10,000, and 100,000 given a multi-digit whole number.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1a_XdCihuC8.mp4/1a_XdCihuC8.mp4</video:content_loc><video:duration>221</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/borrowing-once-example-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xcd3e1c25.jpg</video:thumbnail_loc><video:title>Multi-digit subtraction with regrouping: 6798-3359</video:title><video:description>Sal subtracts 6798-3359 using regrouping.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/RRk5qLd__Ro.mp4/RRk5qLd__Ro.mp4</video:content_loc><video:duration>225</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/borrowing-once-example-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf0c43720.jpg</video:thumbnail_loc><video:title>Multi-digit subtraction with regrouping: 7329-6278</video:title><video:description>Sal subtracts 7329-6278 using regrouping.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8_fT1BsTmt4.mp4/8_fT1BsTmt4.mp4</video:content_loc><video:duration>268</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/4th-grade-illustrative-mathematics/v/estimating-multi-digit-addition-and-subtraction-word-problems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf8a8694c80a598c2.jpg</video:thumbnail_loc><video:title>Estimating multi-digit addition and subtraction word problems</video:title><video:description>Practice using estimation as a strategy to add and subtract larger multi-digit numbers.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Ic4i3L9ivNk.mp4/Ic4i3L9ivNk.mp4</video:content_loc><video:duration>138</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/decimals-and-fractions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1806.jpg</video:thumbnail_loc><video:title>Rewriting decimals as fractions: 2.75</video:title><video:description>Here&apos;s an example of how we convert a decimal to a simplified fraction. Over time this will become second nature to you.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/NzIoHQfStoM.mp4/NzIoHQfStoM.mp4</video:content_loc><video:duration>162</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/common-fractions-and-decimals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x95c2808f6820c075.jpg</video:thumbnail_loc><video:title>Common fractions and decimals</video:title><video:description>Explores the concept of converting common fractions (1/5, 1/4, 1/2) into decimals. Learn the importance of understanding these conversions for real-life applications and for working with multiples of these fractions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lh2mp0aqSh8.mp4/lh2mp0aqSh8.mp4</video:content_loc><video:duration>333</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/5th-grade-foundations-engageny/v/multiplying-whole-numbers-and-applications-6</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/158927009.jpg</video:thumbnail_loc><video:title>Comparing with multiplication: age</video:title><video:description>Sal solves a multiplication comparison word problem.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/bS6EmYzpou4.mp4/bS6EmYzpou4.mp4</video:content_loc><video:duration>159</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/4th-grade-illustrative-mathematics/v/solving-word-problems-involving-multiplicative-comparison</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x959b21ed27e22f5a.jpg</video:thumbnail_loc><video:title>Solving word problems involving multiplicative comparison</video:title><video:description>Learn how to solve word problems involving multiplicative comparison.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/iNPc_UPwEM0.mp4/iNPc_UPwEM0.mp4</video:content_loc><video:duration>176</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/converting-pounds-to-ounces</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23.jpg</video:thumbnail_loc><video:title>Converting pounds to ounces</video:title><video:description>There are 16 ounces in 1 pound. Learn to convert pounds to ounces.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/IrvEHVn-fks.mp4/IrvEHVn-fks.mp4</video:content_loc><video:duration>94</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/converting-yards-into-inches</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/16.jpg</video:thumbnail_loc><video:title>Converting yards into inches</video:title><video:description>Learn to convert between yards, feet, and inches.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8C5kAIKLcZo.mp4/8C5kAIKLcZo.mp4</video:content_loc><video:duration>349</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/4th-grade-illustrative-mathematics/v/finding-side-lengths-of-rectangles-given-the-perimeter</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x58084f1cad042016.jpg</video:thumbnail_loc><video:title>Finding side lengths of rectangles given the perimeter</video:title><video:description>Watch a worked example on finding possible pairs of side lengths of a rectangle given the perimeter.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/NQLhy5DbqQc.mp4/NQLhy5DbqQc.mp4</video:content_loc><video:duration>134</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/4th-grade-illustrative-mathematics/v/using-multiplication-to-compare-perimeters-of-rectangles</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe89cc1f43beec74f.jpg</video:thumbnail_loc><video:title>Using multiplication to compare perimeters of rectangles</video:title><video:description>Learn how to find the perimeter of a rectangle given that the side lengths are a multiple of another rectangle.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/S5rWQJxiBhQ.mp4/S5rWQJxiBhQ.mp4</video:content_loc><video:duration>141</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/4th-grade-illustrative-mathematics/v/finding-the-perimeter-of-a-rhombus</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5b4dbd5f560993a2.jpg</video:thumbnail_loc><video:title>Finding the perimeter of a rhombus</video:title><video:description>Learn how to find the perimeter of a rhombus with fractional side lengths. This example is designed to reinforce skills in fraction arithmetic and multiplication.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/A2Hl7wpOLJ4.mp4/A2Hl7wpOLJ4.mp4</video:content_loc><video:duration>90</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/4th-grade-illustrative-mathematics/v/finding-the-side-length-of-a-parallelogram-given-perimeter</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9e27011a16939f66.jpg</video:thumbnail_loc><video:title>Finding the side length of a parallelogram given perimeter</video:title><video:description>Learn how to find the unknown side length of a parallelogram. As you solve problems, you will apply what you know about adding and subtracting fractions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/x2nFVwpYefc.mp4/x2nFVwpYefc.mp4</video:content_loc><video:duration>83</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/unit-sense-example-for-exercise</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa2bc2142.jpg</video:thumbnail_loc><video:title>Finding reasonable unit of measurement example</video:title><video:description>Sal chooses reasonable units of time activities like baking cookies.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OuaBg3Hjqoc.mp4/OuaBg3Hjqoc.mp4</video:content_loc><video:duration>227</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/intro-to-standard-way-of-multiplying-multi-digit-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0fa45a7026fa5ab7.jpg</video:thumbnail_loc><video:title>Intro to standard way of multiplying multi-digit numbers</video:title><video:description>The standard algorithm for multiplying a multi-digit number by a single digit number involves multiplying each place value by the single digit, and regrouping as necessary. This method is equivalent to breaking the multi-digit number into parts, multiplying each part by the single digit, and adding the results together.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/NuIDwPQLJmk.mp4/NuIDwPQLJmk.mp4</video:content_loc><video:duration>265</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/understanding-the-standard-algorithm-for-multiplication</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x30f46234cfe82375.jpg</video:thumbnail_loc><video:title>Understanding the standard algorithm for multiplication</video:title><video:description>The standard algorithm for multiplying whole numbers involves breaking the numbers down into their place values and multiplying each place value separately. This process is illustrated through three examples: one complete walkthrough, one where the viewer is asked to identify mistakes in incorrect solutions, and one where the viewer is asked to fill in a missing number.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/GOYnrYee1Y0.mp4/GOYnrYee1Y0.mp4</video:content_loc><video:duration>271</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/4th-grade-illustrative-mathematics/v/solving-multi-step-problems-multiplication-camping-items</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2bf9664349a01fb8.jpg</video:thumbnail_loc><video:title>Solving multi-step problems (multiplication): camping items</video:title><video:description>Practice solving multi-step step word problems with multiplication.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/h8ClXSzcIXU.mp4/h8ClXSzcIXU.mp4</video:content_loc><video:duration>155</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/4th-grade-illustrative-mathematics/v/solving-multi-step-problems-multiplication-firewood</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb05d142e612f9a09.jpg</video:thumbnail_loc><video:title>Solving multi-step problems (multiplication): firewood</video:title><video:description>Practice solving multi-step step word problems with multiplication.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/SuTdB6pcpeM.mp4/SuTdB6pcpeM.mp4</video:content_loc><video:duration>140</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/introduction-to-division-with-partial-quotients</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xeb7482a2859662d0.jpg</video:thumbnail_loc><video:title>Introduction to division with partial quotients (no remainder)</video:title><video:description>Sal divides multi-digit numbers by a single-digit numbers using partial quotients.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Ws4Zq-gceSY.mp4/Ws4Zq-gceSY.mp4</video:content_loc><video:duration>376</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/intro-to-remainders</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xcb929e1ca71a635e.jpg</video:thumbnail_loc><video:title>Introduction to remainders</video:title><video:description>Sal shows how a remainder is what&apos;s left over in a division problem.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/P1qyjdh_sIw.mp4/P1qyjdh_sIw.mp4</video:content_loc><video:duration>289</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/division-with-partial-quotients-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa78b245468a7c720.jpg</video:thumbnail_loc><video:title>Division with partial quotients (remainder)</video:title><video:description>Sal divides multi-digit numbers by a single-digit numbers using partial quotients. Answers include remainders.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gamEPRpt9jo.mp4/gamEPRpt9jo.mp4</video:content_loc><video:duration>405</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/4th-grade-illustrative-mathematics/v/solving-multi-step-problems-division-books</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb091e2faddf3db30.jpg</video:thumbnail_loc><video:title>Solving multi-step problems (division): books</video:title><video:description>Practice solving multi-step step word problems with division.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ZbiQiubEH3w.mp4/ZbiQiubEH3w.mp4</video:content_loc><video:duration>142</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/4th-grade-illustrative-mathematics/v/solving-multi-step-problems-division-cookies</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4b851787c3020908.jpg</video:thumbnail_loc><video:title>Solving multi-step problems (division): cookies</video:title><video:description>Practice solving multi-step step word problems with division.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3fWW5SsvPq0.mp4/3fWW5SsvPq0.mp4</video:content_loc><video:duration>129</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/2-step-estimation-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe5e3106c2de872d0.jpg</video:thumbnail_loc><video:title>2-step estimation word problem</video:title><video:description>Sal uses estimation to solve multi-step word problems involving addition, subtraction, multiplication, and division.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hzh10qtOxpg.mp4/hzh10qtOxpg.mp4</video:content_loc><video:duration>185</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/estimating-division-that-results-in-non-whole-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6c251d4a8d28b1c4.jpg</video:thumbnail_loc><video:title>Estimating division that results in non-whole numbers</video:title><video:description>Sal uses estimation to find quotients that are non-whole numbers.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/VJyk81HmcZQ.mp4/VJyk81HmcZQ.mp4</video:content_loc><video:duration>214</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/estimating-quotients</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6b03dedfb1635afd.jpg</video:thumbnail_loc><video:title>Estimating quotients</video:title><video:description>Sal uses estimation to determine if quotients are reasonable or unreasonable.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6RT_dE3W-00.mp4/6RT_dE3W-00.mp4</video:content_loc><video:duration>245</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/4th-grade-illustrative-mathematics/v/composing-and-decomposing-angles</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf3e6dfa68093da00.jpg</video:thumbnail_loc><video:title>Composing and decomposing angles</video:title><video:description>Learn how to determine the size of an angle based on composing and decomposing angles.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/mg05k5blvf4.mp4/mg05k5blvf4.mp4</video:content_loc><video:duration>76</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/4th-grade-illustrative-mathematics/v/finding-an-unknown-angle-measure</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x36b65adcaebd92e0.jpg</video:thumbnail_loc><video:title>Finding an unknown angle measure</video:title><video:description>Learn how to find an unknown angle measure on a diagram, based on composing and decomposing angles.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lshlkVC57uQ.mp4/lshlkVC57uQ.mp4</video:content_loc><video:duration>74</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/4th-grade-math-eureka-squared-aligned/v/estimating-large-sums-and-differences-word-problems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd26e3b9b0ffa07f5.jpg</video:thumbnail_loc><video:title>Estimating large sums and differences word problems</video:title><video:description>Get ready to solve word problems by estimating large sums and differences! Let&apos;s round numbers to make addition and subtraction easier. Estimating helps us make smart guesses in real-life situations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/quGTt2nF4Lg.mp4/quGTt2nF4Lg.mp4</video:content_loc><video:duration>177</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/comparing-place-values</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x19b4a5d9.jpg</video:thumbnail_loc><video:title>Comparing place values</video:title><video:description>Sal compares numbers in different place values.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/dZPOCU10TqY.mp4/dZPOCU10TqY.mp4</video:content_loc><video:duration>150</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/4th-grade-math-eureka-squared-aligned/v/ordering-large-numbers-least-to-greatest</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x55036179cd6e3e6a.jpg</video:thumbnail_loc><video:title>Ordering large numbers: least to greatest</video:title><video:description>Let&apos;s order whole numbers up to 1 billion from least to greatest using place value understanding.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ao-Cn3NlqtQ.mp4/ao-Cn3NlqtQ.mp4</video:content_loc><video:duration>263</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/4th-grade-math-eureka-squared-aligned/v/ordering-large-numbers-greatest-to-least</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x93e3b3b49ac627d0.jpg</video:thumbnail_loc><video:title>Ordering large numbers: greatest to least</video:title><video:description>Let&apos;s order whole numbers up to 1 billion using place value understanding.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Bz-dxrD4xUw.mp4/Bz-dxrD4xUw.mp4</video:content_loc><video:duration>191</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/4th-grade-math-eureka-squared-aligned/v/estimating-large-sums</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x29f7e16f5c50f07d.jpg</video:thumbnail_loc><video:title>Estimating large sums</video:title><video:description>Let&apos;s estimate sums by rounding numbers to the nearest ten, hundred, or thousand to make adding easier. Estimating helps us check our answers and solve problems quickly in real life—like when shopping or planning a party. Get ready for some fun math tricks!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ByodvOXFNns.mp4/ByodvOXFNns.mp4</video:content_loc><video:duration>186</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/4th-grade-math-eureka-squared-aligned/v/estimating-large-differences</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x71770154f045f6d9.jpg</video:thumbnail_loc><video:title>Estimating large differences</video:title><video:description>Let&apos;s round big numbers to the nearest ten, hundred, or thousand to make subtraction easier. Estimating helps us check our answers and solve problems quickly in real life—like when budgeting or figuring out travel time. Let’s make subtraction simple and fun!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jz6QaBJqDOI.mp4/jz6QaBJqDOI.mp4</video:content_loc><video:duration>139</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/2-digit-multiplication-with-grid</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x481bf39b.jpg</video:thumbnail_loc><video:title>Multiplying with distributive property</video:title><video:description>Sal uses the distributive property to multiply 87x63.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3JmnxR8nEi8.mp4/3JmnxR8nEi8.mp4</video:content_loc><video:duration>418</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/estimating-adding-fractions-with-unlike-denominators</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x20d9230a8c34da99.jpg</video:thumbnail_loc><video:title>Estimating adding fractions with unlike denominators</video:title><video:description>Learn all about estimating the sum of fractions with unlike denominators. Practice visualizing fractions and using that understanding to make reasonable estimates when adding them together.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/XR_B9AJe1u4.mp4/XR_B9AJe1u4.mp4</video:content_loc><video:duration>297</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/4th-grade-math-eureka-squared-aligned/v/relating-money-and-place-value</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x144eb4c92f368a09.jpg</video:thumbnail_loc><video:title>Relating money and place value</video:title><video:description>Discover how dollars and cents connect to place value in this engaging video using money to explain tenths and hundredths clearly.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1ZeV2W3rSUs.mp4/1ZeV2W3rSUs.mp4</video:content_loc><video:duration>120</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/4th-grade-math-eureka-squared-aligned/v/relating-money-to-decimals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x798a58c97d17face.jpg</video:thumbnail_loc><video:title>Relating money to decimals</video:title><video:description>Learn different ways to represent decimals as fractions, grids, and money in this fun video.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/UeoZoZmUkyg.mp4/UeoZoZmUkyg.mp4</video:content_loc><video:duration>208</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/4th-grade-math-eureka-squared-aligned/v/adding-decimals-science-experiment</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc6b3965c3f279e62.jpg</video:thumbnail_loc><video:title>Adding decimals: science experiment</video:title><video:description>Practice solving word problems by adding decimals.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/rwIsRzdRlb0.mp4/rwIsRzdRlb0.mp4</video:content_loc><video:duration>84</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fourth-grade-math/v/comparing-fractions-of-different-wholes-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xaedbf86a.jpg</video:thumbnail_loc><video:title>Equivalent fractions and different wholes</video:title><video:description>Sal shows that two fractions are equivalent only if they refer to the same whole.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8VjhtS3KlOY.mp4/8VjhtS3KlOY.mp4</video:content_loc><video:duration>366</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/place-value-with-decimals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x51d339d2d195dbc9.jpg</video:thumbnail_loc><video:title>Place value with decimals</video:title><video:description>Place value and decimals are related. We can begin by reviewing the concept of ones, tens, and hundreds places, and then demonstrates how tenths, hundredths, and thousandths places work. By understanding place value, we can interpret the meaning of each digit in a decimal number.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/wtrrr15mbvQ.mp4/wtrrr15mbvQ.mp4</video:content_loc><video:duration>245</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/multiplying-and-dividing-by-10-100-1000</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd4695fbb10631bae.jpg</video:thumbnail_loc><video:title>Multiplying and dividing by 10, 100, 1000</video:title><video:description>Learn how multiplying and dividing whole numbers by 10, 100, and 1,000 shifts the digits of the number left or right, respectively. Multiplying increases the place value, while dividing decreases it, making the process easier to understand.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/yVg6LyNgIT8.mp4/yVg6LyNgIT8.mp4</video:content_loc><video:duration>524</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/multiplying-and-dividing-by-powers-of-10</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x41a68fb542ebc43b.jpg</video:thumbnail_loc><video:title>Multiplying and dividing by powers of 10</video:title><video:description>Learn about the patterns when multiplying or dividing numbers by powers of 10. Multiplying shifts digits to the left, while dividing shifts them to the right. The exponent determines the number of places digits shift.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jBN69fm8_T0.mp4/jBN69fm8_T0.mp4</video:content_loc><video:duration>302</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/introduction-to-powers-of-10</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc0c28d82e0324ccc.jpg</video:thumbnail_loc><video:title>Introduction to powers of 10</video:title><video:description>Exponents are a way of simplifying the notation for repeated multiplication. When using a base of 10, the exponent tells you how many times to multiply 10 by itself. Converting between exponential notation and standard notation is straightforward: for example, 10 to the second power is the same as 10 times 10, or 100.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Xvsqv2oO2ac.mp4/Xvsqv2oO2ac.mp4</video:content_loc><video:duration>252</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/powers-of-10</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8f37f955.jpg</video:thumbnail_loc><video:title>Using exponents with powers of 10</video:title><video:description>Explore the concept of multiplying by powers of 10. Learn about the pattern of adding zeros when multiplying by 10 and the use of exponents as a shorthand for repeated multiplication. Discover the connection between the number of times 10 is multiplied and the number of zeros in the product.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/YJdCw2fK-Og.mp4/YJdCw2fK-Og.mp4</video:content_loc><video:duration>334</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/patterns-in-zeros-exercise</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4bccbc14.jpg</video:thumbnail_loc><video:title>Exponents and powers of 10 patterns</video:title><video:description>This lesson explains calculations involving powers of ten. It demonstrates how to multiply and divide by these powers, and explains the results of these calculations, such as adding or removing zeroes from the end of a number. Additionally, the lesson discusses how these calculations can shift the placement of a decimal point to the left or right</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pYaIjA4CsKo.mp4/pYaIjA4CsKo.mp4</video:content_loc><video:duration>416</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/thousandths-on-the-number-line</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x53608e02aac6166f.jpg</video:thumbnail_loc><video:title>Thousandths on the number line</video:title><video:description>We can find the value of a point on a number line that falls between two known values, in this case 0.03 and 0.04. It is important to understand place value, specifically the tenths, hundredths, and thousandths places. By dividing the space between the two known values into ten equal segments, it shows that the point is located at 0.038 (or 38 thousandths).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ABHQJFWZGsk.mp4/ABHQJFWZGsk.mp4</video:content_loc><video:duration>140</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/fractions-as-division-by-powers-of-10</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8fdc858a.jpg</video:thumbnail_loc><video:title>Fractions as division by power of 10</video:title><video:description>Explore the concept of multiplying and dividing numbers by powers of 10. Understand how moving the decimal point to the left or right changes the value of a number, and how this relates to the concept of fractions as division.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LohXZt7QzCM.mp4/LohXZt7QzCM.mp4</video:content_loc><video:duration>307</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/comparing-place-values-in-decimals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8be920b7.jpg</video:thumbnail_loc><video:title>Comparing decimal place values</video:title><video:description>Explore the concept of place value in multi-digit numbers, emphasizing how a digit&apos;s value changes based on its position. Understand how a digit in one place represents 10 times as much as it represents in the place to its right and 1/10 of what it represents in the place to its left.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lR_kUUPL8YY.mp4/lR_kUUPL8YY.mp4</video:content_loc><video:duration>340</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/expanding-out-a-decimal-by-place-value</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd4b6caae.jpg</video:thumbnail_loc><video:title>Write decimals in expanded form</video:title><video:description>To write a decimal in expanded form, we need to break down each digit according to its place value. Start with the whole number portion, identifying the hundreds, tens, and ones places. Then, move on to the tenths, hundredths, and thousandths places. Keep in mind the order of operations when combining the expanded terms.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/he4kcTujy30.mp4/he4kcTujy30.mp4</video:content_loc><video:duration>173</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/decimal-place-value-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1805.jpg</video:thumbnail_loc><video:title>Decimals in written form (hundredths)</video:title><video:description>To write a decimal in word form, start by writing out the whole number portion. Next, express the decimal portion as a fraction of hundredths. For clarity, it&apos;s often helpful to simplify multiple terms (such as &quot;one tenth and five hundredths&quot;) into a single fraction (such as &quot;fifteen hundredths&quot;).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/AuD2TX-90Cc.mp4/AuD2TX-90Cc.mp4</video:content_loc><video:duration>211</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/writing-out-a-decimal-in-words</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x40ad4b83.jpg</video:thumbnail_loc><video:title>Decimals in written form (thousandths)</video:title><video:description>Learn how to read and write decimals in different forms, focusing on thousandths. Learn how to decompose a decimal into its parts (20,000, 5/10, and 7/1000) and rewrite it as 20,000 and 507/1000.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/G7QiIkYfeME.mp4/G7QiIkYfeME.mp4</video:content_loc><video:duration>202</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/expressing-decimals-in-multiple-forms</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc6ab61ca967b1e72.jpg</video:thumbnail_loc><video:title>Expressing decimals in multiple forms</video:title><video:description>Learn all about understanding how to express decimals in various forms. Learn to break down decimals into place values, show how to write them in expanded form, separate each decimal part, and explain how to say them in words.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/U3w9ppDv_MU.mp4/U3w9ppDv_MU.mp4</video:content_loc><video:duration>229</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/visual-understanding-of-regrouping-decimals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3e6af5072fc5f4e5.jpg</video:thumbnail_loc><video:title>Visual understanding of regrouping decimals</video:title><video:description>Explore the concept of place value in decimals, focusing on how to regroup value from one place to another. Understand the relationship between ones, tenths, and hundredths in decimal numbers.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/e_KEaTPcPKg.mp4/e_KEaTPcPKg.mp4</video:content_loc><video:duration>319</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/comparing-decimals-2-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x76e3cf20.jpg</video:thumbnail_loc><video:title>Comparing decimals: 9.97 and 9.798</video:title><video:description>To compare two decimals, we should start by looking at the largest place value. If the numbers are the same, continue to smaller place values until we find a difference. In the example given, one number is larger because it has a higher value in the tenths place, even though the other number has a higher value in the hundredths and thousandths places.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/f8B2dBQn3_U.mp4/f8B2dBQn3_U.mp4</video:content_loc><video:duration>264</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/comparing-decimals-4</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/158925084.jpg</video:thumbnail_loc><video:title>Comparing decimals: 156.378 and 156.348</video:title><video:description>This video is all about comparing decimals. Learn how to determine which decimal is greater by comparing each place value, starting from the left and moving right, until a difference is found.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/FwMYoK1QKso.mp4/FwMYoK1QKso.mp4</video:content_loc><video:duration>128</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/comparing-decimals-in-different-representations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x45985c9a79cb6345.jpg</video:thumbnail_loc><video:title>Comparing decimals in different representations</video:title><video:description>This video is all about comparing decimals. Learn how to determine which of two decimals is larger by converting them into a common format. Practice understanding place value and the importance of each digit&apos;s position.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_tk3nWC5OAA.mp4/_tk3nWC5OAA.mp4</video:content_loc><video:duration>268</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/compare-decimals-word-problems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x27d33c81597fc209.jpg</video:thumbnail_loc><video:title>Comparing decimals word problems</video:title><video:description>Explore the concept of comparing decimals. Learn the importance of aligning place values and starting from the largest place value when comparing. The video also demonstrates that more digits doesn&apos;t necessarily mean a larger number.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ELNooV0ymYk.mp4/ELNooV0ymYk.mp4</video:content_loc><video:duration>242</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/ordering-decimals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe6cd87b441d5acc6.jpg</video:thumbnail_loc><video:title>Ordering decimals</video:title><video:description>Practice comparing decimals and learning how to order numbers with decimals from least to greatest. Learn about the importance of examining each decimal place, starting from the left (the largest place value) and moving rightwards.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/RmHmtLQ-pqU.mp4/RmHmtLQ-pqU.mp4</video:content_loc><video:duration>211</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/comparing-decimals-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x231fca9b6108d02c.jpg</video:thumbnail_loc><video:title>Ordering decimals through thousandths</video:title><video:description>Learn all about comparing decimals. It teaches students how to order decimals from least to greatest by comparing each place value, starting from the most significant and moving to the right.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Dese7hoWZMM.mp4/Dese7hoWZMM.mp4</video:content_loc><video:duration>181</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/rounding-decimals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1808.jpg</video:thumbnail_loc><video:title>Worked example: Rounding decimals to nearest tenth</video:title><video:description>Rounding decimals to the nearest tenth can be fun. We can identify the tenths place in the given decimal, 9.564. Then we can look at the digit to the right of the tenths place to determine whether to round up or down. In this case, the answer is to round up to 9.6.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_MIn3zFkEcc.mp4/_MIn3zFkEcc.mp4</video:content_loc><video:duration>86</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/rounding-decimals-on-the-number-line</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfddb821a92c39916.jpg</video:thumbnail_loc><video:title>Rounding decimals on the number line</video:title><video:description>Learn how to round decimals using a number line, visually showing which whole number, tenth, hundredth, or thousandth is closest. Building off intuition of rounding rules and connect rounding to the nearest place value on the number line.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/T3BMIaDUvck.mp4/T3BMIaDUvck.mp4</video:content_loc><video:duration>262</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/rounding-to-the-nearest-tenth-and-hundredth</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xaa5822d8b6021ac6.jpg</video:thumbnail_loc><video:title>Rounding decimals word problems</video:title><video:description>This video dives into the world of rounding decimals. It explores how to adjust decimals to the closest tenth, hundredth, and whole number, all while highlighting the importance of grasping place value.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/IcmAxkEImtI.mp4/IcmAxkEImtI.mp4</video:content_loc><video:duration>272</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/estimating-adding-decimals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5bb1dcccd5e31953.jpg</video:thumbnail_loc><video:title>Estimating decimal addition</video:title><video:description>Learn all about how to estimate when adding decimals. Practice rounding to the nearest whole number and how this can help us get a close approximation of the actual answer.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/dj3tcEbWBDQ.mp4/dj3tcEbWBDQ.mp4</video:content_loc><video:duration>210</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/introduction-to-adding-decimals-tenths</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xcf0f7c39de0ed576.jpg</video:thumbnail_loc><video:title>Introduction to adding decimals: tenths</video:title><video:description>This video introduces the concept of adding decimals, specifically tenths. It explains how to visualize and calculate the addition of tenths using both numerical and visual methods, reinforcing the understanding of decimal addition.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7I_AILEWTL4.mp4/7I_AILEWTL4.mp4</video:content_loc><video:duration>386</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/adding-decimals-with-ones-and-tenths-parts</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xcf7cf31ff1f4c540.jpg</video:thumbnail_loc><video:title>Adding decimals with ones and tenths parts</video:title><video:description>Learn how to add decimals, specifically to the tenths. Practice adding whole numbers first, then adding the decimal parts. Learn the concept of carrying over in decimal addition.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/66_Sb1dP81E.mp4/66_Sb1dP81E.mp4</video:content_loc><video:duration>365</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/andding-decimals-with-hundredths</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb4b36ff6184dd69d.jpg</video:thumbnail_loc><video:title>Adding decimals with hundredths</video:title><video:description>There are different ways to add decimals involving hundredths. One method is to combine the total number of hundredths, while another involves breaking the numbers down into tenths and hundredths and adding them separately. A more complicated example shows how these techniques can be used to arrive at a whole number plus a fraction. Understanding these concepts is important before moving on to faster methods.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/fWi-i_mdUOI.mp4/fWi-i_mdUOI.mp4</video:content_loc><video:duration>417</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/adding-decimals-with-ones-tenths-and-hundredths</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5249a8ffcd932f68.jpg</video:thumbnail_loc><video:title>Adding decimals with ones, tenths and hundredths</video:title><video:description>Learn all about adding decimals, specifically in the hundredths place. Learn about aligning decimal points and adding each place value separately, from hundredths to ones. It also introduces a systematic way to add decimals.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6NBkb98nFOM.mp4/6NBkb98nFOM.mp4</video:content_loc><video:duration>413</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/adding-decimals-example-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdd0d7ae2.jpg</video:thumbnail_loc><video:title>Adding decimals: 9.087+15.31</video:title><video:description>Adding decimals is an essential math skill. To add decimals, such as 9.087 and 15.31, align the decimal points and place values. Fill in any missing digits with zeros to make the numbers the same length. Then, perform the addition as usual, starting with the smallest place value. The result of adding 9.087 and 15.31 is 24.397.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/oLh_sIESQnY.mp4/oLh_sIESQnY.mp4</video:content_loc><video:duration>160</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/adding-decimals-example-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbcb2a374.jpg</video:thumbnail_loc><video:title>Adding decimals: 0.822+5.65</video:title><video:description>Adding decimals is a breeze when you follow these simple steps: First, line up the decimal points and write the numbers one below the other. Next, start adding from the smallest place value (thousandths) and carry over any extra value to the next place if needed. Finally, include the decimal point in your answer. Mastering decimal addition helps build strong math skills for everyday life.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ErHFQUhZ94I.mp4/ErHFQUhZ94I.mp4</video:content_loc><video:duration>106</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/adding-decimals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/4802227.jpg</video:thumbnail_loc><video:title>Adding three decimals</video:title><video:description>Adding decimals is easy when you follow these steps: line up the decimal points, fill in any missing digits with zeros, and then add the numbers from the smallest place value to the largest. By following this method, you can accurately add decimals and solve real-world problems.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/w616LEmrHVE.mp4/w616LEmrHVE.mp4</video:content_loc><video:duration>165</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/estimating-subtracting-decimals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x190b7d981962f9b7.jpg</video:thumbnail_loc><video:title>Estimating decimal subtraction</video:title><video:description>This video is all about learning to estimate when subtracting decimals. It emphasizes the importance of rounding to the nearest whole number and doing quick mental calculations to get an approximate answer. It&apos;s all about getting comfortable with estimation!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LQmAGFCJMqo.mp4/LQmAGFCJMqo.mp4</video:content_loc><video:duration>208</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/strategies-for-subtracting-basic-decimals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbf77dcbc4bed7035.jpg</video:thumbnail_loc><video:title>Strategies for subtracting basic decimals</video:title><video:description>Dive into the world of subtracting decimals, focusing on tenths. It&apos;s all about exploring different strategies like using visual aids, hopping along number lines, and splitting numbers into bite-sized chunks.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/N5xWYgeIWmU.mp4/N5xWYgeIWmU.mp4</video:content_loc><video:duration>348</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/strategies-for-subtracting-more-complex-decimals-with-tenths</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x45933de401946e11.jpg</video:thumbnail_loc><video:title>Strategies for subtracting more complex decimals with tenths</video:title><video:description>Learn all about subtraction of decimals, particularly those in the tenths place. The focus is on various strategies like decomposing whole numbers into tenths and using a number line for visualization.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/IE0HQoLrbX4.mp4/IE0HQoLrbX4.mp4</video:content_loc><video:duration>526</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/more-advanced-subtraction-strategies-with-hundredths</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x06d023890a92da69.jpg</video:thumbnail_loc><video:title>More advanced subtraction strategies with hundredths</video:title><video:description>This video explores the concept of subtracting decimals, specifically hundredths. It demonstrates different strategies for subtracting decimals, emphasizing the importance of understanding place value and the flexibility of breaking down numbers to make subtraction easier.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/URdTZ38JvOI.mp4/URdTZ38JvOI.mp4</video:content_loc><video:duration>302</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/subtraction-strategies-with-hundredths</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd56548451a9410b2.jpg</video:thumbnail_loc><video:title>Subtraction strategies with hundredths</video:title><video:description>This video is all about subtracting decimals, specifically those in the hundredths place. It covers different strategies for subtraction, breaking down the process into manageable steps, and emphasizes the importance of understanding the concept behind the calculations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/GUK9aup5HOs.mp4/GUK9aup5HOs.mp4</video:content_loc><video:duration>339</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/another-example-subtracting-decimals-to-hundredths</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x10e8640f.jpg</video:thumbnail_loc><video:title>Subtracting decimals: 10.1-3.93</video:title><video:description>This video shows how to subtract decimals down to the hundredths place. It emphasizes the importance of aligning decimals and place values, and demonstrates the process of regrouping when subtracting.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/MufbvU4tGh8.mp4/MufbvU4tGh8.mp4</video:content_loc><video:duration>113</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/subtracting-decimals-up-to-hundredths</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x14d899f1.jpg</video:thumbnail_loc><video:title>Subtracting decimals: 9.57-8.09</video:title><video:description>Learn to subtract decimals by aligning the decimal points and place values. Regroup numbers for easier subtraction, and then perform the subtraction for each place value. Mastering decimal subtraction helps build strong math skills and real-world problem-solving abilities.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/o31cLUkS23E.mp4/o31cLUkS23E.mp4</video:content_loc><video:duration>71</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/estimating-with-multiplying-decimals-and-whole-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbdafd84387355135.jpg</video:thumbnail_loc><video:title>Estimating with multiplying decimals and whole numbers</video:title><video:description>Learn all about the concept of estimating products in multiplication problems involving decimals and whole numbers. Understand the importance of rounding to the nearest whole number for easier computation, and demonstrates how this strategy can help make reasonable estimates.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/d3Qg71bZ4Rw.mp4/d3Qg71bZ4Rw.mp4</video:content_loc><video:duration>192</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/strategies-for-multiplying-decimals-and-whole-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x98562a9c2d7fec19.jpg</video:thumbnail_loc><video:title>Strategies for multiplying decimals and whole numbers</video:title><video:description>We can use different methods for multiplying whole numbers with decimals. The first method involves converting the decimal into a fraction and multiplying the numerators and denominators together. The second method involves breaking the decimal into different place values and multiplying each part by the whole number. Estimating the answer beforehand can help check for accuracy</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/yueSfjh2ra4.mp4/yueSfjh2ra4.mp4</video:content_loc><video:duration>413</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/multiplying-decimals-and-whole-numbers-with-visuals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xefa4c5fff318bc4a.jpg</video:thumbnail_loc><video:title>Multiplying decimals and whole numbers with visuals</video:title><video:description>Multiplying whole numbers and decimals can be fun. It starts with simple examples, such as multiplying 3/10 by 4, and then moves on to more complex examples, such as multiplying 52/100 by 3. In each case, we demonstrate how to use a number line or model to visualize the process and find the product.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/K-bA-k_9Rg0.mp4/K-bA-k_9Rg0.mp4</video:content_loc><video:duration>273</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/strategies-for-multiplying-multi-digit-decimals-by-whole-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbec7336ee5b8922d.jpg</video:thumbnail_loc><video:title>Strategies for multiplying multi-digit decimals by whole numbers</video:title><video:description>Learn how to multiply decimals and whole numbers. The video presents two strategies: converting decimals to tenths and multiplying, then converting back, and using estimation to determine where the decimal should go in the answer. Both methods reinforce understanding of place value.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/RtXpRld8vb4.mp4/RtXpRld8vb4.mp4</video:content_loc><video:duration>265</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/estimating-decimal-multiplication</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x341feb4f9b12d753.jpg</video:thumbnail_loc><video:title>Estimating decimal multiplication</video:title><video:description>This video is all about using estimation to simplify the process of multiplying decimals. It emphasizes the idea that rounding numbers to their nearest whole can make multiplication easier and quicker, especially when you&apos;re trying to do it in your head!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1serq4kmeZc.mp4/1serq4kmeZc.mp4</video:content_loc><video:duration>239</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/understanding-decimal-multiplication</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x59c34c596fe1940b.jpg</video:thumbnail_loc><video:title>Understanding decimal multiplication</video:title><video:description>This video introduces multiplying decimals, emphasizing the role of decimal placement in the product. It highlights the usefulness of estimation in simplifying calculations and understanding the relationship between the numbers.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/005032IwRME.mp4/005032IwRME.mp4</video:content_loc><video:duration>160</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/multiplying-decimals-using-estimation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8f65b1eb7d45185c.jpg</video:thumbnail_loc><video:title>Multiplying decimals using estimation</video:title><video:description>Learn all about multiplying decimals by using using estimation. Practice ignoring the decimals first, and multiplying the numbers as wholes. Then, use estimation to find where the decimal should go, ensuring the answer is reasonable.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/VQN6MvdJRx4.mp4/VQN6MvdJRx4.mp4</video:content_loc><video:duration>218</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/developing-strategies-for-multiplying-decimals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9233b8e2c9b8fe4d.jpg</video:thumbnail_loc><video:title>Developing strategies for multiplying decimals</video:title><video:description>This video is all about understanding how to multiply decimals, specifically focusing on the strategy of converting decimals to fractions to make the multiplication process easier. Multiplying decimals can be made easier by thinking of the decimals as fractions. This helps understand what we are multiplying, and it also lays the groundwork for the standard method of decimal multiplication.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xBseQOzMB7A.mp4/xBseQOzMB7A.mp4</video:content_loc><video:duration>307</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/division-strategies-for-decimal-quotients</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbc987a93476de2aa.jpg</video:thumbnail_loc><video:title>Division strategies for decimal quotients</video:title><video:description>There are various methods for division when the quotient is not a whole number. Different examples demonstrate how to use fractions, tenths, and reciprocals to multiply instead of divide so we can arrive at the correct answer.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/zlq_jQYD1mA.mp4/zlq_jQYD1mA.mp4</video:content_loc><video:duration>544</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/divide-whole-numbers-with-decimal-quotients</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x841498d4a5021e52.jpg</video:thumbnail_loc><video:title>Divide whole numbers with decimal quotients: 5÷2</video:title><video:description>This video teaches how to divide whole numbers to get a decimal quotient. It explains two methods to achieve this, emphasizing that division can result in decimals, not just whole numbers or remainders.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/29qKGbhFnf8.mp4/29qKGbhFnf8.mp4</video:content_loc><video:duration>144</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/5th-engage-ny/v/strategies-for-dividing-by-tenths</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x883ba0bf760bbec8.jpg</video:thumbnail_loc><video:title>Strategies for dividing by tenths</video:title><video:description>Sal uses equivalent fractions to divide both whole numbers and decimals by tenths.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/dToPqCXHNDA.mp4/dToPqCXHNDA.mp4</video:content_loc><video:duration>323</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/multiplying-and-dividing-decimals-by-10-100-1000</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbe0687a07ccf2974.jpg</video:thumbnail_loc><video:title>Multiplying and dividing decimals by 10, 100, 1000</video:title><video:description>Explore the concept of multiplying and dividing decimals by 10, 100, and 1000. Learn how each digit in a decimal number shifts places when multiplied or divided by these powers of 10, providing a visual and intuitive understanding of the process.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6fLNcGSa_L4.mp4/6fLNcGSa_L4.mp4</video:content_loc><video:duration>285</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/strategies-for-multiplying-multiples-of-10-100-and-1000</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x392b1ef21a44a7ad.jpg</video:thumbnail_loc><video:title>Strategies for multiplying multiples of 10, 100 and 1000</video:title><video:description>Learn the strategy of estimating in multi-digit multiplication. Watch how to multiply numbers expressed in hundreds, thousands, or tens. Practice this skill by multiplying numbers together and estimating the result, reinforcing their understanding of place value and multiplication.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/iFy0oH-3Pn4.mp4/iFy0oH-3Pn4.mp4</video:content_loc><video:duration>400</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/estimate-multiplying-multi-digit-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa2131c43fbbd8687.jpg</video:thumbnail_loc><video:title>Estimating multi-digit multiplication</video:title><video:description>Learn the skill of estimating the product of multi-digit numbers. Watch a demonstration of the process. The video emphasizes the importance of estimation in simplifying complex multiplication problems</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/plzbnyvdaIQ.mp4/plzbnyvdaIQ.mp4</video:content_loc><video:duration>158</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/multiplying-multi-digit-numbers-6742x23</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x459e2edf1621b728.jpg</video:thumbnail_loc><video:title>Multiplying multi-digit numbers: 6,742x23</video:title><video:description>Learn the standard algorithm for multi-digit multiplication. Watch as the instructor breaks down the process step by step, demonstrating how to multiply each digit and carry over numbers.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lH6ptl4_LCE.mp4/lH6ptl4_LCE.mp4</video:content_loc><video:duration>229</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/more-intuition-on-multiplying-decimals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5cf28b71.jpg</video:thumbnail_loc><video:title>Multiplying decimals: place value</video:title><video:description>Sal uses an understanding of place value to multiply 2.91x3.2.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4IWfJ7-CYfE.mp4/4IWfJ7-CYfE.mp4</video:content_loc><video:duration>389</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/developing-strategies-for-multiplying-two-digit-decimals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc41352bc8de609ea.jpg</video:thumbnail_loc><video:title>Developing strategies for multiplying 2-digit decimals</video:title><video:description>Learn to multiply decimals by treating them as fractions. Practice converting decimals to fractions and then multiplying like usual. Then convert the fractions back to decimals to solve!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ekDTjvF_CJw.mp4/ekDTjvF_CJw.mp4</video:content_loc><video:duration>224</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/minutes-to-hours</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x42f6e58c.jpg</video:thumbnail_loc><video:title>Converting units: minutes to hours</video:title><video:description>Learn how to convert minutes to hours by dividing the minutes by 60. We demonstrate dividing 549 minutes by 60, resulting in 9.15 hours. The video also shows how to express the answer as a mixed number (9 and 3/20).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DLno3b-Xsmo.mp4/DLno3b-Xsmo.mp4</video:content_loc><video:duration>294</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/ordering-metric-distances</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9eceeaf0.jpg</video:thumbnail_loc><video:title>Converting units: metric distance</video:title><video:description>Learn all about converting different metric units to a common unit, in this case, meters. Understand the prefixes like deca, hecto, kilo, milli, and centi, and how they relate to the base unit, meter. This helps us compare and order different measurements.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/mI84WDfhuYA.mp4/mI84WDfhuYA.mp4</video:content_loc><video:duration>242</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/cm-to-meters</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc6caed89.jpg</video:thumbnail_loc><video:title>Converting units: centimeters to meters</video:title><video:description>Learn how to convert centimeters to meters by understanding the meaning of the &quot;centi&quot; prefix, which represents 1/100. We convert 37 centimeters to meters by dividing by 100, resulting in 0.37 meters.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6bQ6HJsAv4A.mp4/6bQ6HJsAv4A.mp4</video:content_loc><video:duration>184</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/converting-gallons-to-quarts-pints-and-cups</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26.jpg</video:thumbnail_loc><video:title>Converting units: US volume</video:title><video:description>Learn how to convert US Customary units of volume (gallons, quarts, pints, and cups). We see the conversion process using an example of converting 3 and 1/2 gallons into cups, emphasizing the relationships between the units.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4uQtJDf7drU.mp4/4uQtJDf7drU.mp4</video:content_loc><video:duration>317</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/unit-conversion-with-fractions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/153770144.jpg</video:thumbnail_loc><video:title>Same length in different units</video:title><video:description>The video dives into the concept of converting US customary units, specifically yards to inches. It emphasizes the importance of understanding the relationships between different units of measurement and demonstrates multiple methods for performing these conversions, including using improper fractions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jFSenp9ueaI.mp4/jFSenp9ueaI.mp4</video:content_loc><video:duration>348</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/unit-word-problem-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xacbe5af6.jpg</video:thumbnail_loc><video:title>Measurement word problem: tea party</video:title><video:description>The video explores the concept of converting metric units within a real-world context. It emphasizes the importance of understanding and applying conversion factors, particularly between milliliters and liters, to solve multi-step problems.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PdHSs5_kx24.mp4/PdHSs5_kx24.mp4</video:content_loc><video:duration>245</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/solving-application-problems-involving-units-of-volume</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/28.jpg</video:thumbnail_loc><video:title>Measurement word problem: blood drive</video:title><video:description>The video dives into the concept of converting units within the US Customary system. It emphasizes the process of moving from smaller units (like pints) to larger ones (like gallons), and how this affects the quantity. It&apos;s all about understanding the relationships between different units of measurement.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/KgoXx_58QyQ.mp4/KgoXx_58QyQ.mp4</video:content_loc><video:duration>209</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/unit-conversion-word-problem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0307b297.jpg</video:thumbnail_loc><video:title>Measurement word problem: distance home</video:title><video:description>Explore the concept of converting units within the US customary system, specifically focusing on how to apply this skill to solve multi-step, real-world problems. Understand the relationships between different units and using that knowledge to navigate complex scenarios.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ZS1OZj_oWao.mp4/ZS1OZj_oWao.mp4</video:content_loc><video:duration>254</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/application-problems-involving-units-of-weight</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25.jpg</video:thumbnail_loc><video:title>Measurement word problem: elevator</video:title><video:description>This video dives into the concept of converting units within the U.S. Customary system. It emphasizes the importance of understanding how different units relate to each other and how to use these relationships to solve real-world problems. It also highlights the process of converting mixed numbers to improper fractions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gnCL_0uA6Ds.mp4/gnCL_0uA6Ds.mp4</video:content_loc><video:duration>428</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/converting-units-of-length</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/22.jpg</video:thumbnail_loc><video:title>Measurement word problem: running laps</video:title><video:description>Understand how to convert units within the US Customary system to solve word problems. Learn about the importance of having all measurements in the same units to accurately solve problems, and demonstrates how to convert between miles, feet, and yards to determine the solution.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/AGFO-ROxH_I.mp4/AGFO-ROxH_I.mp4</video:content_loc><video:duration>484</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/strategies-for-dividing-multiples-of-10-100-and-1000</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb1da7c0dc673d13c.jpg</video:thumbnail_loc><video:title>Strategies for dividing multiples of 10, 100, and 1000</video:title><video:description>Learn the concept of multi-digit division estimation. Watch and understand how to divide numbers that are multiples of 10, 100, and 1000.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/dejocl4sYfw.mp4/dejocl4sYfw.mp4</video:content_loc><video:duration>428</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/approximating-multi-digit-division</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8200e92d374e17e1.jpg</video:thumbnail_loc><video:title>Estimating multi-digit division</video:title><video:description>Learn the concept of estimating multi-digit division problems. Watch examples of how to round numbers to make division easier and practice this skill through guided and independent exercises.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PssLxfFqHoA.mp4/PssLxfFqHoA.mp4</video:content_loc><video:duration>155</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/introduction-to-dividing-by-2-digits</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe3ac590d12d186bd.jpg</video:thumbnail_loc><video:title>Introduction to dividing by 2-digits</video:title><video:description>Learn the art of dividing by two-digit numbers. Watch how to approximate numbers for easier division and practice this skill with examples. The video emphasizes the importance of trial and error in learning multi-digit division.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/KzdbThwGNGI.mp4/KzdbThwGNGI.mp4</video:content_loc><video:duration>297</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/dividing-2-digits-no-remainder</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa5043558.jpg</video:thumbnail_loc><video:title>Dividing by 2-digits: 9815÷65</video:title><video:description>In this math lesson, we learn the process of dividing large numbers, specifically 9,815 divided by 65. The technique involves estimation, multiplication, and subtraction to find the quotient. By following these steps, we discover that the result is 151.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/uCBm8iDyg1s.mp4/uCBm8iDyg1s.mp4</video:content_loc><video:duration>309</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/dividing-by-a-two-digit-number</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0cf3f261.jpg</video:thumbnail_loc><video:title>Dividing by 2-digits: 7182÷42</video:title><video:description>Dividing large numbers by two-digit numbers can be done step by step. Start by fitting the divisor into each part of the dividend, then subtract and bring down the next digit. Estimate the number of times the divisor fits into the new number, and repeat the process until there&apos;s no remainder. This method simplifies complex division problems.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xXIG8ouHcsc.mp4/xXIG8ouHcsc.mp4</video:content_loc><video:duration>169</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/dividing-by-a-2-digit-number-with-a-remainder</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x77b881e5e805a7d9.jpg</video:thumbnail_loc><video:title>Dividing by 2-digits: 4781÷32</video:title><video:description>Learn about dividing large numbers by two-digit numbers can be done step by step. Start by fitting the divisor into each part of the dividend, then subtract and bring down the next digit. Estimate the number of times the divisor fits into the new number, and repeat the process until there&apos;s no remainder.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/cSTRd8WOpNE.mp4/cSTRd8WOpNE.mp4</video:content_loc><video:duration>253</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/approximating-dividing-by-decimals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbb2207b0bf54fcc8.jpg</video:thumbnail_loc><video:title>Estimating decimal division</video:title><video:description>Estimating in decimal division involves rounding numbers to make calculations easier. Practice rounding decimals to the nearest whole number or a simple fraction, then perform the division. This won&apos;t yield an exact result, but a close approximation, which can be useful in many real-life situations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xGbrcOF8Z98.mp4/xGbrcOF8Z98.mp4</video:content_loc><video:duration>176</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/5th-engage-ny/v/multi-digit-division-strategies-for-decimals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x94b7a32c8a78d6d5.jpg</video:thumbnail_loc><video:title>Multi-digit division strategies for decimals</video:title><video:description>Sal uses understanding of place value, expanded form, and fractions to help divide with decimals.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/bRRtp9XdDrY.mp4/bRRtp9XdDrY.mp4</video:content_loc><video:duration>306</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/divide-whole-numbers-with-decimal-quotients-7812</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x66052bb48b026436.jpg</video:thumbnail_loc><video:title>Divide whole numbers with decimal quotients: 78÷12</video:title><video:description>Practice the concept of dividing whole numbers to get a decimal quotient. Learn how to break down division problems by finding multiples and using remainders. It also shows how to simplify fractions and convert them into decimals.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/shSrtFE2OoM.mp4/shSrtFE2OoM.mp4</video:content_loc><video:duration>256</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/pattern-when-dividing-by-tenths-and-hundredths</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb46866692e98d206.jpg</video:thumbnail_loc><video:title>Pattern when dividing by tenths and hundredths</video:title><video:description>This video explores the concept of dividing whole numbers by decimals. It emphasizes the idea that dividing by a decimal like 0.1 or 0.01 is the same as multiplying by 10 or 100, respectively. It uses the strategy of converting whole numbers to tenths or hundredths to make the process clearer.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/W6OAc7NKrSI.mp4/W6OAc7NKrSI.mp4</video:content_loc><video:duration>286</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/visually-adding-fractions-with-unlike-denominators</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2656f61f.jpg</video:thumbnail_loc><video:title>Visually adding fractions: 5/6+1/4</video:title><video:description>To add two fractions with different denominators, you need to find the least common multiple of the denominators. You can then rewrite both fractions with this common denominator, which will allow you to add the numerators together. In the example given, 5/6 and 1/4 are rewritten as 10/12 and 3/12, respectively, resulting in a sum of 13/12.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/fvtv2uYjo_E.mp4/fvtv2uYjo_E.mp4</video:content_loc><video:duration>340</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/visually-subtracting-fractions-with-unlike-denominators</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xcb71b9b2.jpg</video:thumbnail_loc><video:title>Visually subtracting fractions: 3/4-5/8</video:title><video:description>Learn about understanding how to add and subtract fractions with unlike denominators. Practice finding a common denominator, and demonstrates how to visually represent these operations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/poGjjX_VNbM.mp4/poGjjX_VNbM.mp4</video:content_loc><video:duration>226</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/adding-small-fractions-with-unlike-denominators</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbf78b82a.jpg</video:thumbnail_loc><video:title>Adding fractions with unlike denominators</video:title><video:description>Learn how to add two fractions with different denominators. It can be challenging to combine fractions when the denominators don&apos;t match. It is important to find a common denominator. Finally, the resource shows how to find a common multiple of the two denominators in order to convert the fractions so they can be added together.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/bcCLKACsYJ0.mp4/bcCLKACsYJ0.mp4</video:content_loc><video:duration>444</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/subtracting-small-fractions-with-unlike-denominators</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8c50f6df.jpg</video:thumbnail_loc><video:title>Subtracting fractions with unlike denominators</video:title><video:description>To subtract fractions with different denominators, you need to find a common denominator. This can be done by identifying the least common multiple of the two denominators. After rewriting the fractions so they both have the common denominator, you can subtract the numerators as you would with any two fractions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2DPivVFCdqA.mp4/2DPivVFCdqA.mp4</video:content_loc><video:duration>301</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/adding-fractions-with-unlike-denominators-word-problem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1a5c8db9.jpg</video:thumbnail_loc><video:title>Adding fractions word problem: paint</video:title><video:description>Learn how to add and subtract fractions with unlike denominators through a real-world problem. Watch as the problem is broken down step-by-step, practice finding common denominators, and apply this knowledge to determine if the sum or difference of the fractions meets a specific requirement.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PKh5B9xyzSc.mp4/PKh5B9xyzSc.mp4</video:content_loc><video:duration>347</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/subtracting-fractions-with-unlike-denominators-word-problem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x39fd4ded.jpg</video:thumbnail_loc><video:title>Subtracting fractions word problem: tomatoes</video:title><video:description>Learn how to solve word problems involving the addition and subtraction of fractions with unlike denominators. Watch examples being worked out step-by-step, and practice applying the same techniques to solve similar problems.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5fK8HEYNRuQ.mp4/5fK8HEYNRuQ.mp4</video:content_loc><video:duration>199</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/adding-subtracting-mixed-numbers-1-ex-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/915061485.jpg</video:thumbnail_loc><video:title>Adding mixed numbers: 19 3/18 + 18 2/3</video:title><video:description>To add two mixed numbers, you can separate the whole number and fraction parts. Add the whole numbers together as you normally would, and then find a common denominator to add the fractions. Once you have your sum, you may need to simplify the fraction for your final answer.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8Eb5MWwcMMY.mp4/8Eb5MWwcMMY.mp4</video:content_loc><video:duration>141</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/adding-subtracting-mixed-numbers-1-ex-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/915104659.jpg</video:thumbnail_loc><video:title>Subtracting mixed numbers: 7 6/9 - 3 2/5</video:title><video:description>We can subtract two mixed numbers, by converting them to improper fractions. First, multiply the whole number by the denominator and add the numerator to get the improper fraction. Find a common denominator and adjust the numerators accordingly. Subtract the two improper fractions, and simplify the result if possible. Finally, convert the improper fraction back to a mixed number if desired</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/zR3gaFobut4.mp4/zR3gaFobut4.mp4</video:content_loc><video:duration>151</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/adding-mixed-numbers-with-regrouping</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe92731e8.jpg</video:thumbnail_loc><video:title>Adding mixed numbers with regrouping</video:title><video:description>Learn how to add and subtract mixed numbers with unlike denominators. Watch the process of finding a common denominator, converting mixed numbers to improper fractions, and adding or subtracting these fractions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/I01O0r8b-po.mp4/I01O0r8b-po.mp4</video:content_loc><video:duration>308</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/subtracting-mixed-numbers-with-regrouping</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x203af9d9.jpg</video:thumbnail_loc><video:title>Subtracting mixed numbers with regrouping (unlike denominators)</video:title><video:description>To subtract mixed numbers, first align the whole numbers and fractions so they can be subtracted separately. If the fractions have different denominators, find a common denominator and convert them accordingly. If the fraction on the bottom is larger, regroup by borrowing from the whole number on top. This will allow you to complete the subtraction.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/r3M68V9Joac.mp4/r3M68V9Joac.mp4</video:content_loc><video:duration>231</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/adding-and-subtracting-multiple-fractions-with-unlike-denominators</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfee69324.jpg</video:thumbnail_loc><video:title>Adding and subtracting 3 fractions</video:title><video:description>Learn how to add and subtract fractions with unlike denominators. They watch the process of finding a common denominator, then practice adding and subtracting the fractions to solve the problems.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/HSf9O1Domms.mp4/HSf9O1Domms.mp4</video:content_loc><video:duration>323</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/solving-for-the-missing-fraction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa75acfc8.jpg</video:thumbnail_loc><video:title>Solving for the missing fraction</video:title><video:description>Learn how to add and subtract fractions with unlike denominators. Watch examples, practice finding common denominators, and apply these skills to solve problems.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OPpmp-kAuE4.mp4/OPpmp-kAuE4.mp4</video:content_loc><video:duration>340</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/redistributing-trail-mix</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf5dd90fb.jpg</video:thumbnail_loc><video:title>Line plot distribution: trail mix</video:title><video:description>Explore how to interpret data on line plots, specifically focusing on measurements in fractions of a unit. Understand how to redistribute values evenly across a set, and emphasizes the importance of understanding fractions and their operations in this context.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DtWovvMnPrk.mp4/DtWovvMnPrk.mp4</video:content_loc><video:duration>368</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/fractions-as-division</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdbd32e53.jpg</video:thumbnail_loc><video:title>Understanding fractions as division</video:title><video:description>In this video, we learn about the relationship between multiplication and division. Let&apos;s watch how they can undo each other. We can understand this concept with whole numbers and fractions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/c-_yrA-GUow.mp4/c-_yrA-GUow.mp4</video:content_loc><video:duration>404</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/fractions-division-mixed-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf050e223.jpg</video:thumbnail_loc><video:title>Creating mixed numbers with fraction division</video:title><video:description>Learn how to interpret fractions as division problems. Watch examples of how to break down fractions into whole numbers and remainders. Then see Sal practice turning these into mixed numbers.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/g8yk6zQDAek.mp4/g8yk6zQDAek.mp4</video:content_loc><video:duration>310</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/mappers/v/my-share-of-soap-as-a-mixed-number-on-a-number-line</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x851dfbb8.jpg</video:thumbnail_loc><video:title>Mixed numbers on a number line</video:title><video:description>Sal locates 3/2 on a number line.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/V8C15AfL6Gk.mp4/V8C15AfL6Gk.mp4</video:content_loc><video:duration>151</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/creating-a-fraction-through-division-of-whole-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x28264782.jpg</video:thumbnail_loc><video:title>Creating a fraction through division</video:title><video:description>In this video, we&apos;ll learn about the relationship between division and multiplication using fractions. Watch how dividing by a number is the same as multiplying by its reciprocal. Then watch as Sal practices this concept using a fun, everyday example.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Mcm0Q3wGhMo.mp4/Mcm0Q3wGhMo.mp4</video:content_loc><video:duration>165</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/multiplying-fractions-by-whole-numbers-on-the-number-line</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd0821124.jpg</video:thumbnail_loc><video:title>Multiplying fractions by whole numbers on a number line</video:title><video:description>We can multiply fractions by whole numbers on the number line. We multiply them by adding the fraction multiple times, just like we do with whole numbers.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/QDvKqUc7Mj4.mp4/QDvKqUc7Mj4.mp4</video:content_loc><video:duration>111</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/concept-fraction-whole-number-product</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xab5f5140.jpg</video:thumbnail_loc><video:title>Multiplying fractions and whole numbers</video:title><video:description>Multiplying fractions is about combining parts of a whole. When you multiply two fractions together, you&apos;re taking a part of a part. When you multiply a fraction by a whole number, you&apos;re taking multiple copies of that fraction. In both cases, the result is a new fraction that represents a different part of a whole.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/HiNrFT280_Y.mp4/HiNrFT280_Y.mp4</video:content_loc><video:duration>174</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/constructing-numerical-expressions-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x926c9fdf.jpg</video:thumbnail_loc><video:title>Constructing numerical expressions</video:title><video:description>Sometimes, we don&apos;t need to solve an equation right away. Instead, we can use the information in a given word problem to construct a numerical expression that represents the information.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/arY-EUZDNfk.mp4/arY-EUZDNfk.mp4</video:content_loc><video:duration>82</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/visualizing-fraction-products</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x52cf91fc.jpg</video:thumbnail_loc><video:title>Multiplying 2 fractions: fraction model</video:title><video:description>Visuals can be used to multiply fractions in a variety of ways, such as by using fraction models. By drawing rectangles and dividing them into equal parts, we can use an area model to multiply fractions. help to illustrate how the numerators and denominators of the two fractions interact to produce a product.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hr_mTd-oJ-M.mp4/hr_mTd-oJ-M.mp4</video:content_loc><video:duration>297</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/concept-fraction-mult-number-line</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa40b230b.jpg</video:thumbnail_loc><video:title>Multiplying 2 fractions: number line</video:title><video:description>Learn the concept of multiplying fractions by fractions. Watch as the process is visually represented on a number line, helping to understand the &apos;why&apos; behind the procedure.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lJdb4_Fuxvw.mp4/lJdb4_Fuxvw.mp4</video:content_loc><video:duration>286</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/multiplying-fractions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/2600759.jpg</video:thumbnail_loc><video:title>Multiplying 2 fractions: 5/6 x 2/3</video:title><video:description>When multiplying fractions, you first start with the two fractions you want to multiply. You multiply the numerators (the top numbers) together, and then multiply the denominators (the bottom numbers) together. After putting the two results together as a new fraction, you may need to simplify the fraction in order to express it in its lowest terms.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/CTKMK1ZGLuk.mp4/CTKMK1ZGLuk.mp4</video:content_loc><video:duration>146</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/multiplying-mixed-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/2600760.jpg</video:thumbnail_loc><video:title>Multiplying mixed numbers</video:title><video:description>Multiplying mixed numbers is similar to multiplying whole numbers, except that you have to account for the fractional parts as well. By converting mixed numbers into improper fractions, you can multiply the two numbers together in a straightforward way. Once you have the product as an improper fraction, you can convert it back into a mixed number.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/RPhaidW0dmY.mp4/RPhaidW0dmY.mp4</video:content_loc><video:duration>261</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/multiplying-fractions-word-problem-4</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe872bdba.jpg</video:thumbnail_loc><video:title>Multiplying fractions word problem: laundry</video:title><video:description>Learn how to solve word problems involving multiplication of fractions. Watch examples of real-life scenarios where fractions are multiplied, and practice applying the concept to solve similar problems.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/KCehC_3CBBY.mp4/KCehC_3CBBY.mp4</video:content_loc><video:duration>80</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/multiplying-fractions-word-problem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/2600762.jpg</video:thumbnail_loc><video:title>Multiplying fractions word problem: muffins</video:title><video:description>Learn how to solve word problems involving the multiplication of fractions. Watch an example of a real-life scenario where fractions need to be multiplied, and then practice applying this concept to similar problems.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/YJgIGwTysk0.mp4/YJgIGwTysk0.mp4</video:content_loc><video:duration>219</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/multiplying-fractions-word-problem-5</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6ac69445.jpg</video:thumbnail_loc><video:title>Multiplying fractions word problem: bike</video:title><video:description>This video is all about understanding how to multiply fractions and mixed numbers. Watch as the steps are explained in a simple and fun way.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tfjQVtOyoaQ.mp4/tfjQVtOyoaQ.mp4</video:content_loc><video:duration>231</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/multiplication-as-scaling</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc436768c.jpg</video:thumbnail_loc><video:title>Multiplication as scaling with fractions</video:title><video:description>Learn about the concept of multiplication as scaling. Watch and understand how multiplying fractions can be seen as scaling, or resizing, the value of a number. Visualize this concept with various examples, reinforcing their understanding of multiplication as a scaling process.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/yUYDhmQsiXY.mp4/yUYDhmQsiXY.mp4</video:content_loc><video:duration>306</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/visually-dividing-whole-numbers-by-unit-fractions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5fa67069d4745396.jpg</video:thumbnail_loc><video:title>Visually dividing whole numbers by unit fractions</video:title><video:description>In this video, you&apos;ll learn how to divide whole numbers by fractions. You&apos;ll watch examples of dividing wholes into fractional pieces and practice counting those pieces. It&apos;s all about understanding how many fractional parts make up a whole.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0lsDqvH5mDs.mp4/0lsDqvH5mDs.mp4</video:content_loc><video:duration>148</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/example-dividing-a-whole-by-a-unit-fraction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8eae16da06ae1019.jpg</video:thumbnail_loc><video:title>Dividing a whole number by a unit fraction</video:title><video:description>In this video, we&apos;ll learn how to divide a whole number by a fraction. We&apos;ll watch as three whole units are divided into sections, each being one-fourth of a whole. Then see practice problems counting these sections to understand the result of the division.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/b26JxSoZvic.mp4/b26JxSoZvic.mp4</video:content_loc><video:duration>112</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/visually-dividing-unit-fraction-by-a-whole-number</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x845b796cc34be653.jpg</video:thumbnail_loc><video:title>Visually dividing unit fraction by a whole number</video:title><video:description>Learn how to divide fractions by whole numbers. You&apos;ll watch how dividing a fraction into smaller parts changes the denominator. Then, you&apos;ll practice this concept with examples to understand how dividing fractions works.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/RygpFkLCSaM.mp4/RygpFkLCSaM.mp4</video:content_loc><video:duration>180</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/example-diving-a-unit-fraction-by-a-whole-number</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1f9a08b9ecfd5604.jpg</video:thumbnail_loc><video:title>Dividing a unit fraction by a whole number</video:title><video:description>Learn how to divide fractions by whole numbers. Watch as the instructor visually breaks down a fraction into smaller parts. Then, see practice problems that explain how division changes the value of the original fraction.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/QsDMlHW826U.mp4/QsDMlHW826U.mp4</video:content_loc><video:duration>145</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/mappers/v/dividing-a-whole-number-by-a-fraction-word-problem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x32074d93.jpg</video:thumbnail_loc><video:title>Dividing whole numbers by fractions: word problem</video:title><video:description>Learn to solve a word problem that involves dividing a whole number by a unit fraction.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xoXYirs2Mzw.mp4/xoXYirs2Mzw.mp4</video:content_loc><video:duration>152</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/mappers/v/dividing-a-fraction-by-a-whole-number-word-problem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xedf0d036.jpg</video:thumbnail_loc><video:title>Dividing fractions by whole numbers: studying</video:title><video:description>Learn to solve a word problem that involves dividing a unit fraction by a whole number.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/yb7lVnY_VCY.mp4/yb7lVnY_VCY.mp4</video:content_loc><video:duration>155</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/5th-engage-ny/v/rewriting-a-fraction-as-a-decimal</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfca0c1cc.jpg</video:thumbnail_loc><video:title>Rewriting a fraction as a decimal: 3/5</video:title><video:description>To convert a fraction to a decimal, one approach is to rewrite the fraction with a denominator that is a power of ten. This makes it simple to express the fraction as a decimal, with each place to the right of the decimal point corresponding to a different power of ten.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/XHLgY7Z3cb8.mp4/XHLgY7Z3cb8.mp4</video:content_loc><video:duration>240</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/5th-engage-ny/v/rewriting-fraction-as-a-decimal-to-the-hundredths-place</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf8dc2c7a.jpg</video:thumbnail_loc><video:title>Rewriting a fraction as a decimal: 21/60</video:title><video:description>Sal rewrites 21/60 as a decimal.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/E3OfSGjpDoI.mp4/E3OfSGjpDoI.mp4</video:content_loc><video:duration>229</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/translating-expressions-with-parentheses</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0ce997e7.jpg</video:thumbnail_loc><video:title>Translating expressions with parentheses</video:title><video:description>Dive into the world of writing mathematical expressions from verbal statements. Understand the importance of parentheses in expressions, and how they can change the meaning of calculations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ypxHVqE26gI.mp4/ypxHVqE26gI.mp4</video:content_loc><video:duration>551</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/how-we-measure-volume</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x153d2046.jpg</video:thumbnail_loc><video:title>Volume intro</video:title><video:description>Finding volume, length, and area all involve measuring dimensions in order to quantify a certain aspect of an object or space. Although each property requires different calculations, they all rely on the same fundamental principle: taking measurements and using those measurements to derive a numerical value. When finding volume, you are measuring the amount of space that an object occupies.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xMz9WFvox9g.mp4/xMz9WFvox9g.mp4</video:content_loc><video:duration>471</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/measuring-volume-with-unit-cubes</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x10cbe797.jpg</video:thumbnail_loc><video:title>Measuring volume with unit cubes</video:title><video:description>Explore the concept of volume, emphasizing that it&apos;s a measure of how much space something takes up. Practice the idea of measuring volume in cubic units, like cubic feet or cubic inches, by counting the number of unit cubes that fit into a 3D shape.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7WloKabLhII.mp4/7WloKabLhII.mp4</video:content_loc><video:duration>133</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/measuring-volume-as-area-times-length</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf932dab5.jpg</video:thumbnail_loc><video:title>Measuring volume as area times length</video:title><video:description>To calculate the volume of a rectangular prism, you can multiply the dimensions (width, depth, and height) together in any order. For example, a prism that is 2cm wide, 3cm deep, and 4cm tall has a volume of 24 cubic centimeters.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/daCT_24RnIY.mp4/daCT_24RnIY.mp4</video:content_loc><video:duration>442</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/volume-of-a-rectangular-prism-or-box-examples</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x46bdaeef.jpg</video:thumbnail_loc><video:title>Volume of a rectangular prism</video:title><video:description>If you want to know how much stuff you can cram into a box, finding its volume is key. To calculate the volume of a box, you need to know its height, width, and depth. You can find the volume by multiplying these three dimensions together. This formula works regardless of the units you are using (e.g. meters, feet), he method is the same - just make sure your units match up!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/I9efKVtLCf4.mp4/I9efKVtLCf4.mp4</video:content_loc><video:duration>119</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/volume-in-unit-cubes-by-decomposing-shape</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xad903af7.jpg</video:thumbnail_loc><video:title>Volume in unit cubes by decomposing shape</video:title><video:description>Explore the concept of decomposing complex shapes into simpler ones to calculate volume. Understand volume as additive and how to use multiplication of length, width, and height to find the volume of rectangular prisms. Learn how you can approach the same problem differently.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gm87omItizk.mp4/gm87omItizk.mp4</video:content_loc><video:duration>199</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/volume-through-decomposition</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe8255aad.jpg</video:thumbnail_loc><video:title>Volume through decomposition</video:title><video:description>Explore the concept of finding the volume of complex shapes by decomposing them into simpler, non-overlapping rectangular prisms. Understand the additive nature of volume and demonstrates how to calculate the volume of each prism separately before adding them together for the total volume.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/feNWZEln6Nc.mp4/feNWZEln6Nc.mp4</video:content_loc><video:duration>229</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/volume-word-problem-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x21aac844.jpg</video:thumbnail_loc><video:title>Volume word problem: water tank</video:title><video:description>The video dives into the concept of volume, specifically focusing on how to calculate the volume of a complex shape by subtracting the volume of an object within it from the total volume. Understand the formula for volume and its application in real-world problems.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OanPzjf2EYY.mp4/OanPzjf2EYY.mp4</video:content_loc><video:duration>280</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/example-finding-area-with-fractional-sides</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x92847262.jpg</video:thumbnail_loc><video:title>Finding area with fractional sides 1</video:title><video:description>Learn how to calculate the area of rectangles with fractional side lengths. Watch examples of this concept in action and practice applying it to different problems. The video emphasizes understanding the process, not just getting the answer.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/C3RPDVGZdFw.mp4/C3RPDVGZdFw.mp4</video:content_loc><video:duration>227</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/intuition-for-area-with-fractional-side-lengths</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9635a341.jpg</video:thumbnail_loc><video:title>Finding area with fractional sides 2</video:title><video:description>Learn how to calculate the area of rectangles with fractional side lengths. Watch examples of this concept in action, and then see practice problems applying what was shown to solve similar problems.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/UmSe4rh__iU.mp4/UmSe4rh__iU.mp4</video:content_loc><video:duration>422</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/kites-as-a-mathematical-shape</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1b577232.jpg</video:thumbnail_loc><video:title>Kites as a geometric shape</video:title><video:description>The video dives into the world of quadrilaterals, specifically focusing on kites. It explores how kites are defined by two pairs of adjacent, congruent sides. It also highlights that the diagonals of a kite intersect at a 90-degree angle, with one line bisecting the other.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/inlMrf2d-k4.mp4/inlMrf2d-k4.mp4</video:content_loc><video:duration>338</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/introduction-to-the-coordinate-plane</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb7cbc96672feae0c.jpg</video:thumbnail_loc><video:title>Introduction to the coordinate plane</video:title><video:description>When we use coordinates to locate a point on a coordinate plane, we use two numbers to specify the horizontal (x) and vertical (y) positions. The first number in a coordinate pair tells us how far to move left or right from the origin, while the second number tells us how far to move up or down.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pAlq9fFwtus.mp4/pAlq9fFwtus.mp4</video:content_loc><video:duration>408</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/graphing-points-exercise</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xba8b84ab.jpg</video:thumbnail_loc><video:title>Coordinate plane: graphing points</video:title><video:description>The video is all about understanding the basics of the coordinate plane. It explains how to plot points using ordered pairs, with the first number indicating the horizontal (x-axis) movement and the second number showing the vertical (y-axis) movement.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4vNloi-zNjU.mp4/4vNloi-zNjU.mp4</video:content_loc><video:duration>141</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/relationships-between-patterns</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xee7958b1.jpg</video:thumbnail_loc><video:title>Graphing patterns on coordinate plane</video:title><video:description>Learn about understanding numerical patterns. Explore how to generate a second pattern from a given one by applying a rule, in this case, multiplying by 3 and adding 1. Then, graph the pairs of corresponding terms from both patterns on a coordinate plane.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ayRpoJgph0E.mp4/ayRpoJgph0E.mp4</video:content_loc><video:duration>156</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/interpreting-relationships-between-patterns</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3ddc5e72.jpg</video:thumbnail_loc><video:title>Interpreting patterns on coordinate plane</video:title><video:description>Explore the concept of numerical patterns, focusing on how to generate, identify, and graph them on a coordinate plane. Understand the relationship between corresponding terms in two different patterns, and how changes in one pattern affect the other.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/HXg_a9oJ5nA.mp4/HXg_a9oJ5nA.mp4</video:content_loc><video:duration>271</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/interpreting-and-graphing-relationships-between-patterns</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x81be10de.jpg</video:thumbnail_loc><video:title>Interpreting relationships in ordered pairs</video:title><video:description>Explore the concept of numerical patterns, focusing on how to generate, identify, and graph these patterns on a coordinate plane. Understand the relationships between corresponding terms in two different patterns and how these relationships can be represented as ordered pairs.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Muba9-W2FOQ.mp4/Muba9-W2FOQ.mp4</video:content_loc><video:duration>273</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/sequence-relationship-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2d028899.jpg</video:thumbnail_loc><video:title>Graphing sequence relationships</video:title><video:description>Explore the concept of numerical patterns. Understand how to generate two sequences using given rules, identify relationships between corresponding terms, form ordered pairs from these terms, and graph these pairs on a coordinate plane.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/mqsIJucBn6c.mp4/mqsIJucBn6c.mp4</video:content_loc><video:duration>148</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/interpreting-plotted-points</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf713557ca61b7328.jpg</video:thumbnail_loc><video:title>Interpreting plotted points</video:title><video:description>The video explores the concept of interpreting data points on a coordinate plane. It emphasizes understanding the relationship between the x and y axes, in this case, representing hours of exercise and screen time.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9EEJU4Ox-TE.mp4/9EEJU4Ox-TE.mp4</video:content_loc><video:duration>156</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/coordinate-plane-word-problem-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4eee6cc3.jpg</video:thumbnail_loc><video:title>Coordinate plane graphing word problem</video:title><video:description>The video dives into the concept of using a coordinate plane to solve real-world problems. It emphasizes how to plot points on the plane and interpret their values, and how to calculate the distance between two points by counting blocks in both the horizontal and vertical directions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_QKR8I5VE-w.mp4/_QKR8I5VE-w.mp4</video:content_loc><video:duration>126</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/rounding-whole-numbers-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/2600662.jpg</video:thumbnail_loc><video:title>Rounding whole numbers to nearest ten</video:title><video:description>Sal rounds 1585 to the nearest ten.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3jBfLaLrk6I.mp4/3jBfLaLrk6I.mp4</video:content_loc><video:duration>64</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/multiplication-2-the-multiplication-tables</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23826.jpg</video:thumbnail_loc><video:title>Multiplication tables for 2-9</video:title><video:description>Introduction to the multiplication &apos;times tables&apos; from 2-9.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xO_1bYgoQvA.mp4/xO_1bYgoQvA.mp4</video:content_loc><video:duration>927</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/multiplication-6-multiple-digit-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23834.jpg</video:thumbnail_loc><video:title>Multiplying multi-digit numbers</video:title><video:description>Sal shows lots of examples for how to multiply 2- and 3-digit numbers using &quot;standard algorithm&quot;.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-h3Oqhl8fPg.mp4/-h3Oqhl8fPg.mp4</video:content_loc><video:duration>627</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
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<url><loc>https://puzzicle.org/math/5th-grade-foundations-engageny/v/adding-subtracting-mixed-numbers-0-5-ex-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/915206106.jpg</video:thumbnail_loc><video:title>Adding mixed numbers with like denominators</video:title><video:description>Think of a mixed numbers as a number AND a fraction. You can add numbers....you can add fractions with like denominators. Therefore, you can add mixed numbers! Watch.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/EGy1W24EPEI.mp4/EGy1W24EPEI.mp4</video:content_loc><video:duration>95</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
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<url><loc>https://puzzicle.org/math/arithmetic-home/v/multiplication-word-problem-example-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf30d0482.jpg</video:thumbnail_loc><video:title>Multiplication word problem: carrots</video:title><video:description>Multiplication word problem: carrots from Arithmetic (all content)</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/fZtUn_THXnk.mp4/fZtUn_THXnk.mp4</video:content_loc><video:duration>152</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/division-word-problem-example-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4aef016e.jpg</video:thumbnail_loc><video:title>Division word problem: row boat</video:title><video:description>Division word problem: row boat from Arithmetic (all content)</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Z3qRkxzmYnU.mp4/Z3qRkxzmYnU.mp4</video:content_loc><video:duration>108</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
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<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/multiplication-and-division-relationship-for-fractions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x060e4e6d013f18ba.jpg</video:thumbnail_loc><video:title>Multiplication and division relationship for fractions</video:title><video:description>We learn how multiplication and division are related, even when we&apos;re dealing with fractions. Watch how dividing by a number is the same as multiplying by its reciprocal. Then watch Sal practice expressing these relationships using both division and multiplication.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jXA-nMI4Nt4.mp4/jXA-nMI4Nt4.mp4</video:content_loc><video:duration>215</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/5th-grade-math-ny-next-gen/v/drawing-an-area-model-for-the-product-of-two-unit-fractions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0aa96eba85cb8677.jpg</video:thumbnail_loc><video:title>Drawing an area model for the product of two unit fractions</video:title><video:description>A conceptual overview on how to draw an area model that represents a unit fraction of a unit fraction and compare and contrast diagrams.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/o4Lbf7-ffKM.mp4/o4Lbf7-ffKM.mp4</video:content_loc><video:duration>271</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
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<url><loc>https://puzzicle.org/math/5th-grade-math-ny-next-gen/v/fraction-multiplication-area-model-to-expression</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe77b60a5c7741bce.jpg</video:thumbnail_loc><video:title>Fraction multiplication: area model to expression</video:title><video:description>Learn how to represent an area model with a multiplication expression involving a unit fraction and a non-unit fraction.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/IP-M2bXt0HI.mp4/IP-M2bXt0HI.mp4</video:content_loc><video:duration>157</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/5th-grade-math-ny-next-gen/v/fraction-multiplication-expression-to-area-model</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9ff3a1e5536cce4d.jpg</video:thumbnail_loc><video:title>Fraction multiplication: expression to area model</video:title><video:description>Learn how to represent a multiplication expression involving a unit fraction and a non-unit fraction with an area model.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/W4oNi8fmnD4.mp4/W4oNi8fmnD4.mp4</video:content_loc><video:duration>162</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/fraction-division-in-context</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8d7dcf069da61a33.jpg</video:thumbnail_loc><video:title>Fraction division in context</video:title><video:description>In this video, learn how to divide fractions by whole numbers. Watch examples of real-life situations where this skill is useful. We&apos;ll practice dividing a fraction by a whole number to solve problems.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/dnZ0fykw_w0.mp4/dnZ0fykw_w0.mp4</video:content_loc><video:duration>202</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/dividing-fractions-and-whole-number-word-problems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x08d1dc45a957f1e5.jpg</video:thumbnail_loc><video:title>Dividing fractions and whole number word problems</video:title><video:description>This video uses tape diagrams to visually represent division with fractions. It shows how to divide a fraction or a whole number into equal parts. Tape diagrams help us see the process in a clear, simple way.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/HUT8eL1sGhk.mp4/HUT8eL1sGhk.mp4</video:content_loc><video:duration>266</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/5th-grade-math-eureka-squared-aligned/v/multiplying-3-digit-by-2-digit-with-area-models</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2f347bb7d138ac30.jpg</video:thumbnail_loc><video:title>Multiplying 3-digit by 2-digit with area models</video:title><video:description>A worked example showing how to use a diagram to help calculate the product of a 3-digit number and a 2-digit number.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pkYBNJDxWPQ.mp4/pkYBNJDxWPQ.mp4</video:content_loc><video:duration>290</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/5th-grade-math-eureka-squared-aligned/v/multiplying-3-digit-by-2-digit-with-partial-products</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x875486c7b01a97c6.jpg</video:thumbnail_loc><video:title>Multiplying 3 digit by 2 digit with partial products</video:title><video:description>A worked example that shows how to multiply a 3-digit number by a 2-digit number with partial products and make a connection between the area model and the written strategy.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2ru0A_ico_0.mp4/2ru0A_ico_0.mp4</video:content_loc><video:duration>372</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/5th-grade-illustrative-mathematics/v/multiplying-3-digit-by-2-digit-comparing-standard-algorithm-to-partial-products</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0d363a5abe0eb912.jpg</video:thumbnail_loc><video:title>Multiplying 3-digit by 2-digit: comparing standard algorithm to partial products</video:title><video:description>A worked example that shows how to use the standard algorithm to multiply a 3-digit number by a 2-digit number, without composing new units.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/bELurwZ4MLg.mp4/bELurwZ4MLg.mp4</video:content_loc><video:duration>250</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/5th-grade-math-ny-next-gen/v/multiplying-3-digit-by-2-digit-numbers-error-analysis</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x49df1a8b6640cd56.jpg</video:thumbnail_loc><video:title>Multiplying 3-digit by 2-digit numbers: Error analysis</video:title><video:description>Find the error while multiplying 3-digit by 2-digit numbers by checking each step.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/GartEps0cLc.mp4/GartEps0cLc.mp4</video:content_loc><video:duration>108</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/5th-grade-math-ny-next-gen/v/3-digit-by-2-digit-multiplication-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbd04650ac6d626db.jpg</video:thumbnail_loc><video:title>Multiplying 3-digit by 2-digit numbers</video:title><video:description>Multiply 3 digit by 2 digit whole numbers to find a product using the standard algorithm.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3e7WGi_CeAw.mp4/3e7WGi_CeAw.mp4</video:content_loc><video:duration>144</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/5th-grade-illustrative-mathematics/v/estimating-multi-digit-multiplication-word-problems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbc9ee07100febec8.jpg</video:thumbnail_loc><video:title>Estimating multi-digit multiplication word problems</video:title><video:description>Use estimation as a strategy to solve multi-digit multiplication word problems.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/s9pPN7r_cuU.mp4/s9pPN7r_cuU.mp4</video:content_loc><video:duration>129</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/partial-quotient-division</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/258726800.jpg</video:thumbnail_loc><video:title>Partial quotient method of division: introduction</video:title><video:description>Sal demonstrates an alternate to traditional long division that uses estimation</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/R486L0M5cWk.mp4/R486L0M5cWk.mp4</video:content_loc><video:duration>507</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/5th-grade-math-eureka-squared-aligned/v/dividing-by-2-digit-numbers-using-partial-quotients</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x97fe1de016611803.jpg</video:thumbnail_loc><video:title>Dividing 3-digit by 2-digit numbers using partial quotients</video:title><video:description>Learn how to use the partial quotient algorithm to divide a 3-digit number by a 2-digit number. Sal shows two ways to solve the same problem.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/JtORV2GLkPI.mp4/JtORV2GLkPI.mp4</video:content_loc><video:duration>255</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/5th-grade-math-eureka-squared-aligned/v/dividing-4-digit-by-2-digit-numbers-using-partial-quotients</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf6be7d497f8dcf4a.jpg</video:thumbnail_loc><video:title>Dividing 4 digit by 2 digit numbers using partial quotients</video:title><video:description>Worked example showing how to use the partial quotient algorithm to divide a 4-digit number by a 2-digit number.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tpkGUBZ1lJY.mp4/tpkGUBZ1lJY.mp4</video:content_loc><video:duration>404</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/5th-grade-math-eureka-squared-aligned/v/estimating-multi-digit-division-word-problems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc9ae109226c9f0ca.jpg</video:thumbnail_loc><video:title>Estimating multi-digit division word problems</video:title><video:description>Practice using estimation as a strategy to solve multi-digit division word problems.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Ag0zq7TImyY.mp4/Ag0zq7TImyY.mp4</video:content_loc><video:duration>153</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/decimal-intuition-with-grids</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x193de4d9.jpg</video:thumbnail_loc><video:title>Writing decimal numbers shown in grids</video:title><video:description>Sal uses grid diagrams to determine what decimal is represented by a shaded area.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/s9PvbFG2yJA.mp4/s9PvbFG2yJA.mp4</video:content_loc><video:duration>186</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/decimal-multiplication-with-grids</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x25376d934f4123f1.jpg</video:thumbnail_loc><video:title>Decimal multiplication with grids</video:title><video:description>Learn how to use a hundred grid to represent decimal multiplication. Use both vertical and horizontal tenths to represent each multiplier and then use the overlapping areas to find the product.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3Phgu3ExLmY.mp4/3Phgu3ExLmY.mp4</video:content_loc><video:duration>153</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/visually-dividing-a-whole-number-by-a-decimal</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa5be050b00312c10.jpg</video:thumbnail_loc><video:title>Visually dividing a whole number by a decimal</video:title><video:description>This video is all about understanding how to divide whole numbers by decimals. It emphasizes the concept of partitioning whole numbers into equal groups of a certain decimal value, and counting how many of those groups we can make.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/aklVb3Z5jx4.mp4/aklVb3Z5jx4.mp4</video:content_loc><video:duration>152</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/dividing-a-whole-number-by-a-decimal-on-a-number-line</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf5b795a8d75bec5d.jpg</video:thumbnail_loc><video:title>Dividing a whole number by a decimal on a number line</video:title><video:description>Explore the concept of dividing whole numbers by decimals on a number line. Understand the process as making jumps on a number line. Each jump represents a decimal value, and the goal is to determine how many jumps it takes to reach a certain whole number.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PxafebH1u2k.mp4/PxafebH1u2k.mp4</video:content_loc><video:duration>114</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/dividing-whole-numbers-by-decimals-examples</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbf41064ead1d20c8.jpg</video:thumbnail_loc><video:title>Dividing whole numbers by decimals examples</video:title><video:description>One approach to dividing whole numbers by decimals is to convert both numbers into the same base, such as tenths or hundredths. Another technique is to multiply the numerator and denominator to eliminate the decimal from the denominator.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/se7rSl-tHkg.mp4/se7rSl-tHkg.mp4</video:content_loc><video:duration>278</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/visually-dividing-decimal-by-whole-number</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdfb155f57387494f.jpg</video:thumbnail_loc><video:title>Dividing a decimal by a whole number with fraction models</video:title><video:description>The video explores the concept of dividing decimals by whole numbers. It emphasizes visualizing the process, using the idea of converting tenths to hundredths to make division more intuitive.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/rYsK3mI0Nto.mp4/rYsK3mI0Nto.mp4</video:content_loc><video:duration>129</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/dividing-a-decimal-by-a-whole-number-on-the-number-line</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x72b5fb2edf65ed05.jpg</video:thumbnail_loc><video:title>Dividing a decimal by a whole number on the number line</video:title><video:description>The video explores the concept of dividing decimals by whole numbers. It emphasizes understanding division as splitting a quantity into equal parts, and uses the number line as a visual tool to demonstrate this. Then connects this concept to real-world situations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7Wm0VOTPz5Q.mp4/7Wm0VOTPz5Q.mp4</video:content_loc><video:duration>89</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/dividing-a-decimal-by-a-whole-number-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x731aff4073850df2.jpg</video:thumbnail_loc><video:title>Dividing a decimal by a whole number example</video:title><video:description>To divide a decimal by a whole number, you can convert the decimal into a certain number of hundredths. After dividing the whole number into those hundredths, you can then convert the result back into a decimal form.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/bIRwzhhBzEU.mp4/bIRwzhhBzEU.mp4</video:content_loc><video:duration>176</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/regrouping-decimals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x68f5d2be774432d5.jpg</video:thumbnail_loc><video:title>Regrouping with decimals</video:title><video:description>Explore the concept of expressing decimals in different forms. Delve into place value, regrouping, and how to represent the same decimal number in different ways using whole numbers. It&apos;s all about flexibility in understanding decimals!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vZmR_21Dwrg.mp4/vZmR_21Dwrg.mp4</video:content_loc><video:duration>275</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/regrouping-with-decimals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5bceab99.jpg</video:thumbnail_loc><video:title>Regrouping with decimals: 21.3</video:title><video:description>Practice the concept of representing decimals in different forms. Learn about place values, and how regrouping can change the appearance of a number, but not its value.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3szFVS5p_7A.mp4/3szFVS5p_7A.mp4</video:content_loc><video:duration>255</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
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<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/subtracting-fractions-with-unlike-denominators-introduction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdd18d17581f8b2b4.jpg</video:thumbnail_loc><video:title>Subtracting fractions with unlike denominators introduction</video:title><video:description>Learn how to subtract fractions with unlike denominators. Watch the process of finding a common denominator, converting the fractions, and then performing the subtraction.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/SMshimc16LM.mp4/SMshimc16LM.mp4</video:content_loc><video:duration>216</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/fraction-multiplication-as-scaling-examples</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf9a493ca7b9a3264.jpg</video:thumbnail_loc><video:title>Fraction multiplication as scaling examples</video:title><video:description>Learn the concept of multiplication as scaling. Watch examples of how multiplying by a fraction scales a number up or down. Understand that fractions between zero and one make numbers smaller, while fractions greater than one make numbers larger.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/WLvbz6m2Syw.mp4/WLvbz6m2Syw.mp4</video:content_loc><video:duration>218</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/5th-grade-math-ny-next-gen/v/comparing-products-without-multiplying-fractions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5dca92ba20cfea62.jpg</video:thumbnail_loc><video:title>Comparing products without multiplying (fractions)</video:title><video:description>Learn how to compare the value of products between a fraction and a whole number without calculating.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lMcKPVhHI7w.mp4/lMcKPVhHI7w.mp4</video:content_loc><video:duration>87</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/multiplying-and-dividing-decimals-by-10</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3691632a4964cdc0.jpg</video:thumbnail_loc><video:title>Multiplying and dividing decimals by 10</video:title><video:description>This video explores the concept of multiplying and dividing decimals by 10, 100, and 1000. It demonstrates how each digit in a number shifts places when multiplied or divided by powers of 10. The video emphasizes understanding place values and how they change in these operations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/HeiYNlVM-TY.mp4/HeiYNlVM-TY.mp4</video:content_loc><video:duration>243</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
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<url><loc>https://puzzicle.org/math/5th-grade-math-eureka-squared-aligned/v/adding-and-subtracting-3-fractions-indian-accent</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x84fe62877914aea0.jpg</video:thumbnail_loc><video:title>Adding and subtracting 3 fractions</video:title><video:description>Learn how to add and subtract fractions with unlike denominators. They watch the process of finding a common denominator, then practice adding and subtracting the fractions to solve the problems.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0O3IG5u_GUk.mp4/0O3IG5u_GUk.mp4</video:content_loc><video:duration>310</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
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<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/one-step-equation-intuition</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/948578231.jpg</video:thumbnail_loc><video:title>One-step equations intuition</video:title><video:description>In this math lesson, we learn how to solve a balance scale problem with unknown mass. We represent the problem using an algebraic equation, 3x = 9, where x is the unknown mass. By dividing both sides by 3, we find that x = 3, meaning each object has a mass of 3 kilograms.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/kbqO0YTUyAY.mp4/kbqO0YTUyAY.mp4</video:content_loc><video:duration>279</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
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<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/subtracting-decimals-word-problem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1811.jpg</video:thumbnail_loc><video:title>Adding &amp; subtracting decimals word problem</video:title><video:description>In this math lesson, we learn how to manage a bank account balance by adding and subtracting money with decimals. We start with an initial balance, deposit an amount, and then withdraw cash. By performing these calculations, we determine the final account balance.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hy_bDS3aHO4.mp4/hy_bDS3aHO4.mp4</video:content_loc><video:duration>139</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/5th-grade-math-eureka-squared-aligned/v/solving-two-step-word-problems-with-decimals-adding-and-subtracting</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf811ff94362342e7.jpg</video:thumbnail_loc><video:title>Solving two-step word problems with decimals (adding and subtracting)</video:title><video:description>Practice solving two-step word problems that involve decimals. Use different strategies that either add and subtract, subtract then subtract, or subtract and then add.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1c0bHes5eF4.mp4/1c0bHes5eF4.mp4</video:content_loc><video:duration>218</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/dividing-decimals-completely</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa1b83aaa.jpg</video:thumbnail_loc><video:title>Dividing decimals completely</video:title><video:description>Dividing decimals can be made easier by converting them into whole numbers. To do this, multiply both decimals by the same power of 10. Then, perform long division with the new whole numbers. For example, dividing 6.3 by 0.25 becomes 630 divided by 25, resulting in an answer of 25.2.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7JPIX3odZrY.mp4/7JPIX3odZrY.mp4</video:content_loc><video:duration>404</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/5th-grade-math-eureka-squared-aligned/v/understanding-decimal-multiplication-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1b1a4e6108c6c05c.jpg</video:thumbnail_loc><video:title>Understanding decimal multiplication</video:title><video:description>Practice using estimation as a strategy to better understand decimal multiplication. Use the product of whole numbers to help determine the product of decimals with the samedigits in the same order.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LWE3n23M_m0.mp4/LWE3n23M_m0.mp4</video:content_loc><video:duration>238</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/5th-grade-math-eureka-squared-aligned/v/reasoning-through-multiplying-decimal-word-problems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc223d3fd99fa1c7f.jpg</video:thumbnail_loc><video:title>Reasoning through multiplying decimal word problems</video:title><video:description>Practice using estimation and thoughtful reasoning to relate multiplying decimals to multiplying whole numbers.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/JEZB9ARqyw8.mp4/JEZB9ARqyw8.mp4</video:content_loc><video:duration>276</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/5th-grade-math-eureka-squared-aligned/v/intro-to-quadrilateral-indian-accent</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x938b7bcf345fc617.jpg</video:thumbnail_loc><video:title>Intro to quadrilateral</video:title><video:description>There are many different types of quadrilaterals. A quadrilateral is defined as a two-dimensional shape with four sides, four vertices, and four angles. There are two main types: concave and convex. There are also various subcategories of convex quadrilaterals, such as trapezoids, parallelograms, rectangles, rhombi, and squares.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Xb8QJqe347k.mp4/Xb8QJqe347k.mp4</video:content_loc><video:duration>493</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
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<url><loc>https://puzzicle.org/math/5th-grade-math-eureka-squared-aligned/v/volume-of-a-rectangular-prism-indian-accent</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x102bb681a75d2956.jpg</video:thumbnail_loc><video:title>Volume of a rectangular prism</video:title><video:description>If you want to know how much stuff you can cram into a box, finding its volume is key. To calculate the volume of a box, you need to know its height, width, and depth. You can find the volume by multiplying these three dimensions together. This formula works regardless of the units you are using (e.g. meters, feet), he method is the same - just make sure your units match up!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tsyxs2DtRqA.mp4/tsyxs2DtRqA.mp4</video:content_loc><video:duration>119</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
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<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/dividing-fractions-word-problem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/2600767.jpg</video:thumbnail_loc><video:title>Dividing whole numbers &amp; fractions: t-shirts</video:title><video:description>In this math problem, we learn how to calculate the number of baby T-shirts that can be made from 48 yards of fabric. Each T-shirt requires 4/5 yards of fabric. By dividing 48 yards by 4/5 and simplifying, we find out that 60 baby T-shirts can be produced from the given fabric.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PQsgXNggV7Q.mp4/PQsgXNggV7Q.mp4</video:content_loc><video:duration>128</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/intro-to-multiplying-decimals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x634fb6a8.jpg</video:thumbnail_loc><video:title>Intro to multiplying decimals</video:title><video:description>Multiplying decimals is easy and fun! To multiply 9 by 0.6, first rewrite 0.6 as 6 divided by 10. Next, multiply 9 by 6, which equals 54. Finally, divide 54 by 10 by moving the decimal point one place left, resulting in the answer 5.4. Practice makes perfect in mastering decimal multiplication!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/STyoP3rCmb0.mp4/STyoP3rCmb0.mp4</video:content_loc><video:duration>230</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/order-operations-intro</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2b14c51a7861494c.jpg</video:thumbnail_loc><video:title>Order of operations introduction</video:title><video:description>The order of operations is a crucial math concept that ensures consistent results when solving problems with multiple operations. By following PEMDAS (Parentheses, Exponents, Multiplication and Division, and Addition and Subtraction), students can accurately evaluate expressions and avoid common mistakes. Mastering this skill is essential for success in mathematics.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/eoYThjIAhOc.mp4/eoYThjIAhOc.mp4</video:content_loc><video:duration>273</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/more-complicated-order-of-operations-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25759.jpg</video:thumbnail_loc><video:title>Worked example: Order of operations (PEMDAS)</video:title><video:description>The order of operations (PEMDAS) is essential for solving complex math problems. PEMDAS stands for Parentheses, Exponents, Multiplication and Division (same level), and Addition and Subtraction (same level). By following these steps, you can simplify and accurately solve mathematical expressions, ensuring a correct final answer.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/piIcRV2dx7E.mp4/piIcRV2dx7E.mp4</video:content_loc><video:duration>320</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-fifth-grade-math/v/u-s-customary-and-metric-units</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/29.jpg</video:thumbnail_loc><video:title>U.S. customary and metric units</video:title><video:description>This video dives into the world of measurement units, distinguishing between U.S. customary units and metric units. It explores how these units measure different aspects such as length, weight, mass, and volume.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/y2RHWA7t0WM.mp4/y2RHWA7t0WM.mp4</video:content_loc><video:duration>310</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/ratios-intro</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc75b04f2.jpg</video:thumbnail_loc><video:title>Intro to ratios</video:title><video:description>The video explains ratios, which show the relationship between two quantities. Using apples and oranges as an example, it demonstrates how to calculate and reduce ratios (6:9 to 2:3) and how to reverse the ratio (9:6 to 3:2).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/bIKmw0aTmYc.mp4/bIKmw0aTmYc.mp4</video:content_loc><video:duration>238</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/ratio-example-problems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1ee2e077f63d32e9.jpg</video:thumbnail_loc><video:title>Basic ratios</video:title><video:description>In this video, the instructor explains ratios using three examples: amusement park ride lines, Katie&apos;s book collection, and a picture of apples and bananas. Ratios compare two quantities and can be written as &quot;a to b&quot; or &quot;a:b.&quot; The video demonstrates how to find and interpret ratios in various situations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/IjMn7f6bbLA.mp4/IjMn7f6bbLA.mp4</video:content_loc><video:duration>173</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/ratios-as-fractions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x771cad22.jpg</video:thumbnail_loc><video:title>Part:whole ratios</video:title><video:description>In this video, we explore ratios using apples and oranges. We find the simplified ratio of apples to total fruit (2:5) and learn to represent ratios as fractions (2/5). The fraction indicates that 2/5 of the fruit are apples. Key definitions include ratio, simplified ratio, and fraction notation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/UK-_qEDtvYo.mp4/UK-_qEDtvYo.mp4</video:content_loc><video:duration>202</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/equivalent-ratios</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb0b46e6a60931f92.jpg</video:thumbnail_loc><video:title>Equivalent ratios</video:title><video:description>One way to identify equivalent ratios is to determine if you can multiply or divide the corresponding parts of the ratio by the same amount. To do this, look at the two ratios and see if there is a common factor that you can use to scale one ratio to the other. If you can scale one ratio to the other by multiplying or dividing every part of the ratio by the same number, then the two ratios are equivalent.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/eb-GHXCqkhQ.mp4/eb-GHXCqkhQ.mp4</video:content_loc><video:duration>283</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/ratios-for-recipes</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2427758b379e98c9.jpg</video:thumbnail_loc><video:title>Equivalent ratios: recipe</video:title><video:description>Adjusting a cake recipe for different guest numbers involves understanding ratios. Halving ingredients for a smaller cake maintains the same ratio, like eggs to flour (4:3). Ratios ensure consistent taste and quality, regardless of cake size.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/VWO1m0S-a9Y.mp4/VWO1m0S-a9Y.mp4</video:content_loc><video:duration>291</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/ratio-word-problem-examples</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x03004af138555a6d.jpg</video:thumbnail_loc><video:title>Equivalent ratio word problems</video:title><video:description>This video teaches solving ratio word problems, using examples like Yoda Soda for guests, fish ratios in a tank, ice cream sundae ingredients, and dog color ratios at a park. Mastering these techniques helps students tackle real-world math challenges.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/WoZ7-wOy-0w.mp4/WoZ7-wOy-0w.mp4</video:content_loc><video:duration>362</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/understanding-equivalent-ratios</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9b0248c0620f3be9.jpg</video:thumbnail_loc><video:title>Understanding equivalent ratios</video:title><video:description>Sal discusses what it means for two ratios to be equivalent.Comparing ratios is essential for determining equivalent relationships between quantities. By analyzing and simplifying ratios, we can identify if they have the same proportion, helping us make decisions in real-life situations like mixing paint colors or comparing food recipes.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4S3Mbl0JrdY.mp4/4S3Mbl0JrdY.mp4</video:content_loc><video:duration>345</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/ratios-and-double-number-lines</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x64933af9b96eb772.jpg</video:thumbnail_loc><video:title>Ratios and double number lines</video:title><video:description>Double number lines are a helpful tool for understanding and solving ratio problems. They visually represent the relationship between two quantities, making it easier to find the cost or amount of a single unit. Examples include calculating the price of avocados, building model trains, and making snowballs.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-Dg9da1BGsM.mp4/-Dg9da1BGsM.mp4</video:content_loc><video:duration>353</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/solving-ratio-problems-with-tables-exercise</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xcfd31e75.jpg</video:thumbnail_loc><video:title>Solving ratio problems with tables</video:title><video:description>Equivalent ratios have the same relationship between their numerators and denominators. To find missing values in tables, maintain the same ratio. Comparing fractions is easier with common numerators or denominators. Constant speed is represented by a constant ratio between distance and time.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/MaMk6-f3T9k.mp4/MaMk6-f3T9k.mp4</video:content_loc><video:duration>305</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/ratios-with-tape-diagrams</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2db404d5087f60bc.jpg</video:thumbnail_loc><video:title>Ratios with tape diagrams</video:title><video:description>In the video, we explore ratios, which compare two quantities. We learn to find missing values using given ratios and discover equivalent ratios by multiplying or dividing both parts by the same number. Key examples include quilts, paint mixtures, and spells cast by characters.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/suRIY3ULrQo.mp4/suRIY3ULrQo.mp4</video:content_loc><video:duration>270</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/ratios-and-measurement</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4ec0f20cc0f50644.jpg</video:thumbnail_loc><video:title>Ratios and measurement</video:title><video:description>Learn to complete ratio tables and solve unit conversion problems with examples like hours to weeks, yards to miles, millimeters to feet, and dollars per pound to dollars per ounce. Master these techniques to tackle real-world problems with ease.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0qtIHdda19s.mp4/0qtIHdda19s.mp4</video:content_loc><video:duration>417</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/ratios-on-coordinate-plane</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9e49f2b3548a01a6.jpg</video:thumbnail_loc><video:title>Ratios on coordinate plane</video:title><video:description>Ratios represent the relationship between two quantities and can be visualized on a graph. When the ratio is constant, the points form a straight line, illustrating the connection between the quantities. Examples include bakers using flour, car wash charges, and earnings from shoveling snow.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/yVYJRT5hTSo.mp4/yVYJRT5hTSo.mp4</video:content_loc><video:duration>312</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/ratio-word-problem-exercise-example-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xde4f6af2.jpg</video:thumbnail_loc><video:title>Part to whole ratio word problem using tables</video:title><video:description>Discover how to solve ratio problems with a real-life example involving indoor and outdoor playtimes. Learn to use ratios to determine the number of indoor and outdoor playtimes in a class with a 2:3 ratio and 30 total playtimes.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ZJ6y8OVJRw8.mp4/ZJ6y8OVJRw8.mp4</video:content_loc><video:duration>155</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/introduction-to-rates</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x102d9798.jpg</video:thumbnail_loc><video:title>Intro to rates</video:title><video:description>Rates are essential in understanding everyday situations, such as speed, wages, and food consumption. They help us measure and compare quantities, like miles per hour or calories per serving. Rates are closely related to ratios and play a significant role in math subjects like algebra and calculus, making them crucial for problem-solving and analysis.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qGTYSAeLTOE.mp4/qGTYSAeLTOE.mp4</video:content_loc><video:duration>330</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/finding-unit-rates</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1821.jpg</video:thumbnail_loc><video:title>Solving unit rate problem</video:title><video:description>Jayda delivers newspapers on her paper route, taking 3 hours to distribute 189 newspapers. To calculate her rate per hour, divide the total newspapers (189) by the hours taken (3). This results in Jayda delivering 63 newspapers per hour, showcasing her efficiency and speed.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Zm0KaIw-35k.mp4/Zm0KaIw-35k.mp4</video:content_loc><video:duration>151</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/finding-unit-prices</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1822.jpg</video:thumbnail_loc><video:title>Solving unit price problem</video:title><video:description>Nierria earns $75 for tutoring 4 hours. To find her hourly rate, we divide her total earnings by the number of hours worked. By calculating 75 divided by 4, we discover that Nierria makes $18.75 per hour for her tutoring services.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/rpGGMSFO6Ks.mp4/rpGGMSFO6Ks.mp4</video:content_loc><video:duration>116</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/rate-problems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa309573541a756a7.jpg</video:thumbnail_loc><video:title>Rate problems</video:title><video:description>In this math lesson, we learn to find unit rates and use them to solve problems. We first calculate the rate for one unit, like cars washed per day or cost per battery. Then, we multiply the unit rate by the desired quantity to find the answer. This method simplifies complex problems and helps us understand real-world situations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/fpjXtpg_isc.mp4/fpjXtpg_isc.mp4</video:content_loc><video:duration>270</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/practice-computing-and-comparing-rates</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc67f0ee5.jpg</video:thumbnail_loc><video:title>Comparing rates example</video:title><video:description>A conservationist thinks that squirrels exhibit higher aggression rates when crowded together. To test this, they compare three parks with different squirrel populations and areas. By calculating squirrels per hectare, they find Park C to be the most crowded, followed by Park B and Park A. The conservationist expects the highest aggression rate in Park C due to its crowdedness.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/C7bBZa52h-4.mp4/C7bBZa52h-4.mp4</video:content_loc><video:duration>430</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/describing-the-meaning-of-percent</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/4802229.jpg</video:thumbnail_loc><video:title>The meaning of percent</video:title><video:description>In this math lesson, we learn about percentages by shading 20% of a square. The square is divided into 100 smaller squares in a 10x10 grid. To represent 20%, we shade 20 of these smaller squares, which can be done by coloring two rows of 10 squares each. This visual approach helps us understand the concept of percentages.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Lvr2YsxG10o.mp4/Lvr2YsxG10o.mp4</video:content_loc><video:duration>181</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/describing-the-meaning-of-percent-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/4802230.jpg</video:thumbnail_loc><video:title>Meaning of 109%</video:title><video:description>In this lesson, we learn how to represent 109% using shading. We discover that 109% is equivalent to 109 per 100, or 109/100 as a fraction. By shading a complete 10x10 square and an additional 9 squares, we visually demonstrate 109% of a whole square.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/MokI3Fi8jpc.mp4/MokI3Fi8jpc.mp4</video:content_loc><video:duration>142</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/percent-from-fraction-models</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbd10d28340636b83.jpg</video:thumbnail_loc><video:title>Percents from fraction models</video:title><video:description>Converting fractions to percentages is a valuable skill in math. To do this, rewrite the fraction with a denominator of 100, as &quot;percent&quot; means &quot;per 100.&quot; For example, 7/10 equals 70/100, or 70%. Additionally, you can add percentages together, such as 100% + 80% = 180%.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/nV6bRozq5Po.mp4/nV6bRozq5Po.mp4</video:content_loc><video:duration>262</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/finding-percentages-with-a-double-number-line</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd916ed375a5a6d6e.jpg</video:thumbnail_loc><video:title>Finding percentages with a double number line</video:title><video:description>In this math problem, we determine the percentage of students taking the bus to school in a class of 28. By using a double number line, we find that 21 out of 28 students take the bus, which is 3/4 of the class. Converting this fraction to a percentage, we discover that 75% of the students ride the bus to school.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/bVNnQX5nEFg.mp4/bVNnQX5nEFg.mp4</video:content_loc><video:duration>132</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/finding-the-whole-with-a-tape-diagram</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x775680e37171e129.jpg</video:thumbnail_loc><video:title>Finding the whole with a tape diagram</video:title><video:description>Keisha can run 170 meters in one minute today, which is 125% of her distance from three years ago. To find her previous distance, we convert 125% to 5/4 and divide 170 by 5, obtaining 34 meters per fourth. Multiplying 34 by 4 reveals that Keisha could run 136 meters in one minute three years ago.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/M0vf7idRTLA.mp4/M0vf7idRTLA.mp4</video:content_loc><video:duration>184</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/fraction-decimal-and-percent-from-visual-model</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x722ac3f3a18ed682.jpg</video:thumbnail_loc><video:title>Fraction, decimal, and percent from visual model</video:title><video:description>Learn how to convert shaded parts of a square into fractions, decimals, and percentages with ease. Master the skill of representing parts of a whole in different formats, such as simplifying fractions, converting decimals to percentages, and understanding the relationship between them. Boost your math skills and gain confidence in solving real-world problems.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/wwg052FC_Zw.mp4/wwg052FC_Zw.mp4</video:content_loc><video:duration>213</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/representing-a-number-as-a-decimal-percent-and-fraction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/4802231.jpg</video:thumbnail_loc><video:title>Converting percents to decimals &amp; fractions example</video:title><video:description>Converting percentages to decimals and fractions is a fundamental math skill. To convert 18% into a decimal, simply divide by 100, resulting in 0.18. To express it as a simplified fraction, find the greatest common factor, which in this case is 2, and divide both the numerator and denominator by it, giving us 9/50.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-gB1y-PMWfs.mp4/-gB1y-PMWfs.mp4</video:content_loc><video:duration>212</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/taking-a-percentage-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc1057cd3.jpg</video:thumbnail_loc><video:title>Percent of a whole number</video:title><video:description>Discover how to calculate percentages with a simple example: finding 30% of 6. Learn two methods, using fractions and decimals, to solve this problem. Both approaches lead to the same result, showing that 30% of 6 equals 1.8. Master these techniques for everyday calculations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-lUEWEEpmIo.mp4/-lUEWEEpmIo.mp4</video:content_loc><video:duration>127</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/finding-percentages-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7d62667a.jpg</video:thumbnail_loc><video:title>Finding a percent</video:title><video:description>Discover how to calculate percentages with this simple method. First, write the problem as a fraction, then simplify it. Next, convert the fraction to a percentage by making the denominator 100. Alternatively, divide the numbers to get a decimal and multiply by 100 to find the percentage. Master this skill for everyday use.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/FaDtge_vkbg.mp4/FaDtge_vkbg.mp4</video:content_loc><video:duration>213</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/ways-to-rewrite-a-percentage</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x93ebe427634bd289.jpg</video:thumbnail_loc><video:title>Ways to rewrite a percentage</video:title><video:description>Discover how to calculate 2% of 90 using various methods, such as converting percentages to fractions and decimals. Learn to identify correct expressions, like 0.02 times 90 and 2/100 times 90, while eliminating incorrect options. Master percentage calculations with ease and confidence.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/MD5JUwAeg6c.mp4/MD5JUwAeg6c.mp4</video:content_loc><video:duration>120</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/common-percentages</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3f1d902f592c01a6.jpg</video:thumbnail_loc><video:title>Finding common percentages</video:title><video:description>Calculating percentages in your head is a valuable skill. Common percentages like 1%, 10%, 20%, 25%, 50%, and 400% can be easily converted into fractions (e.g., 1% = 1/100, 10% = 1/10). To find the percentage of a number, simply multiply or divide by the corresponding fraction, making mental math quick and efficient.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/GdwjpJwa8Ys.mp4/GdwjpJwa8Ys.mp4</video:content_loc><video:duration>172</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/6th-engage-ny/v/solving-percent-problems-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/15.jpg</video:thumbnail_loc><video:title>Percent word problem: 78 is 15% of what number?</video:title><video:description>In this example, you working with us to find the number that is expressed as a given percentage. We&apos;ll create a simple algebraic equation to solve!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DAikW24_O0A.mp4/DAikW24_O0A.mp4</video:content_loc><video:duration>326</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/another-percent-word-problem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23458.jpg</video:thumbnail_loc><video:title>Percent word problem: guavas</video:title><video:description>We&apos;re putting a little algebra to work to find the full price when you know the discount price in this percent word problem.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/d1oNF88SAgg.mp4/d1oNF88SAgg.mp4</video:content_loc><video:duration>378</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/6th-engage-ny/v/percent-word-problems-1-example-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd369a80b.jpg</video:thumbnail_loc><video:title>Percent word problem: penguins</video:title><video:description>You&apos;re given the percent in this example and asked to find the whole number represented by the percent.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gKywkLHV6Ko.mp4/gKywkLHV6Ko.mp4</video:content_loc><video:duration>209</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/percent-word-problems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x31086a98.jpg</video:thumbnail_loc><video:title>Percent word problem: recycling cans</video:title><video:description>In this math lesson, we learn how to calculate the percentage of recycled cans. Given that 13 out of 20 cans are recycled, we divide 13 by 20 to get 0.65 as a decimal. Multiplying by 100, we find that 65% of cans are recycled, promoting eco-friendly practices and waste reduction.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/AjYil74WrVo.mp4/AjYil74WrVo.mp4</video:content_loc><video:duration>169</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/conceptual-understanding-of-dividing-fractions-by-fractions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa415219d.jpg</video:thumbnail_loc><video:title>Understanding division of fractions</video:title><video:description>Dividing fractions can be understood using number lines and jumps. To divide a fraction like 8/3 by another fraction like 1/3, count the jumps of 1/3 needed to reach 8/3. Alternatively, multiply 8/3 by the reciprocal of the divisor (3/1) to get the same result. This concept applies to other fractions, such as dividing 8/3 by 2/3.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/f3ySpxX9oeM.mp4/f3ySpxX9oeM.mp4</video:content_loc><video:duration>342</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/visually-dividing-a-fraction-by-a-whole-number</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf31f2f8a16d13ba0.jpg</video:thumbnail_loc><video:title>Dividing a fraction by a whole number</video:title><video:description>Dividing fractions by whole numbers can be done visually or using multiplication. To find the result of 2/3 divided by 5, divide 2/3 into 5 equal parts, each representing 2/15 of the whole. Alternatively, multiply 2/3 by 1/5, resulting in 2/15 as the final answer.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1YWyTdtofdE.mp4/1YWyTdtofdE.mp4</video:content_loc><video:duration>233</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/meaning-of-the-reciprocal</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x442482abc85a2d5a.jpg</video:thumbnail_loc><video:title>Meaning of the reciprocal</video:title><video:description>Reciprocals are essential in understanding fractions. To find the reciprocal of a fraction, simply swap the numerator and the denominator. The product of a number and its reciprocal always equals 1. Reciprocals help us determine how many times a specific fraction fits into the whole number 1, making them valuable in various mathematical operations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/yM9Yrz69Tys.mp4/yM9Yrz69Tys.mp4</video:content_loc><video:duration>253</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/whole-number-divided-by-a-fraction-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x609f7c74bf7d7219.jpg</video:thumbnail_loc><video:title>Dividing a whole number by a fraction</video:title><video:description>Dividing a whole number by a fraction involves multiplying the whole number by the fraction&apos;s reciprocal. For example, when dividing 4 by 2/3, multiply 4 by 3/2, resulting in 12/2, which equals 6. This method demonstrates how many sections of the fraction fit into the whole number.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/SPMoNUAbV48.mp4/SPMoNUAbV48.mp4</video:content_loc><video:duration>185</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/dividing-a-whole-number-by-a-fraction-with-reciprocal</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5a6f5d30a8980c41.jpg</video:thumbnail_loc><video:title>Dividing a whole number by a fraction with reciprocal</video:title><video:description>Dividing by a fraction involves finding the reciprocal and multiplying. For example, when dividing 8 by 7/5, first find the reciprocal of 7/5, which is 5/7. Then, multiply 8 by 5/7, resulting in 40/7 or 5 5/7. This method simplifies fraction division and enhances understanding.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/G7c0CBLWVfs.mp4/G7c0CBLWVfs.mp4</video:content_loc><video:duration>216</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/another-dividing-fractions-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4829f4ea.jpg</video:thumbnail_loc><video:title>Dividing fractions: 2/5 ÷ 7/3</video:title><video:description>Dividing fractions is a breeze when you follow these simple steps! First, multiply the first fraction by the reciprocal of the second fraction. Then, multiply the numerators and denominators separately. Voila! You&apos;ve successfully divided two fractions and found your answer. Keep practicing to master this essential math skill.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/m-pRnFIeoNA.mp4/m-pRnFIeoNA.mp4</video:content_loc><video:duration>77</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/dividing-fractions-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/2600764.jpg</video:thumbnail_loc><video:title>Dividing fractions: 3/5 ÷ 1/2</video:title><video:description>Dividing two fractions is the same as multiplying the first fraction by the reciprocal of the second fraction. The first step to dividing fractions is to find the reciprocal (reverse the numerator and denominator) of the second fraction. Next, multiply the two numerators. Then, multiply the two denominators. Finally, simplify the fractions if needed.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tnkPY4UqJ44.mp4/tnkPY4UqJ44.mp4</video:content_loc><video:duration>216</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/dividing-mixed-numbers-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf6a074691b688e71.jpg</video:thumbnail_loc><video:title>Dividing mixed numbers</video:title><video:description>How do we divide mixed numbers? We can convert the mixed numbers to improper fractions, then simplify the division problem by finding the reciprocal of one of the fractions. This video also includes a demonstration of different ways of simplifying the final answer.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tj5AtYoKqvs.mp4/tj5AtYoKqvs.mp4</video:content_loc><video:duration>213</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/writing-fraction-division-story-problems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x402e317ef1ae977a.jpg</video:thumbnail_loc><video:title>Writing fraction division story problems</video:title><video:description>Darryl spent 24 1/4 hours writing a novel chapter, and we explore situations where dividing 24 1/4 by 3/4 is meaningful. Two examples include calculating the number of days spent writing with 45-minute daily sessions and determining the time spent illustrating if it&apos;s 3/4 as long as writing. Creative thinking helps uncover more scenarios.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/UEna8ZEy6k4.mp4/UEna8ZEy6k4.mp4</video:content_loc><video:duration>210</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/area-with-fraction-division-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9b2a4e6a30477412.jpg</video:thumbnail_loc><video:title>Area with fraction division example</video:title><video:description>Discover the length of a yoga mat with a width of 3/5 meters and an area of 1 and 2/25 square meters. Use the formula length = area ÷ width, convert mixed numbers to improper fractions, and simplify. The final dimensions are 3/5 meters wide and 9/5 meters long, perfect for your yoga practice!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6K6tQulp-x8.mp4/6K6tQulp-x8.mp4</video:content_loc><video:duration>199</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/subtracting-decimals-up-to-thousandths-place</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2147024f.jpg</video:thumbnail_loc><video:title>Subtracting decimals: 39.1 - 0.794</video:title><video:description>Learn to subtract decimals by aligning the decimal points and place values. Regroup numbers for easier subtraction, and then perform the subtraction for each place value. Mastering decimal subtraction helps build strong math skills and real-world problem-solving abilities.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lDXaju6JoQ0.mp4/lDXaju6JoQ0.mp4</video:content_loc><video:duration>126</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/subtracting-decimals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/4802228.jpg</video:thumbnail_loc><video:title>Subtracting decimals: 9.005 - 3.6</video:title><video:description>Subtracting decimals is simple when you line up the decimal points and fill in missing zeros. Regroup when needed by borrowing from the whole number and adding to the tenths place. Mastering this skill helps with everyday calculations and improves overall math understanding.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Eq4mVCd-yyo.mp4/Eq4mVCd-yyo.mp4</video:content_loc><video:duration>128</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/decimal-multiplication-place-value</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4aa02467fdcdfd15.jpg</video:thumbnail_loc><video:title>Decimal multiplication place value</video:title><video:description>When we rewrite decimal multiplication using fractions, we can use the commutative and associative properties of multiplication to justify how we place the decimal point in the standard multiplication algorithm.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hdKDVDjUHhs.mp4/hdKDVDjUHhs.mp4</video:content_loc><video:duration>279</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/more-involved-multiplying-decimals-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xad5ace08.jpg</video:thumbnail_loc><video:title>Multiplying challenging decimals</video:title><video:description>Learn to multiply decimals easily by treating them as whole numbers first. Multiply the numbers without decimals, then count the total decimal places in both original numbers. Add the same number of decimal places to the product, and you&apos;ll get the correct answer for the decimal multiplication.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/D5fmcpNygQk.mp4/D5fmcpNygQk.mp4</video:content_loc><video:duration>265</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/dividing-completely-to-get-decimal-answer</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb4d79b88.jpg</video:thumbnail_loc><video:title>Dividing whole numbers to get a decimal</video:title><video:description>In this math lesson, we learn how to divide two numbers and find a decimal answer. We divide 63 by 35, first getting a remainder of 28. To obtain a decimal result, we add a zero to 63, making it 63.0, and then divide 280 by 35. The final answer is 1.8.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xUDlKV8lJbM.mp4/xUDlKV8lJbM.mp4</video:content_loc><video:duration>157</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/dividing-a-whole-number-by-a-decimal</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7b24a2d9.jpg</video:thumbnail_loc><video:title>Dividing a whole number by a decimal</video:title><video:description>Dividing a whole number by a decimal can be simplified by multiplying both numbers by 10, shifting the decimal point to the right. For example, dividing 518 by 0.7 becomes 5,180 divided by 7. Using long division, the result is 740, making the process easier and more manageable.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/cfr-yZxTH8Y.mp4/cfr-yZxTH8Y.mp4</video:content_loc><video:duration>260</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/dividing-a-decimal-by-a-whole-number</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbe7ce751.jpg</video:thumbnail_loc><video:title>Dividing a decimal by a whole number</video:title><video:description>In this math lesson, we learn how to divide decimals using long division. The key is to place the decimal point correctly and treat it like a regular long division problem. By following these steps, we can easily divide 5.005 by 7, resulting in an answer of 0.715.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Z_NHrwK6ALE.mp4/Z_NHrwK6ALE.mp4</video:content_loc><video:duration>126</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/dividing-decimals-with-hundredths</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa7651d1e.jpg</video:thumbnail_loc><video:title>Dividing decimals with hundredths</video:title><video:description>Dividing decimals can be made simple by multiplying both numbers by the same amount to eliminate decimals. For example, when dividing 30.24 by 0.42, multiply both by 100 to get 3,042 divided by 42. Using long division, the final answer is 72, making the process easy and efficient.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Hrjr5f5pZ84.mp4/Hrjr5f5pZ84.mp4</video:content_loc><video:duration>277</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/long-division-with-decimals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x37e1024b.jpg</video:thumbnail_loc><video:title>Long division with decimals</video:title><video:description>How do we divide a decimal by another decimal? One great approach is first to turn both numbers into whole numbers before proceeding with the standard algorithm. Sal Khan shows us how to do this. When using long division, it is important to keep things organized and in neat columns!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/x48CYVaD0xE.mp4/x48CYVaD0xE.mp4</video:content_loc><video:duration>250</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/dividing-decimals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1814.jpg</video:thumbnail_loc><video:title>Dividing by a multi-digit decimal</video:title><video:description>Dividing decimals involves a few simple steps. First, convert the divisor into a whole number by shifting the decimal point to the right. Apply the same process to the dividend. Then, perform regular division with the new numbers. Finally, position the decimal point in the quotient to match the dividend.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Nqts8zW8RxM.mp4/Nqts8zW8RxM.mp4</video:content_loc><video:duration>332</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/6th-engage-ny/v/divisibility-tests-for-2-3-4-5-6-9-10</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1245177424.jpg</video:thumbnail_loc><video:title>Divisibility tests for 2, 3, 4, 5, 6, 9, 10</video:title><video:description>Worked example of basic divisibility tests.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Df9h5t64NlQ.mp4/Df9h5t64NlQ.mp4</video:content_loc><video:duration>393</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/6th-engage-ny/v/recognizing-divisibility</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/2600702.jpg</video:thumbnail_loc><video:title>Recognizing divisibility</video:title><video:description>Recognizing Divisibility.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2G_Jr_XpnY4.mp4/2G_Jr_XpnY4.mp4</video:content_loc><video:duration>386</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/6th-engage-ny/v/the-why-of-the-3-divisibility-rule</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/884395195.jpg</video:thumbnail_loc><video:title>The why of the 3 divisibility rule</video:title><video:description>Why you can add the digits to see if something is divisible by 3</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/NehkLV77ITk.mp4/NehkLV77ITk.mp4</video:content_loc><video:duration>303</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/6th-engage-ny/v/the-why-of-the-9-divisibility-rule</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1245280895.jpg</video:thumbnail_loc><video:title>The why of the 9 divisibility rule</video:title><video:description>Why you can test divisibility by 9 by just adding the digits</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/XAzFGx3Ruig.mp4/XAzFGx3Ruig.mp4</video:content_loc><video:duration>308</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/greatest-common-divisor-factor-exercise</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0fbf66ba.jpg</video:thumbnail_loc><video:title>Greatest common factor examples</video:title><video:description>The greatest common factor (GCF) of a set of numbers is the largest factor that all the numbers share. For example, 12, 20, and 24 have two common factors: 2 and 4. The largest is 4, so we say that the GCF of 12, 20, and 24 is 4. GCF is often used to find common denominators.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/bLTfBvkrfsM.mp4/bLTfBvkrfsM.mp4</video:content_loc><video:duration>410</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/greatest-common-divisor</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23860.jpg</video:thumbnail_loc><video:title>Greatest common factor explained</video:title><video:description>The greatest common divisor (GCD) and greatest common factor (GCF) are the same thing. To find the GCD/GCF of two numbers, list their factors, identify the common factors, and choose the largest one. For example, the GCD/GCF of 12 and 8 is 4. Numbers with a GCD/GCF of 1 are called relatively prime.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jFd-6EPfnec.mp4/jFd-6EPfnec.mp4</video:content_loc><video:duration>380</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/least-common-multiple-exercise</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x19e7b12a.jpg</video:thumbnail_loc><video:title>Least common multiple</video:title><video:description>The least common multiple (LCM) is the smallest number that two or more numbers can divide into evenly. To find the LCM, you can use the prime factorization method or list the multiples of each number. Prime factorization involves breaking down numbers into their prime factors and constructing the smallest number with all the factors. Listing multiples involves finding the smallest shared multiple. Both methods help find the LCM of numbers like 18 and 12.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/znmPfDfsir8.mp4/znmPfDfsir8.mp4</video:content_loc><video:duration>256</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/least-common-multiple-exercise-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xafe97682.jpg</video:thumbnail_loc><video:title>Least common multiple: repeating factors</video:title><video:description>To find the Least Common Multiple (LCM) of two integers, follow these steps: 1) Find the prime factorization of both numbers. 2) Determine which prime factors are needed for the least common multiple (LCM) to be divisible by both numbers. 3) Multiply the necessary prime factors together to get the least common multiple (LCM).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/QUem_2dkB9I.mp4/QUem_2dkB9I.mp4</video:content_loc><video:duration>155</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/least-common-multiple-lcm</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/158925086.jpg</video:thumbnail_loc><video:title>Least common multiple of three numbers</video:title><video:description>The least common multiple (LCM) is the smallest number that is a multiple of two or more numbers. To find the LCM, you can list the multiples of each number and find the smallest one they share, or use prime factorization to break down the numbers into their prime factors and multiply the highest powers of each factor.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/D6yHKOYJiso.mp4/D6yHKOYJiso.mp4</video:content_loc><video:duration>324</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/mappers/v/lcm-and-gcf-greatest-common-factor-word-problems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x59fe3ed2.jpg</video:thumbnail_loc><video:title>GCF &amp; LCM word problems</video:title><video:description>Here we have a couple of word problems--one searching for the least common multiple and the other for the greatest common factor. Just read them with us slowly and follow along. You&apos;ll get it.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1Vb8t7Y-pI0.mp4/1Vb8t7Y-pI0.mp4</video:content_loc><video:duration>514</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/introduction-to-negative-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb2e450a6862bb2df.jpg</video:thumbnail_loc><video:title>Introduction to negative numbers</video:title><video:description>Negative numbers are essential in math, representing values below zero. On a number line, they appear to the left of zero, opposite positive numbers. They&apos;re commonly used in real-world situations like measuring temperatures below freezing. Understanding negative numbers helps us grasp a broader range of mathematical concepts.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/u8UKdNdpkh4.mp4/u8UKdNdpkh4.mp4</video:content_loc><video:duration>184</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/positive-and-negative-decimals-on-a-number-line</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x72f595c1.jpg</video:thumbnail_loc><video:title>Negative decimals on the number line</video:title><video:description>In this fun math lesson, we learn to locate decimals on a number line. By understanding the scale and recognizing positive and negative numbers, we can accurately place dots at specific decimal points like -0.6, 1.9, and 0.5. This skill is essential for mastering decimals and building a strong foundation in math.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/w23DzA68KPE.mp4/w23DzA68KPE.mp4</video:content_loc><video:duration>75</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/points-on-a-number-line</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179310.jpg</video:thumbnail_loc><video:title>Decimals &amp; fractions on the number line</video:title><video:description>Plotting numbers on a number line is a fundamental math skill that helps visualize numerical values. Key points include identifying whole numbers, fractions, and decimals, and placing them accurately on the line. This skill enhances understanding of number relationships and builds a strong foundation for more advanced math concepts.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/uC09taczvOo.mp4/uC09taczvOo.mp4</video:content_loc><video:duration>118</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/mappers/v/number-line-3-exercise-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0546ae25.jpg</video:thumbnail_loc><video:title>Missing numbers on the number line examples</video:title><video:description>Given a few negative numbers on a number line, let&apos;s see if we can determine what negative numbers are elsewhere on the number line.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qW-Ce44ll0Q.mp4/qW-Ce44ll0Q.mp4</video:content_loc><video:duration>188</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/opposite-of-a-number</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe940cca2.jpg</video:thumbnail_loc><video:title>Number opposites</video:title><video:description>Opposites of numbers are essential in understanding number lines and basic math concepts. The opposite of a positive number is its negative counterpart, while the opposite of a negative number is its positive counterpart. Both numbers have the same absolute value but different signs, making them equally distant from zero on the number line.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2Zk6u7Uk5ow.mp4/2Zk6u7Uk5ow.mp4</video:content_loc><video:duration>192</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/negative-symbol-as-opposite</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x771c48fe.jpg</video:thumbnail_loc><video:title>Negative symbol as opposite</video:title><video:description>Opposites in math involve flipping the sign of a number. A positive number&apos;s opposite is the same number but negative, and vice versa. The negative symbol represents the concept of &quot;opposite.&quot; When multiple negative symbols are applied, each one flips the number across the number line, resulting in a positive or negative value.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3-aryZYsoxU.mp4/3-aryZYsoxU.mp4</video:content_loc><video:duration>302</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/compare-rational-numbers-using-a-number-line</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x050d9dcc5093a680.jpg</video:thumbnail_loc><video:title>Compare rational numbers using a number line</video:title><video:description>In this math tutorial, we learn to compare positive and negative numbers, decimals, and fractions using a number line. By visualizing the numbers on a number line, we can easily determine which number is greater or smaller. This method helps build a strong foundation in understanding number relationships and comparisons.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6h0Wi8Dcd0E.mp4/6h0Wi8Dcd0E.mp4</video:content_loc><video:duration>339</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/writing-numerical-inequalities-exercise</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe3dc6ddd.jpg</video:thumbnail_loc><video:title>Numerical inequality word problems</video:title><video:description>In this math lesson, we learn to compare quantities using inequalities. John makes pasta dough with two types of flour, finding that wheat flour (3/2 cups) is greater than regular flour (3/4 cups). We also compare ocean depths, discovering the Diamantina trench is deeper than the Bering Strait. Lastly, John makes noodles, comparing tapioca flour (11/16 cups) and rice flour (3/8 cups).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3HD-Ak_a6VE.mp4/3HD-Ak_a6VE.mp4</video:content_loc><video:duration>208</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/ordering-negative-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/211177353.jpg</video:thumbnail_loc><video:title>Ordering negative numbers</video:title><video:description>Ordering negative numbers can be tricky, but understanding their values is essential. Smaller negative numbers are further from zero, making them less than larger ones. Visualizing them on a number line helps clarify their positions, with the least number on the left and the greatest on the right. Think of owing money or cold temperatures for real-life examples.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/VW6UrPKPInA.mp4/VW6UrPKPInA.mp4</video:content_loc><video:duration>167</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/ordering-rational-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x02e55120.jpg</video:thumbnail_loc><video:title>Ordering rational numbers</video:title><video:description>Learn how to order numbers from least to greatest using a number line. Convert fractions and decimals to mixed numbers or whole numbers, then plot them on the number line. Master this skill by practicing with examples like 7/3, -5/2, 0, -2, -12/4, and -3.25.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/i1i2_9wg6N8.mp4/i1i2_9wg6N8.mp4</video:content_loc><video:duration>254</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/absolute-value-of-integers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179307.jpg</video:thumbnail_loc><video:title>Absolute value examples</video:title><video:description>The absolute value of a number represents its distance from zero on a number line, always resulting in a positive value. This concept is essential in mathematics, as it helps to simplify calculations and understand the magnitude of numbers, regardless of their positive or negative sign. Examples include finding the absolute values of 5, -10, and -12.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/r6hS_8nm1jM.mp4/r6hS_8nm1jM.mp4</video:content_loc><video:duration>142</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/meaning-of-absolute-value</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0532709128cbedba.jpg</video:thumbnail_loc><video:title>Meaning of absolute value</video:title><video:description>Absolute value is a fundamental math concept that measures the distance of a number from zero, regardless of its sign. It&apos;s always a positive value, as it represents the magnitude of a number without considering its direction. This concept is useful in real-world applications, such as calculating distances and comparing heights.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/zpln5ExhkyI.mp4/zpln5ExhkyI.mp4</video:content_loc><video:duration>220</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/comparing-absolute-values</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/211177352.jpg</video:thumbnail_loc><video:title>Comparing absolute values</video:title><video:description>Comparing absolute values helps us understand the distance between numbers and zero on the number line. The absolute value is always positive or zero, and it represents the magnitude of a number. By comparing absolute values, we can determine which number is further from zero, regardless of its positive or negative sign.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hKkBlcnU9pw.mp4/hKkBlcnU9pw.mp4</video:content_loc><video:duration>247</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/sorting-absolute-values-on-number-line</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbe02457f.jpg</video:thumbnail_loc><video:title>Placing absolute values on the number line</video:title><video:description>In this math lesson, we learn to sort values from least to greatest using a number line. We practice with negative numbers, positive numbers, and absolute values. By plotting these values on the number line, we can easily identify their order and improve our understanding of number relationships.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/MFoXK57sw9k.mp4/MFoXK57sw9k.mp4</video:content_loc><video:duration>137</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/comparing-absolute-values-on-number-line</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3c41c0ae.jpg</video:thumbnail_loc><video:title>Comparing absolute values on the number line</video:title><video:description>In this math lesson, we explore absolute values and inequalities using a number line with three numbers: a, b, and c. We determine the truth of four inequalities: a &lt; b, |a| &gt; |b|, |a| &lt; |c|, and a &lt; c. By understanding number positions and absolute values, we can easily solve these inequalities.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/29P6bar7nHc.mp4/29P6bar7nHc.mp4</video:content_loc><video:duration>236</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/values-to-make-absolute-value-inequality-true</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc6d0124b.jpg</video:thumbnail_loc><video:title>Testing solutions to absolute value inequalities</video:title><video:description>In this math lesson, we learn how to determine if given values of x satisfy various absolute value inequalities. We examine three different inequalities and test each x value to see if it meets the inequality&apos;s conditions. By understanding absolute values and inequalities, we can solve real-world problems and improve our mathematical skills.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/fii9QEVJPas.mp4/fii9QEVJPas.mp4</video:content_loc><video:duration>355</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/interpreting-absolute-value</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x22385fa0.jpg</video:thumbnail_loc><video:title>Interpreting absolute value</video:title><video:description>In this weight change scenario, three individuals track their monthly progress. Jenna experiences a 3-pound weight loss, while Sarah gains 2.5 pounds and Bill gains 4 pounds. By plotting these changes on a number line, we can determine that Jenna lost the most weight, Bill had the largest change, and Sarah had the smallest change.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/faUh3bAxomM.mp4/faUh3bAxomM.mp4</video:content_loc><video:duration>226</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/the-coordinate-plane</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23630.jpg</video:thumbnail_loc><video:title>Points on the coordinate plane examples</video:title><video:description>The coordinate plane is a two-dimension surface formed by two number lines. One number line is horizontal and is called the x-axis. The other number line is vertical number line and is called the y-axis. The two axes meet at a point called the origin. We can use the coordinate plane to graph points, lines, and more.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/VhNkWdLGpmA.mp4/VhNkWdLGpmA.mp4</video:content_loc><video:duration>410</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/points-on-the-coordinate-plane</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x08d09f9d.jpg</video:thumbnail_loc><video:title>Finding the point not graphed</video:title><video:description>Learn to spot the missing point on a graph! By comparing coordinate pairs to points on a graph, we can identify which pair isn&apos;t represented. This skill is key in understanding graphs, a fundamental part of math!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/b9H22F0Qbgw.mp4/b9H22F0Qbgw.mp4</video:content_loc><video:duration>63</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/plot-ordered-pairs</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/396277331.jpg</video:thumbnail_loc><video:title>Plotting a point (ordered pair)</video:title><video:description>Plotting ordered pairs on a coordinate plane is like a treasure hunt! The first number tells us how many steps to hop right or left on the x-axis. The second number guides us up or down on the y-axis. So, for (6, -8), we hop 6 steps right and 8 steps down. Voila, we&apos;ve found our treasure!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5ctsUsvIp8w.mp4/5ctsUsvIp8w.mp4</video:content_loc><video:duration>128</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/quadrants-of-coordinate-plane</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/33752747.jpg</video:thumbnail_loc><video:title>Quadrants of the coordinate plane</video:title><video:description>The coordinate plane is divided into four sections, called quadrants. Quadrant I has positive x and y values, Quadrant II has negative x and positive y, Quadrant III has negative x and y, and Quadrant IV has positive x and negative y. The point (-7,7) is in Quadrant II.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1op92ojA6q0.mp4/1op92ojA6q0.mp4</video:content_loc><video:duration>144</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/graphing-points-and-naming-quadrants-exercise</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x02167ace.jpg</video:thumbnail_loc><video:title>Points and quadrants example</video:title><video:description>Plotting points on a graph involves moving along the x and y axes. Positive x-values move right, negative x-values move left. Positive y-values move up, negative y-values move down. The graph is divided into four quadrants, helping us locate points easily.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Jeh5vudjmLI.mp4/Jeh5vudjmLI.mp4</video:content_loc><video:duration>116</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/coordinate-plane-word-problems-exercise</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x52229838.jpg</video:thumbnail_loc><video:title>Coordinate plane word problem examples</video:title><video:description>Milena&apos;s journey from home to the mall involves plotting points on a grid, similar to a coordinate plane. The video explains how to calculate the distance between two points, using the x and y coordinates. It also introduces the concept of plotting points in relation to a central point.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PC_FoyewoIs.mp4/PC_FoyewoIs.mp4</video:content_loc><video:duration>287</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/reflecting-points-exercise</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1d9ac087.jpg</video:thumbnail_loc><video:title>Reflecting points in the coordinate plane</video:title><video:description>Just like looking at a mirror image of yourself, but flipped....a reflection point is the mirror point on the opposite side of the axis. Watch this tutorial and reflect :)</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/INqaHHZGt8w.mp4/INqaHHZGt8w.mp4</video:content_loc><video:duration>215</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/introduction-to-exponents</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfe1a8e1f.jpg</video:thumbnail_loc><video:title>Intro to exponents</video:title><video:description>Exponents represent repeated multiplication, making numbers grow quickly. For example, 2 to the 3rd power means multiplying three 2&apos;s together, resulting in 8. This concept differs from multiplication, which is simply repeated addition. Understanding exponents is essential for mastering higher-level math.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/XZRQhkii0h0.mp4/XZRQhkii0h0.mp4</video:content_loc><video:duration>183</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/the-zeroth-power</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x21137693.jpg</video:thumbnail_loc><video:title>The zeroth power</video:title><video:description>Sal Khan considers two different ways to think about why a number raised to the zero power equals one: 1) if 2^3 = 1x2x2x2, then 2^0 = 1 times zero twos, which equals 1. 2) By following a pattern of decreasing an exponent by one by dividing by the base, we find that when we get to the 0 power, we end up dividing the base by itself, resulting in 1.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TWv6f7rwjF4.mp4/TWv6f7rwjF4.mp4</video:content_loc><video:duration>272</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/exponents-of-decimals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xeeccb03072f11724.jpg</video:thumbnail_loc><video:title>Exponents of decimals</video:title><video:description>Exponents of decimals can be calculated by multiplying the decimal number by itself as many times as the exponent indicates. When multiplying decimals, count the total number of digits to the right of the decimal points in both numbers and place the same number of digits to the right of the decimal point in the product.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/o_urKmMdGK0.mp4/o_urKmMdGK0.mp4</video:content_loc><video:duration>151</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/powers-of-fractions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3603d5d1.jpg</video:thumbnail_loc><video:title>Powers of fractions</video:title><video:description>Raising fractions to a power is a fundamental math skill. To do this, simply multiply the numerators and denominators separately. For example, when raising a fraction like 2/3 to the third power, multiply the numerators (2 × 2 × 2 = 8) and the denominators (3 × 3 × 3 = 27) to get the result 8/27. This method applies to all powers, making it easy to understand and apply.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/oEgeUk_Ix2c.mp4/oEgeUk_Ix2c.mp4</video:content_loc><video:duration>107</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/order-of-operations-with-exponents-examples</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf6436b29.jpg</video:thumbnail_loc><video:title>Order of operations examples: exponents</video:title><video:description>The order of operations (PEMDAS) is essential for solving math expressions correctly. By following Parentheses, Exponents, Multiplication/Division, and Addition/Subtraction, you ensure accurate results. Understanding the impact of parentheses on calculations helps avoid common mistakes and enhances problem-solving skills.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_jiI0AV8Vr4.mp4/_jiI0AV8Vr4.mp4</video:content_loc><video:duration>214</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/comparing-exponent-expressions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe33cab3e2e0db6d6.jpg</video:thumbnail_loc><video:title>Comparing exponent expressions</video:title><video:description>In this math activity, we arrange three math expressions from smallest to largest. We evaluate the expressions: 2 cubed minus 2, 2 squared plus 3 to the power of 0, and 3 squared. We find their values to be 6, 5, and 9. The correct order is 5, 6, and 9.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/kFElpYl7Te0.mp4/kFElpYl7Te0.mp4</video:content_loc><video:duration>129</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/what-is-a-variable</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1027163525.jpg</video:thumbnail_loc><video:title>What is a variable?</video:title><video:description>Variables in math are symbols, often letters, that represent different values in various situations. They help us understand and solve problems with changing values. For example, when calculating total earnings at a job with an hourly wage plus tips, a variable can represent the fluctuating tips, making it easier to determine total income.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tHYis-DP0oU.mp4/tHYis-DP0oU.mp4</video:content_loc><video:duration>198</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/expression-value-change-examples</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfc2a26da.jpg</video:thumbnail_loc><video:title>Expression value intuition</video:title><video:description>Discover how expressions change as variables within them shift. Learn that increasing x in &quot;100 - x&quot; results in a decreasing value, while decreasing x in &quot;5/x + 5&quot; (x remaining positive) leads to an increase. Observe that &quot;3y/2y&quot; stays constant as y increases, maintaining a value of 3/2.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/UvDcEvDC4vg.mp4/UvDcEvDC4vg.mp4</video:content_loc><video:duration>315</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/expression-terms-factors-and-coefficients</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1a00fa7a.jpg</video:thumbnail_loc><video:title>Terms, factors, &amp; coefficients</video:title><video:description>In math expressions, terms are the components added or subtracted, factors are the elements multiplied within each term, and coefficients are the numbers multiplying variables. Understanding these concepts is crucial for effective communication and problem-solving in mathematics.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9_VCk9tWT0Y.mp4/9_VCk9tWT0Y.mp4</video:content_loc><video:duration>441</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/combining-like-terms</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1027260826.jpg</video:thumbnail_loc><video:title>Intro to combining like terms</video:title><video:description>Adding like terms is a fundamental concept in algebra. Coefficients are the numbers in front of variables, and they can be added when the variables are the same. For example, 2x + 3x equals 5x. When dealing with different variables, such as x and y, add them separately, resulting in expressions like 5x + 9y.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/CLWpkv6ccpA.mp4/CLWpkv6ccpA.mp4</video:content_loc><video:duration>273</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/combining-like-terms-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1254705621.jpg</video:thumbnail_loc><video:title>Combining like terms</video:title><video:description>In this lesson, we learned how to add and subtract variables, like apples (a) or x&apos;s. We discovered that when we combine or take away the same variable, we can simply count them up or down. For example, 5x minus 2x equals 3x. This helps us understand basic algebra concepts.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/P6_sK8hRWCA.mp4/P6_sK8hRWCA.mp4</video:content_loc><video:duration>186</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/combining-like-terms-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1254724496.jpg</video:thumbnail_loc><video:title>Combining like terms example</video:title><video:description>In this lesson, we learned how to simplify algebraic expressions by combining like terms. We focused on understanding the intuition behind adding and subtracting coefficients of the same variables. The result is a simplified expression, making it easier to work with and solve problems.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1DgDt6gCUKs.mp4/1DgDt6gCUKs.mp4</video:content_loc><video:duration>223</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/combining-like-terms-with-distribution</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6c739d85.jpg</video:thumbnail_loc><video:title>Combining like terms with distribution</video:title><video:description>Learn to expand and simplify an expression like 3(5x+6) + (7x+2)*4.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5WLjj7Z0AP0.mp4/5WLjj7Z0AP0.mp4</video:content_loc><video:duration>139</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/the-distributive-property</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/2600690.jpg</video:thumbnail_loc><video:title>Distributive property over addition</video:title><video:description>Learn how to apply the distributive law of multiplication over addition and why it works. This is sometimes just called the distributive law or the distributive property.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gl_-E6iVAg4.mp4/gl_-E6iVAg4.mp4</video:content_loc><video:duration>296</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/the-distributive-property-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/2600691.jpg</video:thumbnail_loc><video:title>Distributive property over subtraction</video:title><video:description>Learn how to apply the distributive property of multiplication over subtraction and why it works. This is sometimes just called the distributive property or distributive law.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Badvask-UDU.mp4/Badvask-UDU.mp4</video:content_loc><video:duration>131</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/distributive-property-exercise-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd74094af.jpg</video:thumbnail_loc><video:title>Factor with the distributive property</video:title><video:description>The distributive property helps us factor out the greatest common factor (GCF) in math problems. By finding the GCF of two numbers, we can rewrite the expression as a product, making calculations easier. Understanding this property is essential for simplifying expressions and solving equations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/t7OkENcBrxs.mp4/t7OkENcBrxs.mp4</video:content_loc><video:duration>207</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/distributive-property-with-variables-exercise</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd2339082.jpg</video:thumbnail_loc><video:title>Distributive property with variables</video:title><video:description>To apply the distributive property to an algebraic expression, you multiply each term inside the parentheses by the number or variable outside the parentheses. For example, to simplify 2(x + 3), you would multiply 2 by both x and 3, resulting in 2x + 6.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Jp25LHI9wII.mp4/Jp25LHI9wII.mp4</video:content_loc><video:duration>389</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/equivalent-algebraic-expressions-exercise</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7c5e660c.jpg</video:thumbnail_loc><video:title>Equivalent expressions</video:title><video:description>In this math lesson, we learn how to find equivalent expressions by combining like terms and factoring. We start with an expression like x + 2 - y + x + 2 and simplify it by adding the x terms and factoring out common factors. This helps us compare expressions and solve problems more easily.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/rHNY01R2VSQ.mp4/rHNY01R2VSQ.mp4</video:content_loc><video:duration>118</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/writing-expressions-with-variables-examples</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb9719b96.jpg</video:thumbnail_loc><video:title>Writing basic expressions with variables</video:title><video:description>Learn to write expressions with variables in math! Discover how to represent various operations like addition, subtraction, multiplication, and division using variables. Master the art of creating expressions for real-life situations, such as finding the sum of two numbers or the difference between two values. Boost your algebra skills and become a pro at handling variables!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/640-86yn2wM.mp4/640-86yn2wM.mp4</video:content_loc><video:duration>157</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/algebraic-subtraction-expressions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc191c980ab3e56fb.jpg</video:thumbnail_loc><video:title>Writing algebraic subtraction expressions</video:title><video:description>In this lesson, we learned how to turn word statements into algebraic expressions. We practiced with examples like &quot;two less than x&quot; and &quot;y fewer than three.&quot; Understanding how to translate words into math helps us solve real-life problems and makes algebra more fun!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/eFXcsXnKkjw.mp4/eFXcsXnKkjw.mp4</video:content_loc><video:duration>89</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/why-aren-t-we-using-the-multiplication-sign</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1027377520.jpg</video:thumbnail_loc><video:title>Why aren&apos;t we using the multiplication sign?</video:title><video:description>In algebra, representing multiplication with variables can be tricky due to the similarity between the variable &quot;x&quot; and the multiplication symbol. To avoid confusion, use alternative methods like 2⋅x, 2(x), or 2x. Practice evaluating expressions by substituting given values for variables and following the order of operations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vDaIKB19TvY.mp4/vDaIKB19TvY.mp4</video:content_loc><video:duration>298</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/writing-expressions-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xcd612f07.jpg</video:thumbnail_loc><video:title>Writing expressions with variables</video:title><video:description>To write simple algebraic expressions from mathematical statements, you can follow this procedure: 1. Identify the key terms in the written statement (e.g. &quot;sum,&quot; &quot;product,&quot; &quot;quantity&quot;). 2. Break the statement down into its component parts. 3. Translate each part into algebraic form, using the appropriate symbols and operations. 4. Simplify the expression if needed.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Q1vMNyIP4Us.mp4/Q1vMNyIP4Us.mp4</video:content_loc><video:duration>98</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/writing-expressions-parentheses</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc091e2df450dd50d.jpg</video:thumbnail_loc><video:title>Writing expressions with parentheses</video:title><video:description>In math, using parentheses helps follow the correct order of operations. When multiplying a number by the sum or difference of two terms, like 5 times (x-2) or 10 times (y+3), parentheses ensure the addition or subtraction happens first. This avoids confusion and ensures accurate results.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/cFNbX-2R78M.mp4/cFNbX-2R78M.mp4</video:content_loc><video:duration>92</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/writing-expressions-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbe65fb1e.jpg</video:thumbnail_loc><video:title>Writing expressions with variables &amp; parentheses</video:title><video:description>In this math lesson, we learned about expressions and how to simplify them step by step. We explored adding and multiplying expressions, like negative numbers and variables. By practicing these skills, we can solve more complex algebra problems with ease and confidence.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xLYVo_k0_us.mp4/xLYVo_k0_us.mp4</video:content_loc><video:duration>165</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/writing-basic-expressions-from-word-problems-examples</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x34aac2f6.jpg</video:thumbnail_loc><video:title>Writing basic expressions word problems</video:title><video:description>Susie runs a race at 5 miles per hour for t hours. To find the distance, multiply her speed by time (5t). In a poker game, winnings are split among p players, so each gets $548/p. Phil&apos;s net winnings are x dollars minus the $100 entry fee. Hillary makes 48 chocolate chip cookies and y sugar cookies, totaling 48+y cookies.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lq-2gX3NKCM.mp4/lq-2gX3NKCM.mp4</video:content_loc><video:duration>189</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/more-fancy-expressions-from-word-problems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7b5468c2.jpg</video:thumbnail_loc><video:title>Writing expressions word problems</video:title><video:description>Learn how to write expressions with variables to describe situations described in word problems.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/C_KffdI34ZU.mp4/C_KffdI34ZU.mp4</video:content_loc><video:duration>282</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/variables-and-expressions-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179305.jpg</video:thumbnail_loc><video:title>Evaluating an expression with one variable</video:title><video:description>In this math lesson, we explore the expression 5 t plus 3 to calculate the cost of participating in a hospital raffle fundraiser. By evaluating the expression for different values of t, the number of tickets purchased, we find the costs for buying 1, 8, and 10 tickets, which are 8, 43, and 53 dollars, respectively.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/AJNDeVt9UOo.mp4/AJNDeVt9UOo.mp4</video:content_loc><video:duration>120</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/evaluate-a-formula-using-substitution</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179471.jpg</video:thumbnail_loc><video:title>Evaluating expressions with variables: temperature</video:title><video:description>In this example we have a formula for converting Celsius temperature to Fahrenheit. Let&apos;s substitute the variable with a value (Celsius temp) to get the degrees in Fahrenheit. Great problem to practice with us!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tC1SfxRvtmM.mp4/tC1SfxRvtmM.mp4</video:content_loc><video:duration>75</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/evaluating-expressions-3-exercise</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x27a60b7a.jpg</video:thumbnail_loc><video:title>Evaluating expressions with variables: cubes</video:title><video:description>Discover how to calculate the total surface area of cube-shaped containers with varying side lengths. Learn the formula 6x², where x represents the side length of a cube. Apply this formula to find the surface area of multiple cubes, and add the results to determine the combined surface area that needs painting.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/I9eLKDbc8og.mp4/I9eLKDbc8og.mp4</video:content_loc><video:duration>204</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/evaluating-exponential-expressions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179497.jpg</video:thumbnail_loc><video:title>Evaluating expressions with variables: exponents</video:title><video:description>In this math lesson, we learn to evaluate an algebraic expression with exponents by following the order of operations (PEMDAS). We substitute a given value for the variable, calculate exponents, perform multiplication, and finally, subtraction. By applying these steps, we successfully find the value of the expression.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0uCslW40VHQ.mp4/0uCslW40VHQ.mp4</video:content_loc><video:duration>161</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/evaluating-expressions-in-two-variables</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xcce18b8f.jpg</video:thumbnail_loc><video:title>Evaluating expressions with two variables</video:title><video:description>Evaluating expressions with multiple variables involves substituting given values for each variable and simplifying the expression. By replacing variables with their corresponding values, we can easily compute the result of expressions, even for more complex examples with multiple terms and operations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/S_OX3ByvBSc.mp4/S_OX3ByvBSc.mp4</video:content_loc><video:duration>125</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/evaluating-expressions-in-two-variables-with-decimals-and-fractions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8c62927c.jpg</video:thumbnail_loc><video:title>Evaluating expressions with two variables: fractions &amp; decimals</video:title><video:description>Evaluating expressions with two variables involves substituting the given values for each variable and simplifying the expression. By practicing with examples, we can improve our skills in solving these types of problems, ultimately enhancing our understanding of algebraic expressions and their real-world applications.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/GmD7Czmol0k.mp4/GmD7Czmol0k.mp4</video:content_loc><video:duration>207</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/evaluating-exponent-expressions-with-variables</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7ca1da5f32237ccb.jpg</video:thumbnail_loc><video:title>Evaluating exponent expressions with variables</video:title><video:description>In this math lesson, we learn to evaluate expressions with exponents and variables. We practice substituting values for variables and calculating the results. By mastering this skill, we can solve problems involving exponential expressions, enhancing our understanding of algebra and mathematical concepts.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9K54G5yeR74.mp4/9K54G5yeR74.mp4</video:content_loc><video:duration>181</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/evaluating-expressions-5x2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7fd7ee1eba5733e6.jpg</video:thumbnail_loc><video:title>Evaluating expressions like 5x² &amp; ⅓(6)ˣ</video:title><video:description>Evaluating expressions with exponents involves substituting a given value for the variable and following the order of operations. Calculate the exponent first, then perform any multiplication or division. Mastering this skill is essential for solving more complex algebraic problems and understanding mathematical relationships.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ccyZpjKvJV8.mp4/ccyZpjKvJV8.mp4</video:content_loc><video:duration>86</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/variables-expressions-and-equations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/583878752.jpg</video:thumbnail_loc><video:title>Variables, expressions, &amp; equations</video:title><video:description>In algebra, we use variables like x, y, and z to represent unknown values. Expressions are combinations of variables and numbers, while equations equate two expressions. Variables can take on different values depending on the context, and we can evaluate expressions by substituting values for the variables.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vDqOoI-4Z6M.mp4/vDqOoI-4Z6M.mp4</video:content_loc><video:duration>415</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/testing-solutions-to-equation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1923a9f4.jpg</video:thumbnail_loc><video:title>Testing solutions to equations</video:title><video:description>In this math lesson, we learn how to solve an equation with one variable. We test different values for x to see which one satisfies the equation. By substituting x with the given options, we find the correct solution that makes both sides of the equation equal. Practice makes perfect!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/U9OfQd8poTQ.mp4/U9OfQd8poTQ.mp4</video:content_loc><video:duration>225</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/why-we-do-the-same-thing-to-both-sides-simple-equations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/948454929.jpg</video:thumbnail_loc><video:title>Same thing to both sides of equations</video:title><video:description>In this fun math problem, we have a balanced scale with a mystery mass on one side and several 1-kilogram masses on the other. To find the mystery mass, we remove the same number of 1-kilogram masses from both sides, keeping the scale balanced. Then, we can easily determine the mystery mass&apos;s weight.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5FBDqY41GjU.mp4/5FBDqY41GjU.mp4</video:content_loc><video:duration>152</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/representing-a-relationship-with-a-simple-equation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/948457910.jpg</video:thumbnail_loc><video:title>Representing a relationship with an equation</video:title><video:description>In this lesson, we learn about balancing scales and solving equations. We discover that to find a mystery mass, we can set up an equation using equal signs and balance both sides. By subtracting the same amount from each side, we can solve for the unknown mass, helping us understand the relationship between the two sides of the scale.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/XN48Ba9Ncr8.mp4/XN48Ba9Ncr8.mp4</video:content_loc><video:duration>204</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/intuition-why-we-divide-both-sides</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/948526680.jpg</video:thumbnail_loc><video:title>Dividing both sides of an equation</video:title><video:description>In this lesson, we learn how to find the mass of a mystery object using a balanced scale. By keeping the scale balanced and taking equal portions from both sides, we can determine the mass of the mystery object. This helps us understand the concept of equality in real-life situations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Ye13MIPv6n0.mp4/Ye13MIPv6n0.mp4</video:content_loc><video:duration>194</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/adding-and-subtracting-the-same-thing-from-both-sides</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1032539728.jpg</video:thumbnail_loc><video:title>One-step addition &amp; subtraction equations</video:title><video:description>In this lesson, we learn how to solve simple equations with one unknown variable. To find the unknown, we remove extra numbers by doing the opposite operation on both sides of the equation. This keeps the equation balanced and helps us find the value of the unknown variable.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jWpiMu5LNdg.mp4/jWpiMu5LNdg.mp4</video:content_loc><video:duration>129</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/solving-one-step-equations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179465.jpg</video:thumbnail_loc><video:title>One-step addition equation</video:title><video:description>In this math lesson, we learn to solve simple equations with one variable. We isolate the variable by removing other terms on the same side. For example, if a + 5 = 54, we subtract 5 from both sides to find a = 49. Finally, we check our solution by substituting the value back into the original equation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/VidnbCEOGdg.mp4/VidnbCEOGdg.mp4</video:content_loc><video:duration>114</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/examples-of-one-step-equations-with-fractions-and-decimals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6408645c.jpg</video:thumbnail_loc><video:title>One-step addition &amp; subtraction equations: fractions &amp; decimals</video:title><video:description>In this math lesson, we practice solving equations with variables and fractions. We learn to isolate the variable by adding or subtracting terms from both sides of the equation. This helps us find the value of the variable, making the equation true. Keep practicing and have fun!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/XD-FDGdWnR8.mp4/XD-FDGdWnR8.mp4</video:content_loc><video:duration>272</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/solving-one-step-equations-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179466.jpg</video:thumbnail_loc><video:title>One-step multiplication equations</video:title><video:description>In this math lesson, we learn to solve equations with x divided by a number, like x/3 = 14. To find x, we isolate it by multiplying both sides of the equation by the divisor (3). This gives us x = 42. Finally, we check our answer by substituting x back into the original equation to make sure it&apos;s correct.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DqeMQHomwAU.mp4/DqeMQHomwAU.mp4</video:content_loc><video:duration>143</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/simple-equations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/7.jpg</video:thumbnail_loc><video:title>One-step division equations</video:title><video:description>In this lesson, we learn how to solve simple algebraic equations systematically. We focus on understanding the meaning of equations, like 7x = 14, and using techniques like dividing both sides of the equation by the coefficient to isolate the variable. This method helps us find the value of the unknown variable, making algebra easier and more approachable.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9Ek61w1LxSc.mp4/9Ek61w1LxSc.mp4</video:content_loc><video:duration>666</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/one-step-multiplication-and-division-equations-with-fractions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6dd22c7e.jpg</video:thumbnail_loc><video:title>One-step multiplication &amp; division equations: fractions &amp; decimals</video:title><video:description>In this fun math adventure, we tackle equations with fractions and decimals. We learn to balance equations by applying the same operation on both sides, simplifying fractions, and eliminating decimals. It&apos;s a step-by-step journey to mastering algebra!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/a3acutLstF8.mp4/a3acutLstF8.mp4</video:content_loc><video:duration>471</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/one-step-multiplication-fractional-coefficients</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x24d59f9050daac31.jpg</video:thumbnail_loc><video:title>One-step multiplication equations: fractional coefficients</video:title><video:description>Learn how to solve equations with fractions by using reciprocals. Multiply both sides of the equation by the reciprocal of the fraction to make the coefficient one. This simplifies the equation, making it easier to find the value of the variable.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vksy7e3hY8Q.mp4/vksy7e3hY8Q.mp4</video:content_loc><video:duration>234</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/finding-mistakes-in-one-step-equations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xae320dbc.jpg</video:thumbnail_loc><video:title>Finding mistakes in one-step equations</video:title><video:description>In this lesson, we learned how to spot mistakes in solving algebraic equations. We saw that it&apos;s crucial to apply the same operation to both sides of the equation. We also learned the importance of accurate arithmetic in getting the correct answer. Lastly, we saw that not all steps, even if algebraically correct, help simplify the equation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/CUB5j3Frev0.mp4/CUB5j3Frev0.mp4</video:content_loc><video:duration>252</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/super-yoga-plans-basic-variables-and-equations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1094227108.jpg</video:thumbnail_loc><video:title>Equation word problem: super yoga (1 of 2)</video:title><video:description>Using information from the Super Yoga word problem, explore all the possible combinations and create equations which express the possibilities. Let&apos;s figure out which plan is best!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3tRc6mUumFk.mp4/3tRc6mUumFk.mp4</video:content_loc><video:duration>439</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/super-yoga-plans-solving-one-step-equations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1094119956.jpg</video:thumbnail_loc><video:title>Equation word problem: super yoga (2 of 2)</video:title><video:description>If you&apos;re coming to this video before seeing the previous one, back up! Otherwise, we&apos;re solving one-step equations to learn which Super Plan is the best value for our budget.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hq1bUM2tyg0.mp4/hq1bUM2tyg0.mp4</video:content_loc><video:duration>460</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/constructing-basic-equations-examples</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdd8bfe76.jpg</video:thumbnail_loc><video:title>Modeling with one-step equations</video:title><video:description>Anna wants to throw a pizza party for her birthday. She has $42.50 to spend on pizza boxes that cost $8.50 each. To figure out how many pizzas she can buy, she divides the total money by the cost per box. This concept can also be applied to other situations, like a class selling candy boxes for a fundraiser.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2REbsY4-S70.mp4/2REbsY4-S70.mp4</video:content_loc><video:duration>261</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/testing-solutions-to-inequalities</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9fac0737.jpg</video:thumbnail_loc><video:title>Testing solutions to inequalities</video:title><video:description>Inequalities are like puzzles where you compare two things. You can solve these puzzles by trying different numbers and seeing which ones make the puzzle true. Some numbers will work for one puzzle but not for another. It&apos;s all about finding the right fit!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Yh4TXMVq9eg.mp4/Yh4TXMVq9eg.mp4</video:content_loc><video:duration>310</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/plotting-inequalities-on-a-number-line</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5c4574ba.jpg</video:thumbnail_loc><video:title>Plotting inequalities</video:title><video:description>To plot an inequality, such as x&gt;3, on a number line, first draw a circle over the number (e.g., 3). Then if the sign includes equal to (≥ or ≤), fill in the circle. If the sign does not include equal to (&gt; or &lt;), leave the circle unfilled in. Finally, draw a line going from the circle in the direction of the numbers that make the inequality true.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ilWDSYnTEFs.mp4/ilWDSYnTEFs.mp4</video:content_loc><video:duration>127</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/inequalities-on-a-number-line</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179473.jpg</video:thumbnail_loc><video:title>Plotting an inequality example</video:title><video:description>Drawing a number line helps visualize &apos;x is less than 4&apos;. We mark 4 with a circle, not a dot, because 4 isn&apos;t included. Then, we color the line below 4, showing all values less than 4. Easy peasy, lemon squeezy</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/dTwZ5N126gw.mp4/dTwZ5N126gw.mp4</video:content_loc><video:duration>94</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/real-world-situations-with-inequalities</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5a048673.jpg</video:thumbnail_loc><video:title>Inequalities word problems</video:title><video:description>Inequalities are a handy tool for comparing values. For example, if Eric is shorter than Priti who is 158 cm tall, we write E &lt; 158. If Sydney wears skirts when it&apos;s warmer than 25 degrees, we say T &gt; 25. If Hayley finishes a race after Lola&apos;s 53 seconds, we write H &gt; 53.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/VEIf5TfceAw.mp4/VEIf5TfceAw.mp4</video:content_loc><video:duration>176</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/dependent-independent-variables</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0f276e8512307008.jpg</video:thumbnail_loc><video:title>Dependent &amp; independent variables</video:title><video:description>We introduce independent and dependent variables: how to identify the independent/dependent variable in a given setting, and how we write equations with the dependent variable by itself.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/SGC_d7O7_Eg.mp4/SGC_d7O7_Eg.mp4</video:content_loc><video:duration>139</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/dependent-and-independent-variables-exercise-example-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x03fbe709.jpg</video:thumbnail_loc><video:title>Dependent &amp; independent variables: graphing</video:title><video:description>When you answer math quiz questions, each correct answer earns you 5 points. The number of correct answers (x) and total points (y) are related by the equation y = 5x. This relationship can be visualized on a graph.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0eWm-LY23W0.mp4/0eWm-LY23W0.mp4</video:content_loc><video:duration>60</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/equations-relationships-quantities</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb4c3652f840b25b2.jpg</video:thumbnail_loc><video:title>Writing equations for relationships between quantities</video:title><video:description>In this lesson, we learn how to write equations representing real-world scenarios. First, we explore how to calculate time taken for a walk based on speed and distance. Then, we discover how to determine the amount of water needed in a soup recipe based on the quantity of vegetable stock. Fun, right?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5T9gSp2W3Oc.mp4/5T9gSp2W3Oc.mp4</video:content_loc><video:duration>361</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/analyzing-relationships-between-variables</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4fa4a8d08c7b0412.jpg</video:thumbnail_loc><video:title>Analyzing relationships between variables</video:title><video:description>Rava is studying an electric car. She finds out that the more she charges the car, the further it can go. The relationship is simple and direct: more charging time equals more distance. This helps her predict the car&apos;s range based on how long it&apos;s been charged.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Pf-s9zNDSCk.mp4/Pf-s9zNDSCk.mp4</video:content_loc><video:duration>169</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/intuition-for-area-of-a-parallelogram</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5043d50b.jpg</video:thumbnail_loc><video:title>Area of a parallelogram</video:title><video:description>Discover the magic of geometry! The area of a rectangle and a parallelogram can be calculated in the same way. Just multiply the base by the height! This simple trick works because a parallelogram can be rearranged into a rectangle. Geometry is full of surprises!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hm17lVaor0Q.mp4/hm17lVaor0Q.mp4</video:content_loc><video:duration>177</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/finding-height-of-a-parallelogram</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x96372c65f08c8dce.jpg</video:thumbnail_loc><video:title>Finding height of a parallelogram</video:title><video:description>In this lesson, we learned that the area of a parallelogram equals the base times the height. Given an area of 24 units and a base of 6 units, we used this formula to find the missing height. The answer was 4 units. Isn&apos;t math fun?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/SKe3ItfdzTY.mp4/SKe3ItfdzTY.mp4</video:content_loc><video:duration>102</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/intuition-for-area-of-a-triangle</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x11df81ee.jpg</video:thumbnail_loc><video:title>Area of a triangle</video:title><video:description>The area of a rectangle and a parallelogram is found by multiplying the base by the height. For a triangle, the area is half of a parallelogram&apos;s, so it&apos;s calculated by multiplying the base by the height and then dividing by 2.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/rRTXKQpblEc.mp4/rRTXKQpblEc.mp4</video:content_loc><video:duration>330</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/example-finding-area-of-triangle</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xcc8a19eed3fc9954.jpg</video:thumbnail_loc><video:title>Finding area of triangles</video:title><video:description>The area of a triangle is found by multiplying one half of the base by the height. In our example, the base is 18 and the height is 6. So, half of 18 is 9, and 9 times 6 equals 54 square units.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7N5orPxUoGo.mp4/7N5orPxUoGo.mp4</video:content_loc><video:duration>91</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/triangle-missing-side-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf11586ba7868d7f4.jpg</video:thumbnail_loc><video:title>Triangle missing side example</video:title><video:description>Dive into the world of triangles! Learn how to find a missing piece using just the area and height. Apply this knowledge to solve puzzles and explore the magic hidden in these three-sided shapes. Join the triangle adventure!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/wTkH288r84s.mp4/wTkH288r84s.mp4</video:content_loc><video:duration>189</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/area-of-triangle-in-grid</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x33ae35a0.jpg</video:thumbnail_loc><video:title>Area of a triangle on a grid</video:title><video:description>Learn how to calculate the area of a triangle on a grid.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ukPjc3Oyad4.mp4/ukPjc3Oyad4.mp4</video:content_loc><video:duration>417</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/area-of-strange-quadrilateral</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x995b0cd6.jpg</video:thumbnail_loc><video:title>Area of a quadrilateral on a grid</video:title><video:description>Learn to break up oddly shaped quadrilaterals into shapes where finding the area is more easily determined.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gkifo46--JA.mp4/gkifo46--JA.mp4</video:content_loc><video:duration>234</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/area-of-quadrilateral-with-2-parallel-sides</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfae40098dbd6126d.jpg</video:thumbnail_loc><video:title>Area of quadrilateral with 2 parallel sides</video:title><video:description>Learn how to find the area of a quadrilateral by splitting it into two triangles. Use the formula for triangle area (1/2 base times height) for each triangle. Add the areas together for the total quadrilateral area. It&apos;s as easy as pie...or should I say, as easy as area!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/uEIoh8uWs1U.mp4/uEIoh8uWs1U.mp4</video:content_loc><video:duration>222</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/area-of-a-trapezoid-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9eb86ee6.jpg</video:thumbnail_loc><video:title>Area of trapezoids</video:title><video:description>Area of a trapezoid is found with the formula, A=(a+b)h/2. To find the area of a trapezoid, you need to know the lengths of the two parallel sides (the &quot;bases&quot;) and the height. Add the lengths of the two bases together, and then multiply by the height. Finally, divide by 2 to get the area of the trapezoid.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/j3-XYLnxJDY.mp4/j3-XYLnxJDY.mp4</video:content_loc><video:duration>288</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/area-of-a-kite</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xae34441c.jpg</video:thumbnail_loc><video:title>Area of kites</video:title><video:description>To find the area of a kite, you need to know the lengths of the kite&apos;s two diagonals (the lines that cross through the middle of the kite). Multiply the lengths of the two diagonals together, and then divide by 2. This will give you the area of the kite.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/b8q6i_XPyhk.mp4/b8q6i_XPyhk.mp4</video:content_loc><video:duration>229</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/area-comparisons</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x27919a7f.jpg</video:thumbnail_loc><video:title>Finding area by rearranging parts</video:title><video:description>Discover the magic of quadrilaterals and their areas! We explore how a trapezoid&apos;s area can match a rectangle&apos;s by rearranging its parts. We learn that shapes with the same area can look different. It&apos;s a fantastic journey into the world of geometry!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/MamrTJ7V_Vg.mp4/MamrTJ7V_Vg.mp4</video:content_loc><video:duration>237</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/area-breaking-up-shape</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x74fb422f.jpg</video:thumbnail_loc><video:title>Area of composite shapes</video:title><video:description>We can sometimes calculate the area of a complex shape by dividing it into smaller, more manageable parts. In this example, we can determine the area of two triangles, a rectangle, and a trapezoid, and then add up the areas of the four shapes to get the total area.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/loAA3TCNAvU.mp4/loAA3TCNAvU.mp4</video:content_loc><video:duration>315</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/constructing-polygon-on-coordinate-plane-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd2b8209a.jpg</video:thumbnail_loc><video:title>Drawing a quadrilateral on the coordinate plane example</video:title><video:description>We&apos;re making a four-sided shape called a quadrilateral using line segments! We use four points on a graph: (0,9), (0,-7), (8,-7), and (8,0). We connect these points to form our quadrilateral. Isn&apos;t shape-making fun?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/zxy4KAiSPIc.mp4/zxy4KAiSPIc.mp4</video:content_loc><video:duration>92</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/finding-coordinates-of-missing-vertex-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd94a4f02.jpg</video:thumbnail_loc><video:title>Coordinates of a missing vertex</video:title><video:description>This lesson teaches how to find the missing vertex of a rectangle on a coordinate plane. By understanding that rectangle sides are parallel and vertices form right angles, we can determine that the missing vertex shares its x-coordinate with one vertex and its y-coordinate with another.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/WkiPVButdeg.mp4/WkiPVButdeg.mp4</video:content_loc><video:duration>161</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/area-of-parallelogram-on-coordinate-plane</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbd468ab0.jpg</video:thumbnail_loc><video:title>Area of a parallelogram on the coordinate plane</video:title><video:description>In math, we can find the area of a parallelogram by multiplying the base by the height. The base is one side, and the height is the distance from the base to the opposite side. So, if the base is 12 units and the height is 4 units, the area is 48 square units.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xTcwnhyPN5E.mp4/xTcwnhyPN5E.mp4</video:content_loc><video:duration>128</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/dimensions-of-rectangle-from-coordinates-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd521c318.jpg</video:thumbnail_loc><video:title>Dimensions of a rectangle from coordinates</video:title><video:description>How can we determine the length of a side of a rectangle given the coordinates of its vertices? In this example, by plotting the points on a graph, we can see that the length one side is five because the y-coordinate increases by five from one endpoint to the other.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/fEpINE1fjgc.mp4/fEpINE1fjgc.mp4</video:content_loc><video:duration>231</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/coordinates-of-rectangle-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x621a7bcc.jpg</video:thumbnail_loc><video:title>Coordinates of rectangle example</video:title><video:description>Learn how to sort coordinates from least to greatest using a rectangle diagram. Understand how x, y, and z coordinates relate to each other. Discover that y equals four, z equals three, and x equals two. Master sorting these values in ascending order: x, z, y.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/s2wmcnZi6kE.mp4/s2wmcnZi6kE.mp4</video:content_loc><video:duration>142</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/example-of-shapes-on-a-coordinate-plane</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7442477a5b2dcf62.jpg</video:thumbnail_loc><video:title>Example of shapes on a coordinate plane</video:title><video:description>Plotting points on a coordinate plane can help us draw shapes like rectangles! The points (1,1), (1,6), (9,6), and (9,1) form a rectangle. The x-coordinate tells us how far right to move, and the y-coordinate tells us how far up to go. The rectangle&apos;s height is the difference between the y-coordinates, which is 5.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8V-PdgS2GKc.mp4/8V-PdgS2GKc.mp4</video:content_loc><video:duration>142</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/analyzing-polygon-on-the-coordinate-plane</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x249c50c5.jpg</video:thumbnail_loc><video:title>Parallelogram on the coordinate plane</video:title><video:description>Remember our discussion of the coordinate plane? Sure you do! Let&apos;s graph the given coordinates of three of the polygon vertices, and find where the 4th vertex is.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8ToCxaB7EOE.mp4/8ToCxaB7EOE.mp4</video:content_loc><video:duration>317</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/volume-of-a-rectangular-prism-with-fractional-cubes</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc603bd0d.jpg</video:thumbnail_loc><video:title>Volume with fractional cubes</video:title><video:description>Another way of finding the volume of a rectangular prism involves dividing it into fractional cubes, finding the volume of one, and then multiplying that volume by the number of cubes that fit into our rectangular prism.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tVDslyeLefU.mp4/tVDslyeLefU.mp4</video:content_loc><video:duration>258</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/volume-of-a-rectangular-prism-with-fractional-dimensions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5c1fce1f.jpg</video:thumbnail_loc><video:title>Volume of a rectangular prism: fractional dimensions</video:title><video:description>The video explains how to calculate the volume of a rectangular prism with fractional dimensions. It emphasizes that volume equals the area of the base times the height. To find the volume, multiply the length, width, and height. The video also shows how to simplify fractions during multiplication.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/EJTPGyWqhqc.mp4/EJTPGyWqhqc.mp4</video:content_loc><video:duration>255</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/how-volume-changes-from-changing-dimensions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x06ec522989f5a1c6.jpg</video:thumbnail_loc><video:title>How volume changes from changing dimensions</video:title><video:description>In geometry, altering the dimensions of a rectangular prism impacts its volume. If you double one dimension, the volume doubles. If you double two dimensions, the volume quadruples. When all dimensions are doubled, the volume increases eight times. This is a fundamental concept in understanding volume.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/IShaLZ8CMXY.mp4/IShaLZ8CMXY.mp4</video:content_loc><video:duration>257</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/marbles-in-tank-volume</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa72132ec.jpg</video:thumbnail_loc><video:title>Volume of a rectangular prism: word problem</video:title><video:description>Mario has a fish tank shaped like a right rectangular prism. The tank is filled with marbles and water up to 6.4 cm. When the marbles are removed, the water level drops to 5.9 cm. The volume of water displaced by the marbles is found to be 56.16 cubic centimeters.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/CCysGY2cXUo.mp4/CCysGY2cXUo.mp4</video:content_loc><video:duration>382</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/counting-faces-and-edges-of-3d-shapes</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x86473103952799e4.jpg</video:thumbnail_loc><video:title>Counting faces and edges of 3D shapes</video:title><video:description>Learn about shapes! Discover how to count faces and edges on 3D figures. We explore a transparent shape with five faces and another shape, a square pyramid, with eight edges and five faces. It&apos;s a colorful journey into geometry!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_y17uHBwa_8.mp4/_y17uHBwa_8.mp4</video:content_loc><video:duration>227</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/recognizing-common-3d-shapes</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4821014801c816e7.jpg</video:thumbnail_loc><video:title>Recognizing common 3D shapes</video:title><video:description>Learn about 3D shapes! A square pyramid has a square base. A rectangular prism is a box shape with all rectangular sides. A triangular prism has triangle faces on opposite sides. A sphere is like a globe. A cylinder looks like a can with circular faces on top and bottom. Shapes are fun!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tqxQSSzuXX0.mp4/tqxQSSzuXX0.mp4</video:content_loc><video:duration>209</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/nets-of-polyhedra</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6e267a36.jpg</video:thumbnail_loc><video:title>Intro to nets of polyhedra</video:title><video:description>Admittedly, &quot;nets of polyhedra&quot; sounds like the title of a bad sci-fi movie about man-eating, multi-headed fish. But in reality, nets of polyhedra are just 2D objects that wrap around 3D objects, like wrapping paper around presents.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ZACf9EecFrY.mp4/ZACf9EecFrY.mp4</video:content_loc><video:duration>408</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/surface-area-from-net</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbb4d5fe8.jpg</video:thumbnail_loc><video:title>Surface area using a net: rectangular prism</video:title><video:description>A polyhedron is a three-dimensional shape that has flat surfaces and straight edges. Learn whether or not a certain net could be folded up into a certain rectangular prism.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/m1ZTnl4CNQg.mp4/m1ZTnl4CNQg.mp4</video:content_loc><video:duration>259</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/finding-surface-area-using-net</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xeb3d20c9.jpg</video:thumbnail_loc><video:title>Surface area using a net: triangular prism</video:title><video:description>Here are the steps to compute the surface area of a triangular prism: 1. Find the areas of each of the three rectangular faces, using the formula for the area of a rectangle: length x width. 2. Next, find the area of the two triangular faces, using the formula for the area of a triangle: 1/2 base x height. 3. Add the areas of all five faces together, and you&apos;re done!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/mtMNvnm71Z0.mp4/mtMNvnm71Z0.mp4</video:content_loc><video:duration>214</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/surface-area-of-a-box-using-nets</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x27da95fa.jpg</video:thumbnail_loc><video:title>Surface area of a box using nets</video:title><video:description>Discover the surface area of a cereal box by visualizing a net. Cut and flatten the box to create a 2D shape. Measure the dimensions, calculate the area of each section, and add them up for the total surface area. Fun and practical!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vl1uMOYFyf4.mp4/vl1uMOYFyf4.mp4</video:content_loc><video:duration>284</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/surface-area-of-a-box</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xcd3980f6.jpg</video:thumbnail_loc><video:title>Surface area of a box (cuboid)</video:title><video:description>Surface area is total area on the surface of a three-dimensional shape. To find the surface area of a cuboid which has 6 rectangular faces, add the areas of all 6 faces. Or, you can label the length (l), width (w), and height (h) of the cuboid and use the formula: surface area (SA)=2lw+2lh+2hw.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1iSBNSYhvIU.mp4/1iSBNSYhvIU.mp4</video:content_loc><video:duration>145</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/surface-area-word-problem-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6a82c2200b76ccc5.jpg</video:thumbnail_loc><video:title>Surface area word problem example</video:title><video:description>Akira won a science fair and got a golden pyramid trophy. We want to find out how much gold foil was used. The trophy has a square base and four triangular faces. By calculating the area of these shapes, we can find the total surface area covered by the gold foil.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ODNCH3gSKdA.mp4/ODNCH3gSKdA.mp4</video:content_loc><video:duration>275</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/ways-to-represent-data</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbcceb7d5.jpg</video:thumbnail_loc><video:title>Representing data</video:title><video:description>Data can be represented in multiple ways such as tables, bar graphs, histograms, and frequency plots. These methods provide different perspectives of the same information, helping to answer various questions about the data.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0ZKtsUkrgFQ.mp4/0ZKtsUkrgFQ.mp4</video:content_loc><video:duration>498</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/frequency-tables-and-dot-plots</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9720769d.jpg</video:thumbnail_loc><video:title>Frequency tables &amp; dot plots</video:title><video:description>Frequency tables and dot plots are handy tools in data representation. Frequency tables show how often each value appears, while dot plots provide a visual depiction of this information. These tools can be used to answer various questions about the data.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gdE46YSedvE.mp4/gdE46YSedvE.mp4</video:content_loc><video:duration>439</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/understanding-statistical-questions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xed476f8d.jpg</video:thumbnail_loc><video:title>Statistical questions</video:title><video:description>Statistics is about collecting, presenting, and analyzing data. Variability, a key concept in statistics, refers to how much data points differ from each other. Statistical questions require collecting data with variability to answer. For example, asking about the average number of cars in a parking lot on Monday mornings is a statistical question.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OjzfQDFf7Uk.mp4/OjzfQDFf7Uk.mp4</video:content_loc><video:duration>574</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/histograms-intro</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbfb17dc0.jpg</video:thumbnail_loc><video:title>Creating a histogram</video:title><video:description>A histogram is a graphical display of data using bars of different heights. In a histogram, each bar groups numbers into ranges. Taller bars show that more data falls in that range. A histogram displays the shape and spread of continuous sample data.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gSEYtAjuZ-Y.mp4/gSEYtAjuZ-Y.mp4</video:content_loc><video:duration>442</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/interpreting-histograms</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfeb52bb5.jpg</video:thumbnail_loc><video:title>Interpreting a histogram</video:title><video:description>In a cherry pie store, we use a histogram to understand the distribution of cherries on pies. We create buckets for different ranges of cherries, count the pies in each, and can answer questions about our pie inventory and cherry distribution!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/c02vjunQsJM.mp4/c02vjunQsJM.mp4</video:content_loc><video:duration>269</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/statistics-intro-mean-median-and-mode</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1152738250.jpg</video:thumbnail_loc><video:title>Statistics intro: Mean, median, &amp; mode</video:title><video:description>The mean (average) of a data set is found by adding all numbers in the data set and then dividing by the number of values in the set. The median is the middle value when a data set is ordered from least to greatest. The mode is the number that occurs most often in a data set.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/h8EYEJ32oQ8.mp4/h8EYEJ32oQ8.mp4</video:content_loc><video:duration>534</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/mean-median-and-mode</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/380854779.jpg</video:thumbnail_loc><video:title>Mean, median, &amp; mode example</video:title><video:description>Here we give you a set of numbers and then ask you to find the mean, median, and mode. It&apos;s your first opportunity to practice with us!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/k3aKKasOmIw.mp4/k3aKKasOmIw.mp4</video:content_loc><video:duration>235</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/using-mean-to-find-missing-value</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9cff9877.jpg</video:thumbnail_loc><video:title>Missing value given the mean</video:title><video:description>When babysitting, you forget one child&apos;s age from your records. But, you remember the mean age of the six children is four. Using this mean, you can find the missing age. The total of all ages equals the mean times the number of children. So, you solve for the missing age and find it&apos;s three.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qpbaglogObM.mp4/qpbaglogObM.mp4</video:content_loc><video:duration>303</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/median-and-range-puzzle</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x66204bfe.jpg</video:thumbnail_loc><video:title>Median &amp; range puzzlers</video:title><video:description>In a car dealership with 11 salespeople, the median number of cars sold is six, and the range of cars sold is four. This means the difference between the highest and lowest number of cars sold is four. Therefore, it&apos;s impossible for any salesperson to have sold more than 10 cars.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0cHCpgQD_8k.mp4/0cHCpgQD_8k.mp4</video:content_loc><video:duration>415</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/impact-on-median-and-mean-when-removing-lowest-value-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x04e04a4c.jpg</video:thumbnail_loc><video:title>Impact on median &amp; mean: removing an outlier</video:title><video:description>In this golf game, Ana&apos;s lowest score of 80 was removed due to rule-breaking. This change increased both the mean and median of her remaining scores. However, the mean increased more than the median.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-2OOBEBq9-4.mp4/-2OOBEBq9-4.mp4</video:content_loc><video:duration>337</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/impact-on-median-and-mean-when-increasing-highest-value</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbe8e5c92.jpg</video:thumbnail_loc><video:title>Impact on median &amp; mean: increasing an outlier</video:title><video:description>When a single high score in a group of four friends increases, the mean score also increases, but the median score stays the same. This is because the median is the middle number, which doesn&apos;t change, while the mean is the average of all scores, which does change.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/K1y6Tz_E7oA.mp4/K1y6Tz_E7oA.mp4</video:content_loc><video:duration>256</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/mean-absolute-deviation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x159a61f7.jpg</video:thumbnail_loc><video:title>Mean absolute deviation (MAD)</video:title><video:description>Mean absolute deviation (MAD) of a data set is the average distance between each data value and the mean. Mean absolute deviation is a way to describe variation in a data set. Mean absolute deviation helps us get a sense of how &quot;spread out&quot; the values in a data set are.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/GdIkEngwGNU.mp4/GdIkEngwGNU.mp4</video:content_loc><video:duration>550</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/mean-absolute-deviation-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x05e0f25b.jpg</video:thumbnail_loc><video:title>Mean absolute deviation example</video:title><video:description>This lesson teaches how to calculate the mean and mean absolute deviation (MAD) using a bar graph. The graph shows the number of bubbles blown by four people. The mean is found by adding all the values and dividing by the number of data points. The MAD is calculated by finding the average of the absolute differences from the mean.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DPuK6ZgBGmE.mp4/DPuK6ZgBGmE.mp4</video:content_loc><video:duration>382</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/calculating-interquartile-range-iqr</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x57fc0c82.jpg</video:thumbnail_loc><video:title>Interquartile range (IQR)</video:title><video:description>The IQR describes the middle 50% of values when ordered from lowest to highest. To find the interquartile range (IQR), ​first find the median (middle value) of the lower and upper half of the data. These values are quartile 1 (Q1) and quartile 3 (Q3). The IQR is the difference between Q3 and Q1.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qLYYHWYr8xI.mp4/qLYYHWYr8xI.mp4</video:content_loc><video:duration>372</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/constructing-a-box-and-whisker-plot</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1164226773.jpg</video:thumbnail_loc><video:title>Constructing a box plot</video:title><video:description>Here&apos;s a word problem that&apos;s perfectly suited for a box and whiskers plot to help analyze data. Let&apos;s construct one together, shall we?.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/09Cx7xuIXig.mp4/09Cx7xuIXig.mp4</video:content_loc><video:duration>498</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/reading-box-and-whisker-plots</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/380860448.jpg</video:thumbnail_loc><video:title>Reading box plots</video:title><video:description>Is this some kind of cute cat video? No! Box and whisker plots seek to explain data by showing a spread of all the data points in a sample. The &quot;whiskers&quot; are the two opposite ends of the data. This video is more fun than a handful of catnip.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/b2C9I8HuCe4.mp4/b2C9I8HuCe4.mp4</video:content_loc><video:duration>198</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/box-and-whisker-plot-exercise-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x53757fc0.jpg</video:thumbnail_loc><video:title>Worked example: Creating a box plot (odd number of data points)</video:title><video:description>A box-and-whisker plot is a handy tool for visualizing data. By ordering numbers, we can find the range, median, and quartiles. Practice makes perfect when mastering these concepts!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/m6xURMj2ztk.mp4/m6xURMj2ztk.mp4</video:content_loc><video:duration>198</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/another-example-constructing-box-plot</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3e584ad0.jpg</video:thumbnail_loc><video:title>Worked example: Creating a box plot (even number of data points)</video:title><video:description>Box-and-whiskers plots help visualize data ranges and medians. First, arrange your numbers from least to greatest. The smallest and largest numbers form the &apos;whiskers&apos;. The median of the entire data set splits the &apos;box&apos; in the middle. The medians of the top and bottom halves of the numbers form the &apos;box&apos; boundaries.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/oajrmwCALmc.mp4/oajrmwCALmc.mp4</video:content_loc><video:duration>195</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/interpreting-box-plots</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf95ced63.jpg</video:thumbnail_loc><video:title>Interpreting box plots</video:title><video:description>A box and whisker plot is a handy tool to understand the age distribution of students at a party. It helps us identify the minimum, maximum, median, and quartiles of the data. However, it doesn&apos;t provide specific details like the exact number of students at certain ages.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/oBREri10ZHk.mp4/oBREri10ZHk.mp4</video:content_loc><video:duration>464</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/comparing-dot-plots-histograms-and-box-plots</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x473b5ffc.jpg</video:thumbnail_loc><video:title>Comparing dot plots, histograms, and box plots</video:title><video:description>Data can be represented in various ways such as dot plots, histograms, and box plots. Dot plots and box plots are useful for finding the median, while histograms are great for showing the number of values within a specific range.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/s_w3EJ2Jzw0.mp4/s_w3EJ2Jzw0.mp4</video:content_loc><video:duration>326</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/shapes-of-distributions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdf97fc58.jpg</video:thumbnail_loc><video:title>Shapes of distributions</video:title><video:description>Some distributions are symmetrical, with data evenly distributed about the mean. Other distributions are &quot;skewed,&quot; with data tending to the left or right of the mean. We sometimes say that skewed distributions have &quot;tails.&quot;</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2oJldeE4JcU.mp4/2oJldeE4JcU.mp4</video:content_loc><video:duration>307</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/examples-analyzing-clusters-gaps-peaks-and-outliers-for-distributions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1d0df058.jpg</video:thumbnail_loc><video:title>Clusters, gaps, peaks &amp; outliers</video:title><video:description>This video explores the features of distributions in data sets, like clusters, gaps, and peaks. We learn how to identify outliers, which are data points far from the rest. We also discuss how to spot peaks and clusters in data.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4PXkzcK-b4Y.mp4/4PXkzcK-b4Y.mp4</video:content_loc><video:duration>392</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/6th-grade-foundations-engageny/v/comparing-with-multiplication-exercise</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfadbf044.jpg</video:thumbnail_loc><video:title>Comparing with multiplication</video:title><video:description>Sal solves multiplication comparison problems.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OCwLwaAQlMA.mp4/OCwLwaAQlMA.mp4</video:content_loc><video:duration>137</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/4-digit-times-1-digit-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3c1ecd5d.jpg</video:thumbnail_loc><video:title>Multiplying 4-digit by 1-digit (regrouping)</video:title><video:description>Learn to multiply a 4-digit number by a 1-digit number. In this video, we will multiply 8085 times 9.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/twMdew4Zs8Q.mp4/twMdew4Zs8Q.mp4</video:content_loc><video:duration>204</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/6th-grade-foundations-engageny/v/associative-law-of-multiplication</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/2600689.jpg</video:thumbnail_loc><video:title>Associative law of multiplication</video:title><video:description>Associative Law of Multiplication</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5RzDVNob0-0.mp4/5RzDVNob0-0.mp4</video:content_loc><video:duration>135</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/6th-grade-foundations-engageny/v/multiplying-a-decimal-by-a-power-of-10</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/153770145.jpg</video:thumbnail_loc><video:title>Multiplying a decimal by a power of 10</video:title><video:description>Learn to multiply 0.44 times 1000 using powers of 10.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/mV0RxDZG05A.mp4/mV0RxDZG05A.mp4</video:content_loc><video:duration>227</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/6th-grade-foundations-engageny/v/dividing-a-decimal-by-a-power-of-10</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/153770148.jpg</video:thumbnail_loc><video:title>Dividing a decimal by a power of 10</video:title><video:description>Sal talks about why moving the decimal point to the left when dividing by a power of 10 makes sense.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/W_VhVHRal6o.mp4/W_VhVHRal6o.mp4</video:content_loc><video:duration>198</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/6th-grade-illustrative-math/v/identifying-bases-and-heights-of-parallelograms</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xddba21b4ea9d61fa.jpg</video:thumbnail_loc><video:title>Identifying bases and heights of parallelograms</video:title><video:description>Learn how to identify the base and height of a parallelogram by looking for the perpendicular relationship between them. We&apos;ll practice spotting the height, whether it’s drawn inside the shape or as a dotted line on the outside!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/C3OFtj73N0E.mp4/C3OFtj73N0E.mp4</video:content_loc><video:duration>212</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/6th-grade-illustrative-math/v/special-polyhedra-cube</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7db86bb8ad7c5edf.jpg</video:thumbnail_loc><video:title>Special polyhedra: cube</video:title><video:description>Explore how the cube functions as a unique polyhedron in which every face is a square and every edge meets at a right angle.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/klMANPlTORs.mp4/klMANPlTORs.mp4</video:content_loc><video:duration>413</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/6th-grade-illustrative-math/v/volume-of-a-cube</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xcde3bbe65ae2bf72.jpg</video:thumbnail_loc><video:title>Volume of a cube</video:title><video:description>Discover how to find the volume of a cube by understanding that all its dimensions—length, width, and height—are exactly the same. We’ll see how multiplying the side length by itself three times (V = s^3) allows us to count how many unit cubes fit inside.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6yYnr8FL1fk.mp4/6yYnr8FL1fk.mp4</video:content_loc><video:duration>215</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/6th-grade-illustrative-math/v/part-to-part-ratio-models</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb37a770e8d63a842.jpg</video:thumbnail_loc><video:title>Part-to-part ratio models</video:title><video:description>Learn how to use tape diagrams and visual models to compare two different quantities, like the ratio of blue marbles to red marbles. We’ll practice &quot;splitting&quot; a total into parts to see how changing one piece of the ratio affects the entire set.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3So5vSNtD48.mp4/3So5vSNtD48.mp4</video:content_loc><video:duration>138</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/ratios-with-tape-diagrams-partwhole</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5873e07fce3ea19f.jpg</video:thumbnail_loc><video:title>Ratios with tape diagrams (part:whole)</video:title><video:description>Find the ratio of open-ended to multiple-choice questions. If the ratio is 5:4, it means for every 5 open-ended questions, there are 4 multiple-choice questions. The video then shows how to use this ratio to complete a table with missing values for multiple-choice and total questions.Read a part-to-whole ratio from a tape diagram showing the ratio of the two parts. Then scale up to generate sets of values that the diagram might represent.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/FX8RIxFN7ZI.mp4/FX8RIxFN7ZI.mp4</video:content_loc><video:duration>142</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/simplify-a-ratio-from-a-tape-diagram</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4970efbb4ec23069.jpg</video:thumbnail_loc><video:title>Simplify a ratio from a tape diagram</video:title><video:description>In this problem, we have a mixture of yellow and red paint. There are 12 parts yellow and 8 parts red. We want to find the ratio of red paint to the total paint in the mixture. To do this, we add the parts of red and yellow paint together (8 + 12 = 20). The ratio of red paint to total paint is 8:20.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ElFVoKxX06Y.mp4/ElFVoKxX06Y.mp4</video:content_loc><video:duration>161</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/6th-grade-illustrative-math/v/missing-information-rate-problems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x66397d94c78f35b9.jpg</video:thumbnail_loc><video:title>Missing information: rate problems</video:title><video:description>Discover how to identify the missing piece of information needed to solve a rate problem by organizing known quantities.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Lwog2qzaS20.mp4/Lwog2qzaS20.mp4</video:content_loc><video:duration>236</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/6th-grade-illustrative-math/v/modeling-fraction-equations-with-tape-diagrams-bike-route</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x00d454b62fe39734.jpg</video:thumbnail_loc><video:title>Modeling fraction equations with tape diagrams: bike route</video:title><video:description>Let&apos;s interpret tape diagrams that model fraction division.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/aNywIvg-Q2w.mp4/aNywIvg-Q2w.mp4</video:content_loc><video:duration>125</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/6th-grade-illustrative-math/v/modeling-fraction-expressions-with-tape-diagrams-pasta-salad</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd8293535f69d81b0.jpg</video:thumbnail_loc><video:title>Modeling fraction expressions with tape diagrams: pasta salad</video:title><video:description>Let&apos;s create tape diagrams to solve fraction division problems.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/a7RzJ7piDSc.mp4/a7RzJ7piDSc.mp4</video:content_loc><video:duration>138</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/6th-grade-illustrative-math/v/modeling-expressions-with-mixed-numbers-bracelets</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x50f43ba6e5848dc4.jpg</video:thumbnail_loc><video:title>Modeling expressions with mixed numbers: bracelets</video:title><video:description>Let&apos;s interpret problems and use tape diagrams to model solutions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/JaUu2iS-CuE.mp4/JaUu2iS-CuE.mp4</video:content_loc><video:duration>165</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/dividing-mixed-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/2600765.jpg</video:thumbnail_loc><video:title>Dividing mixed numbers</video:title><video:description>Sal shows us how to change mixed numbers into improper fractions, divide, and then change the answer back to a mixed number.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/51-U-Jkq79A.mp4/51-U-Jkq79A.mp4</video:content_loc><video:duration>161</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/6th-grade-illustrative-math/v/using-volume-for-missing-side-length-mixed-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1d0c60d9997623d9.jpg</video:thumbnail_loc><video:title>Using volume for missing side length (mixed numbers)</video:title><video:description>Let&apos;s learn how to find the missing edge length of a rectangular prism when we already know its volume and two of its dimensions. We&apos;ll use the volume formula V = lwh, plug in what we know, and solve for the unknown, getting great practice with fractions and mixed numbers along the way!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/i-xK4mSdGUg.mp4/i-xK4mSdGUg.mp4</video:content_loc><video:duration>163</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/6th-grade-illustrative-math/v/solving-money-problems-with-decimals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2aa0bf2576be3405.jpg</video:thumbnail_loc><video:title>Solving money problems with decimals</video:title><video:description>Let&apos;s tackle multi-step money problems with decimals, using a real-world shopping context to find things like total revenue and profit. Along the way, we&apos;ll practice estimating our answers to make sure our math is on the right track!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/E64fsviSyV4.mp4/E64fsviSyV4.mp4</video:content_loc><video:duration>258</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/6th-grade-illustrative-math/v/relating-decimal-multiplication-to-fractions-and-place-value</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb222eb9bd2c3cb48.jpg</video:thumbnail_loc><video:title>Relating decimal multiplication to fractions and place value</video:title><video:description>Let&apos;s explore how decimals and fractions are just different ways of writing the same numbers, and how switching between the two forms can make multiplication problems easier to solve. We&apos;ll practice rewriting expressions in multiple ways so we can choose the approach that works best for us!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/FYN7ElO_6Y0.mp4/FYN7ElO_6Y0.mp4</video:content_loc><video:duration>339</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/partial-quotient-method-of-division-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/258726799.jpg</video:thumbnail_loc><video:title>Partial quotient method of division: example using very large numbers</video:title><video:description>Another example of doing long division using the partial quotient method</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/omFelSZvaJc.mp4/omFelSZvaJc.mp4</video:content_loc><video:duration>476</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-4-math-tx/v/solving-two-step-word-problems-involving-adding-and-subtracting-decimals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x889cff953f13e58f.jpg</video:thumbnail_loc><video:title>Solving two-step word problems involving adding and subtracting decimals</video:title><video:description>Practice solving two-step word problems that involve decimals. Use different strategies that either add and subtract, subtract then subtract, or subtract and then add.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/nmYpEiz_89k.mp4/nmYpEiz_89k.mp4</video:content_loc><video:duration>171</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/6th-grade-illustrative-math/v/multiplying-decimals-word-problems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3976c33197f42a0c.jpg</video:thumbnail_loc><video:title>Multiplying decimals word problems</video:title><video:description>Practice multiplying decimals in real-world scenarios.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/D-kaGGEg9yo.mp4/D-kaGGEg9yo.mp4</video:content_loc><video:duration>359</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/6th-grade-illustrative-math/v/multiplying-decimals-two-step-word-problems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x537325b4c9ab73f5.jpg</video:thumbnail_loc><video:title>Multiplying decimals two-step word problems</video:title><video:description>Practice solving real world scenarios using decimals and whole numbers. Use your knowledge of multiplying whole numbers and estimation to make multiplying more friendly!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8Wzjh-CmDHA.mp4/8Wzjh-CmDHA.mp4</video:content_loc><video:duration>323</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/6th-grade-illustrative-math/v/identifying-equations-from-visual-models-tape-diagrams</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x73d83ffa7e56c5be.jpg</video:thumbnail_loc><video:title>Identifying equations from visual models: tape diagrams</video:title><video:description>Learn how to read tape diagrams and translate what we see into one-step equations using variables. We&apos;ll work through two examples together, practice writing the equations they represent, and then solve for the unknown to check that our answer makes sense!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8mrF81QZVF4.mp4/8mrF81QZVF4.mp4</video:content_loc><video:duration>228</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/6th-grade-illustrative-math/v/one-step-division-equations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5f814f842b8c84e4.jpg</video:thumbnail_loc><video:title>One-step division equations</video:title><video:description>In this lesson, we learn how to solve simple algebraic equations systematically. We focus on understanding the meaning of equations, like 7x = 14, and using techniques like dividing both sides of the equation by the coefficient to isolate the variable. This method helps us find the value of the unknown variable, making algebra easier and more approachable.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/WhsOJtZazS8.mp4/WhsOJtZazS8.mp4</video:content_loc><video:duration>618</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/solving-percent-problems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13.jpg</video:thumbnail_loc><video:title>Solving percent problems</video:title><video:description>We&apos;ll use algebra to solve this percent problem.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TvSKeTFsaj4.mp4/TvSKeTFsaj4.mp4</video:content_loc><video:duration>377</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/mappers/v/solving-percent-problems-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/14.jpg</video:thumbnail_loc><video:title>Percent word problem: 100 is what percent of 80?</video:title><video:description>This word problem is expressed simply which can be confusing to some. Take your time and focus on the what is being asked for.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/N4kDzoQOngY.mp4/N4kDzoQOngY.mp4</video:content_loc><video:duration>277</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/6th-grade-illustrative-math/v/equal-and-equivalent-expressions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc6ae6cdb925bd49f.jpg</video:thumbnail_loc><video:title>Equal and equivalent expressions</video:title><video:description>Learn how to simplify expressions and use that skill to figure out when two expressions are always, sometimes, or never equal. We&apos;ll work through examples of each case together so we can build a solid understanding of what it really means for two expressions to be equivalent!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/orsTliP9CU8.mp4/orsTliP9CU8.mp4</video:content_loc><video:duration>217</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/powers-of-zero</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc9cc5314.jpg</video:thumbnail_loc><video:title>Powers of zero</video:title><video:description>Any non-zero number to the zero power equals one. Zero to any positive exponent equals zero. So, what happens when you have zero to the zero power?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/S2PjhiAQMK8.mp4/S2PjhiAQMK8.mp4</video:content_loc><video:duration>201</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/dependent-and-independent-variables-exercise-example-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe757cceb.jpg</video:thumbnail_loc><video:title>Dependent &amp; independent variables: equation</video:title><video:description>We&apos;re flipping the last video on its head and doing the opposite. This time we give you the graph and ask you to express it as an equation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3ACF7L-7Vsg.mp4/3ACF7L-7Vsg.mp4</video:content_loc><video:duration>120</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/6th-grade-illustrative-math/v/modeling-distance-over-time</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf1038ea7a44cb563.jpg</video:thumbnail_loc><video:title>Modeling distance over time</video:title><video:description>Learn how to model the relationship between distance and time using three different representations: an equation, a table, and a graph. We&apos;ll work through each part of a real problem together and explore how all three representations connect to tell the same story about distance and time!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/e6u9VT4d_vY.mp4/e6u9VT4d_vY.mp4</video:content_loc><video:duration>273</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/number-opposites-practice</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1914a298.jpg</video:thumbnail_loc><video:title>Number opposites challenge problems</video:title><video:description>Sal solves a few challenging problems with number opposites on the number line.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vRa6XxykfbY.mp4/vRa6XxykfbY.mp4</video:content_loc><video:duration>188</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/6th-grade-illustrative-math/v/labeling-axes-to-fit-data-sets</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xde4ca3351c48b071.jpg</video:thumbnail_loc><video:title>Labeling axes to fit data sets</video:title><video:description>Let&apos;s learn how to set up a coordinate plane that fits data by carefully choosing the right range and scale for each axis. We&apos;ll work through a real example together and see how thinking through these decisions before we start drawing makes graphing so much easier!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/mFN9Wh8K_uw.mp4/mFN9Wh8K_uw.mp4</video:content_loc><video:duration>251</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/6th-grade-illustrative-math/v/distances-in-the-coordinate-plane-between-reflected-points</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb4be9f355b83939b.jpg</video:thumbnail_loc><video:title>Distances in the coordinate plane (between reflected points)</video:title><video:description>Let&apos;s learn how to find the distance between two points on a coordinate plane when they share the same coordinates but have opposite signs. We&apos;ll discover how the axis between the points is always the midpoint, which means we can find the total distance by doubling each point&apos;s distance from that axis!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-GI96_8q2OE.mp4/-GI96_8q2OE.mp4</video:content_loc><video:duration>330</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/6th-grade-illustrative-math/v/categorical-data-sets</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x36d06ea50e839cf7.jpg</video:thumbnail_loc><video:title>Categorical data sets</video:title><video:description>Let&apos;s explore how data is all around us and learn what makes a data set categorical, including some sneaky examples where numbers are used as labels rather than actual quantities. We&apos;ll look at real-world examples together to build our understanding of how to tell the difference between categorical and numerical data!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Moi2PbI4b48.mp4/Moi2PbI4b48.mp4</video:content_loc><video:duration>224</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/6th-grade-illustrative-math/v/numerical-data-sets</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd3cde909f336f60c.jpg</video:thumbnail_loc><video:title>Numerical data sets</video:title><video:description>explore how data is all around us and learn what makes a data set numerical, where the values represent actual quantities we can measure or count. We&apos;ll work through real-world examples together to deepen our understanding of numerical data and how it differs from categorical data!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ktaTECHDVy0.mp4/ktaTECHDVy0.mp4</video:content_loc><video:duration>204</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/6th-grade-illustrative-math/v/mean</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4298fd56d3b8781c.jpg</video:thumbnail_loc><video:title>Mean</video:title><video:description>Let&apos;s learn how to calculate the mean by adding up all the values in a data set and dividing by the number of values. We&apos;ll also explore how to interpret the mean as a balance point that represents the entire data set with just one number!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_40su2dEvA4.mp4/_40su2dEvA4.mp4</video:content_loc><video:duration>204</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/6th-grade-illustrative-math/v/interpreting-mean</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2e3856042fe75bdc.jpg</video:thumbnail_loc><video:title>Interpreting mean</video:title><video:description>Let&apos;s build an intuitive understanding of what the mean actually tells us about a data set, no calculations needed! By looking at visual representations and real-world contexts, we&apos;ll explore how the mean helps us describe the typical value in a data set and what we can learn by comparing the means of two different groups.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1DuU8GbTPgk.mp4/1DuU8GbTPgk.mp4</video:content_loc><video:duration>165</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/6th-grade-illustrative-math/v/interpreting-variability</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd9ff51b28b917565.jpg</video:thumbnail_loc><video:title>Interpreting variability</video:title><video:description>Let&apos;s build an intuitive understanding of what variability tells us about a data set, without doing any MAD calculations! By exploring visual representations, we&apos;ll learn how to interpret how spread-out data is around its center and what that reveals about consistency in real-world contexts.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/MlrzY0u_aOg.mp4/MlrzY0u_aOg.mp4</video:content_loc><video:duration>188</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/6th-grade-illustrative-math/v/median</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6d2f767ce8fd49dd.jpg</video:thumbnail_loc><video:title>Median</video:title><video:description>Let&apos;s learn what the median is, why we use it as a measure of center, and how to find it by ordering our data and locating the middle value. We&apos;ll also explore how the median is especially useful when our data has an outlier that would otherwise throw off our sense of what&apos;s typical!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jQzoJJRgvcI.mp4/jQzoJJRgvcI.mp4</video:content_loc><video:duration>253</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/interpreting-unequal-ratios</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf891c0d1d760b343.jpg</video:thumbnail_loc><video:title>Interpreting unequal ratios</video:title><video:description>Interpret the ratio of pepper to fish in two recipes to decide which tastes spicier. Akeem&apos;s recipe uses 19 grams of ground pepper for every four catfish fillets, while Tisha uses 25 grams for six fillets. To compare their pepper taste, we can find a common number of fillets. For 12 fillets, Akeem uses 57 grams of pepper, and Tisha uses 50 grams. Therefore, Akeem&apos;s catfish fillets have a stronger pepper taste.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/u6TNiTf2zhQ.mp4/u6TNiTf2zhQ.mp4</video:content_loc><video:duration>191</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/6th-grade-math-eureka-squared-aligned/v/euclidean-algorithm-to-find-gcf</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x49dd9ce0615c1aa1.jpg</video:thumbnail_loc><video:title>Euclidean algorithm to find GCF</video:title><video:description>Learn the subtraction Euclidean Algorithm for finding the GCF: keep subtracting the smaller number from the bigger one. When the two numbers match, that number is the GCF.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OwND6sh6FdU.mp4/OwND6sh6FdU.mp4</video:content_loc><video:duration>197</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/negative-numbers-introduction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/19647488.jpg</video:thumbnail_loc><video:title>Intro to negative numbers</video:title><video:description>Mysterious negative numbers! What ARE they? They are numbers less than zero. If you understand the nature of below zero temperatures, you can understand negative numbers. We&apos;ll help.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Hlal9ME2Aig.mp4/Hlal9ME2Aig.mp4</video:content_loc><video:duration>576</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/6th-grade-math-eureka-squared-aligned/v/constructing-the-coordinate-plane</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe71d85adcf19eb99.jpg</video:thumbnail_loc><video:title>Constructing the coordinate plane</video:title><video:description>Learn to build a coordinate plane by choosing the minimum and maximum values and a clear scale for each axis.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/u2Vdc45X5Zw.mp4/u2Vdc45X5Zw.mp4</video:content_loc><video:duration>426</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-sixth-grade-math/v/order-operations-example-fractions-exponents</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x41b3fbc71efc518a.jpg</video:thumbnail_loc><video:title>Order of operations example: fractions and exponents</video:title><video:description>The order of operations is essential for accurately evaluating complex math expressions. By following the steps of parentheses, exponents, multiplication and division, and finally addition and subtraction, you can simplify expressions and find the correct answer. Mastering these steps ensures a strong foundation in mathematics.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jAVbApE7lJ8.mp4/jAVbApE7lJ8.mp4</video:content_loc><video:duration>237</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/6th-grade-math-eureka-squared-aligned/v/volume-of-composite-solids</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x967c577e9efb1af7.jpg</video:thumbnail_loc><video:title>Volume of composite solids</video:title><video:description>Find volume by decomposing figures into rectangular prisms.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/epUOumtNaws.mp4/epUOumtNaws.mp4</video:content_loc><video:duration>182</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/introduction-to-proportional-relationships</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x042dc5b1.jpg</video:thumbnail_loc><video:title>Intro to proportional relationships</video:title><video:description>To know if a relationship is proportional, you should look at the ratios between the two variables. If the ratio is always the same, the relationship is proportional. If the ratio changes, the relationship is not proportional.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qYjiVWwefto.mp4/qYjiVWwefto.mp4</video:content_loc><video:duration>230</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/analyzing-and-identifying-proportional-relationships-ex3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xcf658b5a.jpg</video:thumbnail_loc><video:title>Proportional relationships: spaghetti</video:title><video:description>Given a table of ratios, watch as we test them for equivalence and determine whether the relationship is proportional.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jNUz0P5MG9M.mp4/jNUz0P5MG9M.mp4</video:content_loc><video:duration>63</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/movie-ticket-proportionality</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xaef37673.jpg</video:thumbnail_loc><video:title>Proportional relationships: movie tickets</video:title><video:description>When going to the movies, is the price you pay proportional to the number of tickets you buy?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-YYTUTrxl28.mp4/-YYTUTrxl28.mp4</video:content_loc><video:duration>106</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/banana-proportionality</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x48c1f191.jpg</video:thumbnail_loc><video:title>Proportional relationships: bananas</video:title><video:description>A proportionality problem about eating bananas.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/bJb4n19sFrs.mp4/bJb4n19sFrs.mp4</video:content_loc><video:duration>177</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/identifying-proportional-relationships-visually</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x919ece65.jpg</video:thumbnail_loc><video:title>Proportional relationships: graphs</video:title><video:description>Learn how to tell proportional relationships by drawing graphs. Key idea: the graph of a proportional relationship is a straight line through the origin.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/C7CY4l99S7M.mp4/C7CY4l99S7M.mp4</video:content_loc><video:duration>439</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/proportional-relationships-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x950881e0e1b45d92.jpg</video:thumbnail_loc><video:title>Proportional relationships</video:title><video:description>Sal determines which ratios are proportionate to a ratio provided in a context.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/HEmwn5jmy2Y.mp4/HEmwn5jmy2Y.mp4</video:content_loc><video:duration>243</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/proportionality-between-side-length-and-perimeter</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x97c4daf2.jpg</video:thumbnail_loc><video:title>Is side length &amp; perimeter proportional?</video:title><video:description>Sal answers the question by drawing a square and thinking about the relationship between side length and perimeter.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9nH3A4riVxs.mp4/9nH3A4riVxs.mp4</video:content_loc><video:duration>159</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/testing-whether-area-is-proportional-to-side-length</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x712a89dd.jpg</video:thumbnail_loc><video:title>Is side length &amp; area proportional?</video:title><video:description>Sal answers the question by drawing a square and thinking about the relationship between side length and area.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Hzz5p0qlObs.mp4/Hzz5p0qlObs.mp4</video:content_loc><video:duration>226</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/constant-of-proportionality-from-equation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x36bcce972ab1db2d.jpg</video:thumbnail_loc><video:title>Constant of proportionality from equation</video:title><video:description>Sal identifies the constant of proportionality from equations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/wXtzBbU_cl8.mp4/wXtzBbU_cl8.mp4</video:content_loc><video:duration>143</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/identifying-constant-of-proportionality-graphically</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x10d4fd17bad36cd0.jpg</video:thumbnail_loc><video:title>Identifying constant of proportionality graphically</video:title><video:description>The video explains the concept of the constant of proportionality in graphs. It shows how to calculate it using the formula Y = KX or Y/X = K, where K is the constant. It also demonstrates how to identify lines with specific constants on a graph.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jihKUWH4Hfc.mp4/jihKUWH4Hfc.mp4</video:content_loc><video:duration>277</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/proportionality-constant-from-table</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x25cab8c41c3a0b83.jpg</video:thumbnail_loc><video:title>Constant of proportionality from table (with equations)</video:title><video:description>Sal identifies the constant of proportionality from table.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5Ilo0pw3iL8.mp4/5Ilo0pw3iL8.mp4</video:content_loc><video:duration>105</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/comparing-proportionality-constants</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x632f1595cd506367.jpg</video:thumbnail_loc><video:title>Comparing proportionality constants</video:title><video:description>Sal compares constants of proportionality in various forms, such as graphs, equations, contexts, diagrams, and tables.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4g5ZEGoYtOA.mp4/4g5ZEGoYtOA.mp4</video:content_loc><video:duration>333</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/interpret-proportionality-constants</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe6bdf10fa34e4b6c.jpg</video:thumbnail_loc><video:title>Interpret proportionality constants</video:title><video:description>Sal interpret what the constant of proportionality means in a context.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/FXpJQXzoXwI.mp4/FXpJQXzoXwI.mp4</video:content_loc><video:duration>200</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/find-an-unknown-in-a-proportion</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/153770146.jpg</video:thumbnail_loc><video:title>Worked example: Solving proportions</video:title><video:description>Learn the reasoning behind solving proportions. We&apos;ll put some algebra to work to get our answers, too.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/GO5ajwbFqVQ.mp4/GO5ajwbFqVQ.mp4</video:content_loc><video:duration>440</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/writing-proportions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/211185145.jpg</video:thumbnail_loc><video:title>Writing proportions example</video:title><video:description>Some examples of writing two ratios and setting them equal to each other to solve proportion word problems.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/96ZEmUbnuU8.mp4/96ZEmUbnuU8.mp4</video:content_loc><video:duration>351</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/find-an-unknown-in-a-proportion-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/153770142.jpg</video:thumbnail_loc><video:title>Proportion word problem: cookies</video:title><video:description>A recipe for oatmeal cookies calls for 2 cups of flour for every 3 cups of oatmeal. How much flour is needed for a big batch of cookies that uses 9 cups of oatmeal?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4ywTWCaLmXE.mp4/4ywTWCaLmXE.mp4</video:content_loc><video:duration>348</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/using-proportion-to-solve-for-variable</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x648638d3.jpg</video:thumbnail_loc><video:title>Proportion word problem: hot dogs</video:title><video:description>Mika can eat 21 hot dogs in 66 minutes. She wants to know how many minutes it would take her to eat 35 hot dogs if she can keep up the same pace.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/s8_14yxp1lQ.mp4/s8_14yxp1lQ.mp4</video:content_loc><video:duration>298</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/equations-of-proportional-relationships</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7d23b788.jpg</video:thumbnail_loc><video:title>Equations for proportional relationships</video:title><video:description>Learn how to write a proportional equation y=kx where k is the so-called &quot;constant of proportionality&quot;.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qcz1Cm_-l50.mp4/qcz1Cm_-l50.mp4</video:content_loc><video:duration>301</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/constructing-an-equation-for-a-proportional-relationship</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x20c99318.jpg</video:thumbnail_loc><video:title>Writing proportional equations from tables</video:title><video:description>Writing an equation to describe the relationship between the number of scoops in an ice cream cone and the price</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/dBGeri4eFv4.mp4/dBGeri4eFv4.mp4</video:content_loc><video:duration>167</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-engage-ny/v/examples-interpreting-graphs-of-proportional-relationships</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6dbbed4b.jpg</video:thumbnail_loc><video:title>Interpreting graphs of proportional relationships</video:title><video:description>Learn how to read and understand graphs of proportional relationships</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/muZmOiiukQE.mp4/muZmOiiukQE.mp4</video:content_loc><video:duration>452</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/determining-rates-with-fractions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4861d7fa.jpg</video:thumbnail_loc><video:title>Rates with fractions</video:title><video:description>Sal solves an example problem with rates with fractions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2DBBKArGfus.mp4/2DBBKArGfus.mp4</video:content_loc><video:duration>307</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/exploring-scale-copies</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x76b3e7a99b5e6187.jpg</video:thumbnail_loc><video:title>Exploring scale copies</video:title><video:description>Sal uses virtual manipulatives to identify figures that scale proportionally.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/z2E_GpucfeA.mp4/z2E_GpucfeA.mp4</video:content_loc><video:duration>112</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/corresponding-points-and-sides-of-scaled-shapes</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc50cc9fa6fa67a46.jpg</video:thumbnail_loc><video:title>Corresponding points and sides of scaled shapes</video:title><video:description>Sal identifies corresponding sides and corresponding points in scale copies of figures.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/FeogTR_omiM.mp4/FeogTR_omiM.mp4</video:content_loc><video:duration>175</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/identifying-scaled-copies</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x575ccd7ff0de3724.jpg</video:thumbnail_loc><video:title>Identifying scale copies</video:title><video:description>Sal looks at side measures on figures to determine if they are scale copies.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/QBiTspq2Wck.mp4/QBiTspq2Wck.mp4</video:content_loc><video:duration>244</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-engage-ny/v/identifying-scale-factors</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x75f35bd8098b3fe6.jpg</video:thumbnail_loc><video:title>Identifying scale factors</video:title><video:description>Sal looks at a figure and a scale copy of the figure to determine what scale factor was used to create the scale copy.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Z3SXp8jDbdU.mp4/Z3SXp8jDbdU.mp4</video:content_loc><video:duration>175</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/identifying-values-in-scale-drawings</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa0f1defc3a6e9244.jpg</video:thumbnail_loc><video:title>Identifying values in scale copies</video:title><video:description>Sal identifies missing side lengths in scale drawings.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/YCjc3uRTq7I.mp4/YCjc3uRTq7I.mp4</video:content_loc><video:duration>229</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/ratio-word-problem-exercise-example-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8db3094d.jpg</video:thumbnail_loc><video:title>Scale drawing: centimeters to kilometers</video:title><video:description>Sal uses ratios to figure out how far apart two cities should be on a map.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tOd2T72eJME.mp4/tOd2T72eJME.mp4</video:content_loc><video:duration>72</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/constructing-scale-drawings</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb773c610.jpg</video:thumbnail_loc><video:title>Making a scale drawing</video:title><video:description>An urban planner needs your help in creating a scale drawing. Let&apos;s use our knowledge about scale factor, length, and area to assist.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/f-gCYOCFMYc.mp4/f-gCYOCFMYc.mp4</video:content_loc><video:duration>198</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/scale-drawings-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x20cf89b2.jpg</video:thumbnail_loc><video:title>Interpreting a scale drawing</video:title><video:description>Understand how a scale drawing is converted into real numbers using the scale factor.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/byjmR7JBXKc.mp4/byjmR7JBXKc.mp4</video:content_loc><video:duration>266</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/scale-drawing-example-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6b901e6c.jpg</video:thumbnail_loc><video:title>Solving a scale drawing word problem</video:title><video:description>See how we solve a word problem by using a scale drawing and finding the scale factor.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/EgOyJJxuuP8.mp4/EgOyJJxuuP8.mp4</video:content_loc><video:duration>351</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/zero-pairs-worked-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x324537f1206956c8.jpg</video:thumbnail_loc><video:title>Zero pairs worked example</video:title><video:description>When we have a positive unit and a negative unit, they add up to zero. We call that a zero pair. Let&apos;s use integer chips to represent the number -2, but not just with 2 negative chips. This will open the door for us to add and subtract with negative numbers.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hwK33GvGIK4.mp4/hwK33GvGIK4.mp4</video:content_loc><video:duration>127</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/adding-with-integer-chips</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x83da0698c825f538.jpg</video:thumbnail_loc><video:title>Adding with integer chips</video:title><video:description>Let&apos;s model and evaluate sums using integer chip diagrams. When all the integer chips are negative, we can just count up our total negatives. When we have a positive integer chip and negative integer chip, those pair up to equal zero. So our sum is whatever chips are left over.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/BqfDKV0gPRE.mp4/BqfDKV0gPRE.mp4</video:content_loc><video:duration>226</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/adding-negative-numbers-on-number-line-examples</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x13e7e4f6.jpg</video:thumbnail_loc><video:title>Adding negative numbers on the number line</video:title><video:description>Sal shows how to model 6 + (-2) using vertical number lines.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3CKpidALDEg.mp4/3CKpidALDEg.mp4</video:content_loc><video:duration>325</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/adding-negative-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/153770154.jpg</video:thumbnail_loc><video:title>Adding negative numbers example</video:title><video:description>Use a number line to add -15 + (-46) + (-29)</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/AcpIO62x2oo.mp4/AcpIO62x2oo.mp4</video:content_loc><video:duration>341</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/signs-of-sums-on-a-number-line</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xaa50e176d0198ec1.jpg</video:thumbnail_loc><video:title>Signs of sums on a number line</video:title><video:description>Let&apos;s build intuition for the sign of sum involving negative and positive numbers. We&apos;ll decide whether each sum ends to the left or right of 0. Then we&apos;ll evaluate exactly to see whether the intuition worked out.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/VBEQgXLhBzU.mp4/VBEQgXLhBzU.mp4</video:content_loc><video:duration>444</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/subtracting-with-integer-chips</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe9d6449e2ebe97f4.jpg</video:thumbnail_loc><video:title>Subtracting with integer chips</video:title><video:description>Let&apos;s model subtraction expressions using positive and negative integer chips. To subtract, we&apos;ll take away the appropriate number of chips. What if we don&apos;t have enough chips to take away? We can add as many zero pairs as we need, because they don&apos;t change the value of the expression.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/yTqhzgpt_9Y.mp4/yTqhzgpt_9Y.mp4</video:content_loc><video:duration>330</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/adding-the-opposite-with-integer-chips</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xeb730da455448485.jpg</video:thumbnail_loc><video:title>Adding the opposite with integer chips</video:title><video:description>Use integer chips to explore the conjecture that subtracting a number gives the same result as adding the opposite of the number.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0O4hGprr71g.mp4/0O4hGprr71g.mp4</video:content_loc><video:duration>311</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/adding-the-opposite-with-number-lines</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x57519ddea4bca03b.jpg</video:thumbnail_loc><video:title>Adding the opposite with number lines</video:title><video:description>Explore the claim that subtracting a number is the same as adding its opposite using number lines. We move to the right on the number line when we add a positive number. We move to the left on the number line both when we subtract a positive number and when we add a negative number. So which direction do we draw the arrow when we subtract a negative number on the number line?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/S5oBJ9aL9QQ.mp4/S5oBJ9aL9QQ.mp4</video:content_loc><video:duration>297</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-basics/v/adding-and-subtracting-negative-number-examples</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xded1ea52.jpg</video:thumbnail_loc><video:title>Adding &amp; subtracting negative numbers</video:title><video:description>Learn how to add and subtract negative numbers. The problems solved in this video are 2 - 3 = -1 and -2 - 3 = -5 and -2 + 3 = 1 and 2 - (-3) = 5 and -2 - (-3).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/NQSN00zL5gg.mp4/NQSN00zL5gg.mp4</video:content_loc><video:duration>247</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/why-subtracting-a-negative-equivalent-to-adding-a-positive</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1244788705.jpg</video:thumbnail_loc><video:title>Subtracting a negative = adding a positive</video:title><video:description>Find out why subtracting a negative number is the same as adding the absolute value of that number.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lBscLuttQq0.mp4/lBscLuttQq0.mp4</video:content_loc><video:duration>93</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/equivalent-expressions-with-negative-rationals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa2ed7747d165fc27.jpg</video:thumbnail_loc><video:title>Equivalent expressions with negative numbers</video:title><video:description>Understand that we can commute and associate terms as long as we keep the signs with the terms. We can also apply the additive identity property and the additive inverse property.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Shvr_SgLPJo.mp4/Shvr_SgLPJo.mp4</video:content_loc><video:duration>613</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/integer-equations-to-describe-diagram</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb8d99f61.jpg</video:thumbnail_loc><video:title>Number equations &amp; number lines</video:title><video:description>Integer equations to describe diagram</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Ddvw2wEBfpc.mp4/Ddvw2wEBfpc.mp4</video:content_loc><video:duration>163</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/graphing-negative-number-addition-and-subtraction-expressions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3cfb7e6fd1638784.jpg</video:thumbnail_loc><video:title>Graphing negative number addition and subtraction expressions</video:title><video:description>Graph addition and subtraction expressions involving negative numbers on the number line. When we add a positive number, we move to the right on the number line. When we add a negative number, we move to the left. When we subtract a number, we move in the opposite direction as we would to add the same number.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LwUMnbV303k.mp4/LwUMnbV303k.mp4</video:content_loc><video:duration>234</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/interpreting-integer-expressions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x79fbd639.jpg</video:thumbnail_loc><video:title>Interpreting numeric expressions example</video:title><video:description>Sal chooses the correct interpretation of the integer expression 3 + (-7).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ahib7LGDysQ.mp4/ahib7LGDysQ.mp4</video:content_loc><video:duration>146</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/absolute-value-as-distance-between-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2149e09f.jpg</video:thumbnail_loc><video:title>Absolute value as distance between numbers</video:title><video:description>In this video, we think about what |a-b| really means, and we verify that |a-b| = |b-a| by looking at an example.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/t4xOkpP8FgE.mp4/t4xOkpP8FgE.mp4</video:content_loc><video:duration>330</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/interpreting-absolute-value-as-distance</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2357089f.jpg</video:thumbnail_loc><video:title>Interpreting absolute value as distance</video:title><video:description>In this video, we work through a bunch of examples that stretch our thinking on absolute value.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/K759mIqpvOU.mp4/K759mIqpvOU.mp4</video:content_loc><video:duration>654</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/associative-commutative-with-negatives</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7fab7267219829a6.jpg</video:thumbnail_loc><video:title>Associative and commutative properties of addition with negatives</video:title><video:description>The commutative and associative properties apply to addition, but not to subtraction. Rewriting subtraction as addition of the opposite is a superpower that suddenly lets us use the commutative and associative properties (without changing the value of the expression) in expressions that previously had subtraction involved.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/uHWDJHerbGQ.mp4/uHWDJHerbGQ.mp4</video:content_loc><video:duration>298</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/adding-fractions-with-different-signs</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179314.jpg</video:thumbnail_loc><video:title>Adding fractions with different signs</video:title><video:description>Use a number line to add fractions with different signs.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/QS1LMomm0Gk.mp4/QS1LMomm0Gk.mp4</video:content_loc><video:duration>382</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/adding-and-subtracting-fractions-with-negatives</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4eac6603b14fea42.jpg</video:thumbnail_loc><video:title>Adding and subtracting fractions with negatives</video:title><video:description>Use the properties of addition to strategically add and subtract fractions with negatives and unlike denominators. We can rewrite the subtraction as adding the opposite so that the addition properties will apply.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/nhJ60MCLeCU.mp4/nhJ60MCLeCU.mp4</video:content_loc><video:duration>225</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/comparing-rational-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/158922111.jpg</video:thumbnail_loc><video:title>Comparing rational numbers</video:title><video:description>Comparing Rational Numbers</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/VZOHWaw5dqM.mp4/VZOHWaw5dqM.mp4</video:content_loc><video:duration>419</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/adding-and-subtracting-a-decimal-percentage-and-fraction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6f64c4e8.jpg</video:thumbnail_loc><video:title>Adding &amp; subtracting rational numbers: 79% - 79.1 - 58 1/10</video:title><video:description>Sal evaluates 79% - 79.1 - 58 1/10.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/FSpSrZQzzVs.mp4/FSpSrZQzzVs.mp4</video:content_loc><video:duration>269</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/adding-fractions-decimals-and-percentages</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x45f7c965.jpg</video:thumbnail_loc><video:title>Adding &amp; subtracting rational numbers: 0.79 - 4/3 - 1/2 + 150%</video:title><video:description>Sal evaluates 0.79 - 4/3 - 1/2 + 150%.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xEDnwEOOf7Y.mp4/xEDnwEOOf7Y.mp4</video:content_loc><video:duration>274</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/why-a-negative-times-a-negative-is-a-positive</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/867458280.jpg</video:thumbnail_loc><video:title>Why a negative times a negative is a positive</video:title><video:description>Use the distributive property to understand the products of negative numbers.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/rK4sXm_MPWo.mp4/rK4sXm_MPWo.mp4</video:content_loc><video:duration>347</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/why-a-negative-times-a-negative-makes-intuitive-sense</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1244872792.jpg</video:thumbnail_loc><video:title>Why a negative times a negative makes sense</video:title><video:description>Use the repeated addition model of multiplication to give an understanding of multiplying negative numbers.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pzQY-9Nmtws.mp4/pzQY-9Nmtws.mp4</video:content_loc><video:duration>374</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/multiplying-positive-and-negative-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/862036603.jpg</video:thumbnail_loc><video:title>Multiplying positive &amp; negative numbers</video:title><video:description>Learn some rules of thumb for multiplying positive and negative numbers.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/47wjId9k2Hs.mp4/47wjId9k2Hs.mp4</video:content_loc><video:duration>334</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/dividing-positive-and-negative-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/862107118.jpg</video:thumbnail_loc><video:title>Dividing positive and negative numbers</video:title><video:description>Discover the basics of dividing with negative numbers.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/bQ-KR3clFgs.mp4/bQ-KR3clFgs.mp4</video:content_loc><video:duration>292</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/converting-fractions-to-decimals-ex2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/915095642.jpg</video:thumbnail_loc><video:title>Fraction to decimal: 11/25</video:title><video:description>Sal writes 11/25 as a decimal.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/sCVyvfOLI6U.mp4/sCVyvfOLI6U.mp4</video:content_loc><video:duration>93</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/converting-fractions-to-decimals-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/158925085.jpg</video:thumbnail_loc><video:title>Worked example: Converting a fraction (7/8) to a decimal</video:title><video:description>Learn how to write the fraction, 7/8 as a decimal.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Y1V5mZaMfTk.mp4/Y1V5mZaMfTk.mp4</video:content_loc><video:duration>137</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/converting-fractions-to-decimals-ex1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/915084910.jpg</video:thumbnail_loc><video:title>Fraction to decimal with rounding</video:title><video:description>Sal writes 16/21 as a rounded decimal.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/NM8qTo361ic.mp4/NM8qTo361ic.mp4</video:content_loc><video:duration>195</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/multiplying-negative-and-positive-fractions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x747283e7.jpg</video:thumbnail_loc><video:title>Multiplying positive and negative fractions</video:title><video:description>See examples of multiplying and dividing fractions with negative numbers.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pi3WWQ0q6Lc.mp4/pi3WWQ0q6Lc.mp4</video:content_loc><video:duration>273</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/examples-of-dividing-negative-fractions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x91b6f5a7.jpg</video:thumbnail_loc><video:title>Dividing negative fractions</video:title><video:description>Dividing by a fraction is the same as multiplying by its reciprocal. To multiply fractions, we multiply the numerators together and the denominators together.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/H0q9Fqb8YT4.mp4/H0q9Fqb8YT4.mp4</video:content_loc><video:duration>251</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/negative-signs-in-numerators-and-denominators</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6e35dcba.jpg</video:thumbnail_loc><video:title>Negative signs in fractions</video:title><video:description>Sal finds equivalent expressions to -g/h.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9eSPhvhuInw.mp4/9eSPhvhuInw.mp4</video:content_loc><video:duration>308</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/making-sense-of-hairy-fractions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x372e1287.jpg</video:thumbnail_loc><video:title>Simplifying complex fractions</video:title><video:description>Learn how to take complex looking fractions and make them much, much simpler.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/K2b8iMPY11I.mp4/K2b8iMPY11I.mp4</video:content_loc><video:duration>319</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/rational-number-expressions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfbb8940b.jpg</video:thumbnail_loc><video:title>Expressions with rational numbers</video:title><video:description>Learn to compare expressions with positive and negative fractions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/a_Wi-6SRBTc.mp4/a_Wi-6SRBTc.mp4</video:content_loc><video:duration>359</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/arithmetic-properties-with-negative-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc98aaf32.jpg</video:thumbnail_loc><video:title>Equivalent expressions with negative numbers (multiplication and division)</video:title><video:description>In this video, we figure out whether or not some expressions are equivalent. To do this, we think about properties of multiplication and division.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hmtJV49AWio.mp4/hmtJV49AWio.mp4</video:content_loc><video:duration>502</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/why-dividing-by-zero-is-undefined</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/871510490.jpg</video:thumbnail_loc><video:title>Why dividing by zero is undefined</video:title><video:description>As much as we would like to have an answer for &quot;what&apos;s 1 divided by 0?&quot; it&apos;s sadly impossible to have an answer. The reason, in short, is that whatever we may answer, we will then have to agree that that answer times 0 equals to 1, and that cannot be ​true, because anything times 0 is 0.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/SQzjzStU1RQ.mp4/SQzjzStU1RQ.mp4</video:content_loc><video:duration>248</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/order-of-operations-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179327.jpg</video:thumbnail_loc><video:title>Order of operations example</video:title><video:description>Simplify this tricky expression using the order of operations. Expression include negative numbers and exponents.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gjrGd9TjjnY.mp4/gjrGd9TjjnY.mp4</video:content_loc><video:duration>276</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/negative-number-word-problems-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xefd871cb.jpg</video:thumbnail_loc><video:title>Negative number word problem: temperatures</video:title><video:description>Use a number line to solve a word problem that includes a negative number.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Oo2vGhVkvDo.mp4/Oo2vGhVkvDo.mp4</video:content_loc><video:duration>262</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/finding-initial-temperature-from-temperature-changes</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2ae483b7.jpg</video:thumbnail_loc><video:title>Negative number word problem: Alaska</video:title><video:description>In this video, we figure out the temperature in Fairbanks, Alaska by adding and subtracting negative numbers.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/t4jDcc8IIBM.mp4/t4jDcc8IIBM.mp4</video:content_loc><video:duration>218</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/interpreting-negative-number-statements</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbfc0f373.jpg</video:thumbnail_loc><video:title>Interpreting negative number statements</video:title><video:description>The examples in this video use negative numbers to represent real world situations. What are these negative numbers really telling us?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ioH0PUdUW3M.mp4/ioH0PUdUW3M.mp4</video:content_loc><video:duration>257</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/interpreting-multiplication-and-division-of-negative-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x630b911f.jpg</video:thumbnail_loc><video:title>Interpreting multiplication &amp; division of negative numbers</video:title><video:description>Let&apos;s think about the meaning of negative numbers in different situations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/mPLCXCscqI8.mp4/mPLCXCscqI8.mp4</video:content_loc><video:duration>275</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/adding-integers-find-the-missing-value</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0b4107d070724b99.jpg</video:thumbnail_loc><video:title>Adding integers: find the missing value</video:title><video:description>Use number lines to find missing addends in addition equations with integers. When we add a positive value, we move to the right on the number line. When we add a negative value, we move to the left.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jA1vyOrzlOE.mp4/jA1vyOrzlOE.mp4</video:content_loc><video:duration>182</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/subtracting-integers-find-the-missing-value</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc219bb304356f328.jpg</video:thumbnail_loc><video:title>Subtracting integers: find the missing value</video:title><video:description>Use number lines to find missing numbers in subtraction equations with integers. Arrows to the left equivalently mean adding a negative number and subtracting a positive number of the same magnitude. Arrows to the right equivalently mean adding a positive number and subtracting a negative number of the same magnitude.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/HsPEStiHQS0.mp4/HsPEStiHQS0.mp4</video:content_loc><video:duration>414</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/substitution-with-negative-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3c5fb2bf.jpg</video:thumbnail_loc><video:title>Substitution with negative numbers</video:title><video:description>Practice substituting positive and negative values for variables.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/XkRD9lv_y44.mp4/XkRD9lv_y44.mp4</video:content_loc><video:duration>478</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/understanding-variables-representing-integers-on-number-line</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9db5c19c.jpg</video:thumbnail_loc><video:title>Ordering expressions</video:title><video:description>Let&apos;s get some practice thinking about adding and subtracting variables representing positive and negative numbers on the number line.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/wRBPzExOH2A.mp4/wRBPzExOH2A.mp4</video:content_loc><video:duration>410</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/combining-like-terms-and-the-distributive-property</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1027316723.jpg</video:thumbnail_loc><video:title>Combining like terms with negative coefficients &amp; distribution</video:title><video:description>We&apos;ve learned about order of operations and combining like terms. Let&apos;s layer the distributive property on top of this.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3NHSwiv_pSE.mp4/3NHSwiv_pSE.mp4</video:content_loc><video:duration>247</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/combining-like-terms-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1254690345.jpg</video:thumbnail_loc><video:title>Combining like terms with negative coefficients</video:title><video:description>This example of combining like terms in an expression gets a little hairy. Pay attention.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/FNnmseBlvaY.mp4/FNnmseBlvaY.mp4</video:content_loc><video:duration>279</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/simplifying-expressions-involving-rational-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1750bfec.jpg</video:thumbnail_loc><video:title>Combining like terms with rational coefficients</video:title><video:description>Learn how to rewrite algebraic expressions by combining like terms. The expressions in this video have decimal and fraction coefficients.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/rtNuo7R3scY.mp4/rtNuo7R3scY.mp4</video:content_loc><video:duration>256</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/factoring-algebraic-expressions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa57a0279.jpg</video:thumbnail_loc><video:title>The distributive property with variables</video:title><video:description>Learn how to apply the distributive property to factor out the greatest common factor from an algebraic expression like 2+4x.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/I6TBBzIvgB8.mp4/I6TBBzIvgB8.mp4</video:content_loc><video:duration>374</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/factoring-linear-binomials</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa1e260c1.jpg</video:thumbnail_loc><video:title>Factoring with the distributive property</video:title><video:description>Sal shows how to factor the expression 4x+18 into the expression 2(2x+9).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/mbb3msmX2xs.mp4/mbb3msmX2xs.mp4</video:content_loc><video:duration>208</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/equivalent-expressions-with-distribution-and-negative-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x71d68e5f.jpg</video:thumbnail_loc><video:title>Equivalent expressions: negative numbers &amp; distribution</video:title><video:description>Learn how to identify equivalent expressions using your knowledge of the distributive property and negative numbers.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Xtcylk5r0g8.mp4/Xtcylk5r0g8.mp4</video:content_loc><video:duration>240</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/interpreting-linear-expressions-example-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd74549ff.jpg</video:thumbnail_loc><video:title>Interpreting linear expressions: flowers</video:title><video:description>Let&apos;s practice matching expressions to their meaning in this example of interpreting linear expressions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/edVnqL2Z59A.mp4/edVnqL2Z59A.mp4</video:content_loc><video:duration>122</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/interpreting-linear-expressions-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdc8d5607.jpg</video:thumbnail_loc><video:title>Interpreting linear expressions: diamonds</video:title><video:description>We match the expressions to their meaning in this example. We&apos;re reinforcing our knowledge of linear expressions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ao9cx8JlJIU.mp4/ao9cx8JlJIU.mp4</video:content_loc><video:duration>112</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/why-we-do-the-same-thing-to-both-sides-two-step-equations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/948504421.jpg</video:thumbnail_loc><video:title>Intro to two-step equations</video:title><video:description>Here&apos;s how we solve a two step equation. It begins with the concept of equality: what we do to one side of the equation must be done to the other.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_y_Q3_B2Vh8.mp4/_y_Q3_B2Vh8.mp4</video:content_loc><video:duration>312</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/equations-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8.jpg</video:thumbnail_loc><video:title>Two-step equations intuition</video:title><video:description>This example demonstrates how we solve an equation expressed such: ax + b = c. It&apos;s a little more complicated than previous examples, but you can do it!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/XoEn1LfVoTo.mp4/XoEn1LfVoTo.mp4</video:content_loc><video:duration>521</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/solving-equations-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26777.jpg</video:thumbnail_loc><video:title>Worked example: two-step equations</video:title><video:description>Sal solves the equation -16 = x/4 + 2. It takes two steps because he first has to subtract 2 from both sides and then multiply both sides by 4.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/p5e5mf_G3FI.mp4/p5e5mf_G3FI.mp4</video:content_loc><video:duration>184</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/two-step-equations-with-decimals-and-fractions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe1652ad7.jpg</video:thumbnail_loc><video:title>Two-step equations with decimals and fractions</video:title><video:description>Learn how to solve equations that involve decimals and fractions. The equations shown in this video are called &quot;two-step&quot; equations because they each take two steps to solve.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/BOIA9wsM4ok.mp4/BOIA9wsM4ok.mp4</video:content_loc><video:duration>471</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/two-step-equations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23616.jpg</video:thumbnail_loc><video:title>Two-step equations with decimals and fractions</video:title><video:description>Let&apos;s practice some two step equations, some of which require merging terms and using the distributive property.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tuVd355R-OQ.mp4/tuVd355R-OQ.mp4</video:content_loc><video:duration>830</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/mistakes-in-solving-equations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf5d268b2.jpg</video:thumbnail_loc><video:title>Find the mistake: two-step equations</video:title><video:description>When doing algebra, we sometimes make mistakes! It&apos;s important to be able to check our own work (and other people&apos;s work) for correctness.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6q8mk7z72AU.mp4/6q8mk7z72AU.mp4</video:content_loc><video:duration>228</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/basic-linear-equation-word-problem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1243194170.jpg</video:thumbnail_loc><video:title>Two-step equation word problem: computers</video:title><video:description>Learn how to construct and solve a basic linear equation to solve a word problem.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/roHvNNFXr4k.mp4/roHvNNFXr4k.mp4</video:content_loc><video:duration>286</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/application-problems-with-equation-in-one-variable</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179470.jpg</video:thumbnail_loc><video:title>Two-step equation word problem: garden</video:title><video:description>Here&apos;s a nifty word problem in which we find the dimensions of a garden given only the perimeter. Let&apos;s create an equation to solve!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/iimpwYBiKNg.mp4/iimpwYBiKNg.mp4</video:content_loc><video:duration>122</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/linear-equation-word-problem-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdfc35e50.jpg</video:thumbnail_loc><video:title>Two-step equation word problem: oranges</video:title><video:description>Learn how to solve a word problem by writing an equation to model the situation. In this video, we use the linear equation 210(t-5) = 41,790.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xKH1Evwu150.mp4/xKH1Evwu150.mp4</video:content_loc><video:duration>359</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/inequalities-using-multiplication-and-division</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23662.jpg</video:thumbnail_loc><video:title>One-step inequalities examples</video:title><video:description>Our discussion of linear inequalities begins with multiplying and dividing by negative numbers. Pay attention for the word &quot;swap.&quot; Super important!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PNXozoJWsWc.mp4/PNXozoJWsWc.mp4</video:content_loc><video:duration>627</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/one-step-inequalities-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179475.jpg</video:thumbnail_loc><video:title>One-step inequalities: -5c ≤ 15</video:title><video:description>In addition to solving the inequality, we&apos;ll graph the solution. Remember to swap if you mutiply both sides of the inequality by a negative number.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/D1cKk48kz-E.mp4/D1cKk48kz-E.mp4</video:content_loc><video:duration>174</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/inequalities</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26815.jpg</video:thumbnail_loc><video:title>One-step inequality word problem</video:title><video:description>Inequalities are more than abstract concepts and exercises. They help solve real life problems. Here&apos;s an example.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/FZ2APP6-grU.mp4/FZ2APP6-grU.mp4</video:content_loc><video:duration>129</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/solving-inequalities</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26814.jpg</video:thumbnail_loc><video:title>Two-step inequalities</video:title><video:description>Two-step inequalities are slightly more complicated than one-step inequalities (duh!). This is a worked example of solving ⅔&gt;-4y-8⅓.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/y7QLay8wrW8.mp4/y7QLay8wrW8.mp4</video:content_loc><video:duration>272</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/interpreting-inequalities</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26813.jpg</video:thumbnail_loc><video:title>Two-step inequality word problem: apples</video:title><video:description>We&apos;ll talk you through this fun and challenging inequality problem.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/wo7DSaPP8hQ.mp4/wo7DSaPP8hQ.mp4</video:content_loc><video:duration>399</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/writing-and-using-inequalities-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26821.jpg</video:thumbnail_loc><video:title>Two-step inequality word problem: R&amp;B</video:title><video:description>Let&apos;s tackle this word problem together. We&apos;ll interpret the information and then construct a linear inequality to solve it.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pbLiN8D9gAk.mp4/pbLiN8D9gAk.mp4</video:content_loc><video:duration>121</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/circles-radius-diameter-and-circumference</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24957.jpg</video:thumbnail_loc><video:title>Radius, diameter, circumference &amp; π</video:title><video:description>Learn how the number Pi allows us to relate the radius, diameter, and circumference of a circle.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jyLRpr2P0MQ.mp4/jyLRpr2P0MQ.mp4</video:content_loc><video:duration>665</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/parts-of-a-circle</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/370305280.jpg</video:thumbnail_loc><video:title>Labeling parts of a circle</video:title><video:description>Radius, diameter, center, and circumference--all are parts of a circle. Let&apos;s go through each and understand how they are defined.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/04N79tItPEA.mp4/04N79tItPEA.mp4</video:content_loc><video:duration>121</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/area-of-a-circle</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/370305273.jpg</video:thumbnail_loc><video:title>Area of a circle</video:title><video:description>The area of a circle is pi times the radius squared (A = π r²). Learn how to use this formula to find the area of a circle when given the diameter.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ZyOhRgnFmIY.mp4/ZyOhRgnFmIY.mp4</video:content_loc><video:duration>242</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/relating-circumference-and-area</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x450a23885a563c76.jpg</video:thumbnail_loc><video:title>Relating circumference and area</video:title><video:description>Sal uses formulas and a specific example to see how area and circumference relate.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-jqWW22FMdI.mp4/-jqWW22FMdI.mp4</video:content_loc><video:duration>291</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/partial-circle-area-and-arc-length</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6f26a88613dd9b5a.jpg</video:thumbnail_loc><video:title>Partial circle area and arc length</video:title><video:description>Sal finds the area of a semicircle and the arc length of a partial circle.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/YjWCDdNlXxc.mp4/YjWCDdNlXxc.mp4</video:content_loc><video:duration>180</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/perimeter-and-area-of-a-non-standard-polygon</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/372432668.jpg</video:thumbnail_loc><video:title>Perimeter &amp; area of composite shapes</video:title><video:description>Sal finds perimeter and area of a non-standard polygon.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7S1MLJOG-5A.mp4/7S1MLJOG-5A.mp4</video:content_loc><video:duration>183</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/solid-geometry-volume</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/60129394.jpg</video:thumbnail_loc><video:title>Volume of triangular prism &amp; cube</video:title><video:description>Using the formulas for the volume of triangular prism and cube to solve some solid geometry problems.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ZqzAOZ9pP9Q.mp4/ZqzAOZ9pP9Q.mp4</video:content_loc><video:duration>236</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/growing-by-a-percentage</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23456.jpg</video:thumbnail_loc><video:title>Growing by a percentage</video:title><video:description>In this example we grow a whole number by a percentage of itself. Growing by percentage is a common skill often used when figuring how much is owed or earned with interest.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/X2jVap1YgwI.mp4/X2jVap1YgwI.mp4</video:content_loc><video:duration>582</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/percent-word-problem-examples</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x367a706c14a18040.jpg</video:thumbnail_loc><video:title>Percent word problem: magic club</video:title><video:description>Sal solves percent word problems including percent comparisons and percent of change.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/e1Cd0XL5OEs.mp4/e1Cd0XL5OEs.mp4</video:content_loc><video:duration>479</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/tax-discount-and-tip-examples</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc0cdcf37b1a134e9.jpg</video:thumbnail_loc><video:title>Percent word problems: tax and discount</video:title><video:description>Sal solves percent word problems involving tax, tip, and discounts.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jb_RwR_Eso4.mp4/jb_RwR_Eso4.mp4</video:content_loc><video:duration>348</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/scale-factors-and-area</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2c11f01900e1665c.jpg</video:thumbnail_loc><video:title>Scale factors and area</video:title><video:description>Sal explore how scale factor affects the area of a scaled figure.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/h-qwno7n5F4.mp4/h-qwno7n5F4.mp4</video:content_loc><video:duration>364</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/basic-probability</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/185786265.jpg</video:thumbnail_loc><video:title>Intro to theoretical probability</video:title><video:description>We give you an introduction to probability through the example of flipping a quarter and rolling a die.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/uzkc-qNVoOk.mp4/uzkc-qNVoOk.mp4</video:content_loc><video:duration>498</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/simple-probability</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/380860447.jpg</video:thumbnail_loc><video:title>Simple probability: yellow marble</video:title><video:description>In order to find the probability of picking a yellow marble from a bag, we have to first determine the number of possible outcomes, and then how many of them meet our constraints.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/yUaI0JriZtY.mp4/yUaI0JriZtY.mp4</video:content_loc><video:duration>176</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/probability-1-module-examples</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/60107867.jpg</video:thumbnail_loc><video:title>Simple probability: non-blue marble</video:title><video:description>In this example we are figuring out the probability of randomly picking a non-blue marble from a bag. Again, we&apos;ll have to think about the possible outcomes first.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/mLE-SlOZToc.mp4/mLE-SlOZToc.mp4</video:content_loc><video:duration>596</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/experimental-probability</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfc5cab7c.jpg</video:thumbnail_loc><video:title>Experimental probability</video:title><video:description>Based on past experience, we can make reasonable estimates of the likelihood of future events.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/RdehfQJ8i_0.mp4/RdehfQJ8i_0.mp4</video:content_loc><video:duration>415</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/compound-sample-spaces</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x905af91a.jpg</video:thumbnail_loc><video:title>Sample spaces for compound events</video:title><video:description>Explore the notion of a &quot;sample space&quot;. See a sample space represented as a tree diagram, table, and list.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PR-A3UAO7_0.mp4/PR-A3UAO7_0.mp4</video:content_loc><video:duration>550</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/events-and-outcomes-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/27092.jpg</video:thumbnail_loc><video:title>Die rolling probability</video:title><video:description>We&apos;re thinking about the probability of rolling doubles on a pair of dice. Let&apos;s create a grid of all possible outcomes.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/O4Qnsubo2tg.mp4/O4Qnsubo2tg.mp4</video:content_loc><video:duration>315</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/probability-from-compound-sample-space</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5634e573.jpg</video:thumbnail_loc><video:title>Probability of a compound event</video:title><video:description>Learn how to use sample space diagrams to find probabilities.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6zWPgvEMVlE.mp4/6zWPgvEMVlE.mp4</video:content_loc><video:duration>303</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/tree-diagram-to-count-outcomes</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x31590e02.jpg</video:thumbnail_loc><video:title>Count outcomes using tree diagram</video:title><video:description>Tree diagrams display all the possible outcomes of an event. Each branch in a tree diagram represents a possible outcome. Tree diagrams can be used to find the number of possible outcomes and calculate the probability of possible outcomes.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Zxvc6iPKdec.mp4/Zxvc6iPKdec.mp4</video:content_loc><video:duration>271</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/counting-pot-and-flower-scenarios</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xcc826c9d.jpg</video:thumbnail_loc><video:title>Counting outcomes: flower pots</video:title><video:description>Find the number of ways you can put four types of flowers into three types of pots.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/B_vAlneziHo.mp4/B_vAlneziHo.mp4</video:content_loc><video:duration>155</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/comparing-theoretical-to-experimental-probabilites</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfb9f61b0.jpg</video:thumbnail_loc><video:title>Theoretical and experimental probabilities</video:title><video:description>Compare expected probabilities to what really happens when we run experiments.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tXlcE_K_C-Y.mp4/tXlcE_K_C-Y.mp4</video:content_loc><video:duration>422</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/intuitive-sense-of-probabilities</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5f14b7ab.jpg</video:thumbnail_loc><video:title>Intuitive sense of probabilities</video:title><video:description>Think about what probabilities really mean. What does a probability of 0 mean? How about 1?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/KFgvOQtH0Z0.mp4/KFgvOQtH0Z0.mp4</video:content_loc><video:duration>531</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/making-predictions-with-probability</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd724ea03.jpg</video:thumbnail_loc><video:title>Making predictions with probability</video:title><video:description>Predict the number of times a spinner will land on an elephant. The theoretical probability helps us get close with our prediction, but we can&apos;t know for sure until we actually spin the spinner.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8bK-xfh8-rY.mp4/8bK-xfh8-rY.mp4</video:content_loc><video:duration>305</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/constructing-probability-model-from-observations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x94fb291d.jpg</video:thumbnail_loc><video:title>Probability models example: frozen yogurt</video:title><video:description>Model the probability of a frozen yogurt line having 0, 1, or 2 people in it.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/BIpsQIJUCC8.mp4/BIpsQIJUCC8.mp4</video:content_loc><video:duration>445</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/reasonable-samples</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6db9c771.jpg</video:thumbnail_loc><video:title>Reasonable samples</video:title><video:description>To make a valid conclusion, you&apos;ll need a representaive, not skewed, sample.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/aKAw-DyZa6g.mp4/aKAw-DyZa6g.mp4</video:content_loc><video:duration>257</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/comparing-swim-times-at-the-olympics</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xba691b00.jpg</video:thumbnail_loc><video:title>Comparing distributions with dot plots (example problem)</video:title><video:description>Sal examines two distributions in dot plots to draw conclusions about the times of Olympic swimmers.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/KXDOOmquZag.mp4/KXDOOmquZag.mp4</video:content_loc><video:duration>240</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/complementary-and-supplementary-angles</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/263439064.jpg</video:thumbnail_loc><video:title>Complementary &amp; supplementary angles</video:title><video:description>Learn about complementary and supplementary angles, as well as the definitions of adjacent and straight angles.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/BTnAlNSgNsY.mp4/BTnAlNSgNsY.mp4</video:content_loc><video:duration>511</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/angles-at-the-intersection-of-two-lines</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/263439063.jpg</video:thumbnail_loc><video:title>Vertical angles</video:title><video:description>By using our knowledge of supplementary, adjacent, and vertical angles, we can solve problems involving the intersection of two lines. Including this one!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_7aUxFzTG5w.mp4/_7aUxFzTG5w.mp4</video:content_loc><video:duration>439</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/solving-for-unknown-angles</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb15e7f87.jpg</video:thumbnail_loc><video:title>Find measure of vertical angles</video:title><video:description>Given two intersecting lines and the measure of vertical angles, watch as we solve to find the measure of the remaining angles.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TOobWKx1xe0.mp4/TOobWKx1xe0.mp4</video:content_loc><video:duration>180</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/pie-splitting</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa2a27151.jpg</video:thumbnail_loc><video:title>Find measure of angles word problem</video:title><video:description>Solve this word problem to find the measure of angles. In this example you&apos;ll split up a pie (don&apos;t forget to share!)</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3u9Ux29MSXE.mp4/3u9Ux29MSXE.mp4</video:content_loc><video:duration>274</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/example-using-algebra-to-find-measure-of-supplementary-angles</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2e4ad4ea.jpg</video:thumbnail_loc><video:title>Equation practice with supplementary angles</video:title><video:description>Given the algebraic expressions that represent a pair of supplementary angles, Sal forms and solves an equation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/zNtbi4OJs9I.mp4/zNtbi4OJs9I.mp4</video:content_loc><video:duration>157</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/example-using-algebra-to-find-measure-of-complementary-angles</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0fe8e133.jpg</video:thumbnail_loc><video:title>Equation practice with complementary angles</video:title><video:description>Given the algebraic expressions that represent a pair of complementary angles, learn how to form and solve an equation to find an unknown angle.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/XDOH9Ul2OOM.mp4/XDOH9Ul2OOM.mp4</video:content_loc><video:duration>153</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/constructing-right-isosceles</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3961d04a.jpg</video:thumbnail_loc><video:title>Construct a right isosceles triangle</video:title><video:description>Can you build a triangle that is both a right triangle and an isosceles triangle?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lohMwoq3WFA.mp4/lohMwoq3WFA.mp4</video:content_loc><video:duration>86</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/constructing-triangles-with-constraints</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa363a49e.jpg</video:thumbnail_loc><video:title>Construct a triangle with constraints</video:title><video:description>Here&apos;s a challenge: in this problem we are given constraints and asked to construct a triangle. It can be done! You&apos;ll learn about degenerate triangles, too.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/E78ji1uBtSA.mp4/E78ji1uBtSA.mp4</video:content_loc><video:duration>239</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/triangle-inqequality-theorem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1242820000.jpg</video:thumbnail_loc><video:title>Triangle inequality theorem</video:title><video:description>Intuition behind the triangle inequality theorem</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/KlKYvbigBqs.mp4/KlKYvbigBqs.mp4</video:content_loc><video:duration>352</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-engage-ny/v/ordering-triangle-sides-and-angles</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xac0d898b.jpg</video:thumbnail_loc><video:title>Ordering triangle sides and angles example</video:title><video:description>Sal first solves a problem where he orders the sides of a triangle given the angles, then solves a problem where he orders the angles of a triangle given the sides.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/I5eTOBsvUK8.mp4/I5eTOBsvUK8.mp4</video:content_loc><video:duration>169</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/vertical-slice-of-rectangular-pyramid</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x938fa80f.jpg</video:thumbnail_loc><video:title>Slicing a rectangular pyramid</video:title><video:description>What happens when you slice vertically into a rectangular pyramid? What kind of geometric shape results?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hoa1RBk4dTo.mp4/hoa1RBk4dTo.mp4</video:content_loc><video:duration>210</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/ways-to-cut-a-cube</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x73ceab49.jpg</video:thumbnail_loc><video:title>Ways to cross-section a cube</video:title><video:description>Learn about all the different ways we can obtain cross-sections of a cube.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/aSokFEpoJFM.mp4/aSokFEpoJFM.mp4</video:content_loc><video:duration>443</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/circumference-from-area</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x875f3feb.jpg</video:thumbnail_loc><video:title>Finding circumference of a circle when given the area</video:title><video:description>Learn how to find the circumference, the distance around a circle, when given the area.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Rcb7ZUTOQ1I.mp4/Rcb7ZUTOQ1I.mp4</video:content_loc><video:duration>113</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/area-of-shaded-region</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1f3c3d07.jpg</video:thumbnail_loc><video:title>Area of a shaded region</video:title><video:description>Here&apos;s a fun one: find the area of a shaded region where you first determine the area of a square and then the area of a circle.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gbGghzo7yEM.mp4/gbGghzo7yEM.mp4</video:content_loc><video:duration>91</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/radius-change-impact</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x057e031d.jpg</video:thumbnail_loc><video:title>Impact of increasing the radius</video:title><video:description>If we change the radius of a circle, how does the circumference and area change?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/GB9Rqsah2gs.mp4/GB9Rqsah2gs.mp4</video:content_loc><video:duration>211</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/volume-of-gold-ring</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd26b50ec.jpg</video:thumbnail_loc><video:title>Volume word problem: gold ring</video:title><video:description>See if you can find the incremental volume of a ring in cubic inches. You&apos;ll need to put to use your knowledge of how to measure volume.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ViFLPsLTO1k.mp4/ViFLPsLTO1k.mp4</video:content_loc><video:duration>160</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/crates-in-boxcar</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9b271d72.jpg</video:thumbnail_loc><video:title>Volume of rectangles inside rectangles</video:title><video:description>How many crates can we fit into a boxcar? We&apos;ll explain that there&apos;s more than one way to solve for the volume in this problem.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/AxHAQ5l45FE.mp4/AxHAQ5l45FE.mp4</video:content_loc><video:duration>287</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-foundations-engageny/v/usain-bolt-s-average-speed</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1254749169.jpg</video:thumbnail_loc><video:title>Finding average speed or rate</video:title><video:description>Using the formula for finding distance we can determine Usian Bolt&apos;s average speed, or rate, when he broke the world record in 2009 in the 100m. Watch.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/mt6Nq0dzFjo.mp4/mt6Nq0dzFjo.mp4</video:content_loc><video:duration>795</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-foundations-engageny/v/inequalities-in-one-variable-1-exercise</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc0d659df.jpg</video:thumbnail_loc><video:title>Inequality word problem: one variable</video:title><video:description>This time we&apos;re creating a variable to represent a number, and then writing an inequality. We&apos;re building on our knowledge.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/aINeMQH77jg.mp4/aINeMQH77jg.mp4</video:content_loc><video:duration>147</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-foundations-engageny/v/identifying-percent-amount-and-base</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/153770143.jpg</video:thumbnail_loc><video:title>Identifying percent amount and base</video:title><video:description>Sal identifies the percent, amount, and base in a percent problem.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/JaScdH47PYg.mp4/JaScdH47PYg.mp4</video:content_loc><video:duration>152</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/identifying-corresponding-parts-of-scaled-copies</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x459c0342676e7ea6.jpg</video:thumbnail_loc><video:title>Identifying corresponding parts of scaled copies</video:title><video:description>Identifying corresponding parts of scaled copies from 7th grade math</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/o07enwTfSpU.mp4/o07enwTfSpU.mp4</video:content_loc><video:duration>151</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/identifying-scale-factors-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x99c36e33e74c162f.jpg</video:thumbnail_loc><video:title>Identifying scale factor in drawings</video:title><video:description>Identify the scale factor used to create a scale copy.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ZeY1mgog2YQ.mp4/ZeY1mgog2YQ.mp4</video:content_loc><video:duration>86</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-illustrative-math/v/corresponding-angles-in-scaled-figures</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdea105d2193935de.jpg</video:thumbnail_loc><video:title>Corresponding angles in scaled figures</video:title><video:description>Students learn to compare two scale drawings of the same object made with different scales. Identify how the lengths, widths, or areas change as the scale changes.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6x5Ekb3TV70.mp4/6x5Ekb3TV70.mp4</video:content_loc><video:duration>216</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-illustrative-math/v/corresponding-angles-and-distances-in-scaled-figures</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x76db62100159f634.jpg</video:thumbnail_loc><video:title>Corresponding angles and distances in scaled figures</video:title><video:description>Students learn that two figures may have either corresponding side lengths with equivalent ratios OR corresponding angle measures equal, and still NOT be scaled copies. We must see that both characteristics are present to be certain that two shapes are scaled copies.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/igH_ogbq1UY.mp4/igH_ogbq1UY.mp4</video:content_loc><video:duration>210</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-illustrative-math/v/corresponding-distances-in-scaled-figures</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc72d0c0e6a1244b0.jpg</video:thumbnail_loc><video:title>Corresponding distances in scaled figures</video:title><video:description>Learn how to find the measurements of distances on scaled figures that are not side lengths.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-3gU16Etzaw.mp4/-3gU16Etzaw.mp4</video:content_loc><video:duration>149</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/interpreting-scale-factors-in-drawings</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x59907ba1ca7a8d9c.jpg</video:thumbnail_loc><video:title>Interpreting scale factors in drawings</video:title><video:description>Sal interprets a scale factor to determine if a scale copy will be larger or smaller than the original figure.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Rgi1z9r5hOk.mp4/Rgi1z9r5hOk.mp4</video:content_loc><video:duration>86</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-illustrative-math/v/reciprocal-scale-factors</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdb270652215b795a.jpg</video:thumbnail_loc><video:title>Reciprocal scale factors</video:title><video:description>Explore how scale factors relate in scaled copies. Learn why the scale factor from the copy back to the original is the reciprocal of the scale factor from the original to the copy.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ocEor9YWaXQ.mp4/ocEor9YWaXQ.mp4</video:content_loc><video:duration>149</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/scaled-drawings-worked-examples</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xcfa89ee54e1b4d14.jpg</video:thumbnail_loc><video:title>Scale drawings</video:title><video:description>Sal finds a missing side length in a scale drawing when given either a set of corresponding side lengths or one side length and the scale factor.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/XUOPGqKGbjk.mp4/XUOPGqKGbjk.mp4</video:content_loc><video:duration>213</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/creating-scale-drawings</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x01989a848c05e686.jpg</video:thumbnail_loc><video:title>Creating scale drawings</video:title><video:description>Sal uses real world contexts to create scale drawings on a grid.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TASA6V5fGT8.mp4/TASA6V5fGT8.mp4</video:content_loc><video:duration>138</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-illustrative-math/v/comparing-different-scales</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0f434f9940990e67.jpg</video:thumbnail_loc><video:title>Comparing different scales</video:title><video:description>Students learn to compare two scale drawings of the same object made with different scales. Identify how the lengths, widths, or areas change as the scale changes.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ofRwYtHPGSQ.mp4/ofRwYtHPGSQ.mp4</video:content_loc><video:duration>233</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-illustrative-math/v/equivalent-scales</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4c8dabc5f1400d37.jpg</video:thumbnail_loc><video:title>Equivalent scales</video:title><video:description>Learn how to identify equivalent scales with different units.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5HhDK7TH4Ag.mp4/5HhDK7TH4Ag.mp4</video:content_loc><video:duration>125</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-illustrative-math/v/writing-scales-with-and-without-units</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x16dbb65ea55e53f8.jpg</video:thumbnail_loc><video:title>Writing scales with and without units</video:title><video:description>Learn how to write scales with and without units.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LPgqrInAxqk.mp4/LPgqrInAxqk.mp4</video:content_loc><video:duration>155</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-illustrative-math/v/comparing-scales-with-different-units</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x86fed3cf9432379e.jpg</video:thumbnail_loc><video:title>Comparing scales with different units</video:title><video:description>Learn how to compare scales that have different units.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/s7_jHLMXvys.mp4/s7_jHLMXvys.mp4</video:content_loc><video:duration>122</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/example-identifying-a-proportional-relatioship-given-a-constant-of-proportionali</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x08a5abf4706ddad6.jpg</video:thumbnail_loc><video:title>Constant of proportionality from tables</video:title><video:description>Identifying proportionality constants by looking at tables of values.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/rzDQ_ZIpi84.mp4/rzDQ_ZIpi84.mp4</video:content_loc><video:duration>154</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/identifying-the-constant-of-proportionality</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x15418d80a6af0b42.jpg</video:thumbnail_loc><video:title>Identifying the constant of proportionality from equation</video:title><video:description>The constant of proportionality is a key concept in math. It&apos;s the number that we multiply one variable by to get another in a proportional relationship. This can be seen in everyday situations like cooking or in equations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/rj7DweP8e58.mp4/rj7DweP8e58.mp4</video:content_loc><video:duration>231</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/example-writing-proportional-equations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbc9814cbfad8288a.jpg</video:thumbnail_loc><video:title>Writing proportional equations</video:title><video:description>Sal figures out the constant of proportionality when dealing with a constant rate.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/MRFrQXDZim0.mp4/MRFrQXDZim0.mp4</video:content_loc><video:duration>130</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-illustrative-math/v/using-equations-and-tables-to-represent-proportional-relationships</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4b25a03394be3666.jpg</video:thumbnail_loc><video:title>Using equations and tables to represent proportional relationships</video:title><video:description>Learn to make connections between equations and tables in proportional relationships.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OccfgY3juXE.mp4/OccfgY3juXE.mp4</video:content_loc><video:duration>89</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-illustrative-math/v/analyzing-proportionality-using-equations-and-tables-bike-rental</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x31f8b1035a008531.jpg</video:thumbnail_loc><video:title>Analyzing proportionality using equations and tables: bike rental</video:title><video:description>Learn about analyzing proportionality using equations and tables in a bike rental scenario.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pXA_8bRSjGM.mp4/pXA_8bRSjGM.mp4</video:content_loc><video:duration>233</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-illustrative-math/v/analyzing-proportionality-using-equations-and-tables-distance</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2d174db7ceaa9822.jpg</video:thumbnail_loc><video:title>Analyzing proportionality using equations and tables: distance</video:title><video:description>Learn about analyzing proportionality using equations and tables in a distance scenario.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qMcdQDfolA8.mp4/qMcdQDfolA8.mp4</video:content_loc><video:duration>142</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/constant-of-proportionality-from-graph</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3cde70670ae56928.jpg</video:thumbnail_loc><video:title>Constant of proportionality from graph</video:title><video:description>In this lesson, we learn about the constant of proportionality in a graph. It&apos;s the number we multiply by x to get y. In our example, when x increases, y increases three times as much. So, our constant of proportionality is 3.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/n_UHN9t3cNg.mp4/n_UHN9t3cNg.mp4</video:content_loc><video:duration>110</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/interpreting-graphs-of-proportional-relationships</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf0607b55dc5b25fd.jpg</video:thumbnail_loc><video:title>Interpreting graphs of proportional relationships</video:title><video:description>Worked example interpreting graphs of proportional relationships</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ApstXGJtRrE.mp4/ApstXGJtRrE.mp4</video:content_loc><video:duration>162</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/comparing-constants-of-proportionality</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8ccefb0267cc2b7f.jpg</video:thumbnail_loc><video:title>Comparing constants of proportionality</video:title><video:description>Working example comparing constants of proportionality.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/oZxbLuJ1U5w.mp4/oZxbLuJ1U5w.mp4</video:content_loc><video:duration>272</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-illustrative-math/v/interpreting-constant-of-proportionality-in-graphs</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc0936937fcdedda7.jpg</video:thumbnail_loc><video:title>Interpreting constant of proportionality in graphs</video:title><video:description>Learn how to identify and interpret the constant of proportionality from a graph of a proportional relationship, including what the special point (1, k) means in a real-world context.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/e_1M6jOLv68.mp4/e_1M6jOLv68.mp4</video:content_loc><video:duration>146</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-illustrative-math/v/constant-of-proportionality-in-both-directions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc4a88d0794954878.jpg</video:thumbnail_loc><video:title>Constant of proportionality in both directions</video:title><video:description>Learn how to use graphs of proportional relationships to identify and interpret constants of proportionality.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/D42p5dXb4-s.mp4/D42p5dXb4-s.mp4</video:content_loc><video:duration>117</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-illustrative-math/v/comparing-constants-of-proportionality-graphically</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf603b35d88aea0cd.jpg</video:thumbnail_loc><video:title>Comparing constants of proportionality graphically</video:title><video:description>Learn how to use graphs of proportional relationships to identify and interpret constants of proportionality.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/b3VcacQ90hE.mp4/b3VcacQ90hE.mp4</video:content_loc><video:duration>199</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-illustrative-math/v/explaining-the-relationship-between-diameter-and-circumference-ordered-pairs</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x03ee9d053d7b3ea0.jpg</video:thumbnail_loc><video:title>Explaining the relationship between diameter and circumference: ordered pairs</video:title><video:description>Learn to generalize that the relationship between diameter and circumference is proportional and that the constant of proportionality is a little more than 3.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/HfsOzAx_bbo.mp4/HfsOzAx_bbo.mp4</video:content_loc><video:duration>142</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-illustrative-math/v/explaining-the-relationship-between-diameter-and-circumference-from-a-graph</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc10b39030bc04f6b.jpg</video:thumbnail_loc><video:title>Explaining the relationship between diameter and circumference from a graph</video:title><video:description>Learn to generalize that the relationship between diameter and circumference is proportional and that the constant of proportionality is a little more than 3.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/nuUsOGJCFCI.mp4/nuUsOGJCFCI.mp4</video:content_loc><video:duration>233</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-illustrative-math/v/using-the-relationship-between-diameter-and-circumference-to-find-an-incorrect-m</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x915db6868b920264.jpg</video:thumbnail_loc><video:title>Identifying incorrect circle measurements</video:title><video:description>Learn to generalize that the relationship between diameter and circumference is proportional and that the constant of proportionality is a little more than 3.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/iXHGujDaEqI.mp4/iXHGujDaEqI.mp4</video:content_loc><video:duration>121</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-illustrative-math/v/using-the-relationship-between-diameter-and-circumference-to-find-reasonable-app</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0136accb61421384.jpg</video:thumbnail_loc><video:title>Approximating diameter and circumference</video:title><video:description>Learn to generalize that the relationship between diameter and circumference is proportional and that the constant of proportionality is a little more than 3.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Q4mpvsjJGyI.mp4/Q4mpvsjJGyI.mp4</video:content_loc><video:duration>124</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/finding-radius-and-diameter-from-circumference</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x395b2629.jpg</video:thumbnail_loc><video:title>Radius &amp; diameter from circumference</video:title><video:description>Sal finds the radius and diameter of a circle given the circumference.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/yWGeFDXgQvg.mp4/yWGeFDXgQvg.mp4</video:content_loc><video:duration>216</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-illustrative-math/v/estimating-area-of-a-circle-with-upper-and-lower-bounds</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfac73d70e07be1cb.jpg</video:thumbnail_loc><video:title>Estimating area of a circle with upper and lower bounds</video:title><video:description>Learn how to estimate the area inside different circles on a grid.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Qm1vXiVDyoY.mp4/Qm1vXiVDyoY.mp4</video:content_loc><video:duration>165</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-illustrative-math/v/estimating-area-of-a-circle-using-polygons-high-estimate</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb68b7fd79d033814.jpg</video:thumbnail_loc><video:title>Estimating area of a circle using polygons: high estimate</video:title><video:description>Learn how to estimate the area inside different circles on a grid.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7cW2Jf_dOLM.mp4/7cW2Jf_dOLM.mp4</video:content_loc><video:duration>190</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-illustrative-math/v/estimating-area-of-a-circle-using-polygons-low-estimate</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xca9e4e583efc6039.jpg</video:thumbnail_loc><video:title>Estimating area of a circle using polygons: low estimate</video:title><video:description>Learn how to estimate the area inside different circles on a grid.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/nscKNWbt2sE.mp4/nscKNWbt2sE.mp4</video:content_loc><video:duration>123</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-illustrative-math/v/expressing-a-fractional-increase-as-a-fraction-of-the-original</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb98450221fcb8fdb.jpg</video:thumbnail_loc><video:title>Expressing a fractional increase as a fraction of the original</video:title><video:description>Learn about expressing a fractional increase as a fraction of the original by working through a piano practice example.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3AhufdthqEc.mp4/3AhufdthqEc.mp4</video:content_loc><video:duration>124</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-illustrative-math/v/writing-expressions-for-a-fraction-of-a-quantity</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7bde6d373f5818f0.jpg</video:thumbnail_loc><video:title>Writing expressions for a fraction of a quantity</video:title><video:description>Learn about writing equivalent expressions for a remaining quantity.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Qn5AEUWHbb8.mp4/Qn5AEUWHbb8.mp4</video:content_loc><video:duration>88</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-illustrative-math/v/interpreting-a-tape-diagram-showing-a-fractional-increase-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xabc7a92a9e37f910.jpg</video:thumbnail_loc><video:title>Interpreting a tape diagram showing a fractional increase</video:title><video:description>Learn about interpreting tape diagrams that represent fractional increases by matching them to real-world contexts.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jmdaLhmXkoI.mp4/jmdaLhmXkoI.mp4</video:content_loc><video:duration>148</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/converting-a-fraction-to-a-repeating-decimal</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa06e19a6.jpg</video:thumbnail_loc><video:title>Converting a fraction to a repeating decimal</video:title><video:description>To convert a fraction like 19/27 into a decimal, you should divide 27 into 19, and use the remainder to figure out the decimal. The decimal begins 0.703703..., and the notation for a repeating decimal like this is to write the numbers that repeat and then put a line above them. The first six digits of the decimal should be included in the answer.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Y2-tz27nKoQ.mp4/Y2-tz27nKoQ.mp4</video:content_loc><video:duration>265</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-illustrative-math/v/expressing-a-percent-decrease-as-a-percentage-of-the-original</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x725600cc9a3846c7.jpg</video:thumbnail_loc><video:title>Expressing a percent decrease as a percentage of the original</video:title><video:description>Learn about expressing a percent decrease as a percentage of the original amount using a library book checkout example.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/kjSQSBne0wg.mp4/kjSQSBne0wg.mp4</video:content_loc><video:duration>123</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-illustrative-math/v/writing-expressions-for-a-percent-increase</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7eeb241903b4eb66.jpg</video:thumbnail_loc><video:title>Writing expressions for a percent increase</video:title><video:description>Learn about writing equivalent expressions for a total amount after a percent increase using a blanket collection example.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lwctkmKBDxA.mp4/lwctkmKBDxA.mp4</video:content_loc><video:duration>120</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-illustrative-math/v/interpreting-a-tape-diagram-showing-a-fractional-increase</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf9f50973bae9bd5d.jpg</video:thumbnail_loc><video:title>Interpreting a tape diagram to find percent increase</video:title><video:description>Learn about using a tape diagram to describe one quantity as a percent greater than another using a plant height example.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/n21E7OzXOwI.mp4/n21E7OzXOwI.mp4</video:content_loc><video:duration>100</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
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<url><loc>https://puzzicle.org/math/7th-grade-illustrative-math/v/finding-the-volume-of-a-prism-with-a-polygon-base-on-a-grid</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x804ced09ff2ed6d5.jpg</video:thumbnail_loc><video:title>Finding the volume of a prism with a polygon base on a grid</video:title><video:description>Learn how to find the volume of a hexagonal prism by using a grid to calculate the area of the base and then multiplying by the height.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0X8Oo013zIc.mp4/0X8Oo013zIc.mp4</video:content_loc><video:duration>152</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-illustrative-math/v/making-a-prediction-based-on-results-from-a-single-experiment</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x919b6a4c442a1840.jpg</video:thumbnail_loc><video:title>Making a prediction based on results from a single experiment</video:title><video:description>Learn how to use experimental data to estimate the probability of an outcome and predict what is most likely to happen next.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lv9qmWir61I.mp4/lv9qmWir61I.mp4</video:content_loc><video:duration>133</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-illustrative-math/v/comparing-two-experiments-to-predict-the-better-chance</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xccc5edf98115253b.jpg</video:thumbnail_loc><video:title>Comparing two experiments to predict the better chance</video:title><video:description>Learn how to compare experimental probabilities given as fractions with different denominators to determine which outcome is more likely.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/rp4sEjQbvno.mp4/rp4sEjQbvno.mp4</video:content_loc><video:duration>161</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-illustrative-math/v/classifying-outcomes-using-likelihood-terms</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc0608f26a32b4500.jpg</video:thumbnail_loc><video:title>Classifying outcomes using likelihood terms</video:title><video:description>Learn how to use the number of favorable outcomes out of total outcomes to identify whether an event is unlikely, likely, certain, or impossible.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/weyF8fSxoXQ.mp4/weyF8fSxoXQ.mp4</video:content_loc><video:duration>115</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-illustrative-math/v/matching-a-probability-value-to-a-likelihood-term</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xefa0c2256fdb6017.jpg</video:thumbnail_loc><video:title>Matching a probability value to a likelihood term</video:title><video:description>Learn how to match a probability value to the correct likelihood term, from impossible to certain.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pW7iL7MdXmA.mp4/pW7iL7MdXmA.mp4</video:content_loc><video:duration>94</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-illustrative-math/v/comparing-two-probability-values-expressed-in-different-forms</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x027645dc59692bee.jpg</video:thumbnail_loc><video:title>Comparing two probability values expressed in different forms</video:title><video:description>Learn how to compare probabilities expressed in different forms, such as percents and decimals, to determine which outcome is more likely.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4KUg8dcCnQI.mp4/4KUg8dcCnQI.mp4</video:content_loc><video:duration>74</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-illustrative-math/v/identifying-valid-simulations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe6f331f230f9b79e.jpg</video:thumbnail_loc><video:title>Identifying valid simulations</video:title><video:description>Learn how to evaluate whether a simulation accurately models a real-world situation by checking that the probability in the simulation matches the probability in the situation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/sgpbnajY250.mp4/sgpbnajY250.mp4</video:content_loc><video:duration>176</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-illustrative-math/v/selecting-a-valid-simulation-for-a-multi-step-event</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xaea073e7905851aa.jpg</video:thumbnail_loc><video:title>Selecting a valid simulation for a multi-step event</video:title><video:description>Learn how to choose a simulation that correctly models a real-world probability by checking that both the probability and the number of trials match the situation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/rMvfxpoAaOA.mp4/rMvfxpoAaOA.mp4</video:content_loc><video:duration>124</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-illustrative-math/v/estimating-probability-from-a-simulation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x16c9e0c00cbdf1b6.jpg</video:thumbnail_loc><video:title>Estimating probability from a simulation</video:title><video:description>Learn how to use simulation results to estimate the probability of a compound event by identifying how many trials produced the desired outcome.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4xK62sct1fY.mp4/4xK62sct1fY.mp4</video:content_loc><video:duration>160</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-illustrative-math/v/determining-whether-a-sample-is-representative-using-center</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd0e0eab65fcea2f9.jpg</video:thumbnail_loc><video:title>Determining whether a sample is representative using center</video:title><video:description>Learn how to calculate a sample mean and compare it to a population mean to determine whether a sample is a reasonable representation of the population.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/zrwLq2Decck.mp4/zrwLq2Decck.mp4</video:content_loc><video:duration>178</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-illustrative-math/v/identifying-the-most-representative-sample-using-shape-center-and-spread</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x70805a8e961173aa.jpg</video:thumbnail_loc><video:title>Identifying the most representative sample using shape, center, and spread</video:title><video:description>Learn how to identify the most representative sample by comparing the shape and spread of sample dot plots to the population dot plot.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/QPqigb5jgR0.mp4/QPqigb5jgR0.mp4</video:content_loc><video:duration>185</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-illustrative-math/v/estimating-a-population-count-from-a-random-sample</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3c46154d4d096f69.jpg</video:thumbnail_loc><video:title>Estimating a population count from a random sample</video:title><video:description>Learn how to use survey data from a sample to make a proportional estimate about a larger population.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/SpCYrTAzhjc.mp4/SpCYrTAzhjc.mp4</video:content_loc><video:duration>157</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-illustrative-math/v/comparing-populations-using-mad</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa20d8ee974cbcc1c.jpg</video:thumbnail_loc><video:title>Comparing populations using MAD</video:title><video:description>Learn how to determine whether two sample means are meaningfully different by comparing the difference in means to twice the larger MAD.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/QhmATB1SkQs.mp4/QhmATB1SkQs.mp4</video:content_loc><video:duration>190</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-illustrative-math/v/comparing-populations-using-iqr</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5ce09b4ce3cb9f24.jpg</video:thumbnail_loc><video:title>Comparing populations using IQR</video:title><video:description>Learn how to use box plots to compare the medians and IQRs of two samples and decide whether the difference in typical values is meaningful.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/s013HOLgMWM.mp4/s013HOLgMWM.mp4</video:content_loc><video:duration>236</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-illustrative-math/v/drawing-conclusions-from-sample-data</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbc9dfb6a851524a9.jpg</video:thumbnail_loc><video:title>Drawing conclusions from sample data</video:title><video:description>Learn how to identify what information is needed to determine whether a difference in sample medians is meaningful, and why the IQR is required to make that judgment.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/E3DrQ7bfh7s.mp4/E3DrQ7bfh7s.mp4</video:content_loc><video:duration>110</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/introduction-proportional-relationships</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbec0045658d07365.jpg</video:thumbnail_loc><video:title>Introduction to proportional relationships</video:title><video:description>Proportional relationships are relationships between two variables where their ratios are equivalent. Another way to think about them is that, in a proportional relationship, one variable is always a constant value times the other. That constant is known as the &quot;constant of proportionality&quot;.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/l-HtxhClZ-0.mp4/l-HtxhClZ-0.mp4</video:content_loc><video:duration>312</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-math-eureka-squared-aligned/v/relating-side-lengths-in-similar-figures</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe51649b42c20dad7.jpg</video:thumbnail_loc><video:title>Relating side lengths in similar figures</video:title><video:description>Given a pair of similar figures, write proportion statements that relate a side with an unknown length to known side lengths, using both ratios within and between the similar shapes. Then solve for the unknown side length.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/zuV24mxOEfU.mp4/zuV24mxOEfU.mp4</video:content_loc><video:duration>267</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/similar-triangle-basics</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/284859451.jpg</video:thumbnail_loc><video:title>Intro to triangle similarity</video:title><video:description>Sal explains what it means for triangles to be similar, and how this follows from the definition of similarity.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9ThXDY9Y3oU.mp4/9ThXDY9Y3oU.mp4</video:content_loc><video:duration>557</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-math-eureka-squared-aligned/v/checking-triangle-similarity-with-side-length-ratios</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe93ac197a6317522.jpg</video:thumbnail_loc><video:title>Checking triangle similarity with side length ratios</video:title><video:description>Given a triangle with the side lengths labeled, determine which other triangles are similar to it, based on ratios of side lengths between the figures.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5hhHMEp1Zng.mp4/5hhHMEp1Zng.mp4</video:content_loc><video:duration>267</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/similarity-example-problems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/284859450.jpg</video:thumbnail_loc><video:title>Solving similar triangles</video:title><video:description>Sal solves two problems where a missing side length is found by proving that triangles are similar and using this to find the measure.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/R-6CAr_zEEk.mp4/R-6CAr_zEEk.mp4</video:content_loc><video:duration>457</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/exponents-with-negative-bases</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x77666c47.jpg</video:thumbnail_loc><video:title>Exponents with negative bases</video:title><video:description>Learn to what we know about negative numbers to determine how negative bases with exponents are affected and what patterns develop. Also learn how order of operations affect the pattern.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vEZea0EThus.mp4/vEZea0EThus.mp4</video:content_loc><video:duration>270</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/powers-of-1-and-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb66d1c1a.jpg</video:thumbnail_loc><video:title>1 and -1 to different powers</video:title><video:description>Different exponents affect the value of a number: when raised to the power of zero, any number equals one; when raised to an even power, negative numbers yield positive results; and when raised to an odd power, negative numbers yield negative results.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jYOfMszfzAQ.mp4/jYOfMszfzAQ.mp4</video:content_loc><video:duration>368</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/multistep-word-problems-example-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf59a9468.jpg</video:thumbnail_loc><video:title>Rational number word problem: school report</video:title><video:description>First visualize this word problem then use subtraction and multiplication of decimals and fractions to get at the answer.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/GwycEivqYYI.mp4/GwycEivqYYI.mp4</video:content_loc><video:duration>220</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/multistep-word-problems-example-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x602a9681.jpg</video:thumbnail_loc><video:title>Rational number word problem: cosmetics</video:title><video:description>Remember units of measurement? Convert minutes into hours and put your knowledge of fractions to work in this word problem.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/QfsK8ZyC_bE.mp4/QfsK8ZyC_bE.mp4</video:content_loc><video:duration>145</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/rational-number-word-problem-example-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x19dfbdfd.jpg</video:thumbnail_loc><video:title>Rational number word problem: computers</video:title><video:description>In this word problem, we&apos;ll compare the weight of two objects using a ratio of integers. We&apos;ll practice simplifying a fraction, too.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/oqAgaGeBOAU.mp4/oqAgaGeBOAU.mp4</video:content_loc><video:duration>153</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/rational-number-word-problem-example-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x608113aa.jpg</video:thumbnail_loc><video:title>Rational number word problem: stock</video:title><video:description>Use your knowledge of proportions and fractions to determine shareholders profit in this word problem.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/KiVGac1aBt8.mp4/KiVGac1aBt8.mp4</video:content_loc><video:duration>248</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/proof-vertical-angles-are-equal</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/263439066.jpg</video:thumbnail_loc><video:title>Vertical angles are congruent proof</video:title><video:description>Proving that vertical angles are equal</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/wRBMmiNHQaE.mp4/wRBMmiNHQaE.mp4</video:content_loc><video:duration>291</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-seventh-grade-math/v/using-algebra-to-find-the-measures-of-vertical-angles</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x67c17e9a.jpg</video:thumbnail_loc><video:title>Equation practice with vertical angles</video:title><video:description>Given algebraic expressions that represent a pair of vertical angles, Sal forms and solves an equation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2CZrkdtgeNU.mp4/2CZrkdtgeNU.mp4</video:content_loc><video:duration>154</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-math-eureka-squared-aligned/v/modeling-two-step-equations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x89a6dc7b61763998.jpg</video:thumbnail_loc><video:title>Modeling two step equations</video:title><video:description>Let&apos;s use algebra tiles to model and solve two-step equations with integer coefficients in one variable. We&apos;ll see how each step of the model connects with how we can show the same step algebraically.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/w3XjNDBc5sI.mp4/w3XjNDBc5sI.mp4</video:content_loc><video:duration>231</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-math-eureka-squared-aligned/v/writing-two-step-word-problems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x21173d321f0837d3.jpg</video:thumbnail_loc><video:title>Writing two step word problems</video:title><video:description>Let&apos;s write some contexts to represent a two-step equation and inequality in one variable. We&apos;ll consider what makes sense with a negative rate of change and what the unknown we&apos;d be solving for in each case would be.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/nMXNCvmhomY.mp4/nMXNCvmhomY.mp4</video:content_loc><video:duration>293</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-math-eureka-squared-aligned/v/modeling-two-step-inequalities</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfbc387dea89fd93d.jpg</video:thumbnail_loc><video:title>Modeling two step inequalities</video:title><video:description>We can use algebra tiles to model and solve two-step inequalities with integer coefficients in one variable in the same way that we model equations. Let&apos;s solve an inequality with a positive coefficient, but negative constants.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/t1DiyNTwMLU.mp4/t1DiyNTwMLU.mp4</video:content_loc><video:duration>178</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-math-eureka-squared-aligned/v/modeling-inequalities-with-negative-coefficients</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc616985760ca27b4.jpg</video:thumbnail_loc><video:title>Modeling inequalities with negative coefficients</video:title><video:description>How do we make negative 3 equal groups? We&apos;ll use algebra tiles to model and solve an inequality of the form Ax + B is greater than C, where A is negative. Let&apos;s connect the model to the algebraic representation to really understand what happens with the inequality symbol when we divide or multiply both sides of the inequality by a negative number.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/npLlPecY8Ic.mp4/npLlPecY8Ic.mp4</video:content_loc><video:duration>391</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-math-eureka-squared-aligned/v/relating-diameter-and-circumference</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3650e6f98d15f99e.jpg</video:thumbnail_loc><video:title>Relating diameter and circumference</video:title><video:description>Write algebraic expressions relating pi and the different parts of a circle.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/s2vnzKp3EPQ.mp4/s2vnzKp3EPQ.mp4</video:content_loc><video:duration>432</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/informal-argument-for-the-area-of-circle-formula</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x778456ed.jpg</video:thumbnail_loc><video:title>Area of a circle intuition</video:title><video:description>Using triangles to create an informal argument for the area of a circle formula.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/a2L27dTOyHk.mp4/a2L27dTOyHk.mp4</video:content_loc><video:duration>566</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-math-eureka-squared-aligned/v/area-of-composite-figure-with-circles</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe26ece7269c17cb6.jpg</video:thumbnail_loc><video:title>Area of composite figure with circles</video:title><video:description>Find the area of a composite figure by splitting it into a triangle and fractions of circles.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/nuOD3-4ZOlg.mp4/nuOD3-4ZOlg.mp4</video:content_loc><video:duration>225</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-math-eureka-squared-aligned/v/area-composite-figure-parallelograms</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3843fcd6513844f3.jpg</video:thumbnail_loc><video:title>Area of composite figure with parallelograms</video:title><video:description>Find the area of a composite figure by splitting it into congruent parallelograms and rectangles.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lHxLRfxqdN4.mp4/lHxLRfxqdN4.mp4</video:content_loc><video:duration>119</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-math-eureka-squared-aligned/v/total-and-lateral-surface-area-using-a-net-rectangular-pyramid</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9b27361786920930.jpg</video:thumbnail_loc><video:title>Total and lateral surface area using a net rectangular pyramid</video:title><video:description>A rectangular pyramid has 5 faces, a rectangular base and 4 triangular lateral faces. Given the net of a rectangular pyramid, let&apos;s determine the lateral and total surface area of the figure. The total surface area is the area of all the faces, and the lateral surface area leaves out the base.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/rKSZA9sHNlY.mp4/rKSZA9sHNlY.mp4</video:content_loc><video:duration>229</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-math-eureka-squared-aligned/v/lateral-surface-area-using-a-net-triangular-prism</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xca67fe7f8d820429.jpg</video:thumbnail_loc><video:title>Lateral surface area using a net triangular prism</video:title><video:description>Given the net of a triangular prism, we&apos;ll determine the lateral surface area of the figure. The lateral surface area is the sum of the area of all of the faces except for the 2 parallel triangular bases.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/fFVFOdPRxxk.mp4/fFVFOdPRxxk.mp4</video:content_loc><video:duration>142</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-math-eureka-squared-aligned/v/volume-of-rectangular-pyramid-part-1-cube</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xcf1390864d5d8df1.jpg</video:thumbnail_loc><video:title>Volume of rectangular pyramids using cubes</video:title><video:description>Explore why the formula for the volume of rectangular pyramids has a 1/3 in it! We&apos;ll start by investigating with a cube.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tDNCy8dalPY.mp4/tDNCy8dalPY.mp4</video:content_loc><video:duration>91</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-math-eureka-squared-aligned/v/volume-of-rectangular-pyramid-part-2-rectangular-prism</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfe9b10e15c2f2354.jpg</video:thumbnail_loc><video:title>Volume of rectangular pyramids using rectangular prisms</video:title><video:description>Explore why the formula for the volume of a rectangular pyramid has a 1/3 in it! We&apos;ll investigate a general rectangular prism.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PPey8fjuH84.mp4/PPey8fjuH84.mp4</video:content_loc><video:duration>268</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/comparing-proportional-relationships-exercise-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xedb42f94.jpg</video:thumbnail_loc><video:title>Rates &amp; proportional relationships example</video:title><video:description>Let&apos;s compare unit rates in equations and graphs. Learn how a change in &apos;x&apos; affects &apos;y&apos; in an equation like y = 6.5x, and see how this compares to the rate of change in a graph. Uncover why one might increase at a slower pace than the other.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/kHQCDrWTDv8.mp4/kHQCDrWTDv8.mp4</video:content_loc><video:duration>85</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/comparing-proportional-relationships-exercise</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1ce04c40.jpg</video:thumbnail_loc><video:title>Rates &amp; proportional relationships: gas mileage</video:title><video:description>Maria and Nadia calculate their speed on a road trip to Toronto using distance and time. We compare different speeds using equations and tables. Then, we reinforce the concept by comparing the revolution speeds of records.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/F6rtQczAYco.mp4/F6rtQczAYco.mp4</video:content_loc><video:duration>199</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-math-eureka-squared-aligned/v/combining-discounts</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdf3304cf3c490071.jpg</video:thumbnail_loc><video:title>Combining discounts</video:title><video:description>Let&apos;s calculate prices with multiple discounts applied to each. We&apos;ll explore how the order of the discounts affects the final price.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/wR-qdDkOzC8.mp4/wR-qdDkOzC8.mp4</video:content_loc><video:duration>270</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-math-eureka-squared-aligned/v/comparing-discounts</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe170683fa18c8862.jpg</video:thumbnail_loc><video:title>Comparing discounts</video:title><video:description>Let&apos;s compare the prices and discounts available at different stores and determine the lowest price available for a purchase for different quantities of the object. We&apos;ll also consider other factors besides price that might influence where we choose to make a purchase.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ZxCrTlHnUu0.mp4/ZxCrTlHnUu0.mp4</video:content_loc><video:duration>242</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-1-eureka-squared-aligned/v/calculating-simple-compound-interest</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xed3bba74863d1e86.jpg</video:thumbnail_loc><video:title>Calculating simple &amp; compound interest</video:title><video:description>Calculate and compare simple interest and compound interest earnings.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/79HS3N1IBt8.mp4/79HS3N1IBt8.mp4</video:content_loc><video:duration>394</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/7th-grade-math-eureka-squared-aligned/v/compound-events-tree-diagram</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3b1c6fb6.jpg</video:thumbnail_loc><video:title>Compound events example with tree diagram</video:title><video:description>Sal figures out the probability of flipping three coins and getting at least two tails.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4fBXIcO0It4.mp4/4fBXIcO0It4.mp4</video:content_loc><video:duration>144</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/independent-events-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/27095.jpg</video:thumbnail_loc><video:title>Independent events example: test taking</video:title><video:description>Have you ever taken a test and discovered you have no choice but to guess on a couple of problems? In this example problem, we are considering the probability of two independent events occurring.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/VWAfEbgf1Po.mp4/VWAfEbgf1Po.mp4</video:content_loc><video:duration>284</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/compound-probability-of-independent-events</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/191769945.jpg</video:thumbnail_loc><video:title>Compound probability of independent events</video:title><video:description>Learn how to calculate probabilities of coin flips using two methods: listing all possible outcomes or multiplying independent events. Understand what independent events are and how to avoid the gambler&apos;s fallacy. Review fractions and how the sum of all probabilities equals one.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xSc4oLA9e8o.mp4/xSc4oLA9e8o.mp4</video:content_loc><video:duration>360</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/lebron-asks-about-the-chances-of-making-10-free-throws</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/753767269.jpg</video:thumbnail_loc><video:title>Free-throw probability</video:title><video:description>Our friend and Cleveland Cavalier, LeBron James, asks Sal how to determine the probability of making 10 free throws in a row. Hint: the answer is surprising!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/iMqCSgqzmiQ.mp4/iMqCSgqzmiQ.mp4</video:content_loc><video:duration>425</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/lebron-asks-about-free-throws-versus-three-pointers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1022209423.jpg</video:thumbnail_loc><video:title>Three-pointer vs free-throw probability</video:title><video:description>Our friend and Cleveland Cavalier, LeBron James, asks Sal if there&apos;s a high probability of making three free throws in a row or one three-pointer. Before solving the problem, jot down what you think the answer will be!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PddbEVNMgTY.mp4/PddbEVNMgTY.mp4</video:content_loc><video:duration>347</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/probability-with-playing-cards-and-venn-diagrams</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/185786264.jpg</video:thumbnail_loc><video:title>Probability with Venn diagrams</video:title><video:description>Want to learn some probability? This video explains the probability of drawing a Jack or a Heart from a deck of 52 cards. It uses a Venn diagram to illustrate the concept of overlapping events and how to calculate the combined probability. Key definitions include &quot;equally likely events&quot; and &quot;overlapping events&quot;.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/obZzOq_wSCg.mp4/obZzOq_wSCg.mp4</video:content_loc><video:duration>602</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/addition-rule-for-probability</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/188066789.jpg</video:thumbnail_loc><video:title>Addition rule for probability</video:title><video:description>Venn diagrams and the addition rule for probability</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/QE2uR6Z-NcU.mp4/QE2uR6Z-NcU.mp4</video:content_loc><video:duration>643</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/probability/v/random-numbers-for-experimental-probability</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8e152fdf6ff0b58e.jpg</video:thumbnail_loc><video:title>Random numbers for experimental probability</video:title><video:description>Using a list of random number to calculate an experimental probability.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vjGINFbV8Cs.mp4/vjGINFbV8Cs.mp4</video:content_loc><video:duration>449</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/random-number-list-to-run-experiment</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x67e16aadb45da1f7.jpg</video:thumbnail_loc><video:title>Random number list to run experiment</video:title><video:description>Using a list of random numbers to simulate multiple trials of an experiment.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2AVLfSRpmfg.mp4/2AVLfSRpmfg.mp4</video:content_loc><video:duration>451</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-basics/v/adding-integers-with-different-signs</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179312.jpg</video:thumbnail_loc><video:title>Adding numbers with different signs</video:title><video:description>Use a number line to add 15 + (-46) + 29</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/NrVvu7cM8_o.mp4/NrVvu7cM8_o.mp4</video:content_loc><video:duration>332</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/negative-number-practice</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2ef60d58.jpg</video:thumbnail_loc><video:title>Addition &amp; subtraction: find the missing value (part 1 of 2)</video:title><video:description>Sal solves some missing value problems: -1 = 7 - __ and -10 + __ = -5 and 4 = -2 + __ and 6 + __ = -8</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-4bTgmmWI9k.mp4/-4bTgmmWI9k.mp4</video:content_loc><video:duration>333</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/even-more-negative-number-practice</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf26670ad.jpg</video:thumbnail_loc><video:title>Addition &amp; subtraction: find the missing value (part 2 of 2)</video:title><video:description>Sal solves more missing value problems: 4 = -8 - __ and __ - (-2) = -7 and -4 = __ - 9</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/KNGa11O2uLE.mp4/KNGa11O2uLE.mp4</video:content_loc><video:duration>400</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/mappers/v/adding-and-subtracting-three-fractions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xeff72154.jpg</video:thumbnail_loc><video:title>Adding &amp; subtracting fractions</video:title><video:description>Add and subtract negative fractions with unlike denominators.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9tmtDBpqq9s.mp4/9tmtDBpqq9s.mp4</video:content_loc><video:duration>156</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/raising-a-number-to-the-0th-and-1st-power</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2bba124f.jpg</video:thumbnail_loc><video:title>The 0 &amp; 1st power</video:title><video:description>Different ways of thinking about exponents. Raising a number to an exponent means multiplying that number by itself a certain number of times. Any non-zero number raised to the zero power will be equal to one, and that any number raised to the first power will be equal to itself.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/dAvosUEUH6I.mp4/dAvosUEUH6I.mp4</video:content_loc><video:duration>307</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/multiplying-and-dividing-even-and-odd-numbers-of-negatives</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4940c781.jpg</video:thumbnail_loc><video:title>Even &amp; odd numbers of negatives</video:title><video:description>We can figure out whether multiplication and division problems give us a positive or negative result by thinking about how many negative numbers are used in the computation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/XHHYA2Ug9lk.mp4/XHHYA2Ug9lk.mp4</video:content_loc><video:duration>426</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/thinking-about-the-sign-of-expressions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0fa0d50a.jpg</video:thumbnail_loc><video:title>Sign of expressions challenge problems</video:title><video:description>Some examples that test our understanding of what happens when we multply or divide a bunch of positive or negative numbers.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Pms4cBWwPSU.mp4/Pms4cBWwPSU.mp4</video:content_loc><video:duration>519</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/exponent-properties-involving-products</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23686.jpg</video:thumbnail_loc><video:title>Exponent properties with products</video:title><video:description>To simplify expressions with exponents, there are a few properties that may help. One is that when two numbers with the same base are multiplied, the exponents can be added. Another is that when a number with an exponent is raised to another exponent, the exponents can be multiplied.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/zM_p7tfWvLU.mp4/zM_p7tfWvLU.mp4</video:content_loc><video:duration>840</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/products-and-exponents-raised-to-an-exponent-properties</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7c5d0111.jpg</video:thumbnail_loc><video:title>Exponent properties with parentheses</video:title><video:description>Learn two exponent properties: (ab)^c = (a^c)*(b^c) and (a^b)^c = a ^ (b*c). See WHY they work and HOW to use them. In other words, multiplying two numbers, then raising the product to an exponent is the same as raising each number to that exponent and then multiplying. Raising a number to an exponent and then to another exponent equals raising the base to the product of the two exponents.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/SwqOrUWzDY8.mp4/SwqOrUWzDY8.mp4</video:content_loc><video:duration>358</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/exponent-properties-involving-quotients</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23688.jpg</video:thumbnail_loc><video:title>Exponent properties with quotients</video:title><video:description>Learn how to simplify expressions like (5^6)/(5^2). Also learn how 1/(a^b) is the same as a^-b. Towards the end of the video, we practice simplifying more complex expressions like (25 * x * y^6)/(20 * y^5 * x^2).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/AR1uqNbjM5s.mp4/AR1uqNbjM5s.mp4</video:content_loc><video:duration>562</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/negative-exponents</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9ecf1c5c.jpg</video:thumbnail_loc><video:title>Negative exponents</video:title><video:description>Negative exponents can be rewritten in two ways. Firstly, start with 1 and divide it by 2 the same number of times as the exponent. Secondly, take the reciprocal of the base and raise it to the positive exponent.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/JnpqlXN9Whw.mp4/JnpqlXN9Whw.mp4</video:content_loc><video:duration>434</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/negative-exponent-intuition</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25767.jpg</video:thumbnail_loc><video:title>Negative exponent intuition</video:title><video:description>How do negative exponents work? Let&apos;s build our intuition about why a^(-b) = 1/(a^b) and how this definition keeps exponent rules consistent. Continue the pattern of decreasing exponents by dividing by &apos;a&apos;, and see how it extends to zero and negative powers. While we&apos;re at it, we&apos;ll see why a^0 =1.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Tqpcku0hrPU.mp4/Tqpcku0hrPU.mp4</video:content_loc><video:duration>278</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/multiplying-multiples-of-powers-of-10</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x36950ef2.jpg</video:thumbnail_loc><video:title>Multiplying multiples of powers of 10</video:title><video:description>Let&apos;s multiply (9 * 10^9) (-2 * 10^-3) using the power of exponents! Change the order of multiplication to make it easier, multiply the non-powers first. and then simplify the powers of 10. Remember, multiplying by a negative changes the sign of the product. It&apos;s all about using exponent properties to simplify the product.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tV8cMNYi4q4.mp4/tV8cMNYi4q4.mp4</video:content_loc><video:duration>161</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/approximating-with-powers-of-10</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc45ba77a.jpg</video:thumbnail_loc><video:title>Approximating with powers of 10</video:title><video:description>How much larger was the world population than the US population in 2014? We can use division and powers of 10 to get a sense of just how many times as large the world population was. Is there really such a big difference between 10 to the 8th and 10 to the 9th? You bet there is!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Xl724v0CU7E.mp4/Xl724v0CU7E.mp4</video:content_loc><video:duration>250</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/scientific-notation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/4802223.jpg</video:thumbnail_loc><video:title>Scientific notation examples</video:title><video:description>Scientific notation is a way of writing very large or very small numbers. A number is written in scientific notation when a number between 1 and 10 is multiplied by a power of 10. For example, 650,000,000 can be written in scientific notation as 6.5 ✕ 10^8. Created by Sal Khan and CK-12 Foundation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/i6lfVUp5RW8.mp4/i6lfVUp5RW8.mp4</video:content_loc><video:duration>686</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/scientific-notation-i</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179507.jpg</video:thumbnail_loc><video:title>Scientific notation example: 0.0000000003457</video:title><video:description>Can you imagine if you had to do calculations with very, very small numbers? How would you handle all those zeros to the right of the decimal? Thank goodness for scientific notation!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6phoVfGKKec.mp4/6phoVfGKKec.mp4</video:content_loc><video:duration>252</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-basics/v/scientific-notation-example-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179508.jpg</video:thumbnail_loc><video:title>Multiplying in scientific notation example</video:title><video:description>Scientific notation shows a number (greater than or equal to 1 and less than 10) times a power of 10. To multiply two numbers in scientific notation, we can rearrange the equation with the associative and commutative properties. If the final product is not in scientific notation, we can regroup a factor of 10.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xxAFh-qHPPA.mp4/xxAFh-qHPPA.mp4</video:content_loc><video:duration>323</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/multiplying-and-dividing-in-scientific-notation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdf6e3aee.jpg</video:thumbnail_loc><video:title>Multiplying &amp; dividing in scientific notation</video:title><video:description>In order to simplify multiplication and division using scientific notation, you should multiply and divide numbers with the same base, and add or subtract the exponents. Through this process, complex expressions can be simplified into a single value multiplied with 10 to a certain power. As an example, 7 times 10 to the fifth over 2 times 10 to the negative 2 times 2.5 times 10 to the ninth can be simplified to 1.4 times 10 to the negative 2. Scientific notation helps to simplify complex equations that involve multiplying and dividing numbers with the same base.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/497oIjqRPco.mp4/497oIjqRPco.mp4</video:content_loc><video:duration>173</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/multiplying-in-scientific-notation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/466009718.jpg</video:thumbnail_loc><video:title>Multiplying three numbers in scientific notation</video:title><video:description>Multiplying really big or really small numbers is much easier when using scientific notation. When we multiply numbers in scientific notation, we can commute and associate the factors. That lets us multiply the decimal factors first. Then we can use exponent properties to multiply the powers of 10.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/67jn5Zv-myg.mp4/67jn5Zv-myg.mp4</video:content_loc><video:duration>455</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/subtracting-in-scientific-notation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0c719c2c.jpg</video:thumbnail_loc><video:title>Subtracting in scientific notation</video:title><video:description>Learn how to subtract numbers written in scientific notation. The problem solved in this video is (4.1 * 10^-2) - (2.6 * 10^-3).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ios3QL9t9LQ.mp4/ios3QL9t9LQ.mp4</video:content_loc><video:duration>253</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/simplifying-a-complicated-expression-into-scientific-notation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x80584388.jpg</video:thumbnail_loc><video:title>Simplifying in scientific notation challenge</video:title><video:description>Let&apos;s explore how to simplify expressions with numbers in scientific notation. We&apos;ll transform numbers into scientific notation, multiply and divide them, and then reassemble them. It&apos;s a cool and useful method for handling large or small numbers!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/EbmgLiSVACU.mp4/EbmgLiSVACU.mp4</video:content_loc><video:duration>352</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/calculating-red-blood-cells-in-the-body-using-scientific-notation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x767b7883.jpg</video:thumbnail_loc><video:title>Scientific notation word problem: red blood cells</video:title><video:description>Vampires and math students want to know: How many red blood cells are in the a human body? We can find the answer using scientific notation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0lOpqmTdtzk.mp4/0lOpqmTdtzk.mp4</video:content_loc><video:duration>286</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/scientific-notation-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26898.jpg</video:thumbnail_loc><video:title>Scientific notation word problem: U.S. national debt</video:title><video:description>Ever wonder what your part of the national debt is? It might surprise you. What isn&apos;t surprising is that you can use scientific notation and division to figure out the answer.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/XJBwJjP2_hM.mp4/XJBwJjP2_hM.mp4</video:content_loc><video:duration>381</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/scientific-notation-3-new</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179509.jpg</video:thumbnail_loc><video:title>Scientific notation word problem: speed of light</video:title><video:description>It is possible to simplify multiplication and division using scientific notation. This can be used to calculate the distance between the sun and the earth, which is 1.5 times 10 to the 11th power meters. This is an incredibly large distance and difficult to visualize. Scientific notation can be used to simplify calculations and understand large numbers. This involves using the commutative property to rearrange the numbers and multiplying the units, and then adding the exponents to simplify the equation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/dD71fFNwVJw.mp4/dD71fFNwVJw.mp4</video:content_loc><video:duration>267</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-engage-ny/v/sets-overview</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2563c48d.jpg</video:thumbnail_loc><video:title>Introduction to geometric transformations</video:title><video:description>How are virtual sets built in the computer? Pixar uses geometric transformations in animation to manipulate the position, orientation, and size of objects. This process involves story reels, set dressing, and camera staging. Each shot is carefully crafted, using math as the foundation!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lR0kyOdT86E.mp4/lR0kyOdT86E.mp4</video:content_loc><video:duration>186</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/identifying-transformations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3d83ba250d08dc20.jpg</video:thumbnail_loc><video:title>Identifying transformations</video:title><video:description>Let&apos;s look at four types of transformations: rotations (spinning a shape around a point), translations (shifting a shape), reflections (flipping a shape over a line), and dilations (shrinking or expanding a shape). We practice identifying these transformations in different pairs of figures.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/K7QTjFdUIyk.mp4/K7QTjFdUIyk.mp4</video:content_loc><video:duration>227</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/translating-points</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x154b1155a0199523.jpg</video:thumbnail_loc><video:title>Translating points</video:title><video:description>Let&apos;s practice translations on a coordinate plane. A translation is a way to move a point or shape by a certain number of units in a certain direction. For example, we can translate a point by moving it 5 units left and 3 units up. We describe this translation algebraically using the coordinates (x-5, y+3).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/SxxzfojT1Pw.mp4/SxxzfojT1Pw.mp4</video:content_loc><video:duration>231</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/drawing-image-of-translation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x03952f21.jpg</video:thumbnail_loc><video:title>Translating shapes</video:title><video:description>In translations, we slide a shape around on a grid. We use the letter &quot;T&quot; to represent translations. We move every point of the shape a certain distance left or right, and up or down, to create a new shape that&apos;s the same size and shape as the original. We call the new shape the image.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/g_ijRF_NMLk.mp4/g_ijRF_NMLk.mp4</video:content_loc><video:duration>115</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/formal-translation-tool-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x38f28d5c.jpg</video:thumbnail_loc><video:title>Determining translations</video:title><video:description>We can find the translation by figuring out how much the x- and y-coordinates need to change to map one triangle onto the other. We map each point to its corresponding point in the other triangle. Moving left means the translation of x is negative, and moving down means the translation of y is negative.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/BrYEuO7fwMw.mp4/BrYEuO7fwMw.mp4</video:content_loc><video:duration>92</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/rotating-points</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0dcf739db7b81a07.jpg</video:thumbnail_loc><video:title>Rotating points</video:title><video:description>Positive rotation angles mean we turn counterclockwise. Negative angles are clockwise. We can think of a 60 degree turn as 1/3 of a 180 degree turn. A 90 degree turn is 1/4 of the way around a full circle. The angle goes from the center to first point, then from the center to the image of the point.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0NYbQPcdxg8.mp4/0NYbQPcdxg8.mp4</video:content_loc><video:duration>110</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/defining-rotation-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5a934725.jpg</video:thumbnail_loc><video:title>Determining rotations</video:title><video:description>To see the angle of rotation, we draw lines from the center to the same point in the shape before and after the rotation. Counterclockwise rotations have positive angles, while clockwise rotations have negative angles. Then we estimate the angle. For example, 30 degrees is 1/3 of a right angle.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6pH-7pciYU8.mp4/6pH-7pciYU8.mp4</video:content_loc><video:duration>177</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/reflecting-points</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2b4f6a857249e629.jpg</video:thumbnail_loc><video:title>Reflecting points</video:title><video:description>We can plot points after reflecting them across a line, like the x-axis or y-axis. Reflections create mirror images of points, keeping the same distance from the line. When we reflect across the y-axis, the image point is the same height, but has the opposite position from left to right.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/F77xiSlCehI.mp4/F77xiSlCehI.mp4</video:content_loc><video:duration>225</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/reflecting-shapes</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc5d517f510449447.jpg</video:thumbnail_loc><video:title>Reflecting shapes</video:title><video:description>Let&apos;s reflect a quadrilateral across the x-axis. To do this, we find new points (A&apos;, B&apos;, C&apos;, D&apos;) by keeping the same x-coordinates and changing the y-coordinates to their opposite signs. This creates a flipped image of the original quadrilateral.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lfBDOQddTD0.mp4/lfBDOQddTD0.mp4</video:content_loc><video:duration>158</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/determining-reflections</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xae5156462a07bf1d.jpg</video:thumbnail_loc><video:title>Determining reflections</video:title><video:description>A line of reflection is an imaginary line that flips one shape onto another. We find this line by finding the halfway points between matching points on the source and image triangles. All of the halfway points are on the line. Once we find that line, it shows how one triangle reflects onto the other.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/435Ipnmp7bA.mp4/435Ipnmp7bA.mp4</video:content_loc><video:duration>100</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/finding-measures-using-rigid-transformations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9324fd9746376a81.jpg</video:thumbnail_loc><video:title>Finding measures using rigid transformations</video:title><video:description>Finding measures after a rigid transformation, like a reflection, is pretty simple! Since the shape and size stay the same, the lengths of corresponding sides and angle measures remain unchanged. Area and perimeter depend on the side lengths, so they stay the same too. So, if we know the measures of the original figure, we can use those same measures for the transformed figure.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7y4FGCvNgB8.mp4/7y4FGCvNgB8.mp4</video:content_loc><video:duration>296</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/rigid-transformations-preserved-properties</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x89713b044e601426.jpg</video:thumbnail_loc><video:title>Rigid transformations: preserved properties</video:title><video:description>Rigid transformations, like rotations and reflections, change a shape&apos;s position but keep its size and shape. These transformations preserve side lengths, angle measures, perimeter, and area. But they might not keep the same coordinates or relationships to lines outside the figure.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/brccWoewXiI.mp4/brccWoewXiI.mp4</video:content_loc><video:duration>420</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/mapping-shapes</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x43371bfd817e219c.jpg</video:thumbnail_loc><video:title>Mapping shapes</video:title><video:description>Let&apos;s find the right sequence of rigid transformations (like rotations, translations, and reflections) to map one triangle onto another. Different sequences can work, but order matters. So, it&apos;s important to test each one to see if it maps the triangles correctly.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/QOXBJ2X1_9k.mp4/QOXBJ2X1_9k.mp4</video:content_loc><video:duration>531</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/testing-congruence-by-transformations-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdfa0c35c.jpg</video:thumbnail_loc><video:title>Congruent shapes &amp; transformations</video:title><video:description>If we can map one figure onto another using rigid transformations, they are congruent. They are still congruent if we need to use more than one transformation to map it. They aren&apos;t if we use a transformation that changes the size of the shape.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/KZMRhWdzEPo.mp4/KZMRhWdzEPo.mp4</video:content_loc><video:duration>103</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/another-congruence-by-transformation-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5172fee3.jpg</video:thumbnail_loc><video:title>Non-congruent shapes &amp; transformations</video:title><video:description>Congruent shapes are the same size and shape. Rigid transformations, like translations, keep shapes congruent, but dilations are not rigid transformations because they change the size. So, if we use a dilation to map one shape onto another, they are not congruent.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7Rb3V-HyVD8.mp4/7Rb3V-HyVD8.mp4</video:content_loc><video:duration>123</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-engage-ny/v/sat-math-s6-easier</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8e8c18af.jpg</video:thumbnail_loc><video:title>Congruence and similarity — Basic example</video:title><video:description>Watch Sal work through a basic congruence and similarity problem.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/XcXmLHra3aA.mp4/XcXmLHra3aA.mp4</video:content_loc><video:duration>259</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-engage-ny/v/sat-math-s6-harder</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1adedf5e.jpg</video:thumbnail_loc><video:title>Congruence and similarity — Harder example</video:title><video:description>Watch Sal work through a harder Congruence and similarity problem.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/nKpHg25_AdM.mp4/nKpHg25_AdM.mp4</video:content_loc><video:duration>198</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/angles-formed-by-parallel-lines-and-transversals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/263439061.jpg</video:thumbnail_loc><video:title>Angles, parallel lines, &amp; transversals</video:title><video:description>Parallel lines are lines in the same plane that go in the same direction and never intersect. When a third line, called a transversal, crosses these parallel lines, it creates angles. Some angles are equal, like vertical angles (opposite angles) and corresponding angles (same position at each intersection).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/H-E5rlpCVu4.mp4/H-E5rlpCVu4.mp4</video:content_loc><video:duration>427</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/figuring-out-angles-between-transversal-and-parallel-lines</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc5b28d56.jpg</video:thumbnail_loc><video:title>Missing angles with a transversal</video:title><video:description>When a third line called a transversal crosses two parallel lines, we can find the measures of angles using properties like corresponding angles, vertical angles, and supplementary angles. If we know just one of the angle measurements, these properties help us find all the missing angle measurements.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2WjGD3LZEWo.mp4/2WjGD3LZEWo.mp4</video:content_loc><video:duration>136</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/using-algebra-to-find-measures-of-angles-formed-from-transversal</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa92ee636.jpg</video:thumbnail_loc><video:title>Measures of angles formed by a transversal</video:title><video:description>When parallel lines are crossed by another line called a transversal, special angles are formed. We can find the measures of these angles using algebra and the relationships between the angles, like congruent angles and supplementary angles. Once we solve for the variable, we use that value to figure out the angle measures.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Ld7Vxb5XV6A.mp4/Ld7Vxb5XV6A.mp4</video:content_loc><video:duration>281</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/proof-sum-of-measures-of-angles-in-a-triangle-are-180</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/265540637.jpg</video:thumbnail_loc><video:title>Angles in a triangle sum to 180° proof</video:title><video:description>The sum of the interior angle measures of a triangle always adds up to 180°. We can draw a line parallel to the base of any triangle through its third vertex. Then we use transversals, vertical angles, and corresponding angles to rearrange those angle measures into a straight line, proving that they must add up to 180°.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6s1CI3uuhko.mp4/6s1CI3uuhko.mp4</video:content_loc><video:duration>268</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/triangle-angle-example-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/265540642.jpg</video:thumbnail_loc><video:title>Triangle exterior angle example</video:title><video:description>An exterior angle is formed outside a triangle by extending a side. Its measure is equal to the sum of the two non-adjacent interior angle measures, thanks to the fact that all angle measures in a triangle add up to 180 degrees.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hmj3_zbz2eg.mp4/hmj3_zbz2eg.mp4</video:content_loc><video:duration>363</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/triangle-angle-example-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/265540638.jpg</video:thumbnail_loc><video:title>Worked example: Triangle angles (intersecting lines)</video:title><video:description>Learn how to find unknown angles in triangles and intersecting lines. We use concepts like supplementary angles (angles that add up to 180°), vertical angles (opposite angles made by two crossing lines), and exterior angles (angles outside a triangle). There are lots of ways to think about this problem.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/eTwnt4G5xE4.mp4/eTwnt4G5xE4.mp4</video:content_loc><video:duration>295</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/triangle-angle-example-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/265540640.jpg</video:thumbnail_loc><video:title>Worked example: Triangle angles (diagram)</video:title><video:description>We have a right triangle that&apos;s split into several smaller right triangles. The angle measures in any triangle always add up to 180 degrees. By using this fact and looking at complementary (adding up to 90 degrees) and supplementary (adding up to 180 degrees) angles, we can find the missing angle measures in the triangles.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/iqeGTtyzQ1I.mp4/iqeGTtyzQ1I.mp4</video:content_loc><video:duration>342</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/challenging-triangle-angle-problem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/265540635.jpg</video:thumbnail_loc><video:title>Triangle angle challenge problem</video:title><video:description>Learn about the sum of exterior angles in a polygon, specifically a pentagon. We find out that the sum of exterior angles is always the same, no matter the shape of the pentagon. To understand this, we use interior angles and divide the pentagon into triangles.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/95logvV8nXY.mp4/95logvV8nXY.mp4</video:content_loc><video:duration>517</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/finding-more-angles</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/265540639.jpg</video:thumbnail_loc><video:title>Triangle angle challenge problem 2</video:title><video:description>Find angle measures in triangles when the given measures are algebraic expressions. The key idea is that the sum of all angles in a triangle is always 180 degrees. We can also use parallel lines and transversals to find angle measures.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0gzSreH8nUI.mp4/0gzSreH8nUI.mp4</video:content_loc><video:duration>365</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/bhaskara-s-proof-of-pythagorean-theorem-avi</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1199369003.jpg</video:thumbnail_loc><video:title>Bhaskara&apos;s proof of the Pythagorean theorem</video:title><video:description>The 12th century Indian mathematician Bhaskara developed an elegant visual proof of the Pythagorean Theorem. Bhaskara uses a square and four congruent right triangles, rearranged in two ways, to prove this theorem. He shows that in a right triangle, the square of the longest side (hypotenuse) is equal to the sum of the squares of the other two sides.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1ul8g55dYA4.mp4/1ul8g55dYA4.mp4</video:content_loc><video:duration>543</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/thinking-about-dilations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1854dd51.jpg</video:thumbnail_loc><video:title>Dilating shapes: expanding</video:title><video:description>Let&apos;s dilate a rectangle around a point P using a scale factor 1 2/3. This changes the size of the rectangle while keeping its shape. Because 1 2/3 is bigger than 1, most of the points get farther from P. Point P stays in place, because a distance of 0 times any scale factor is still 0.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6dyWKD_JPhI.mp4/6dyWKD_JPhI.mp4</video:content_loc><video:duration>159</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/scaling-down-a-triangle-by-half</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x86399361.jpg</video:thumbnail_loc><video:title>Dilating shapes: shrinking by 1/2</video:title><video:description>Dilations are transformations that change the size of a shape and its distance from the center of dilation. When the center is the origin, we can change the distance by multiplying the x- and y-coordinates by the scale factor. That&apos;s how we find the new positions of the points after dilation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qlWZJ21O63s.mp4/qlWZJ21O63s.mp4</video:content_loc><video:duration>146</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/dilating-points-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd9ea6a29c4a9812f.jpg</video:thumbnail_loc><video:title>Dilating points</video:title><video:description>Dilations are a way to stretch or shrink shapes around a point called the center of dilation. The amount we stretch or shrink is called the scale factor. If the scale factor is greater than 1, the shape stretches. If it&apos;s between 0 and 1, the shape shrinks.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/N0_HfmxdbCg.mp4/N0_HfmxdbCg.mp4</video:content_loc><video:duration>187</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/dilation-scale-factor</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x76dc81a4313d7166.jpg</video:thumbnail_loc><video:title>Dilations: scale factor</video:title><video:description>Dilations make a shape bigger or smaller. A scale factor tells us how much to multiply by the side lengths to change the size. The scale factor is the ratio of the side length in the new shape (image) to the side length in the corresponding side in the original shape (pre-image). Each pair of corresponding sides has the same factor.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/b4ORXN7a0-w.mp4/b4ORXN7a0-w.mp4</video:content_loc><video:duration>299</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/dilations-and-properties</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb836462d55b30b93.jpg</video:thumbnail_loc><video:title>Dilations and properties</video:title><video:description>Dilations can change the lengths of a shape and its distance from the center, but they keep the angle measures the same. What does this mean about coordinates, side lengths, perimeter, and area?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/chdnDLbSbU8.mp4/chdnDLbSbU8.mp4</video:content_loc><video:duration>323</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/similarity-postulates</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/284859449.jpg</video:thumbnail_loc><video:title>Triangle similarity postulates/criteria</video:title><video:description>Sal reviews all the different ways we can determine that two triangles are similar. This is similar to the congruence criteria, only for similarity!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7bO0TmJ6Ba4.mp4/7bO0TmJ6Ba4.mp4</video:content_loc><video:duration>734</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/similar-triangle-example-problems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/289578994.jpg</video:thumbnail_loc><video:title>Determining similar triangles</video:title><video:description>Multiple examples where Sal analyzes the similarity of triangles.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Ly86lwq_2gc.mp4/Ly86lwq_2gc.mp4</video:content_loc><video:duration>563</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/testing-similarity-through-transformations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfc5aad45.jpg</video:thumbnail_loc><video:title>Similar shapes &amp; transformations</video:title><video:description>Two shapes are similar if we can change one shape into the other using rigid transformations (like moving or rotating) and dilations (making it bigger or smaller). Other kinds of transformations can change the angles or the ratios of lengths in a figure. If we need those types of transformations, the shapes are not similar.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/H-YuW_uckz4.mp4/H-YuW_uckz4.mp4</video:content_loc><video:duration>158</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/the-pythagorean-theorem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/2600799.jpg</video:thumbnail_loc><video:title>Intro to the Pythagorean theorem</video:title><video:description>The Pythagorean theorem is a cornerstone of math that helps us find the missing side length of a right triangle. In a right triangle with sides A, B, and hypotenuse C, the theorem states that A² + B² = C². The hypotenuse is the longest side, opposite the right angle.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/AA6RfgP-AHU.mp4/AA6RfgP-AHU.mp4</video:content_loc><video:duration>646</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/pythagorean-theorem-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26903.jpg</video:thumbnail_loc><video:title>Pythagorean theorem example</video:title><video:description>The Pythagorean theorem states that in a right triangle, the sum of the squares of the two shorter sides equals the square of the longest side (the hypotenuse). We can apply the theorem to find the missing side length of a right triangle, even when the missing length is one of the shorter sides.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/O64YFlX1_aI.mp4/O64YFlX1_aI.mp4</video:content_loc><video:duration>257</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/pythagorean-theorem-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26766.jpg</video:thumbnail_loc><video:title>Pythagorean theorem word problem: carpet</video:title><video:description>If we draw the diagonal on a rectangular carpet, then its length, width, and diagonal form a right triangle. Since we know the length and diagonal measurements, we can use the Pythagorean theorem to solve for the missing width of the carpet.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/T0IOrRETWhI.mp4/T0IOrRETWhI.mp4</video:content_loc><video:duration>180</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/pythagorean-theorem-with-right-triangle</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb26b2a89796216fc.jpg</video:thumbnail_loc><video:title>Pythagorean theorem with isosceles triangle</video:title><video:description>To find the value of a base (x) in an isosceles triangle, first split the triangle into two congruent right triangles by drawing an altitude. Then, use the Pythagorean theorem to create an equation involving x. Finally, solve the equation to find the unknown base, x.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TjOlZr_2uW4.mp4/TjOlZr_2uW4.mp4</video:content_loc><video:duration>228</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/pythagorean-theorem-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26902.jpg</video:thumbnail_loc><video:title>Pythagorean theorem word problem: fishing boat</video:title><video:description>If we assume that the mast of a boat is at a right angle to the deck, then we can model the length of a rope stretched between the mast and deck as the hypotenuse of a right triangle. Then we can use the Pythagorean theorem to relate the lengths.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/JVrkLIcA2qw.mp4/JVrkLIcA2qw.mp4</video:content_loc><video:duration>272</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-basics/v/soccer-thiago</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x19541b96.jpg</video:thumbnail_loc><video:title>Thiago asks: How much time does a goalkeeper have to react to a penalty kick?</video:title><video:description>Sal uses the Pythagorean theorem to answer a question posed by a soccer superstar!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/XtJwkIacpi8.mp4/XtJwkIacpi8.mp4</video:content_loc><video:duration>725</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/garfield-s-proof-of-the-pythagorean-theorem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1199652424.jpg</video:thumbnail_loc><video:title>Garfield&apos;s proof of the Pythagorean theorem</video:title><video:description>Former U.S. President James Garfield wrote a proof of the Pythagorean theorem. He used a trapezoid made of two identical right triangles and half of a square to show that the sum of the squares of the two shorter sides equals the square of the longest side of a right triangle.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/EINpkcphsPQ.mp4/EINpkcphsPQ.mp4</video:content_loc><video:duration>536</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/pythagorean-theorem-proof-using-similarity</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/290279020.jpg</video:thumbnail_loc><video:title>Pythagorean theorem proof using similarity</video:title><video:description>Proof of the Pythagorean Theorem using similarity</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LrS5_l-gk94.mp4/LrS5_l-gk94.mp4</video:content_loc><video:duration>592</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/another-pythagorean-theorem-proof</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1199568849.jpg</video:thumbnail_loc><video:title>Another Pythagorean theorem proof</video:title><video:description>Visually proving the Pythagorean Theorem</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/rcBaqkGp7CA.mp4/rcBaqkGp7CA.mp4</video:content_loc><video:duration>623</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/equations-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/9.jpg</video:thumbnail_loc><video:title>Intro to equations with variables on both sides</video:title><video:description>Learn how to solve the equation 2x + 3 = 5x - 2 with the variable on both sides. We start by visualizing the equation, then isolate the variable by performing the same operations on both sides. Finally, we solve the equation to find the value of the variable.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/f15zA0PhSek.mp4/f15zA0PhSek.mp4</video:content_loc><video:duration>533</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/solving-equations-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26778.jpg</video:thumbnail_loc><video:title>Equations with variables on both sides: 20-7x=6x-6</video:title><video:description>Solving equations like 20 - 7x = 6x - 6 with the variable on both sides involves a few steps! First, we add or subtract terms from both sides to separate constants and variables to different sides of the equation. Then, we simplify to isolate the variable. Finally, we check our answer by plugging it back into the original equation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1c5HY3z4k8M.mp4/1c5HY3z4k8M.mp4</video:content_loc><video:duration>246</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/solving-equations-with-the-distributive-property-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26780.jpg</video:thumbnail_loc><video:title>Equation with variables on both sides: fractions</video:title><video:description>To solve the equation (3/4)x + 2 = (3/8)x - 4, we first eliminate fractions by multiplying both sides by the least common multiple of the denominators. Then, we add or subtract terms from both sides of the equation to group the x-terms on one side and the constants on the other. Finally, we solve and check as normal.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PL9UYj2awDc.mp4/PL9UYj2awDc.mp4</video:content_loc><video:duration>290</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/ex-2-multi-step-equation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1242815904.jpg</video:thumbnail_loc><video:title>Equation with the variable in the denominator</video:title><video:description>The variable x is in the denominator in 7 - 10/x = 2 + 15/x. We can multiply both sides of the equation by x to turn it into a more familiar, linear form without fractions. From there, we isolate the variable to solve. P.S. x cannot equal zero, because then the equation would be undefined.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Z7C69xP08d8.mp4/Z7C69xP08d8.mp4</video:content_loc><video:duration>204</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/solving-equations-with-the-distributive-property</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26779.jpg</video:thumbnail_loc><video:title>Equations with parentheses</video:title><video:description>When an equation such as -9 - (9x - 6) = 3(4x + 6) has parentheses, we can distribute without changing the value of each side. Then combine like terms. Next, we move all the x-terms to one side and the constants to the other. Finally, we solve for x.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/YZBStgZGyDY.mp4/YZBStgZGyDY.mp4</video:content_loc><video:duration>364</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/number-of-solutions-to-linear-equations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x60d48e64.jpg</video:thumbnail_loc><video:title>Number of solutions to equations</video:title><video:description>A linear equation could have exactly 1, 0, or infinite solutions. If we can solve the equation and get something like x=b where b is a specific number, then we have one solution. If we end up with a statement that&apos;s always false, like 3=5, then there&apos;s no solution. If we end up with a statement that&apos;s always true, like 5=5, then there are infinite solutions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qsL_5Y8uWPU.mp4/qsL_5Y8uWPU.mp4</video:content_loc><video:duration>328</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/equation-special-cases</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179469.jpg</video:thumbnail_loc><video:title>Worked example: number of solutions to equations</video:title><video:description>Sal attempts to solve 8(3x + 10) = 28x - 14 - 4x only to find that the equation has no solution.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/zKotuhQWIRg.mp4/zKotuhQWIRg.mp4</video:content_loc><video:duration>115</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/number-of-solutions-to-linear-equations-ex-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x62c9e8fa.jpg</video:thumbnail_loc><video:title>Creating an equation with no solutions</video:title><video:description>Sal shows how to complete the equation -11x + 4 = __x + __ so that it has no solutions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/uQs100shv-A.mp4/uQs100shv-A.mp4</video:content_loc><video:duration>83</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/number-of-solutions-to-linear-equations-ex-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdfacc6f3.jpg</video:thumbnail_loc><video:title>Creating an equation with infinitely many solutions</video:title><video:description>Sal shows how to complete the equation 4(x - 2) + x = 5x + __ so that it has infinitely many solutions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Dq0xFgQB9qo.mp4/Dq0xFgQB9qo.mp4</video:content_loc><video:duration>100</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/graphing-proportional-relationships-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x13c3e512.jpg</video:thumbnail_loc><video:title>Graphing proportional relationships: unit rate</video:title><video:description>In proportional relationships, the unit rate is the slope of the line. Changes in x lead to steady changes in y when there&apos;s a proportional relationship. We can use the unit rate to write and graph an equation of the line that represents the relationship.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1F7LAJEVp-U.mp4/1F7LAJEVp-U.mp4</video:content_loc><video:duration>271</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/graphing-proportional-relationships-example-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5794411e.jpg</video:thumbnail_loc><video:title>Graphing proportional relationships from a table</video:title><video:description>Let&apos;s graph a proportional relationship from a table of values. The graph of a proportional relationship is a line, so we can graph from any 2 points in the table. The slope of the line represents the unit rate, so changes in x and y values determine the slope.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/R32xBmxXj2E.mp4/R32xBmxXj2E.mp4</video:content_loc><video:duration>72</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/graphing-proportional-relationships-example-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x683c6b9a.jpg</video:thumbnail_loc><video:title>Graphing proportional relationships from an equation</video:title><video:description>Let&apos;s graph the equation y = 2.5x. For every increase of 1 in x, y increases by 2.5. We call this the &quot;unit rate&quot; or &quot;slope&quot;. The graph shows a proportional relationship because y changes at a constant rate as x changes and because y is 0 when x is 0.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LoKEPEPaNm4.mp4/LoKEPEPaNm4.mp4</video:content_loc><video:duration>189</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-engage-ny/v/determining-a-linear-equation-by-trying-out-values-from-a-table</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5fa37e27.jpg</video:thumbnail_loc><video:title>Testing solutions to linear equations</video:title><video:description>Sal figures out which equation was used to generate a table of x and y values.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/WU9g4CvZyR0.mp4/WU9g4CvZyR0.mp4</video:content_loc><video:duration>216</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/plotting-x-y-relationships</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/33752746.jpg</video:thumbnail_loc><video:title>Graphing a linear equation: 5x+2y=20</video:title><video:description>We can graph a the linear equation like 5x + 2y = 20 by rewriting it so y is isolated, then plugging in x values to find their corresponding y-values in a table. We can then graph those x-y pairs as points on a graph.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/86NwKBcOlow.mp4/86NwKBcOlow.mp4</video:content_loc><video:duration>269</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/finding-x-intercept-of-a-line</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6bca96e9.jpg</video:thumbnail_loc><video:title>x-intercept of a line</video:title><video:description>Sal determines the x-intercept of a linear equation from a graph. Afterwards, he checks his work by plugging values back into the equation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xiIQQNufFuU.mp4/xiIQQNufFuU.mp4</video:content_loc><video:duration>103</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/finding-intercepts-for-a-linear-function-from-a-table</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe3701afe.jpg</video:thumbnail_loc><video:title>Intercepts from a table</video:title><video:description>The y-intercept is the y-coordinate when x=0, and the x-intercept is the x-coordinate when y=0. The y-intercept is not in the table. Since the table represents a line, there&apos;s a constant rate of change of y with respect to x. So we can find that pattern and fill in skipped values from the table to find the y-intercept.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/CGZZINHT0I8.mp4/CGZZINHT0I8.mp4</video:content_loc><video:duration>240</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/x-and-y-intercepts</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26802.jpg</video:thumbnail_loc><video:title>Intercepts from an equation</video:title><video:description>Let&apos;s graph -5x + 4y = 20 from its intercepts. Intercepts are the places where a line crosses the x- and y-axes. When a line crosses the x-axis, the y value is 0. That&apos;s the x-intercept. When a line crosses the y-axis, the x value is 0. That&apos;s the y-intercept. The line passes through those points.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xGmef7lFc5w.mp4/xGmef7lFc5w.mp4</video:content_loc><video:duration>248</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/x-and-y-intercepts-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26803.jpg</video:thumbnail_loc><video:title>Worked example: intercepts from an equation</video:title><video:description>Let&apos;s find the x- and y-intercepts of the equation 2y + 1/3x = 12, where a line crosses the x-axis (the x-intercept) and the y-axis (the y-intercept) on a graph. To find the x-intercept, we make y equal to 0 and solve the equation for x. To find the y-intercept, we make x equal to 0 and solve for y.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/405boztgZig.mp4/405boztgZig.mp4</video:content_loc><video:duration>205</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/slope-intuition-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4d473b5b.jpg</video:thumbnail_loc><video:title>Slope &amp; direction of a line</video:title><video:description>A line that&apos;s flat has a slope of 0. If a line goes up as you move to the right, it has a positive slope. The steeper it is, the bigger the slope. If a line goes down as you move to the right, it has a negative slope. The steeper it is, the more negative the slope.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6_9xNMtwnfs.mp4/6_9xNMtwnfs.mp4</video:content_loc><video:duration>155</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/slope-of-a-line</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26800.jpg</video:thumbnail_loc><video:title>Worked example: slope from graph</video:title><video:description>The slope of a line is rise over run. Learn how to calculate the slope of the line in a graph by finding the change in y and the change in x.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/R948Tsyq4vA.mp4/R948Tsyq4vA.mp4</video:content_loc><video:duration>280</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/graphical-slope-of-a-line</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/33752751.jpg</video:thumbnail_loc><video:title>Slope of a line: negative slope</video:title><video:description>Slope is like a hill&apos;s steepness. We find it by dividing the vertical change (rise) by the horizontal change (run). If we move right on a graph and go up, the slope is positive. If we go down, it&apos;s negative. We can find the slope between any two points on a line, and it&apos;s always the same.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/81SseQCpGws.mp4/81SseQCpGws.mp4</video:content_loc><video:duration>240</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/slope-of-a-line-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/33752752.jpg</video:thumbnail_loc><video:title>Worked example: slope from two points</video:title><video:description>Let&apos;s find the slope of the line that goes through the ordered pairs (4,2) and (-3, 16). The slope, or steepness, of a line is found by dividing the vertical change (rise) by the horizontal change (run). The formula is slope =(y₂ - y₁)/(x₂ - x₁), where (x₁, y₁) and (x₂, y₂) are the coordinates of two points on the line.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/WkspBxrzuZo.mp4/WkspBxrzuZo.mp4</video:content_loc><video:duration>432</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/slope-of-a-line-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/33752753.jpg</video:thumbnail_loc><video:title>Slope of a horizontal line</video:title><video:description>When two points have the same y-value, it means they lie on a horizontal line. The slope of such a line is 0, and you will also find this by using the slope formula.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/CFSHq099Mx0.mp4/CFSHq099Mx0.mp4</video:content_loc><video:duration>305</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/graphing-a-line-in-slope-intercept-form</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26804.jpg</video:thumbnail_loc><video:title>Graph from slope-intercept equation</video:title><video:description>To graph a linear equation in slope-intercept form, we can use the information given by that form. For example, y=2x+3 tells us that the slope of the line is 2 and the y-intercept is at (0,3). This gives us one point the line goes through, and the direction we should continue from that point to draw the entire line.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/uk7gS3cZVp4.mp4/uk7gS3cZVp4.mp4</video:content_loc><video:duration>181</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/graphs-using-slope-intercept-form</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23638.jpg</video:thumbnail_loc><video:title>Slope-intercept equation from graph</video:title><video:description>Learn to write equations in slope-intercept form for three different lines.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9wOalujeZf4.mp4/9wOalujeZf4.mp4</video:content_loc><video:duration>671</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/equation-of-a-line-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/33752754.jpg</video:thumbnail_loc><video:title>Slope-intercept equation from slope &amp; point</video:title><video:description>Learn how to write an equation in slope-intercept form (y=mx+b) for the line with a slope of -3/4 that goes through the point (0,8). We identify the slope (m) and y-intercept (b) to create our equation y = (-3/4)*x + 8.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/AqFwKecNaTk.mp4/AqFwKecNaTk.mp4</video:content_loc><video:duration>226</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/equation-of-a-line-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/33752756.jpg</video:thumbnail_loc><video:title>Slope-intercept equation from two points</video:title><video:description>Given two points on a line, we can write an equation for that line by finding the slope between those points, then solving for the y-intercept in the slope-intercept equation y=mx+b. In this example, we write an equation of the line that passes through the points (-1,6) and (5,-4).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/XMJ72mtMn4Y.mp4/XMJ72mtMn4Y.mp4</video:content_loc><video:duration>402</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/slope-intercept-form-from-table</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdf2c138e.jpg</video:thumbnail_loc><video:title>Slope-intercept form from a table</video:title><video:description>Learn how to write an equation of the line that matches up to a table of values.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3Ayt7mOd_To.mp4/3Ayt7mOd_To.mp4</video:content_loc><video:duration>266</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/converting-to-slope-intercept-form</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26806.jpg</video:thumbnail_loc><video:title>Converting to slope-intercept form</video:title><video:description>Learn to convert equations like 4x + 2y = -8 into slope-intercept form.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/V6Xynlqc_tc.mp4/V6Xynlqc_tc.mp4</video:content_loc><video:duration>307</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/linear-equations-in-slope-intercept-form</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23646.jpg</video:thumbnail_loc><video:title>Slope-intercept form problems</video:title><video:description>Learn how to solve problems involving writing an equation in slope-intercept form.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5fkh01mClLU.mp4/5fkh01mClLU.mp4</video:content_loc><video:duration>898</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/similar-triangles-to-prove-that-the-slope-is-constant-for-a-line</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x208e430a.jpg</video:thumbnail_loc><video:title>Proving slope is constant using similarity</video:title><video:description>Sal uses a clever proof involving similar triangles to show that slope is constant for a line.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/24WMbh1BBKc.mp4/24WMbh1BBKc.mp4</video:content_loc><video:duration>476</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/idea-behind-point-slope-form</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x917b105d.jpg</video:thumbnail_loc><video:title>Intro to point-slope form</video:title><video:description>Point-slope is the general form y-y₁=m(x-x₁) for linear equations. It emphasizes the slope of the line and a point on the line (that is not the y-intercept). Watch this video to learn more about it and see some examples.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/K_OI9LA54AA.mp4/K_OI9LA54AA.mp4</video:content_loc><video:duration>367</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/trolls-tolls-and-systems-of-equations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1095856196.jpg</video:thumbnail_loc><video:title>Systems of equations: trolls, tolls (1 of 2)</video:title><video:description>A troll forces us to use algebra to figure out the make-up of his currency. We end up setting up a system of equations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OcNt-36QKu8.mp4/OcNt-36QKu8.mp4</video:content_loc><video:duration>411</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/solving-the-troll-riddle-visually</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1095783741.jpg</video:thumbnail_loc><video:title>Systems of equations: trolls, tolls (2 of 2)</video:title><video:description>Solving the system of equations visually. Now we can save the prince/princess.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/H-HfmyUzPw8.mp4/H-HfmyUzPw8.mp4</video:content_loc><video:duration>341</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/testing-a-solution-for-a-system-of-equations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/33752762.jpg</video:thumbnail_loc><video:title>Testing a solution to a system of equations</video:title><video:description>Sal checks whether (-1,7) is a solution of the system: x+2y=13 and 3x-y=-11.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/SkMNREAMNvc.mp4/SkMNREAMNvc.mp4</video:content_loc><video:duration>158</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/solving-linear-systems-by-graphing</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23674.jpg</video:thumbnail_loc><video:title>Systems of equations with graphing</video:title><video:description>When solving systems of linear equations, one method is to graph both equations on the same coordinate plane. The intersection of the two lines represents a solution that satisfies both equations. Other, more mathematical, methods may also be used.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5a6zpfl50go.mp4/5a6zpfl50go.mp4</video:content_loc><video:duration>510</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/graphings-systems-of-equations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/33752761.jpg</video:thumbnail_loc><video:title>Systems of equations with graphing: 5x+3y=7 &amp; 3x-2y=8</video:title><video:description>To solve a system of linear equations by graphing, you need to graph each equation separately. Find two points on each line and connect them. The point where the two lines intersect is the solution to the system of equations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/MRAIgJmRmag.mp4/MRAIgJmRmag.mp4</video:content_loc><video:duration>395</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/solving-systems-graphically</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1112700719.jpg</video:thumbnail_loc><video:title>Systems of equations with graphing: y=7/5x-5 &amp; y=3/5x-1</video:title><video:description>Sal graphs the following system of equations and solves it by looking for the intersection point: y=7/5x-5 and y=3/5x-1.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/VhH2nEDCd68.mp4/VhH2nEDCd68.mp4</video:content_loc><video:duration>142</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/graphical-systems-application-problem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/33752765.jpg</video:thumbnail_loc><video:title>Systems of equations with graphing: chores</video:title><video:description>Graphical Systems Application Problem</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3mimxluSVBo.mp4/3mimxluSVBo.mp4</video:content_loc><video:duration>319</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-engage-ny/v/solving-systems-by-elimination-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26882.jpg</video:thumbnail_loc><video:title>Systems of equations with elimination: 3t+4g=6 &amp; -6t+g=6</video:title><video:description>Sal solves the system of equations 3t + 4g = 6 and -6t + g = 6 using elimination.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Y6JsEja15Vk.mp4/Y6JsEja15Vk.mp4</video:content_loc><video:duration>225</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-engage-ny/v/addition-elimination-method-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/33752772.jpg</video:thumbnail_loc><video:title>Systems of equations with elimination: x+2y=6 &amp; 4x-2y=14</video:title><video:description>Learn to use elimination to solve the system of equations x + 2y = 6 and 4x - 2y = 14.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0P0SCQf-hWQ.mp4/0P0SCQf-hWQ.mp4</video:content_loc><video:duration>218</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-engage-ny/v/addition-elimination-method-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/33752773.jpg</video:thumbnail_loc><video:title>Systems of equations with elimination: -3y+4x=11 &amp; y+2x=13</video:title><video:description>Sal solves the system of equations -3y + 4x = 11 and y + 2x = 13 using elimination.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hJOqGkWElNs.mp4/hJOqGkWElNs.mp4</video:content_loc><video:duration>266</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-engage-ny/v/addition-elimination-method-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/33752774.jpg</video:thumbnail_loc><video:title>Systems of equations with elimination: 2x-y=14 &amp; -6x+3y=-42</video:title><video:description>Sal solves the system of equations 2x - y = 14 and -6x + 3y = -42 using elimination.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/mKu0L46Qed4.mp4/mKu0L46Qed4.mp4</video:content_loc><video:duration>305</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-engage-ny/v/solving-systems-by-elimination-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26883.jpg</video:thumbnail_loc><video:title>Systems of equations with elimination: 4x-2y=5 &amp; 2x-y=2.5</video:title><video:description>Sal solves the system of equations 4x - 2y = 5 and 2x - y = 2.5 using elimination.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Dqp6xOeR3Ls.mp4/Dqp6xOeR3Ls.mp4</video:content_loc><video:duration>297</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/simple-elimination-practice</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1112791956.jpg</video:thumbnail_loc><video:title>Systems of equations with elimination: x-4y=-18 &amp; -x+3y=11</video:title><video:description>Sal solves the following system of equations by eliminating x: x-4y=-18 and -x+3y=11.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/NPXTkj75-AM.mp4/NPXTkj75-AM.mp4</video:content_loc><video:duration>359</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-engage-ny/v/systems-with-elimination-practice</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1115141430.jpg</video:thumbnail_loc><video:title>Systems of equations with elimination: 6x-6y=-24 &amp; -5x-5y=-60</video:title><video:description>Sal solves the system of equations 6x - 6y = -24 and -5x - 5y = -60 using elimination.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/u5dPUHjagSI.mp4/u5dPUHjagSI.mp4</video:content_loc><video:duration>331</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/the-substitution-method</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/33752769.jpg</video:thumbnail_loc><video:title>Systems of equations with substitution: 2y=x+7 &amp; x=y-4</video:title><video:description>When solving a system of equations using substitution, you can isolate one variable and substitute it with an expression from another equation. This will allow you to solve for one variable, which you can then use to solve for the other.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/uzyd_mIJaoc.mp4/uzyd_mIJaoc.mp4</video:content_loc><video:duration>279</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/solving-systems-by-substitution-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26879.jpg</video:thumbnail_loc><video:title>Systems of equations with substitution: y=4x-17.5 &amp; y+2x=6.5</video:title><video:description>Learn to solve the system of equations y = 4x - 17.5 and y + 2x = 6.5 using substitution.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/wB3QCk0MGuw.mp4/wB3QCk0MGuw.mp4</video:content_loc><video:duration>246</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/practice-using-substitution-for-systems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1116433408.jpg</video:thumbnail_loc><video:title>Systems of equations with substitution: -3x-4y=-2 &amp; y=2x-5</video:title><video:description>Learn to solve the system of equations -3x - 4y = -2 and y = 2x - 5 using substitution.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/GWZKz4F9hWM.mp4/GWZKz4F9hWM.mp4</video:content_loc><video:duration>261</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/solving-systems-by-substitution-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26880.jpg</video:thumbnail_loc><video:title>Systems of equations with substitution: 9x+3y=15 &amp; y-x=5</video:title><video:description>Learn to solve the system of equations 9x + 3y = 15 and y - x = 5 using substitution.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0BgUKHTW37E.mp4/0BgUKHTW37E.mp4</video:content_loc><video:duration>364</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/substitution-method-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/33752770.jpg</video:thumbnail_loc><video:title>Systems of equations with substitution: y=-5x+8 &amp; 10x+2y=-2</video:title><video:description>Learn to solve the system of equations y = -5x + 8 and 10x + 2y = -2 using substitution.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2VeqrZ_PMiY.mp4/2VeqrZ_PMiY.mp4</video:content_loc><video:duration>224</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/solving-systems-by-substitution-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26878.jpg</video:thumbnail_loc><video:title>Systems of equations with substitution: y=-1/4x+100 &amp; y=-1/4x+120</video:title><video:description>Learn to solve the system of equations y = -1/4x + 100 and y = -1/4x + 120 using substitution.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/HJV_HY0Sh0s.mp4/HJV_HY0Sh0s.mp4</video:content_loc><video:duration>224</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/using-a-system-of-equations-to-find-the-price-of-apples-and-oranges</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9cf8703a.jpg</video:thumbnail_loc><video:title>Systems of equations with elimination: apples and oranges</video:title><video:description>Sal solves a word problem about the price of apples and oranges by creating a system of equations and solving it.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gRntusF_tVI.mp4/gRntusF_tVI.mp4</video:content_loc><video:duration>306</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/solving-systems-by-elimination</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26881.jpg</video:thumbnail_loc><video:title>Systems of equations with elimination: TV &amp; DVD</video:title><video:description>Sal solves a word problem about the weights of TVs and DVDs by creating a system of equations and solving it.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/z1hz8-Kri1E.mp4/z1hz8-Kri1E.mp4</video:content_loc><video:duration>351</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/king-s-cupcakes-solving-systems-by-elimination</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1112847811.jpg</video:thumbnail_loc><video:title>Systems of equations with elimination: King&apos;s cupcakes</video:title><video:description>Sal uses simple elimination to figure out how many cupcakes are eaten by children and adults.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xCIHAjsZCE0.mp4/xCIHAjsZCE0.mp4</video:content_loc><video:duration>540</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-engage-ny/v/addition-elimination-method-4</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/33752775.jpg</video:thumbnail_loc><video:title>Systems of equations with elimination: Sum/difference of numbers</video:title><video:description>Sal finds two numbers that sum to 70 and have a difference of 24.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DxSmZ0MDSxM.mp4/DxSmZ0MDSxM.mp4</video:content_loc><video:duration>158</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/how-many-bags-of-potato-chips-do-people-eat</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1114711148.jpg</video:thumbnail_loc><video:title>Systems of equations with elimination: potato chips</video:title><video:description>Sal solves another system of equations using elimination.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/VuJEidLhY1E.mp4/VuJEidLhY1E.mp4</video:content_loc><video:duration>561</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/understanding-systems-of-equations-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6f9a8813.jpg</video:thumbnail_loc><video:title>Systems of equations with elimination: coffee and croissants</video:title><video:description>Sal solves a word problem about the price of coffee and croissant by creating a system of equations and solving it.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/grmmM_KhQ4U.mp4/grmmM_KhQ4U.mp4</video:content_loc><video:duration>255</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/substitution-method-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/33752771.jpg</video:thumbnail_loc><video:title>Systems of equations with substitution: coins</video:title><video:description>Sal solves a word problem about the number of nickels and quarters in a piggy bank by creating a system of equations and solving it.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/v6L8--MlnKo.mp4/v6L8--MlnKo.mp4</video:content_loc><video:duration>358</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/solving-systems-with-substitution</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1115394533.jpg</video:thumbnail_loc><video:title>Systems of equations with substitution: potato chips</video:title><video:description>To solve a system of equations using substitution... 1. Isolate one of the variables in one of the equations, e.g. rewrite 2x+y=3 as y=3-2x. 2. You can now express the isolated variable using the other one. *Substitute* that expression into the second equation, e.g. rewrite x+2y=5 as x+2(3-2x)=5. 3. Now you have an equation with one variable! Solve it, and use what you got to find the other variable.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2EwPpga_XPw.mp4/2EwPpga_XPw.mp4</video:content_loc><video:duration>321</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-engage-ny/v/algebraic-word-problem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26781.jpg</video:thumbnail_loc><video:title>Systems of equations with substitution: shelves</video:title><video:description>Sal solves a system of equations to figure out how long a couple of different shelves will be.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/cNlwi6lUCEM.mp4/cNlwi6lUCEM.mp4</video:content_loc><video:duration>482</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/ex-2-age-word-problem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1242705398.jpg</video:thumbnail_loc><video:title>Age word problem: Imran</video:title><video:description>Sal solves the following age word problem: In 40 years, Imran will be 11 times as old as he is right now. How old is he right now?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/KyHvVJWjW6Y.mp4/KyHvVJWjW6Y.mp4</video:content_loc><video:duration>223</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/ex-3-age-word-problem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1242500916.jpg</video:thumbnail_loc><video:title>Age word problem: Ben &amp; William</video:title><video:description>Sal solves the following age word problem: William is 4 times as old as Ben. 12 years ago, William was 7 times as old as Ben. How old is Ben now?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/RGbA2IyJILY.mp4/RGbA2IyJILY.mp4</video:content_loc><video:duration>388</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/ex-1-age-word-problem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1242638298.jpg</video:thumbnail_loc><video:title>Age word problem: Arman &amp; Diya</video:title><video:description>Sal solves the following age word problem: Arman is 18. Diya is 2. How many years will it take for Arman to be 3 times as old as Diya?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/W-5liMGKgHA.mp4/W-5liMGKgHA.mp4</video:content_loc><video:duration>321</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/consistent-and-inconsistent-systems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/33752763.jpg</video:thumbnail_loc><video:title>Solutions to systems of equations: consistent vs. inconsistent</video:title><video:description>A consistent system of equations has at least one solution, and an inconsistent system has no solution. Watch an example of analyzing a system to see if it&apos;s consistent or inconsistent.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Ix8Nne-a-KQ.mp4/Ix8Nne-a-KQ.mp4</video:content_loc><video:duration>329</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/inconsistent-systems-of-equations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1116349757.jpg</video:thumbnail_loc><video:title>Systems of equations number of solutions: fruit prices (1 of 2)</video:title><video:description>Sal gives an example of a system of equations that has no solution!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/NJRyxmommqQ.mp4/NJRyxmommqQ.mp4</video:content_loc><video:duration>565</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/infinite-solutions-to-systems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1116483367.jpg</video:thumbnail_loc><video:title>Systems of equations number of solutions: fruit prices (2 of 2)</video:title><video:description>Sal gives an example of a system of equations that has infinite solutions!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/MpRUEGD2-_c.mp4/MpRUEGD2-_c.mp4</video:content_loc><video:duration>428</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-engage-ny/v/solving-systems-by-graphing-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26877.jpg</video:thumbnail_loc><video:title>Systems of equations number of solutions: y=3x+1 &amp; 2y+4=6x</video:title><video:description>Sal graphs a system of equations to find the number of solutions it has.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/F5Nb6cIRZLU.mp4/F5Nb6cIRZLU.mp4</video:content_loc><video:duration>308</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/independent-and-dependent-systems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/561902042.jpg</video:thumbnail_loc><video:title>Solutions to systems of equations: dependent vs. independent</video:title><video:description>A dependent system of equations has infinite solutions, and an independent system has a single solution. Watch an example of analyzing a system to see if it&apos;s dependent or independent.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/WSpF5uvApLA.mp4/WSpF5uvApLA.mp4</video:content_loc><video:duration>310</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/practice-thinking-about-number-of-solutions-to-systems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1116353804.jpg</video:thumbnail_loc><video:title>Number of solutions to a system of equations graphically</video:title><video:description>Sal determines how many solutions the following system of equations has by considering its graph: 10x-2y=4 and 10x-2y=16.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/SuB1gkto9LU.mp4/SuB1gkto9LU.mp4</video:content_loc><video:duration>396</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-engage-ny/v/constructing-solutions-to-systems-of-equations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x736f77fe.jpg</video:thumbnail_loc><video:title>Forming systems of equations with different numbers of solutions</video:title><video:description>Sal write an equation that along with the equation 4x + 5y = 2 forms a system of equations with infinitely many solutions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Z96vkuybvjE.mp4/Z96vkuybvjE.mp4</video:content_loc><video:duration>381</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-engage-ny/v/comparing-celsius-and-farenheit-temperature-scales</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/33.jpg</video:thumbnail_loc><video:title>Comparing Celsius and Fahrenheit temperature scales</video:title><video:description>Comparing Celsius and Fahrenheit temperature scales</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/aASUZqJCHHA.mp4/aASUZqJCHHA.mp4</video:content_loc><video:duration>170</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-engage-ny/v/converting-farenheit-to-celsius</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/153770151.jpg</video:thumbnail_loc><video:title>Converting Fahrenheit to Celsius</video:title><video:description>To convert from Celsius to Fahrenheit, we can use the formula F = 9/5C + 32, where C is the temperature in degrees Celsius and F is the temperature in degrees Fahrenheit. To convert from Fahrenheit to Celsius we can use the formula C = 5/9(F - 32).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/NqbkvEK46xM.mp4/NqbkvEK46xM.mp4</video:content_loc><video:duration>178</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/what-is-a-function</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2ec1ec8a.jpg</video:thumbnail_loc><video:title>What is a function?</video:title><video:description>Functions assign a single output for each of their inputs. In this video, we see examples of various kinds of functions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/kvGsIo1TmsM.mp4/kvGsIo1TmsM.mp4</video:content_loc><video:duration>477</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/understanding-function-notation-example-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1292edd2.jpg</video:thumbnail_loc><video:title>Worked example: Evaluating functions from equation</video:title><video:description>Learn how to evaluate f(x)=49-x² at x=5.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Id6UovYjd-M.mp4/Id6UovYjd-M.mp4</video:content_loc><video:duration>59</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/understanding-function-notation-example-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbdf4c75d.jpg</video:thumbnail_loc><video:title>Worked example: Evaluating functions from graph</video:title><video:description>Evaluating a function at x=-1 using the graph of that function.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/kzYtx_AqzjM.mp4/kzYtx_AqzjM.mp4</video:content_loc><video:duration>44</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/difference-between-equations-and-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1254705646.jpg</video:thumbnail_loc><video:title>Equations vs. functions</video:title><video:description>Equations and functions are not the same thing, but they can be related in several ways. Watch Jesse Roe and Sal talk about the difference between equations and functions</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/l3iXON1xEC4.mp4/l3iXON1xEC4.mp4</video:content_loc><video:duration>258</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/solving-for-a-variable-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26783.jpg</video:thumbnail_loc><video:title>Manipulating formulas: temperature</video:title><video:description>Sal takes the formula for converting from Fahrenheit temperature to Celsius, and solves it for F so it serves to convert from Celsius to Fahrenheit.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/BR5yFOt0zao.mp4/BR5yFOt0zao.mp4</video:content_loc><video:duration>161</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/testing-if-a-relationship-is-a-function</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26791.jpg</video:thumbnail_loc><video:title>Testing if a relationship is a function</video:title><video:description>Learn to determine if points on a graph represent a function.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3SO1BQQ9_1E.mp4/3SO1BQQ9_1E.mp4</video:content_loc><video:duration>143</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/relations-and-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/357917981.jpg</video:thumbnail_loc><video:title>Relations and functions</video:title><video:description>Learn to determine if a relation given by a set of ordered pairs is a function.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Uz0MtFlLD-k.mp4/Uz0MtFlLD-k.mp4</video:content_loc><video:duration>417</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/graphical-relations-and-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/357917979.jpg</video:thumbnail_loc><video:title>Recognizing functions from graph</video:title><video:description>Checking whether a given set of points can represent a function. For the set to represent a function, each domain element must have one corresponding range element at most.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qGmJ4F3b5W8.mp4/qGmJ4F3b5W8.mp4</video:content_loc><video:duration>247</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/recognizing-functions-example-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9cd7b997.jpg</video:thumbnail_loc><video:title>Checking if a table represents a function</video:title><video:description>Sal determines if y is a function of x from looking at a table.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lEhf75ma7Ww.mp4/lEhf75ma7Ww.mp4</video:content_loc><video:duration>76</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/recognizing-functions-example-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe1f24412.jpg</video:thumbnail_loc><video:title>Recognizing functions from verbal description</video:title><video:description>Checking whether y can be described as a function of x if y is always three more than twice x.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tBRW-CyJE6k.mp4/tBRW-CyJE6k.mp4</video:content_loc><video:duration>91</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/functional-relationships-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26790.jpg</video:thumbnail_loc><video:title>Recognizing functions from table</video:title><video:description>Checking whether a table of people and their heights can represent a function that assigns a height to a name.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5cK86VKoBPw.mp4/5cK86VKoBPw.mp4</video:content_loc><video:duration>280</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/recognizing-functions-example-5</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe4c1673b.jpg</video:thumbnail_loc><video:title>Recognizing functions from verbal description word problems</video:title><video:description>Checking whether a description of the price of an order can be represented as a function of the shipping cost.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/z45UEiPaE8c.mp4/z45UEiPaE8c.mp4</video:content_loc><video:duration>203</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/recognizing-functions-example-4</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xce131edd.jpg</video:thumbnail_loc><video:title>Checking if an equation represents a function</video:title><video:description>Sal determines if y is a function of x from looking at an equation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/QWLcNxQ3KvQ.mp4/QWLcNxQ3KvQ.mp4</video:content_loc><video:duration>213</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/recognizing-functions-example-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5b15777f.jpg</video:thumbnail_loc><video:title>Does a vertical line represent a function?</video:title><video:description>Explaining why a vertical line doesn&apos;t represent a function.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_npwsLh0vws.mp4/_npwsLh0vws.mp4</video:content_loc><video:duration>100</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/cylinder-volume-and-surface-area</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/60129395.jpg</video:thumbnail_loc><video:title>Cylinder volume &amp; surface area</video:title><video:description>A cylinder&apos;s volume is π r² h, and its surface area is 2π r h + 2π r². Learn how to use these formulas to solve an example problem.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gL3HxBQyeg0.mp4/gL3HxBQyeg0.mp4</video:content_loc><video:duration>487</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/volume-of-a-sphere</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/372432663.jpg</video:thumbnail_loc><video:title>Volume of a sphere</video:title><video:description>The formula for the volume of a sphere is V = 4/3 π r³, where V = volume and r = radius. The radius of a sphere is half its diameter. So, to calculate the volume of a sphere given the diameter of the sphere, you can first calculate the radius, then the volume.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/IelS2vg7JO8.mp4/IelS2vg7JO8.mp4</video:content_loc><video:duration>155</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/volume-cone-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8cc61186.jpg</video:thumbnail_loc><video:title>Volume of a cone</video:title><video:description>The formula for the volume of a cone is V=1/3hπr². Learn how to use this formula to solve an example problem.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hC6zx9WAiC4.mp4/hC6zx9WAiC4.mp4</video:content_loc><video:duration>344</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/recognizing-linear-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26798.jpg</video:thumbnail_loc><video:title>Recognizing linear functions</video:title><video:description>Learn to recognize if a function is linear.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/AZroE4fJqtQ.mp4/AZroE4fJqtQ.mp4</video:content_loc><video:duration>241</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/linear-and-nonlinear-functions-example-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7f5ef1b0.jpg</video:thumbnail_loc><video:title>Linear &amp; nonlinear functions: table</video:title><video:description>Learn to determine if a table of values represents a linear function.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Pt-Tn6L60-o.mp4/Pt-Tn6L60-o.mp4</video:content_loc><video:duration>146</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/linear-and-nonlinear-functions-example-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf9937022.jpg</video:thumbnail_loc><video:title>Linear &amp; nonlinear functions: word problem</video:title><video:description>Learn to determine if the relationship described in a word problem is a function.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OWPVZoxNe-U.mp4/OWPVZoxNe-U.mp4</video:content_loc><video:duration>215</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/linear-and-nonlinear-functions-example-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa6a89fbd.jpg</video:thumbnail_loc><video:title>Linear &amp; nonlinear functions: missing value</video:title><video:description>Learn to find the missing value in a table to make sure it represents a linear equation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/HUnF0mZmMKc.mp4/HUnF0mZmMKc.mp4</video:content_loc><video:duration>133</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/interpreting-a-graph-exercise-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x98c9e2aa.jpg</video:thumbnail_loc><video:title>Interpreting a graph example</video:title><video:description>Learn to interpret the graphs of a linear functions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/YyjpeoxdUXc.mp4/YyjpeoxdUXc.mp4</video:content_loc><video:duration>143</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/comparing-features-of-functions-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x198644d9.jpg</video:thumbnail_loc><video:title>Comparing linear functions: equation vs. graph</video:title><video:description>Sal is given the formula of a linear function and the graph of another, and is asked to determine which function increases faster.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/fZO-JylMFqY.mp4/fZO-JylMFqY.mp4</video:content_loc><video:duration>143</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/comparing-features-of-functions-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfd98bb7a.jpg</video:thumbnail_loc><video:title>Comparing linear functions: same rate of change</video:title><video:description>Sal is given a table of values of a linear function and four linear graphs, and is asked to determine which graph has the same rate of change as the function represented in the table.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/wl2iQAuQl7Y.mp4/wl2iQAuQl7Y.mp4</video:content_loc><video:duration>156</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/comparing-features-of-functions-5</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x63490941.jpg</video:thumbnail_loc><video:title>Comparing linear functions: faster rate of change</video:title><video:description>Sal is given a table of values of a linear function and four linear graphs, and is asked to determine which graph increases faster than the function represented in the table.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/QYoNHOjr7Rg.mp4/QYoNHOjr7Rg.mp4</video:content_loc><video:duration>220</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/constructing-scatter-plot</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x486a060d.jpg</video:thumbnail_loc><video:title>Constructing a scatter plot</video:title><video:description>Does the time an exam happens affects the scores? Aubrey gathered info. Then she made a scatter plot with the time of day on the bottom (on the horizontal axis) and the scores on the side (on the vertical axis). She didn&apos;t find a clear pattern.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/sHbX58y5D4U.mp4/sHbX58y5D4U.mp4</video:content_loc><video:duration>152</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/scatter-plot-interpreting</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x905613d7.jpg</video:thumbnail_loc><video:title>Example of direction in scatterplots</video:title><video:description>There are two graphs. One shows the relationship between study time and test grades. Do you get better grades if you study more? The other graph shows the relationship between shoe size and grades. Do you get better grades if you wear larger shoes?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Jpbm5YgciqI.mp4/Jpbm5YgciqI.mp4</video:content_loc><video:duration>146</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/trends-in-smoking-scatter-plot</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x95ffaffd.jpg</video:thumbnail_loc><video:title>Scatter plot: smokers</video:title><video:description>In a negative linear association, as one variable goes up, the other variable goes down at a constant rate. In this case, the percent of adults who smoke drops 0.5% each time the year goes up. In the right graph, the points go down by about 0.5% each year. There should be no points far away from the main trend.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/F5uiFXECnVY.mp4/F5uiFXECnVY.mp4</video:content_loc><video:duration>155</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/estimating-the-line-of-best-fit-exercise</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x61240c40.jpg</video:thumbnail_loc><video:title>Estimating the line of best fit exercise</video:title><video:description>The &quot;line of best fit&quot; is a line that shows the pattern of data points. If we can find a good line, it means there is a linear trend. If not, it means there is no linear trend. We can&apos;t ignore points that don&apos;t fit the trend.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ioieTr41L24.mp4/ioieTr41L24.mp4</video:content_loc><video:duration>77</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/smoking-1945-extrapolation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x47ddceeb.jpg</video:thumbnail_loc><video:title>Line of best fit: smoking in 1945</video:title><video:description>The scatter plot shows how many adults in America smoked from year to year. We can guess how many smoked in 1945 by drawing a line that slopes down through the points. Then we see how high the line would be 20 years earlier.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/d4WE4SnhBDU.mp4/d4WE4SnhBDU.mp4</video:content_loc><video:duration>287</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/interpreting-trend-line</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5409e0ad.jpg</video:thumbnail_loc><video:title>Interpreting a trend line</video:title><video:description>The graph shows how studying affects test scores. The line slope of 15 means that for each extra hour of studying, there is usually a 15-point increase in test score. But it&apos;s not a guarantee. Some students may do better or worse than the trend.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/mfX_yUvwJho.mp4/mfX_yUvwJho.mp4</video:content_loc><video:duration>208</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/interpreting-linear-graphs</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/370285953.jpg</video:thumbnail_loc><video:title>Linear graphs word problems</video:title><video:description>Sal discusses how we would go about making sense of the direction of a linear graph that represents a relationship between two real-world quantities.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xR9r38mZjK4.mp4/xR9r38mZjK4.mp4</video:content_loc><video:duration>305</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/interpreting-features-of-linear-functions-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x97976348.jpg</video:thumbnail_loc><video:title>Linear graphs word problem: cats</video:title><video:description>Sal finds the y-intercept and the slope of a linear relationship representing someone accumulating cats! He then interprets what the y-intercept and the slope mean in that context.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qo5jU_V6JVo.mp4/qo5jU_V6JVo.mp4</video:content_loc><video:duration>163</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/interpreting-features-of-linear-functions-example-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x77591b48.jpg</video:thumbnail_loc><video:title>Linear equations word problems: volcano</video:title><video:description>Sal finds the y-intercept and the slope of a linear relationship representing someone climbing a volcano. He then interprets what the y-intercept and the slope mean in that context.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/eLUmpX_h9sw.mp4/eLUmpX_h9sw.mp4</video:content_loc><video:duration>358</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/slope-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26801.jpg</video:thumbnail_loc><video:title>Linear equations word problems: earnings</video:title><video:description>Sal finds the slope of a linear relationship between the number of work hours and the money earned. He then interprets what this slope means in that context.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jTCZfMMcHBo.mp4/jTCZfMMcHBo.mp4</video:content_loc><video:duration>243</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/exploring-linear-relationships</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26797.jpg</video:thumbnail_loc><video:title>Modeling with linear equations: snow</video:title><video:description>Sal uses a linear equation to model the amount of snow on the ground.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qPx7i1jwXX4.mp4/qPx7i1jwXX4.mp4</video:content_loc><video:duration>298</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/comparing-features-of-functions-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6b95f0e9.jpg</video:thumbnail_loc><video:title>Comparing linear functions word problem: climb</video:title><video:description>Sal is given the formula and a table of values that represent two people climbing a wall, and is asked to determine which one started out higher.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/MKErxh58RME.mp4/MKErxh58RME.mp4</video:content_loc><video:duration>284</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/comparing-features-of-functions-4</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xda657261.jpg</video:thumbnail_loc><video:title>Comparing linear functions word problem: walk</video:title><video:description>Sal is given a table of values that represents four people walking to school, and is asked to determine which one started out farther from the school.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/NOsnG2DkGKM.mp4/NOsnG2DkGKM.mp4</video:content_loc><video:duration>224</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/comparing-features-of-functions-6</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x09dee3a1.jpg</video:thumbnail_loc><video:title>Comparing linear functions word problem: work</video:title><video:description>Sal is given a table of values that represents a person walking to work, and is asked to determine which verbal description represents someone starting at the same distance from work.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/kJIqoTw_Og8.mp4/kJIqoTw_Og8.mp4</video:content_loc><video:duration>226</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/application-problem-with-graph</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/33752750.jpg</video:thumbnail_loc><video:title>Linear function example: spending money</video:title><video:description>Sal solves an interesting application problem using a linear model.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ljROszF_rqs.mp4/ljROszF_rqs.mp4</video:content_loc><video:duration>322</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/word-problem-solving-4</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23644.jpg</video:thumbnail_loc><video:title>Modeling with linear equations: gym membership &amp; lemonade</video:title><video:description>Constructing linear equations to solve word problems</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5EdbPz1ZVn0.mp4/5EdbPz1ZVn0.mp4</video:content_loc><video:duration>605</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/fitting-a-line-to-data</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23654.jpg</video:thumbnail_loc><video:title>Fitting a line to data</video:title><video:description>Sal creates a scatter plot and then fits a line to data on the median California family income.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OhUkMQtBGmE.mp4/OhUkMQtBGmE.mp4</video:content_loc><video:duration>468</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/two-way-frequency-tables-and-venn-diagrams</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1d9a21e3.jpg</video:thumbnail_loc><video:title>Two-way frequency tables and Venn diagrams</video:title><video:description>Sometimes data belongs to more than one category. For example, candies might have chocolate, coconut, both, or neither. We can use Venn diagrams and two-way tables. Venn diagrams show sets and their overlaps. Two-way tables organize data in rows and columns. Both methods help show relationships between categories.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/l5MrtV7ZN88.mp4/l5MrtV7ZN88.mp4</video:content_loc><video:duration>383</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/two-way-relative-frequency-tables</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb908feeb.jpg</video:thumbnail_loc><video:title>Two-way relative frequency tables</video:title><video:description>Relative frequencies show how often something happens compared to the total number of times it could happen. In our example, we calculate the relative frequency of accidents for SUVs by dividing the number of SUVs that had accidents by the total number of SUVs. This gives us a percentage or fraction that tells us how common accidents are for that type of vehicle.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_ETPMszULXc.mp4/_ETPMszULXc.mp4</video:content_loc><video:duration>268</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/interpreting-two-way-tables</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xaae200df.jpg</video:thumbnail_loc><video:title>Interpreting two-way tables</video:title><video:description>Two-way tables let us sort a group in two ways. For example, we see how men and women voted in the 2012 US presidential election. We can compare the percentages of men and women who voted for each candidate. Two-way tables help us understand how categories relate.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/MarqSlyz-lU.mp4/MarqSlyz-lU.mp4</video:content_loc><video:duration>104</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/introduction-to-square-roots</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa58e57f6.jpg</video:thumbnail_loc><video:title>Intro to square roots</video:title><video:description>Learn about the square root symbol (the principal root) and what it means to find a square root. Also learn how to solve simple square root equations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/mbc3_e5lWw0.mp4/mbc3_e5lWw0.mp4</video:content_loc><video:duration>324</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/introduction-to-cube-roots</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x63d365e2.jpg</video:thumbnail_loc><video:title>Intro to cube roots</video:title><video:description>Learn the meaning of cube roots and how to find them. Also learn how to find the cube root of a negative number.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/87_qIofPwhg.mp4/87_qIofPwhg.mp4</video:content_loc><video:duration>481</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/finding-cube-roots</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/126711578.jpg</video:thumbnail_loc><video:title>Worked example: Cube root of a negative number</video:title><video:description>Learn how to find the cube root of negative 512 by breaking it down into prime factors. When we find groups of three of the same factor, we know that&apos;s a factor of the cube root. It helps to remember that -1*-1*-1 is -1, so the cube root of -1 is itself.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DKh16Th8x6o.mp4/DKh16Th8x6o.mp4</video:content_loc><video:duration>258</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/finding-square-root-of-decimal</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4451110d.jpg</video:thumbnail_loc><video:title>Square root of decimal</video:title><video:description>Learn how to find the square root of a decimal number. The problem solved in this video is p^2 = 0.81.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tRHLEWSUjrQ.mp4/tRHLEWSUjrQ.mp4</video:content_loc><video:duration>184</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/dimensions-of-cube-from-volume</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc5cba819.jpg</video:thumbnail_loc><video:title>Dimensions of a cube from its volume</video:title><video:description>When we know the volume of a cube, we can use the cube root of the volume to find the length of each side. We&apos;ll need to factor the volume and find 3 equal groups of factors. The value of one group is the length of one side of the cube.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/GpOxsRF1Cjc.mp4/GpOxsRF1Cjc.mp4</video:content_loc><video:duration>215</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/introduction-to-rational-and-irrational-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2d1f5fa7.jpg</video:thumbnail_loc><video:title>Intro to rational &amp; irrational numbers</video:title><video:description>Learn the difference between rational and irrational numbers, learn how to identify them, and discover why some of the most famous numbers in mathematics, like Pi and e, are actually irrational. Did you know that there&apos;s always an irrational number between any two rational numbers?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/cLP7INqs3JM.mp4/cLP7INqs3JM.mp4</video:content_loc><video:duration>355</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/recognizing-irrational-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x00ce2e4a.jpg</video:thumbnail_loc><video:title>Classifying numbers: rational &amp; irrational</video:title><video:description>We can write any rational number as the ratio of two integers. We cannot write irrational numbers, such as the square root of 8 and pi, in this way. Learn other forms, such as decimals, in which these types of numbers can appear.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/d9pO2z2qvXU.mp4/d9pO2z2qvXU.mp4</video:content_loc><video:duration>138</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/categorizing-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd693fe85.jpg</video:thumbnail_loc><video:title>Classifying numbers</video:title><video:description>There are many categories we can use to classify numbers. Some of those categories are rational numbers, irrational numbers, integers, and whole numbers. Rational numbers are represented as a fraction of two integers, while irrational numbers cannot be represented as a fraction of two integers. Integers are positive and negative numbers that don’t involve fractions or decimals. Whole numbers are a subset of integers — they are non-negative integers.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-QHff5pRdM8.mp4/-QHff5pRdM8.mp4</video:content_loc><video:duration>529</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/approximating-square-roots-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x83a7e947.jpg</video:thumbnail_loc><video:title>Approximating square roots</video:title><video:description>Learn how to find the approximate values of square roots. The examples used in this video are √32, √55, and √123. The technique used is to compare the squares of whole numbers to the number we&apos;re taking the square root of.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Lh7NMBPFVZw.mp4/Lh7NMBPFVZw.mp4</video:content_loc><video:duration>288</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/approximating-square-roots</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/125518448.jpg</video:thumbnail_loc><video:title>Approximating square roots to hundredths</video:title><video:description>Let&apos;s approximate the square root of 45 without a calculator. We&apos;ll explore how to find the perfect squares around 45 and use them to make an educated guess. Then, we&apos;ll refine our guess by squaring it to see how close we get to 45.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/EFVrAk61xjE.mp4/EFVrAk61xjE.mp4</video:content_loc><video:duration>432</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/coverting-repeating-decimals-to-fractions-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/351466917.jpg</video:thumbnail_loc><video:title>Converting repeating decimals to fractions (part 1 of 2)</video:title><video:description>The process of converting a repeating decimal to a fraction can be broken down into a few easy steps. To start, set the decimal equal to a variable. Multiply the decimal by 10 and subtract the original decimal from it. Finally, divide both sides by 9 to obtain the fractional form of the decimal. For example, 0.7 repeating would be 7/9, and 1.2 repeating would be 11/9.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/FPNhCVZlbJs.mp4/FPNhCVZlbJs.mp4</video:content_loc><video:duration>243</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/coverting-repeating-decimals-to-fractions-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/351405953.jpg</video:thumbnail_loc><video:title>Converting repeating decimals to fractions (part 2 of 2)</video:title><video:description>Repeated decimals can be converted into fractions by shifting the decimal to the right and subtracting the decimals. To do this, multiply the number by 10 to the second power, then subtract. For example, 0.363636 repeating is 4/11 and 0.7141414 repeating is 707/990. Another example is 3.257257257 repeating, which is 3254/999. This calculation can be done in the head or by borrowing. After the subtraction, the numerator and denominator can be reduced and the fraction can be simplified.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Ihws0d-WLzU.mp4/Ihws0d-WLzU.mp4</video:content_loc><video:duration>546</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/sorting-irrational-numbers-involving-radicals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc4d6526d.jpg</video:thumbnail_loc><video:title>Comparing irrational numbers with radicals</video:title><video:description>Learn how to sort a bunch of numbers (4√2 2√3 3√2 √17 3√3 5) from least to greatest without using a calculator.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/KibTbfkoPTs.mp4/KibTbfkoPTs.mp4</video:content_loc><video:duration>329</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/comparing-values-with-calculator</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x44e869e5.jpg</video:thumbnail_loc><video:title>Comparing values with calculator</video:title><video:description>Let&apos;s use the technique of squaring to compare values. We first compare 22.9% to an arbitrary value, 0.3, and then square 0.3 to compare it to the square root of 0.45. This helps us understand which value is larger without needing a calculator.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PuRsXST9EZU.mp4/PuRsXST9EZU.mp4</video:content_loc><video:duration>241</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-engage-ny/v/example-finding-distance-with-pythagorean-theorem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6c0e0c41583be82e.jpg</video:thumbnail_loc><video:title>Finding distance with Pythagorean theorem</video:title><video:description>Sal finds the distance between two points with the Pythagorean theorem.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/apkT6rVE8qo.mp4/apkT6rVE8qo.mp4</video:content_loc><video:duration>221</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/distance-formula</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23756.jpg</video:thumbnail_loc><video:title>Distance formula</video:title><video:description>Learn how to find the distance between two points by using the distance formula, which is an application of the Pythagorean theorem. We can rewrite the Pythagorean theorem as d=√((x_2-x_1)²+(y_2-y_1)²) to find the distance between any two points.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/nyZuite17Pc.mp4/nyZuite17Pc.mp4</video:content_loc><video:duration>579</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/area-of-an-isosceles-triangle</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3249b1b3b5e14fc2.jpg</video:thumbnail_loc><video:title>Use Pythagorean theorem to find area of an isosceles triangle</video:title><video:description>We can find the area of an isosceles triangle using the Pythagorean theorem. Once we recognize the triangle as isosceles, we divide it into congruent right triangles. Then we use the theorem to find the height. Last, we calculate the area with the formula: 1/2 × base × height.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/yZ4CbopnVBg.mp4/yZ4CbopnVBg.mp4</video:content_loc><video:duration>240</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/pythagoriean-theorem-in-3d</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5a21eae7.jpg</video:thumbnail_loc><video:title>Pythagorean theorem in 3D</video:title><video:description>Discover how to find the length of an edge in a 3D shape using the Pythagorean theorem! This fun math lesson explores right pyramids and rectangular prisms, guiding you through solving for unknown lengths by applying the theorem multiple times.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1UQ5IbihJNI.mp4/1UQ5IbihJNI.mp4</video:content_loc><video:duration>356</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/applying-volume-of-solids</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd5c92d1bf1929ee0.jpg</video:thumbnail_loc><video:title>Applying volume of solids</video:title><video:description>Calculate the volume of a grain hopper and then use the given rate to solve an applied problem.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/dp3my9MnmOM.mp4/dp3my9MnmOM.mp4</video:content_loc><video:duration>455</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/perimeter-and-area-basics</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/283213901.jpg</video:thumbnail_loc><video:title>Perimeter &amp; area</video:title><video:description>Perimeter is the distance around the outside of a shape. For example, if you walk around the edge of a playground, you&apos;re measuring its perimeter. Area is the amount of space inside a shape. For example, if you want to put new tiles on your kitchen floor, you need to know the area of the room to know how many tiles to buy.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LoaBd-sPzkU.mp4/LoaBd-sPzkU.mp4</video:content_loc><video:duration>505</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-grade-illustrative-math/v/identifying-rigid-transformations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x80eeb454428561c6.jpg</video:thumbnail_loc><video:title>Identifying rigid transformations</video:title><video:description>Describe the movement of shapes informally and formally using the terms “clockwise,” “counterclockwise,” “translations,” “rotations,” and “reflections” of figures.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8mkTsVgSJe4.mp4/8mkTsVgSJe4.mp4</video:content_loc><video:duration>396</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-grade-illustrative-math/v/rotating-line-segments</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x973676fe440d470b.jpg</video:thumbnail_loc><video:title>Rotating line segments</video:title><video:description>Draw and label a diagram of a line segment rotated 90 degrees clockwise or counterclockwise about a given center.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Wmb3ZVfVUuc.mp4/Wmb3ZVfVUuc.mp4</video:content_loc><video:duration>287</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/introduction-to-transformations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7856e9c3.jpg</video:thumbnail_loc><video:title>Rigid transformations intro</video:title><video:description>Transformations in math involve changing a shape&apos;s position or which way the shape points. There are three main types: translations (moving the shape), rotations (turning the shape), and reflections (flipping the shape like a mirror image). Rigid transformations keep the shape&apos;s size and angles the same. The image is the shape in its new position and direction.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/XiAoUDfrar0.mp4/XiAoUDfrar0.mp4</video:content_loc><video:duration>443</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-grade-illustrative-math/v/rigid-transformations-of-parallel-lines</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc49d2ace8ebfabf7.jpg</video:thumbnail_loc><video:title>Rigid transformations of parallel lines</video:title><video:description>Discover why parallel lines stay parallel even after you rotate, reflect, or translate them.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PbLM99ay7LI.mp4/PbLM99ay7LI.mp4</video:content_loc><video:duration>220</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-grade-illustrative-math/v/alternate-interior-angles</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x03a2c099a54d7fb1.jpg</video:thumbnail_loc><video:title>Alternate interior angles</video:title><video:description>Identify alternate interior angles made by a transversal connecting two parallel lines and use that information to find missing angle measures.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/mbxSy9TTTbM.mp4/mbxSy9TTTbM.mp4</video:content_loc><video:duration>253</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-grade-illustrative-math/v/dilating-points-on-a-circular-grid</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9d851b8004f8b9a1.jpg</video:thumbnail_loc><video:title>Dilating points on a circular grid</video:title><video:description>Identify the image of a dilation on a circular grid given a scale factor and center of dilation, and determine the scale factor of a dilation by comparing the distances of original and image points from the center of dilation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Uc-UqvEhcQw.mp4/Uc-UqvEhcQw.mp4</video:content_loc><video:duration>186</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-grade-illustrative-math/v/dilating-figures-on-a-circular-grid</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x04ac4eadc36cc6e1.jpg</video:thumbnail_loc><video:title>Dilating figures on a circular grid</video:title><video:description>Identify the image of a dilation on a circular grid given a scale factor and center of dilation, and determine the scale factor of a dilation by comparing the distances of original and image points from the center of dilation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/B0fCqf_FDPU.mp4/B0fCqf_FDPU.mp4</video:content_loc><video:duration>134</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-grade-illustrative-math/v/identifying-center-of-dilation-with-no-grid</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa55a1ad414b16cd2.jpg</video:thumbnail_loc><video:title>Identifying center of dilation with no grid</video:title><video:description>Identify the center of dilation without a grid by drawing rays through corresponding vertices and determining where they intersect.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0-PM-gN4rog.mp4/0-PM-gN4rog.mp4</video:content_loc><video:duration>107</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-grade-illustrative-math/v/dilating-figures-with-no-grid</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4990e32ae03ca0ec.jpg</video:thumbnail_loc><video:title>Dilating figures with no grid</video:title><video:description>Understand how to create and describe dilations without a grid, using a center and scale factor, and explain how the scale factor affects the size and position of a figure.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7ng5GV40W9Q.mp4/7ng5GV40W9Q.mp4</video:content_loc><video:duration>100</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/dilations-intro</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4095f44e644d564a.jpg</video:thumbnail_loc><video:title>Dilations intro</video:title><video:description>Dilations are a type of non-rigid transformation. They change the size of a shape by scaling it up or down, making it bigger or smaller. Unlike rigid transformations, dilations do not keep the shape&apos;s size the same.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Kv-lyVmQ5ps.mp4/Kv-lyVmQ5ps.mp4</video:content_loc><video:duration>91</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/comparing-side-lengths-after-dilation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1eac271a.jpg</video:thumbnail_loc><video:title>Side lengths after dilation</video:title><video:description>In a dilation, if the scale factor is greater than 1, the shape will stretch away from the center of dilation, getting larger. If the scale factor is between 0 and 1, the shape will shrink towards the center, getting smaller. All the lengths in the figure change by the same scale factor.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2yjSAarzWF8.mp4/2yjSAarzWF8.mp4</video:content_loc><video:duration>133</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-grade-illustrative-math/v/determining-similarity-in-polygons</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x38cb3631e04f21e6.jpg</video:thumbnail_loc><video:title>Determining similarity in polygons</video:title><video:description>Understand that similar polygons have congruent corresponding angles and proportional corresponding side lengths, and use both conditions together to determine whether two polygons are similar.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PZEUpMiOn6M.mp4/PZEUpMiOn6M.mp4</video:content_loc><video:duration>220</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-grade-illustrative-math/v/identifying-similar-triangles</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7e0662cecf4192f0.jpg</video:thumbnail_loc><video:title>Identifying similar triangles</video:title><video:description>Identify similar triangles by finding two pairs of congruent angles.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/E7KfcxpKF7c.mp4/E7KfcxpKF7c.mp4</video:content_loc><video:duration>163</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-grade-illustrative-math/v/introducing-triangle-similarity</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1eeea9da473fd69a.jpg</video:thumbnail_loc><video:title>Introducing triangle similarity</video:title><video:description>Introduce triangle similarity by explaining that similar triangles have the same shape but different sizes. Show that similarity can be determined by verifying either that corresponding angles are congruent or that corresponding sides are proportional.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/AZSUyrOqFBg.mp4/AZSUyrOqFBg.mp4</video:content_loc><video:duration>465</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-grade-illustrative-math/v/finding-missing-lengths-in-slope-triangles</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2852efd7c7410824.jpg</video:thumbnail_loc><video:title>Finding missing lengths in slope triangles</video:title><video:description>Calculate missing side lengths in similar triangles by using proportional reasoning within triangles and scale factors between triangles.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/MKl9otX8gwA.mp4/MKl9otX8gwA.mp4</video:content_loc><video:duration>145</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-grade-illustrative-math/v/side-lengths-in-similar-triangles</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa15952ef65933850.jpg</video:thumbnail_loc><video:title>Side lengths in similar triangles</video:title><video:description>Calculate missing side lengths in similar triangles by using proportional reasoning within triangles and scale factors between triangles.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5GrAoRoV7co.mp4/5GrAoRoV7co.mp4</video:content_loc><video:duration>278</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/introduction-to-slope</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf91ad68e.jpg</video:thumbnail_loc><video:title>Intro to slope</video:title><video:description>Slope tells us how steep a line is. It&apos;s like measuring how quickly a hill goes up or down. We find the slope by seeing how much we go up or down (vertical change) for each step to the right (horizontal change). If a line goes up 2 steps for every 1 step to the right, its slope is 2.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/MeU-KzdCBps.mp4/MeU-KzdCBps.mp4</video:content_loc><video:duration>416</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-grade-illustrative-math/v/drawing-lines-for-a-given-slope</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb3b4fd4b2c6e43d6.jpg</video:thumbnail_loc><video:title>Drawing lines for a given slope</video:title><video:description>Define slope as the ratio of vertical to horizontal change, draw lines with specific slopes, and justify the similarity of slope triangles.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/BI1aS8-PdyU.mp4/BI1aS8-PdyU.mp4</video:content_loc><video:duration>127</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-grade-illustrative-math/v/finding-points-on-a-line-when-given-an-equation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb18be98d27e98a71.jpg</video:thumbnail_loc><video:title>Finding points on a line when given an equation</video:title><video:description>Verify whether a point lies on a line by substituting its coordinates into the line&apos;s equation and confirming the resulting ratio is equivalent.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7eeaXv6brQ8.mp4/7eeaXv6brQ8.mp4</video:content_loc><video:duration>137</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-grade-illustrative-math/v/writing-the-equation-of-a-line-with-a-positive-slope</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x92dff0810cd001dc.jpg</video:thumbnail_loc><video:title>Writing the equation of a line with a positive slope</video:title><video:description>Create an equation of a line with a positive slope on the coordinate plane using knowledge of similar triangles.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Q53TQP6eimk.mp4/Q53TQP6eimk.mp4</video:content_loc><video:duration>430</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-grade-illustrative-math/v/interpreting-and-comparing-proportional-relationships</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1e48ece36b726bac.jpg</video:thumbnail_loc><video:title>Interpreting and comparing proportional relationships</video:title><video:description>Practice comparing the speeds of four wind-up robots by reading their distance-vs-time graphs and figuring out which one is the slowest.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/txRmzpNHtYI.mp4/txRmzpNHtYI.mp4</video:content_loc><video:duration>86</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-grade-illustrative-math/v/comparing-scale-in-proportional-relationship-graphs</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc37deb5297ec4883.jpg</video:thumbnail_loc><video:title>Comparing scale in proportional relationship graphs</video:title><video:description>Practice graphing proportional relationships from equations like y = kx on coordinate planes with varying axis scales. Learn to recognize when differently-scaled graphs actually represent the same relationship.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/CdMUBpFP2ro.mp4/CdMUBpFP2ro.mp4</video:content_loc><video:duration>170</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-grade-illustrative-math/v/comparing-proportional-and-nonproportional-linear-relationships</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0b6e964bf4bcbfc2.jpg</video:thumbnail_loc><video:title>Comparing proportional and nonproportional linear relationships</video:title><video:description>Compare a proportional relationship to a nonproportional linear one using a cup-stacking scenario, testing whether stack height is proportional to the number of cups. Find the rate of change from a graph and interpret the vertical-axis intercept as a starting value rather than zero.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0ESzVmo0hJY.mp4/0ESzVmo0hJY.mp4</video:content_loc><video:duration>228</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-grade-illustrative-math/v/using-equations-to-represent-linear-relationships</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x30190501c24f3357.jpg</video:thumbnail_loc><video:title>Using equations to represent linear relationships</video:title><video:description>Write an equation for a linear relationship from a real-world context, and connect it to the same relationship shown as a verbal description, table, and graph. Find the rate of change and initial value from the context, then see how the equation, table, and graph all tell the same story.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qGRtaBart38.mp4/qGRtaBart38.mp4</video:content_loc><video:duration>52</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-grade-illustrative-math/v/interpreting-slope-and-y-intercept</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc240148546b7a224.jpg</video:thumbnail_loc><video:title>Interpreting slope and y-intercept</video:title><video:description>Given the graph of a linear relationship in a real-world context, interpret what the slope and vertical intercept mean within that story. The focus is on explaining what each feature represents, not on computing values or writing an equation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PrjV4zv8Xck.mp4/PrjV4zv8Xck.mp4</video:content_loc><video:duration>146</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-grade-illustrative-math/v/comparing-graphs-of-linear-relationships-with-different-y-intercepts</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x69c9b603e665e525.jpg</video:thumbnail_loc><video:title>Comparing graphs of linear relationships with different y-intercepts</video:title><video:description>Compare two linear relationships with the same rate of change but different initial values, graphed together in a real-world context. See how equal slopes produce parallel lines, with the gap between them reflecting the difference in starting values.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6Nig8sO_a3A.mp4/6Nig8sO_a3A.mp4</video:content_loc><video:duration>129</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/introduction-to-intercepts</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9cb60d6a.jpg</video:thumbnail_loc><video:title>Intro to intercepts</video:title><video:description>Learn what x- and y-intercepts are. The equations used in this video are y = 0.5x - 3 and 5x + 6y = 30.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LNSB0N6esPU.mp4/LNSB0N6esPU.mp4</video:content_loc><video:duration>393</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/slope-intercept-intro-examples</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbe126b648573616d.jpg</video:thumbnail_loc><video:title>Worked examples: slope-intercept intro</video:title><video:description>Worked examples practicing the relationship between slope, y-intercept, and linear equation in slope-intercept form.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qgsNNqmlLoA.mp4/qgsNNqmlLoA.mp4</video:content_loc><video:duration>226</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/checking-ordered-pair-solutions-to-equations-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9a47991d.jpg</video:thumbnail_loc><video:title>Solutions to 2-variable equations</video:title><video:description>The solution of an equation with one variable is a number. How does the solution of a 2-variable equation look like? Well, it is an ordered pair. Learn more about it and how to test solutions to 2-variable equations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qk69pR91R00.mp4/qk69pR91R00.mp4</video:content_loc><video:duration>155</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/checking-ordered-pair-solutions-to-equations-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6e2674bb.jpg</video:thumbnail_loc><video:title>Worked example: solutions to 2-variable equations</video:title><video:description>How do you check if an ordered pair is a solution to a given equation? You need to plug in the numbers and see what equality results. Watch this video to see a worked example.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/d3VMo1VWFvc.mp4/d3VMo1VWFvc.mp4</video:content_loc><video:duration>146</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-grade-illustrative-math/v/writing-and-graphing-linear-equations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x634a21346bd2d17a.jpg</video:thumbnail_loc><video:title>Writing and graphing linear equations</video:title><video:description>Write an equation in the form Ax + By = C from a real-world context where two quantities trade off to keep a fixed total, then graph the relationship. This form fits naturally when neither variable depends on the other, since both simply vary together to maintain that constant total.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LH5xq2SPAeU.mp4/LH5xq2SPAeU.mp4</video:content_loc><video:duration>272</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-grade-illustrative-math/v/determining-solutions-to-2-variable-equations-and-graphs</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x49f8282296fc12d3.jpg</video:thumbnail_loc><video:title>Determining solutions to 2-variable equations and graphs</video:title><video:description>Check whether ordered pairs are solutions to a two-variable linear equation by substituting and verifying. Connect this back to the graph: every point on the line is a solution, and any point off the line is not.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jOS45lOWXdI.mp4/jOS45lOWXdI.mp4</video:content_loc><video:duration>83</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-grade-illustrative-math/v/calculating-solutions-to-a-linear-equation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe0520e7003312201.jpg</video:thumbnail_loc><video:title>Calculating solutions to a linear equation</video:title><video:description>Given a two-variable linear equation and a value for one variable, calculate the value of the other variable that makes the pair a solution. This builds the substitution skill needed to find missing coordinates and complete solution tables.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/JAhG2bRH55I.mp4/JAhG2bRH55I.mp4</video:content_loc><video:duration>110</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/graphing-solutions-to-2-variable-linear-equations-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7686ff2c.jpg</video:thumbnail_loc><video:title>Completing solutions to 2-variable equations</video:title><video:description>Given a 2-variable equation and the x or y values of a solution, Sal finds the value of the other variable in the solution.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/EHR-YDwrrhM.mp4/EHR-YDwrrhM.mp4</video:content_loc><video:duration>431</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/descartes-and-cartesian-coordinates</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/578962249.jpg</video:thumbnail_loc><video:title>Intro to the coordinate plane</video:title><video:description>Descartes created a system of two perpendicular axes (the x and y axes) which could be used to plot points in a plane. This enabled the visualization of algebraic equations in geometric form. For example, a linear equation like y = 2x + 1 could be plotted as a line on the coordinate plane, while a quadratic equation like y = x^2 could be plotted as a parabola. This linked algebra and geometry through the use of graphs.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/N4nrdf0yYfM.mp4/N4nrdf0yYfM.mp4</video:content_loc><video:duration>682</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/slope-from-equation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7c5573fa2851b201.jpg</video:thumbnail_loc><video:title>Slope from equation</video:title><video:description>Worked examples of finding the slope of a line given its equation, using many forms of equations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/G4r9PpYQiL8.mp4/G4r9PpYQiL8.mp4</video:content_loc><video:duration>379</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-1-eureka-squared-aligned/v/equation-with-variables-on-both-sides-fractions-indian-accent</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2dd6070ceda1ccc6.jpg</video:thumbnail_loc><video:title>Equation with variables on both sides: fractions</video:title><video:description>To solve the equation (3/4)x + 2 = (3/8)x - 4, we first eliminate fractions by multiplying both sides by the least common multiple of the denominators. Then, we add or subtract terms from both sides of the equation to group the x-terms on one side and the constants on the other. Finally, we solve and check as normal.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/MWHBSLGI-Tk.mp4/MWHBSLGI-Tk.mp4</video:content_loc><video:duration>289</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/sum-consecutive-integers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x32215d81.jpg</video:thumbnail_loc><video:title>Sums of consecutive integers</video:title><video:description>When solving a math problems involving consecutive integers, we can use algebra to set up an equation to solve for the smallest of the four integers.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8CJ6Qdcoxsc.mp4/8CJ6Qdcoxsc.mp4</video:content_loc><video:duration>319</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/sum-of-consecutive-odd-integers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26782.jpg</video:thumbnail_loc><video:title>Sum of integers challenge</video:title><video:description>The sum of three consecutive odd integers is 231. First let&apos;s identify the integers. If the smallest is x, what is the value of the next odd integer? Then we set up an equation, adding all three integers to get their total. We can solve for x, the smallest integer. Once we know the smallest, what is the largest integer?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/d8De3xcVmnw.mp4/d8De3xcVmnw.mp4</video:content_loc><video:duration>273</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/systems-word-problem-with-no-solution</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa7908d53.jpg</video:thumbnail_loc><video:title>System of equations word problem: no solution</video:title><video:description>Systems of equations can be used to solve many real-world problems. In this video, we solve a problem about a toy factory. In this case, the problem has no viable solution, which means the information describes an impossible situation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/SRn3WhhS6vs.mp4/SRn3WhhS6vs.mp4</video:content_loc><video:duration>303</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-grade-illustrative-math/v/rules-of-input-output-tables</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x360eafae76e6b5ca.jpg</video:thumbnail_loc><video:title>Rules of input-output tables</video:title><video:description>Learn how input-output diagrams work, where a rule transforms each input into a corresponding output. Practice identifying the rule from given pairs and applying it to find new outputs.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/h8vFG2Ov43c.mp4/h8vFG2Ov43c.mp4</video:content_loc><video:duration>84</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/understanding-function-notation-example-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5860a542.jpg</video:thumbnail_loc><video:title>Function notation example</video:title><video:description>Sal uses function notation to help Frank figure out how much water he can put in his balloon.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/IXRMVcoqRRQ.mp4/IXRMVcoqRRQ.mp4</video:content_loc><video:duration>133</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/create-function-from-equation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0c7d59f7.jpg</video:thumbnail_loc><video:title>Obtaining a function from an equation</video:title><video:description>Equations and functions are not the same thing, but they can be related in several ways. In this video, we obtain a function from an equation. The function represents the same relationship between the quantities in the equation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OOim0QPsJ9o.mp4/OOim0QPsJ9o.mp4</video:content_loc><video:duration>184</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-grade-illustrative-math/v/graphs-of-functions-in-context</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbaa8c569ce9e817b.jpg</video:thumbnail_loc><video:title>Graphs of functions in context</video:title><video:description>Interpret points on graphs, including some that don&apos;t represent functions, and draw graphs to model real-world contexts. Explain which quantity depends on which, identifying which variable is a function of the other.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/sVxImbpK8AI.mp4/sVxImbpK8AI.mp4</video:content_loc><video:duration>122</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-grade-illustrative-math/v/interpreting-piecewise-linear-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7381d074929b3ea3.jpg</video:thumbnail_loc><video:title>Interpreting piecewise linear functions</video:title><video:description>Calculate the rate of change across different segments of a piecewise linear graph and interpret what each rate means in context. Practice modeling a nonlinear function using a piecewise linear approximation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8OeKOVeIZMQ.mp4/8OeKOVeIZMQ.mp4</video:content_loc><video:duration>131</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-grade-illustrative-math/v/relating-height-and-volume-of-cylinders</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x36f913dff566a550.jpg</video:thumbnail_loc><video:title>Relating height and volume of cylinders</video:title><video:description>Explore how height and volume relate as a linear function in the context of filling cylinders.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xSNzGtTEC1U.mp4/xSNzGtTEC1U.mp4</video:content_loc><video:duration>224</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-grade-illustrative-math/v/calculating-dimensions-of-a-cylinder</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6a8d4eb0b326c0dd.jpg</video:thumbnail_loc><video:title>Calculating dimensions of a cylinder</video:title><video:description>Use the cylinder volume formula to solve for a missing dimension, height or radius, when the volume and other dimension are given. Work through a table of cylinder dimensions and look for patterns.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0tc_fga-Tq0.mp4/0tc_fga-Tq0.mp4</video:content_loc><video:duration>100</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-grade-illustrative-math/v/calculating-dimensions-of-a-cone</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x936d531dd3666b82.jpg</video:thumbnail_loc><video:title>Calculating dimensions of a cone</video:title><video:description>Given the volume of a cone and one dimension, use the cone volume formula to find the missing dimension. Explain the reasoning behind each step of the calculation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7p3YR2wYT7U.mp4/7p3YR2wYT7U.mp4</video:content_loc><video:duration>96</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-grade-illustrative-math/v/estimating-volume-of-hemispheres</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe903e13906de6142.jpg</video:thumbnail_loc><video:title>Estimating volume of hemispheres</video:title><video:description>Calculate the volumes of a cylinder and cone sharing the same radius and height, using them as upper and lower bounds for a hemisphere with that same radius. Use this reasoning to estimate the hemisphere&apos;s volume.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/zFYso4nHDUc.mp4/zFYso4nHDUc.mp4</video:content_loc><video:duration>266</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/example-estimating-from-regression-line</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdc4d346d7f8b65c6.jpg</video:thumbnail_loc><video:title>Estimating with linear regression (linear models)</video:title><video:description>A line of best fit is a straight line that shows the relationship between two sets of data. We can use the line to make predictions. To find the best equation for the line, we look at the slope and the y-intercept. Remember, this is just a model, so it&apos;s not always perfect!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TWkYalFn8lo.mp4/TWkYalFn8lo.mp4</video:content_loc><video:duration>203</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-grade-illustrative-math/v/exploring-negative-exponents-with-a-base-of-10</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe32dca70e931d530.jpg</video:thumbnail_loc><video:title>Exploring negative exponents with a base of 10</video:title><video:description>Build intuition for negative exponents using base 10, seeing how the same exponent rules extend into negative territory. Use patterns from repeated multiplication and division by 10 to make sense of what negative exponents mean.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/777jxRvzmNc.mp4/777jxRvzmNc.mp4</video:content_loc><video:duration>115</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-grade-illustrative-math/v/exponent-properties-with-parentheses-indian-accent</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xce8b849c8e4fa8fa.jpg</video:thumbnail_loc><video:title>Exponent properties with parentheses</video:title><video:description>Learn two exponent properties: (ab)^c = (a^c)*(b^c) and (a^b)^c = a ^ (b*c). See WHY they work and HOW to use them. In other words, multiplying two numbers, then raising the product to an exponent is the same as raising each number to that exponent and then multiplying. Raising a number to an exponent and then to another exponent equals raising the base to the product of the two exponents.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/RUwsqBQmozA.mp4/RUwsqBQmozA.mp4</video:content_loc><video:duration>253</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-grade-illustrative-math/v/negative-exponents-indian-accent</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1b05d8532e54ed79.jpg</video:thumbnail_loc><video:title>Negative exponents</video:title><video:description>Negative exponents can be rewritten in two ways. Firstly, start with 1 and divide it by 2 the same number of times as the exponent. Secondly, take the reciprocal of the base and raise it to the positive exponent.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/G-v0wwQuGXA.mp4/G-v0wwQuGXA.mp4</video:content_loc><video:duration>434</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/multiplying-and-dividing-powers-with-integer-exponents</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x51aac3781797c497.jpg</video:thumbnail_loc><video:title>Multiplying &amp; dividing powers (integer exponents)</video:title><video:description>For any base a and any integer exponents n and m, aⁿ⋅aᵐ=aⁿ⁺ᵐ. For any nonzero base, aⁿ/aᵐ=aⁿ⁻ᵐ. These are worked examples for using these properties with integer exponents.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/CZ5ne_mX5_I.mp4/CZ5ne_mX5_I.mp4</video:content_loc><video:duration>264</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/powers-of-products-and-quotients-integer-exponents</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x77dba0123ee2609c.jpg</video:thumbnail_loc><video:title>Powers of products &amp; quotients (integer exponents)</video:title><video:description>For any integers a and b and for any exponents n, (a⋅b)ⁿ=aⁿ⋅bⁿ and (a/b)ⁿ=aⁿ/bⁿ. These are worked examples for using these properties with integer exponents.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/dC1ojsMi1yU.mp4/dC1ojsMi1yU.mp4</video:content_loc><video:duration>404</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-grade-illustrative-math/v/exponent-properties-with-products-indian-accent</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8204aa93c32cc151.jpg</video:thumbnail_loc><video:title>Exponent properties with products</video:title><video:description>To simplify expressions with exponents, there are a few properties that may help. One is that when two numbers with the same base are multiplied, the exponents can be added. Another is that when a number with an exponent is raised to another exponent, the exponents can be multiplied.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pQ5hkjM-E1E.mp4/pQ5hkjM-E1E.mp4</video:content_loc><video:duration>762</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-grade-illustrative-math/v/representing-numbers-using-powers-of-10</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd7edb4f6fd20ef42.jpg</video:thumbnail_loc><video:title>Representing numbers using powers of 10</video:title><video:description>Learn how to write very large and very small numbers as multiples of powers of 10. Practice converting numbers into this form to make their size easier to understand and compare.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9QuCWeJOgwI.mp4/9QuCWeJOgwI.mp4</video:content_loc><video:duration>257</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-grade-illustrative-math/v/small-numbers-on-the-number-line</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb150d95f0607ff7e.jpg</video:thumbnail_loc><video:title>Small numbers on the number line</video:title><video:description>Use a number line to place very small numbers, coordinating their decimal forms with multiples of powers of 10, including negative exponents. Practice matching the two representations to build a sense of scale.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/25eC1INldxI.mp4/25eC1INldxI.mp4</video:content_loc><video:duration>93</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-grade-illustrative-math/v/large-numbers-on-the-number-line</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x67c4ca83d55553a0.jpg</video:thumbnail_loc><video:title>Large numbers on the number line</video:title><video:description>Use a number line to place very large numbers, coordinating their decimal forms with multiples of powers of 10. Practice matching the two representations to build a sense of scale.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/XHofFxtaMKI.mp4/XHofFxtaMKI.mp4</video:content_loc><video:duration>102</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-grade-illustrative-math/v/solving-problems-using-powers-of-10-in-context</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x91a53676a6ed0286.jpg</video:thumbnail_loc><video:title>Solving problems using powers of 10 in context</video:title><video:description>Work through real-world problems involving very large or very small quantities, identifying what information is needed to solve them. Use exponent rules and powers of 10 to organize the numbers and work out a solution.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xAOJ5sJslWU.mp4/xAOJ5sJslWU.mp4</video:content_loc><video:duration>167</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-grade-illustrative-math/v/finding-the-area-of-a-tilted-square</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x272b80a734f8eb6e.jpg</video:thumbnail_loc><video:title>Finding the area of a tilted square</video:title><video:description>Find the area of a tilted square drawn on a grid, where its sides don&apos;t run along the gridlines. Practice using the grid to reason about area when the usual side-length approach doesn&apos;t directly apply.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/P_Y5W7BXCH4.mp4/P_Y5W7BXCH4.mp4</video:content_loc><video:duration>133</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-grade-illustrative-math/v/relating-side-lengths-and-areas-of-squares</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa84d9da78f15f3b2.jpg</video:thumbnail_loc><video:title>Relating side lengths and areas of squares</video:title><video:description>Introduce square roots as the side length of a square with a given area. Estimate a square&apos;s side length by comparing it to squares with known, nearby areas.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/G7uDwEvu_Wk.mp4/G7uDwEvu_Wk.mp4</video:content_loc><video:duration>91</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-grade-illustrative-math/v/finding-side-lengths-of-triangles</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb1cbe5860d862c04.jpg</video:thumbnail_loc><video:title>Finding side lengths of triangles</video:title><video:description>Discover the Pythagorean theorem by exploring patterns in the side lengths of right triangles. Introduce the terms legs and hypotenuse along the way.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/q2kKuZMqpv4.mp4/q2kKuZMqpv4.mp4</video:content_loc><video:duration>167</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-grade-illustrative-math/v/converting-repeating-decimals-to-fractions-part-1-of-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x88fb36b6bdb70d06.jpg</video:thumbnail_loc><video:title>Converting repeating decimals to fractions (part 1 of 2)</video:title><video:description>Converting repeating decimals to fractions (part 1 of 2) (Indian Accent)</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/GMXAckRulSU.mp4/GMXAckRulSU.mp4</video:content_loc><video:duration>242</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-grade-illustrative-math/v/converting-repeating-decimals-to-fractions-part-2-of-2-india</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf2cfbfea21ff221e.jpg</video:thumbnail_loc><video:title>Converting repeating decimals to fractions (part 2 of 2)</video:title><video:description>Converting repeating decimals to fractions (part 2 of 2) (Indian Accent)</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4hrdbrDtT_M.mp4/4hrdbrDtT_M.mp4</video:content_loc><video:duration>545</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/8th-grade-illustrative-math/v/solving-aspect-ratio-problems-with-the-pythagorean-theorem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x55a2e859eb7c2298.jpg</video:thumbnail_loc><video:title>Solving aspect ratio problems with the Pythagorean theorem</video:title><video:description>Solve an aspect-ratio problem end to end with the Pythagorean theorem, setting up an equation from a given ratio and diagonal length. Solve for the unknown, find the actual side lengths, and finish by calculating the area.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/R32NVZowWMY.mp4/R32NVZowWMY.mp4</video:content_loc><video:duration>232</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/number-sets-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/27078.jpg</video:thumbnail_loc><video:title>Worked example: classifying numbers</video:title><video:description>How do repeating decimals fit into the number sets? We&apos;ll explore if a number like 3.4028 repeating is a real number, a rational number, or both. We&apos;ll use multiplication and subtraction, plus a bit of algebra, to convince ourselves of whether or not there is a fraction representation of the number.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qfQv8GzyjB4.mp4/qfQv8GzyjB4.mp4</video:content_loc><video:duration>412</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/equilateral-and-isosceles-example-problems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/281570418.jpg</video:thumbnail_loc><video:title>Isosceles &amp; equilateral triangles problems</video:title><video:description>Isosceles triangles have two congruent sides and two congruent base angles. Equilateral triangles have all side lengths equal and all angle measures equal. We use these properties to find missing angles in composite figures. The problems are partly from Art of Problem Solving, by Richard Rusczyk.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7FTNWE7RTfQ.mp4/7FTNWE7RTfQ.mp4</video:content_loc><video:duration>387</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/example-identifying-the-center-of-dilation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb795568ffba397e7.jpg</video:thumbnail_loc><video:title>Dilations: center</video:title><video:description>Determining the center of dilation, given a figure and its image under a dilation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/rDj0WNzp-f8.mp4/rDj0WNzp-f8.mp4</video:content_loc><video:duration>163</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/similarity-example-where-same-side-plays-different-roles</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/289578995.jpg</video:thumbnail_loc><video:title>Solving similar triangles: same side plays different roles</video:title><video:description>Sal finds a missing side length in a problem where the same side plays different roles in two similar triangles.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Tal_fgREll0.mp4/Tal_fgREll0.mp4</video:content_loc><video:duration>365</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/standard-form-for-linear-equations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x03fa0ba8.jpg</video:thumbnail_loc><video:title>Intro to linear equation standard form</video:title><video:description>The standard form for linear equations in two variables is Ax+By=C. For example, 2x+3y=5 is a linear equation in standard form. When an equation is given in this form, it&apos;s pretty easy to find both intercepts (x and y). This form is also very useful when solving systems of two linear equations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6CFE60iP2Ug.mp4/6CFE60iP2Ug.mp4</video:content_loc><video:duration>487</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/examples-of-slopes-and-equations-of-horizontal-and-vertical-lines</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc9aa084efcd925fa.jpg</video:thumbnail_loc><video:title>Horizontal &amp; vertical lines</video:title><video:description>Worked examples identifying the equations and slope of horizontal and vertical lines.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/J43CIbKpdWc.mp4/J43CIbKpdWc.mp4</video:content_loc><video:duration>315</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/positive-and-negative-slope</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x77a4dfa1.jpg</video:thumbnail_loc><video:title>Positive &amp; negative slope</video:title><video:description>Sal analyzes what it means for a slope to be positive or negative (spoiler: it affects the direction of the line!)</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/EQoNfxToez0.mp4/EQoNfxToez0.mp4</video:content_loc><video:duration>302</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/slope-intercept-form</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x989ab2a9.jpg</video:thumbnail_loc><video:title>Intro to slope-intercept form</video:title><video:description>Slope-intercept form (y=mx+b) of linear equations highlights the slope (m) and the y-intercept (b) of a line. Watch this video to learn more about it and see some examples.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/IL3UCuXrUzE.mp4/IL3UCuXrUzE.mp4</video:content_loc><video:duration>540</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/parallel-lines</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26808.jpg</video:thumbnail_loc><video:title>Parallel lines from equation</video:title><video:description>Sal determines which pairs out of a few given linear equations are parallel.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/T-aCweuimis.mp4/T-aCweuimis.mp4</video:content_loc><video:duration>228</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/parallel-lines-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26809.jpg</video:thumbnail_loc><video:title>Parallel lines from equation (example 2)</video:title><video:description>Sal determines which pairs out of a few given linear equations are parallel.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lOWXZFP8Vuc.mp4/lOWXZFP8Vuc.mp4</video:content_loc><video:duration>183</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/parallel-lines-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26810.jpg</video:thumbnail_loc><video:title>Parallel lines from equation (example 3)</video:title><video:description>Sal determines which pairs out of a few given linear equations are parallel.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/y5yNi08cr6I.mp4/y5yNi08cr6I.mp4</video:content_loc><video:duration>162</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/point-slope-and-slope-intercept-form-from-two-points</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x51bcef9f.jpg</video:thumbnail_loc><video:title>Point-slope &amp; slope-intercept equations</video:title><video:description>Point-slope is the general form y-y₁=m(x-x₁) for linear equations. It emphasizes the slope of the line and a point on the line (that is not the y-intercept). We can rewrite an equation in point-slope form to be in slope-intercept form y=mx+b, to highlight the same line&apos;s slope and y-intercept.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LtpXvUCrgrM.mp4/LtpXvUCrgrM.mp4</video:content_loc><video:duration>427</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/solving-systems-graphically-examples</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf2261778.jpg</video:thumbnail_loc><video:title>Systems of equations with graphing: exact &amp; approximate solutions</video:title><video:description>Sal solves a system of two linear equations in standard form, and then approximates the solution of a system whose solution isn&apos;t clearly visible.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/o4pbAQgJYjI.mp4/o4pbAQgJYjI.mp4</video:content_loc><video:duration>356</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/solving-systems-by-graphing-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26876.jpg</video:thumbnail_loc><video:title>Number of solutions to a system of equations</video:title><video:description>Sal is given three lines on the coordinate plane, and identifies one system of two lines that has a single solution, and one system that has no solution.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/BNHLzEv6Mjg.mp4/BNHLzEv6Mjg.mp4</video:content_loc><video:duration>206</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/examples-algebraically-analyzing-solutions-to-systems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7a8c8c42.jpg</video:thumbnail_loc><video:title>Number of solutions to a system of equations algebraically</video:title><video:description>Sal solves several examples where he reasons about the number of solutions of systems of equations using algebraic reasoning.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ogEddosP1G8.mp4/ogEddosP1G8.mp4</video:content_loc><video:duration>361</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/understanding-systems-of-equations-example-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2a69cbaa.jpg</video:thumbnail_loc><video:title>How many solutions does a system of linear equations have if there are at least two?</video:title><video:description>Sal answers this question for you!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/bzseeIVEslA.mp4/bzseeIVEslA.mp4</video:content_loc><video:duration>132</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/system-of-equations-distances-word-problem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc63ae76c.jpg</video:thumbnail_loc><video:title>System of equations word problem: walk &amp; ride</video:title><video:description>Systems of equations can be used to solve many real-world problems. In this video, we solve a problem about distances walking and riding bus to school.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Q0tTfe2lKIc.mp4/Q0tTfe2lKIc.mp4</video:content_loc><video:duration>420</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/system-with-not-enough-information</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8883c043.jpg</video:thumbnail_loc><video:title>System of equations word problem: infinite solutions</video:title><video:description>Systems of equations can be used to solve many real-world problems. In this video, we solve a problem about a vegetable farmer. In this case, the problem has infinite solutions, which means there&apos;s not enough information to find a single solution.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/njb6xYF0GZ0.mp4/njb6xYF0GZ0.mp4</video:content_loc><video:duration>301</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/graphing-linear-functions-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe11cda5c.jpg</video:thumbnail_loc><video:title>Linear functions word problem: fuel</video:title><video:description>Sal is given a verbal description of a real-world relationship involving a truck&apos;s fuel consumption, and is asked to draw the graph that represents this relationship.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/AAmVITyDXbc.mp4/AAmVITyDXbc.mp4</video:content_loc><video:duration>330</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/graphing-linear-functions-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5a10148b.jpg</video:thumbnail_loc><video:title>Linear functions word problem: pool</video:title><video:description>Sal is given a verbal description of a real-world relationship involving a pool being filled with water, and is asked to draw the graph that represents this relationship.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/zSVrr8K_CiI.mp4/zSVrr8K_CiI.mp4</video:content_loc><video:duration>192</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/constructing-linear-functions-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x32996275.jpg</video:thumbnail_loc><video:title>Linear functions word problem: iceberg</video:title><video:description>Sal is given a verbal description of a real-world relationship involving a melting iceberg, and is asked to find the formula of the function that represents this relationship.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/W7H-VcaSSu8.mp4/W7H-VcaSSu8.mp4</video:content_loc><video:duration>395</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-eighth-grade-math/v/constructing-linear-functions-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x40f2b455.jpg</video:thumbnail_loc><video:title>Linear functions word problem: paint</video:title><video:description>Sal is given a verbal description of a real-world relationship involving a person painting his room, and is asked to find the formula of the function that represents this relationship.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5c9N_1PEfHw.mp4/5c9N_1PEfHw.mp4</video:content_loc><video:duration>503</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/the-beauty-of-algebra</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/563207734.jpg</video:thumbnail_loc><video:title>The beauty of algebra</video:title><video:description>Algebra is a language that helps us understand the world around us. It&apos;s not just about numbers, it&apos;s about abstract ideas that can be applied to many areas like economics, physics, and even the fundamental structure of the universe.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/kpCJyQ2usJ4.mp4/kpCJyQ2usJ4.mp4</video:content_loc><video:duration>607</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/why-all-the-letters-in-algebra</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1254552768.jpg</video:thumbnail_loc><video:title>Why all the letters in algebra?</video:title><video:description>In algebra, we often want to work with general concepts instead of specific numbers. Using letters allows us to represent quantities that could change or that we don&apos;t know the value of yet. Letters can also be used to generalize formulas or equations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Tm98lnrlbMA.mp4/Tm98lnrlbMA.mp4</video:content_loc><video:duration>184</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/adding-and-subtracting-polynomials-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26920.jpg</video:thumbnail_loc><video:title>Adding polynomials</video:title><video:description>Learn how to simplify polynomials by combining like terms! Discover the power of adding and subtracting terms with the same degree of x. Uncover the magic of removing parentheses and grouping similar terms together to simplify complex expressions. Master the art of polynomial simplification!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ahdKdxsTj8E.mp4/ahdKdxsTj8E.mp4</video:content_loc><video:duration>121</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/subtracting-polynomials</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179515.jpg</video:thumbnail_loc><video:title>Subtracting polynomials</video:title><video:description>Master the art of adding and subtracting polynomials! Learn how to distribute negative signs across terms, combine like terms, and simplify expressions. This skill is key to understanding algebra and making math easier.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5ZdxnFspyP8.mp4/5ZdxnFspyP8.mp4</video:content_loc><video:duration>127</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/multiply-monomials-intro</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xcef25551.jpg</video:thumbnail_loc><video:title>Multiplying monomials</video:title><video:description>Learn how to multiply monomials like a pro! Discover how to multiply numbers and variables separately, then combine them for the final answer. Explore how exponent properties come into play when multiplying variables. Dive into examples with different variables for variety.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7EplN4Ch98Q.mp4/7EplN4Ch98Q.mp4</video:content_loc><video:duration>196</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/multiplying-and-dividing-monomials-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26915.jpg</video:thumbnail_loc><video:title>Multiplying monomials to find area: two variables</video:title><video:description>Sal expresses the area of a rectangle with length 4xy and width 2y as a monomial.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/p_61XhXdlxI.mp4/p_61XhXdlxI.mp4</video:content_loc><video:duration>112</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/multiplying-monomials</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179516.jpg</video:thumbnail_loc><video:title>Multiplying monomials to find area</video:title><video:description>Learn to express the area of a rectangle with length 4y and width 2y as a monomial.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ssY1dFl7d30.mp4/ssY1dFl7d30.mp4</video:content_loc><video:duration>65</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/missing-values-in-monomial-multiplication</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0ae662f7.jpg</video:thumbnail_loc><video:title>Multiplying monomials challenge</video:title><video:description>Sal finds the values of coefficients a and b that make (3x^a)(bx^4)=-24x^6 true for all x-values.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/mzULbezO6iA.mp4/mzULbezO6iA.mp4</video:content_loc><video:duration>212</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/dividing-monomials</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179522.jpg</video:thumbnail_loc><video:title>Simplifying rational expressions (old video)</video:title><video:description>Sal simplifies (28b^6)/(7b) as 4b^5.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4Eax48gDg9g.mp4/4Eax48gDg9g.mp4</video:content_loc><video:duration>56</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/area-model-of-monomial-polynomial-multiplication</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb60519c0.jpg</video:thumbnail_loc><video:title>Multiplying monomials by polynomials: area model</video:title><video:description>Discover how to calculate the area of complex shapes using algebra! By breaking down a rectangle into smaller parts, we can find the total area by multiplying the height and width of each part. This method introduces us to the concept of multiplying monomials by polynomials.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/bkZYILrmFRU.mp4/bkZYILrmFRU.mp4</video:content_loc><video:duration>94</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/multiplying-monomials-by-polynomials</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179517.jpg</video:thumbnail_loc><video:title>Multiplying monomials by polynomials</video:title><video:description>Discover how to multiply monomials by polynomials using the distributive property. Learn to simplify expressions by multiplying coefficients and adding exponents. Get a handle on negative terms and see how they affect the final result. It&apos;s all about breaking down complex problems into simpler steps!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pD2-H15ucNE.mp4/pD2-H15ucNE.mp4</video:content_loc><video:duration>163</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/missing-values-in-monomial-polynomial-multiplication</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xffe234f4.jpg</video:thumbnail_loc><video:title>Multiplying monomials by polynomials challenge</video:title><video:description>Sal finds the values of coefficients c, d, and f that make -2y(y²+cy-3)=dy³+12y²+fy true for all y-values.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/NADPP4wlo1Q.mp4/NADPP4wlo1Q.mp4</video:content_loc><video:duration>258</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/difference-of-squares-pattern-for-simple-binomials</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7f0427db.jpg</video:thumbnail_loc><video:title>Special products of the form (x+a)(x-a)</video:title><video:description>Sal introduces difference of squares expressions. For example, (x+3)(x-3) is expanded as x²-9.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/JfuisfEdnjk.mp4/JfuisfEdnjk.mp4</video:content_loc><video:duration>294</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/special-polynomials-products-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179520.jpg</video:thumbnail_loc><video:title>Special products of the form (ax+b)(ax-b)</video:title><video:description>Sal expands the difference of squares (2x+8)(2x-8) as 4x²-64.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/h6HmHjkA034.mp4/h6HmHjkA034.mp4</video:content_loc><video:duration>149</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/pattern-for-squaring-simple-binomials</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2269fa10.jpg</video:thumbnail_loc><video:title>Squaring binomials of the form (x+a)²</video:title><video:description>Sal introduces perfect square expressions. For example, (x+7)² is expanded as x²+14x+49.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xH_GllPuymc.mp4/xH_GllPuymc.mp4</video:content_loc><video:duration>343</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/square-a-binomial</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179521.jpg</video:thumbnail_loc><video:title>Squaring binomials of the form (ax+b)²</video:title><video:description>Sal expands the perfect square (7x+10)² as 49x^2+140x+100.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xjkbR7Gjgjs.mp4/xjkbR7Gjgjs.mp4</video:content_loc><video:duration>218</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/factor-completely-common-factor</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc451daa13b239dcf.jpg</video:thumbnail_loc><video:title>Factoring completely with a common factor</video:title><video:description>We can factor quadratics by first pulling out a common factor so the result looks like a(x+b)(x+c).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/FoTD41xzF5Q.mp4/FoTD41xzF5Q.mp4</video:content_loc><video:duration>240</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/factoring-quadratics-common-factor</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa72408d04d9c47df.jpg</video:thumbnail_loc><video:title>Factoring quadratics with a common factor</video:title><video:description>We can factor quadratics by first pulling out a common factor so the result looks like a(x+b)(x+c).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/m6uOqU91ypI.mp4/m6uOqU91ypI.mp4</video:content_loc><video:duration>185</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/difference-of-squares-intro</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7514a13c1dd4ff7b.jpg</video:thumbnail_loc><video:title>Difference of squares intro</video:title><video:description>When an expression can be viewed as the difference of two perfect squares, i.e. a²-b², then we can factor it as (a+b)(a-b). For example, x²-25 can be factored as (x+5)(x-5). This method is based on the pattern (a+b)(a-b)=a²-b², which can be verified by expanding the parentheses in (a+b)(a-b).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/HLNSouzygw0.mp4/HLNSouzygw0.mp4</video:content_loc><video:duration>294</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/identifying-perfect-square-trinomials</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2957b9f5.jpg</video:thumbnail_loc><video:title>Identifying perfect square form</video:title><video:description>Sal shows how we can identify that a trinomial has the &quot;perfect square&quot; form.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4STGvuoBi5U.mp4/4STGvuoBi5U.mp4</video:content_loc><video:duration>277</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/perfect-square-factorization-intro</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0c1a3582bef51e96.jpg</video:thumbnail_loc><video:title>Perfect square factorization intro</video:title><video:description>When an expression has the general form a²+2ab+b², then we can factor it as (a+b)². For example, x²+10x+25 can be factored as (x+5)². This method is based on the pattern (a+b)²=a²+2ab+b², which can be verified by expanding the parentheses in (a+b)(a+b).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/JX5Zvh6swmo.mp4/JX5Zvh6swmo.mp4</video:content_loc><video:duration>319</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/factoring-perfect-square-trinomials</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179582.jpg</video:thumbnail_loc><video:title>Factoring perfect squares</video:title><video:description>Sal factors 25x^2-30x+9 as (5x-3)^2 or as (-5x+3)^2.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/liRNTieIU_k.mp4/liRNTieIU_k.mp4</video:content_loc><video:duration>294</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/u09-l2-t1-we1-factoring-special-products-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26989.jpg</video:thumbnail_loc><video:title>Factoring perfect squares: negative common factor</video:title><video:description>Sal factors -4t^2-12t-9 as -1(2t+3)^2.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/XuwldEyWjH0.mp4/XuwldEyWjH0.mp4</video:content_loc><video:duration>232</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/factoring-simple-quadratic-expression</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0da5d332.jpg</video:thumbnail_loc><video:title>Factoring quadratics as (x+a)(x+b)</video:title><video:description>Sal factors x²-3x-10 as (x+2)(x-5) using the sum-product form: (x+a)(x+b)=x²+(a+b)x+a*b.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/D3a8NnpQ2vU.mp4/D3a8NnpQ2vU.mp4</video:content_loc><video:duration>394</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/factoring-polynomials-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1228073357.jpg</video:thumbnail_loc><video:title>Factoring quadratics as (x+a)(x+b) (example 2)</video:title><video:description>Sal factors x^2-14x+40 as (x-4)(x-10) and x^2-x-12 as (x+3)(x-4).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1kfq0aR3ASs.mp4/1kfq0aR3ASs.mp4</video:content_loc><video:duration>260</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/factoring-quadratic-expressions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23710.jpg</video:thumbnail_loc><video:title>More examples of factoring quadratics as (x+a)(x+b)</video:title><video:description>Can&apos;t get enough of Sal factoring simple quadratics? Here&apos;s a handful of examples just for you!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/eF6zYNzlZKQ.mp4/eF6zYNzlZKQ.mp4</video:content_loc><video:duration>990</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/solving-for-constants-in-perfect-square-polynomial</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x052132a2.jpg</video:thumbnail_loc><video:title>Factoring perfect squares: missing values</video:title><video:description>Sal analyzes the factorization of x^2+5x+c as (x+d)^2 to find the values of the missing coefficients c and d.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/oIslHyWJHEY.mp4/oIslHyWJHEY.mp4</video:content_loc><video:duration>159</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/simplifying-rational-expressions-introduction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23782.jpg</video:thumbnail_loc><video:title>Reducing rational expressions to lowest terms</video:title><video:description>Learn how to simplify rational expressions, which are fractions with variable expressions in the numerator and denominator. This video also shows how to factor the expressions and cancel out common factors, just like with rational numbers. Don&apos;t forget to exclude values of x that would make the denominator zero, since those would make the expression undefined.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7Uos1ED3KHI.mp4/7Uos1ED3KHI.mp4</video:content_loc><video:duration>922</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math3/v/simplifying-rational-expressions-w-common-monomial-factors</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x71dfabf5.jpg</video:thumbnail_loc><video:title>Simplifying rational expressions: common monomial factors</video:title><video:description>Sal simplifies the rational expressions (14x²+7x)/(14x) and (17z³+17z²)/(34z³-51z²) by taking common factors and canceling them.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/XFwQV-KCudw.mp4/XFwQV-KCudw.mp4</video:content_loc><video:duration>419</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/adding-and-subtracting-rational-expressions-with-like-denominators</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbecbe152.jpg</video:thumbnail_loc><video:title>Adding &amp; subtracting rational expressions: like denominators</video:title><video:description>Sal adds 6/(2x²-7) + (-3x-8)/(2x²-7) and subtracts (9x²+3)/(14x²-9) - (-3x²+5)/(14x²-9).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/rmYlCuiC5uY.mp4/rmYlCuiC5uY.mp4</video:content_loc><video:duration>225</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/algebraic-expression-adding-fractions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe973c6c7.jpg</video:thumbnail_loc><video:title>Intro to adding rational expressions with unlike denominators</video:title><video:description>Sal rewrites a/b+c/d as a single rational expression.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/w7NhLkQynS8.mp4/w7NhLkQynS8.mp4</video:content_loc><video:duration>164</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/adding-rational-expression-w-unlike-denominators</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x220777a7.jpg</video:thumbnail_loc><video:title>Adding rational expression: unlike denominators</video:title><video:description>Learn how to add rational expressions with different denominators by finding a common denominator, multiplying the numerators and denominators by the same factors, and simplifying the result. A rational expression is a fraction with polynomials in the numerator and denominator.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DrE_iiw1Mvk.mp4/DrE_iiw1Mvk.mp4</video:content_loc><video:duration>311</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/subtracting-rational-expressions-w-unlike-denominators</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe3210011.jpg</video:thumbnail_loc><video:title>Subtracting rational expressions: unlike denominators</video:title><video:description>Sal rewrites (-5x)/(8x+7)-(6x³)/(3x+1) as (-48x⁴-42x³-15x²-5x)/(8x+7)(3x+1).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/evmDZkDvlNw.mp4/evmDZkDvlNw.mp4</video:content_loc><video:duration>287</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/subtracting-rational-expressions-w-factored-denominators</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x282a4135.jpg</video:thumbnail_loc><video:title>Subtracting rational expressions: factored denominators</video:title><video:description>Sal subtracts two rational expressions whose denominators are factored. The denominators aren&apos;t the same but they share a factor.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/j8cKFzj5V6g.mp4/j8cKFzj5V6g.mp4</video:content_loc><video:duration>288</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/multiplying-and-dividing-rational-expressions-monomial-numerator-denominator</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xda27881a.jpg</video:thumbnail_loc><video:title>Multiplying &amp; dividing rational expressions: monomials</video:title><video:description>Sal multiplies (6x³/5) X (2/3x) and divides (2x⁴/7) ➗ (5x⁴/4).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6nALFmvvgds.mp4/6nALFmvvgds.mp4</video:content_loc><video:duration>356</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math3/v/multiplying-and-dividing-rational-expressions-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/27015.jpg</video:thumbnail_loc><video:title>Multiplying rational expressions</video:title><video:description>Sal multiplies and simplifies (a²-4)/(a²-1) X (a+1)/(a+2).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/f-wz_ZzSDdg.mp4/f-wz_ZzSDdg.mp4</video:content_loc><video:duration>292</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math3/v/multiplying-and-dividing-rational-expressions-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/27016.jpg</video:thumbnail_loc><video:title>Dividing rational expressions</video:title><video:description>Sal divides and simplifies (2p+6)/(p+5) ➗ (10)/(4p+20).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gcnk8TnzsLc.mp4/gcnk8TnzsLc.mp4</video:content_loc><video:duration>250</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math3/v/multiplying-and-dividing-rational-expressions-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/27014.jpg</video:thumbnail_loc><video:title>Multiplying rational expressions: multiple variables</video:title><video:description>Sal multiplies and simplifies (3x²y)/(2ab) X (14a²b)/(18xy²).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3GL69IA2q4s.mp4/3GL69IA2q4s.mp4</video:content_loc><video:duration>218</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math3/v/dividing-rational-expressions-w-unknown-expression</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdc5c1290.jpg</video:thumbnail_loc><video:title>Dividing rational expressions: unknown expression</video:title><video:description>Sal finds the polynomial D for which (20y²-80)/D ÷ (4y²-8y)/(y³+9y²)=1 is true for all values of y for which it&apos;s defined.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/54ZFp4CwWEg.mp4/54ZFp4CwWEg.mp4</video:content_loc><video:duration>362</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/midpoint-formula</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23758.jpg</video:thumbnail_loc><video:title>Midpoint formula</video:title><video:description>Learn how to use the midpoint formula to find the midpoint of a line segment on the coordinate plane, or find the endpoint of a line segment given one point and the midpoint.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Ez_-RwV9WVo.mp4/Ez_-RwV9WVo.mp4</video:content_loc><video:duration>401</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/volume-of-pyramids-intuition</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3e58b9e685faa0ed.jpg</video:thumbnail_loc><video:title>Volume of pyramids intuition</video:title><video:description>The volume of a pyramid is a fraction of the volume of the rectangular prism that encloses it. We can find out what that fraction is by cutting a prism into several pyramids.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/fD52yzLF8DA.mp4/fD52yzLF8DA.mp4</video:content_loc><video:duration>509</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/volumes-of-cones-intuition</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe65e41d409141ca6.jpg</video:thumbnail_loc><video:title>Volumes of cones intuition</video:title><video:description>Use Cavalieri&apos;s Principle to establish that the formula for the volume of a cone is the same as the formula for the volume of a pyramid (1/3 * base area * height).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LmBViMOeYXg.mp4/LmBViMOeYXg.mp4</video:content_loc><video:duration>342</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/steps-when-solving-equations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb929087f.jpg</video:thumbnail_loc><video:title>Describing steps when solving equations</video:title><video:description>Sal lists the steps necessary in order to solve a linear equation. This is useful for thinking more strategically about equations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LzYJVsvqS50.mp4/LzYJVsvqS50.mp4</video:content_loc><video:duration>136</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/missing-steps</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9c0b1421.jpg</video:thumbnail_loc><video:title>Figuring out missing algebraic step</video:title><video:description>There is a hidden step in Steven&apos;s solution to solving an equation. There are different ways to solve an equation. To find Steven&apos;s missing step, we can see what we would do in the equation. Then we can see if another step will get us to the work Sten is showing. If not, we can try solving a different way.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/RXgj09NXNWo.mp4/RXgj09NXNWo.mp4</video:content_loc><video:duration>114</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/one-step-inequalities</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179474.jpg</video:thumbnail_loc><video:title>One-step inequality involving addition</video:title><video:description>How to solve and graph one-step inequalities.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/17a443nL7Qw.mp4/17a443nL7Qw.mp4</video:content_loc><video:duration>114</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/inequalities-using-addition-and-subtraction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23660.jpg</video:thumbnail_loc><video:title>Inequalities using addition and subtraction</video:title><video:description>Inequalities Using Addition and Subtraction</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/UTs4uZhu5t8.mp4/UTs4uZhu5t8.mp4</video:content_loc><video:duration>468</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/multi-step-inequalities-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/153770149.jpg</video:thumbnail_loc><video:title>Inequalities with variables on both sides</video:title><video:description>Sal solves the inequality -3p-7&lt;p+9, draws the solution on a number line and checks a few values to verify the solution.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/SgKBBUFaGb4.mp4/SgKBBUFaGb4.mp4</video:content_loc><video:duration>338</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/multi-step-inequalities-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179489.jpg</video:thumbnail_loc><video:title>Inequalities with variables on both sides (with parentheses)</video:title><video:description>Sal solves the inequality 5x+7&gt;3(x+1), draws the solution on a number line and checks a few values to verify the solution.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/XOAn5z8mkvI.mp4/XOAn5z8mkvI.mp4</video:content_loc><video:duration>227</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/multi-step-inequalities</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/547403341.jpg</video:thumbnail_loc><video:title>Multi-step inequalities</video:title><video:description>Sal solves several multi-step linear inequalities.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xOxvyeSl0uA.mp4/xOxvyeSl0uA.mp4</video:content_loc><video:duration>482</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/2-variable-linear-equations-graphs</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x82b3a036.jpg</video:thumbnail_loc><video:title>Two-variable linear equations intro</video:title><video:description>Learn about a class of equations in two variables that&apos;s called &quot;linear equations.&quot; They are called that way because their graph is a line. These are the most basic and probably most useful equations you will ever know!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/AOxMJRtoR2A.mp4/AOxMJRtoR2A.mp4</video:content_loc><video:duration>501</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/less-obvious-slope-intercept-form</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbb26a1d9b606a0a4.jpg</video:thumbnail_loc><video:title>Slope and y-intercept from equation</video:title><video:description>In an equation in slope-intercept form (y=mx+b) the slope is m and the y-intercept is b. We can also rewrite certain equations to look more like slope-intercept form. For example, y=x can be rewritten as y=1x+0, so its slope is 1 and its y-intercept is 0.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Z65mz__8DQ0.mp4/Z65mz__8DQ0.mp4</video:content_loc><video:duration>250</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/solving-systems-of-equations-by-multiplication</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23680.jpg</video:thumbnail_loc><video:title>Systems of equations with elimination (and manipulation)</video:title><video:description>In some cases, we need to slightly manipulate a system of equations before we can solve it using the elimination method. See how it&apos;s done in this video.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/wYrxKGt_bLg.mp4/wYrxKGt_bLg.mp4</video:content_loc><video:duration>721</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/why-we-do-the-same-thing-to-both-sides-basic-systems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/948327843.jpg</video:thumbnail_loc><video:title>Why can we subtract one equation from the other in a system of equations?</video:title><video:description>The example of a scale where we try to achieve balance helps to explain why we can subtract one equation from the other in a system of equations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/h9ZgZimXn2Q.mp4/h9ZgZimXn2Q.mp4</video:content_loc><video:duration>493</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/graphing-inequalities</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23672.jpg</video:thumbnail_loc><video:title>Intro to graphing two-variable inequalities</video:title><video:description>Learn how to graph two-variable linear inequalities like y≤4x+3.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/unSBFwK881s.mp4/unSBFwK881s.mp4</video:content_loc><video:duration>483</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/graphing-linear-inequalities-in-two-variables-example-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/2600589.jpg</video:thumbnail_loc><video:title>Graphing two-variable inequalities</video:title><video:description>Sal graphs the inequality y&lt;3x+5.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/FnrqBgot3jM.mp4/FnrqBgot3jM.mp4</video:content_loc><video:duration>183</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/graphing-linear-inequalities-in-two-variables-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26874.jpg</video:thumbnail_loc><video:title>Two-variable inequalities from their graphs</video:title><video:description>Sal is given a graph and he analyzes it to find the two-variable inequality it represents.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/YBYu5aZPLeg.mp4/YBYu5aZPLeg.mp4</video:content_loc><video:duration>200</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/sample-variance</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1163970906.jpg</video:thumbnail_loc><video:title>Sample variance</video:title><video:description>We delve into measuring variability in quantitative data, focusing on calculating sample variance and population variance. The importance of using a sample size minus one (n-1) for a more accurate estimate is highlighted. The distinction between sample mean and population mean is also clarified.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/iHXdzfF7UEs.mp4/iHXdzfF7UEs.mp4</video:content_loc><video:duration>638</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/sample-standard-deviation-and-bias</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6ad248d1.jpg</video:thumbnail_loc><video:title>Sample standard deviation and bias</video:title><video:description>Sal shows an example of calculating standard deviation and bias.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DNAnQBhGpRw.mp4/DNAnQBhGpRw.mp4</video:content_loc><video:duration>573</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/visual-standard-deviation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfc2e7c96cfe32c07.jpg</video:thumbnail_loc><video:title>Visually assessing standard deviation</video:title><video:description>Worked examples visually assessing the standard distribution.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-iCMQoCJFBY.mp4/-iCMQoCJFBY.mp4</video:content_loc><video:duration>229</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/origins-of-algebra</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/565175118.jpg</video:thumbnail_loc><video:title>Origins of algebra</video:title><video:description>Where did the word &quot;Algebra&quot; and its underlying ideas come from? Algebra, a key branch of mathematics, has a rich history. The term &apos;algebra&apos; comes from an Arabic word meaning &apos;restoration&apos; or &apos;completion&apos;. Significant contributions to algebra were made by Diophantus in Greece, Brahmagupta in India, and al-Khwarizmi in Baghdad, who is often credited with giving algebra its name.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_LDR1_Prveo.mp4/_LDR1_Prveo.mp4</video:content_loc><video:duration>438</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/abstract-ness</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/565149394.jpg</video:thumbnail_loc><video:title>Abstract-ness</video:title><video:description>Abstraction is like taking a real thing and turning it into an idea. We can use a cube as an example. Even though cubes can look different in real life, the abstract idea of what a cube is stays the same.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ZOYRb2sYrL0.mp4/ZOYRb2sYrL0.mp4</video:content_loc><video:duration>420</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/creativity-important-in-algebra</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x12ce07a329691eb8.jpg</video:thumbnail_loc><video:title>Creativity break: Why is creativity important in algebra?</video:title><video:description>Algebra is a creative problem-solving tool, similar to art. Just as an artist uses different techniques and brushes to create a masterpiece, algebra combines various mathematical tools to solve complex problems. It&apos;s not about memorizing solutions, but about using your knowledge in innovative ways.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/SjZfW07DbMo.mp4/SjZfW07DbMo.mp4</video:content_loc><video:duration>82</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/creativity-stem-jobs</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x76a1dad8aa3e70d2.jpg</video:thumbnail_loc><video:title>Creativity break: Why is creativity important in STEM jobs?</video:title><video:description>Experts share why creativity plays an important role in STEM jobs.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ynvn3jqxcX4.mp4/ynvn3jqxcX4.mp4</video:content_loc><video:duration>97</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/why-zero-divided-by-zero-is-undefined-indeterminate</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/871532281.jpg</video:thumbnail_loc><video:title>The problem with dividing zero by zero</video:title><video:description>One can argue that 0/0 is ​0, because 0 divided by anything is 0. Another one can argue that 0/0 is ​1, because anything divided by itself is 1. And that&apos;s exactly the problem! Whatever we say 0/0 equals to, we contradict one crucial property of numbers or another. To avoid &quot;breaking math,&quot; we simply say that 0/0 is undetermined.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PDReqvXfkBA.mp4/PDReqvXfkBA.mp4</video:content_loc><video:duration>146</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/undefined-and-indeterminate</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/871539458.jpg</video:thumbnail_loc><video:title>Undefined &amp; indeterminate expressions</video:title><video:description>Revisiting the problems of dividing any number by zero and dividing zero by zero. Using general mathematical considerations, we see why those are undefined and indeterminate problems.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lHdlHTsXbZg.mp4/lHdlHTsXbZg.mp4</video:content_loc><video:duration>452</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/why-we-do-the-same-thing-to-both-sides-multi-step-equations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/948601082.jpg</video:thumbnail_loc><video:title>Why we do the same thing to both sides: Variable on both sides</video:title><video:description>We will use a scale to try to achieve balance and help explain why we do the same thing to both sides of an equation, even when the variable appears on both sides.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vkhYFml0w6c.mp4/vkhYFml0w6c.mp4</video:content_loc><video:duration>456</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/reasoning-with-linear-equations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfe28aa3bc9f3418d.jpg</video:thumbnail_loc><video:title>Reasoning with linear equations</video:title><video:description>When we perform operations to manipulate equations, some operations produce equivalent equations, while others don&apos;t necessarily produce equivalent equations. When we&apos;re solving an equation, we need to use operations that guarantee equivalence.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/BV-TGIMUXaw.mp4/BV-TGIMUXaw.mp4</video:content_loc><video:duration>460</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/linear-equations-with-unknown-coefficients</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdb214b95.jpg</video:thumbnail_loc><video:title>Linear equations with unknown coefficients</video:title><video:description>Sal solves the equations ax+3x=bx+5 and a(5-x)=bx-8 for x. Note that these equations include other unknowns (a and b) but we solve them for x.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/adPgapI-h3g.mp4/adPgapI-h3g.mp4</video:content_loc><video:duration>335</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/why-algebra-important</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8f0df416e19126f4.jpg</video:thumbnail_loc><video:title>Why is algebra important to learn?</video:title><video:description>Professionals share why algebra is important to learn.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/H4g0GZsgq0I.mp4/H4g0GZsgq0I.mp4</video:content_loc><video:duration>46</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/using-inequalities-to-solve-problems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe2ceae424fad445f.jpg</video:thumbnail_loc><video:title>Using inequalities to solve problems</video:title><video:description>We can use inequalities to solve problems in a given context.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/E6rn-YD_2_Q.mp4/E6rn-YD_2_Q.mp4</video:content_loc><video:duration>220</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/compund-inequalities</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179490.jpg</video:thumbnail_loc><video:title>Compound inequalities: OR</video:title><video:description>Sal solves the compound inequality 5z+7&lt;27 OR -3z≤18.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0YErxSShF0A.mp4/0YErxSShF0A.mp4</video:content_loc><video:duration>271</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/compund-inequalities-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179491.jpg</video:thumbnail_loc><video:title>Compound inequalities: AND</video:title><video:description>Sal solves the compound inequality 3y+7&lt;2y AND 4y+8&gt;-48.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/d2cnQ5ahHgE.mp4/d2cnQ5ahHgE.mp4</video:content_loc><video:duration>313</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/compound-inequalities-4</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179493.jpg</video:thumbnail_loc><video:title>A compound inequality with no solution</video:title><video:description>Sal solves the compound inequality 5x-3&lt;12 AND 4x+1&gt;25, only to realize there&apos;s no x-value that makes both inequalities true.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ZF_cZ-GX9PI.mp4/ZF_cZ-GX9PI.mp4</video:content_loc><video:duration>161</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/compound-inequalities-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/153754478.jpg</video:thumbnail_loc><video:title>Double inequalities</video:title><video:description>Sal solves the double inequality -16≤3x+5≤20, which is the same as the compound inequality -16≤3x+5 AND 3x+5≤20.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/cvB8b4AACyE.mp4/cvB8b4AACyE.mp4</video:content_loc><video:duration>268</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/compound-inequalities</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23666.jpg</video:thumbnail_loc><video:title>Compound inequalities examples</video:title><video:description>Sal solves several compound linear inequalities.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/A3xPhzs-KBI.mp4/A3xPhzs-KBI.mp4</video:content_loc><video:duration>705</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/dimensional-analysis-units-algebraically</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x49104b67.jpg</video:thumbnail_loc><video:title>Intro to dimensional analysis</video:title><video:description>Sal shows how we can treat units of measurement algebraically, and use these tools in order to convert between different units of the same quantity.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hIAdCTNi1S8.mp4/hIAdCTNi1S8.mp4</video:content_loc><video:duration>389</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/thinking-about-reasonable-units-to-describe-a-rate</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa36759d8.jpg</video:thumbnail_loc><video:title>Same rate with different units</video:title><video:description>Sal shows how we can describe the rate 50 km per hour in a variety of different units, using dimensional analysis.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/d5lcGCbV5cM.mp4/d5lcGCbV5cM.mp4</video:content_loc><video:duration>595</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/realize-liked-algebra</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9c052287ee65491c.jpg</video:thumbnail_loc><video:title>Creativity break: When did you first realize that you liked algebra</video:title><video:description>Experts share when they first realized that they liked algebra and mathematics.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4l1t-_Eb2MI.mp4/4l1t-_Eb2MI.mp4</video:content_loc><video:duration>102</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/appropriate-units</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfc37075b5d039482.jpg</video:thumbnail_loc><video:title>Defining appropriate quantities for modeling</video:title><video:description>Examples for different ways to define how quantities of interest are calculated in a modeling problem.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/717zfRdog9s.mp4/717zfRdog9s.mp4</video:content_loc><video:duration>371</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/interpreting-units-in-formulas</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdc3ada78.jpg</video:thumbnail_loc><video:title>Formulas and units: Volume of a pool</video:title><video:description>When using formulas to calculate real-world quantities, we need to make sure our units are consistent. In this video, the base area of a pool is given in square meters while its height is given in centimeters. In order to use the formula for volume, we need to convert one of the measurements to units that match the other measurement.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/nziP-8PeZqY.mp4/nziP-8PeZqY.mp4</video:content_loc><video:duration>200</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/interpreting-units-in-formulas-novel</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc8a101e6.jpg</video:thumbnail_loc><video:title>Formulas and units: Comparing rates</video:title><video:description>When using formulas to calculate real-world quantities, we need to make sure our units are consistent. In this video, one growth rate is given in centimeters per week and the other is given in millimeters per day. In order to compare which rate is faster, we need to convert one of the rates to units that match the other rate.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/IuvsQjW1qa4.mp4/IuvsQjW1qa4.mp4</video:content_loc><video:duration>222</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/reporting-measurements</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x39704acdb26c489a.jpg</video:thumbnail_loc><video:title>Reporting measurements</video:title><video:description>We should think about the appropriate level of precision of different measurements in modeling problems.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/UEe81kJtY8A.mp4/UEe81kJtY8A.mp4</video:content_loc><video:duration>363</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/using-units-to-solve-problems-toy-factory</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb97ff210e26f3ff6.jpg</video:thumbnail_loc><video:title>Using units to solve problems: Toy factory</video:title><video:description>In word problems that involve multiple quantities, we can use the units of the quantities to guide our solution. In this video, we find the value of toys produced at a factory using information that involves many different quantities, not all of which are useful for our problem.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ocOXYiborsw.mp4/ocOXYiborsw.mp4</video:content_loc><video:duration>183</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/using-units-to-solve-problems-road-trip</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa84111c831c35125.jpg</video:thumbnail_loc><video:title>Using units to solve problems: Road trip</video:title><video:description>In word problems that involve multiple quantities, we can use the units of the quantities to guide our solution. In this video, we find the cost of fuel for a road trip, using information that involves many different quantities, not all of which are useful for our problem.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_UAQJw_q4p4.mp4/_UAQJw_q4p4.mp4</video:content_loc><video:duration>234</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/unit-conversion-example-drug-dosage</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1622153.jpg</video:thumbnail_loc><video:title>Using units to solve problems: Drug dosage</video:title><video:description>Future doctors and nurses out there, take note. This unit conversion word problem deals with converting drug dosage units, something that is commonly done in hospitals. Give it a try with us.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ScvuRb6vsz4.mp4/ScvuRb6vsz4.mp4</video:content_loc><video:duration>644</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/math-creativity-changing-world</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x10e3af1862147e0b.jpg</video:thumbnail_loc><video:title>Creativity break: How are math and creativity changing the world?</video:title><video:description>Experts share examples of how math and creativity are changing the world.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/nFnRRdvaS9g.mp4/nFnRRdvaS9g.mp4</video:content_loc><video:duration>116</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/graph-from-point-slope</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x895c45614b6db41b.jpg</video:thumbnail_loc><video:title>Graphing a line given point and slope</video:title><video:description>Practice graphing a line given its slope and a point the line passes through.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5mgH-_5UJ54.mp4/5mgH-_5UJ54.mp4</video:content_loc><video:duration>131</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/slope-from-table</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x99364552bda42485.jpg</video:thumbnail_loc><video:title>Calculating slope from tables</video:title><video:description>Practice calculating the slope of a line given some points on the line shown in a table.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pGsicLglzY8.mp4/pGsicLglzY8.mp4</video:content_loc><video:duration>159</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/slope-intercepts-context</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5028a8b98bc6bc16.jpg</video:thumbnail_loc><video:title>Slope, x-intercept, y-intercept meaning in context</video:title><video:description>Practice determining what each of the slope, x-intercept, and y-intercept represent in a given linear relationship.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/XQlaZuh7E8w.mp4/XQlaZuh7E8w.mp4</video:content_loc><video:duration>240</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/slope-intercept-meaning</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa831a69862ad1434.jpg</video:thumbnail_loc><video:title>Slope and intercept meaning in context</video:title><video:description>Practice determining which feature of a linear model (the slope, the x-intercept, or the y-intercept) is useful for answering a given question in context.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TYbN--4KHIk.mp4/TYbN--4KHIk.mp4</video:content_loc><video:duration>140</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/slope-intercept-meaning-table</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbf6179b0a74c3a3e.jpg</video:thumbnail_loc><video:title>Slope and intercept meaning from a table</video:title><video:description>Given a linear relationship in a table, Sal graphs the relationship to explore what the slope and intercepts mean in the given context.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/nc9XHXlxSyM.mp4/nc9XHXlxSyM.mp4</video:content_loc><video:duration>416</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/find-slope-intercepts-table</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd76ee344ace70dc8.jpg</video:thumbnail_loc><video:title>Finding slope and intercepts from tables</video:title><video:description>Given a linear relationship in a table, practice finding the slope and intercepts.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/g98OfN5cWy4.mp4/g98OfN5cWy4.mp4</video:content_loc><video:duration>324</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/comparing-linear-rates-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x74532e0e2faa26b7.jpg</video:thumbnail_loc><video:title>Comparing linear rates example</video:title><video:description>Compare the positions of two creatures moving at constant speed and determine when one catches up with the other.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/AoMjn2qKvXs.mp4/AoMjn2qKvXs.mp4</video:content_loc><video:duration>483</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/apply-creativity-algebra</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9b5c46a2ee2957db.jpg</video:thumbnail_loc><video:title>Creativity break: How do you apply creativity in algebra</video:title><video:description>Experts share how we can apply creativity in algebra, mathematics, and problem solving.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2vAMs-KM7UA.mp4/2vAMs-KM7UA.mp4</video:content_loc><video:duration>100</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/linear-equation-word-problems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd699d2b73e7bff12.jpg</video:thumbnail_loc><video:title>Linear equation word problems</video:title><video:description>Linear equation word problems</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/w6R8rywmgek.mp4/w6R8rywmgek.mp4</video:content_loc><video:duration>221</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/construct-linear-equation-context</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x794eb725ba1416d2.jpg</video:thumbnail_loc><video:title>Constructing linear equations from context</video:title><video:description>Given a written description of a linear relationship in a some context, write an equation that represents the linear relationship described.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hBpI9IfmMKg.mp4/hBpI9IfmMKg.mp4</video:content_loc><video:duration>187</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/standard-form-rules</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc5589921cbd30812.jpg</video:thumbnail_loc><video:title>Clarifying standard form rules</video:title><video:description>Clarifying standard form rules</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PfSsLjnnS60.mp4/PfSsLjnnS60.mp4</video:content_loc><video:duration>289</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/converting-from-slope-intercept-to-standard-form</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf4b68996.jpg</video:thumbnail_loc><video:title>Converting from slope-intercept to standard form</video:title><video:description>We can rewrite an equation in slope-intercept form (y=mx+b) to be in standard form (Ax+By=C) instead. In this example, we rewrite the slope-intercept equation y=2/3x+4/7 in standard form.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/XOIhNVeLfWs.mp4/XOIhNVeLfWs.mp4</video:content_loc><video:duration>309</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/point-slope-and-standard-form</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26807.jpg</video:thumbnail_loc><video:title>Writing linear equations in all forms</video:title><video:description>Sal finds the equation of a line that passes through (-3,6) and (6,0) in point-slope, slope-intercept, and standard form.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-6Fu2T_RSGM.mp4/-6Fu2T_RSGM.mp4</video:content_loc><video:duration>476</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/get-into-creative-zone</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8ec4a97e981ddb6e.jpg</video:thumbnail_loc><video:title>Creativity break: What do you do to get into your creative zone?</video:title><video:description>Experts share what they do to get into their creative zone.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7WjlO5u3Vqo.mp4/7WjlO5u3Vqo.mp4</video:content_loc><video:duration>97</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/setting-up-system</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0227afd4a0dd6307.jpg</video:thumbnail_loc><video:title>Setting up a system of equations from context example (pet weights)</video:title><video:description>Practice writing a system of linear equations that fits the constraints in a word problem.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/HftghcUXaEg.mp4/HftghcUXaEg.mp4</video:content_loc><video:duration>119</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/setting-up-systems-weight-price</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x711262ce541d80e9.jpg</video:thumbnail_loc><video:title>Setting up a system of linear equations example (weight and price)</video:title><video:description>Practice writing a system of linear equations that fits the constraints in a word problem.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pL4PXSXH-R8.mp4/pL4PXSXH-R8.mp4</video:content_loc><video:duration>252</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/interpret-points-systems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3922ec65b7d6722c.jpg</video:thumbnail_loc><video:title>Interpreting points in context of graphs of systems</video:title><video:description>Given a graph of a system of equations and a context, practice interpreting what various points represent in that system.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_hW1OzRlx50.mp4/_hW1OzRlx50.mp4</video:content_loc><video:duration>339</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/elimination-strategies</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x82f52d65de01cb07.jpg</video:thumbnail_loc><video:title>Elimination strategies</video:title><video:description>Practice identifying strategies for eliminating variables in a system of equations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5jgSW5Jb-Y8.mp4/5jgSW5Jb-Y8.mp4</video:content_loc><video:duration>436</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/identifying-equivalent-systems-of-equations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x146f77c8.jpg</video:thumbnail_loc><video:title>Worked example: equivalent systems of equations</video:title><video:description>Sal analyzes a couple of systems of equations and determines whether they have the same solution as a third given system.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/XstL_x4ucm4.mp4/XstL_x4ucm4.mp4</video:content_loc><video:duration>331</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/identifying-non-equivalent-systems-of-equations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1b00a657.jpg</video:thumbnail_loc><video:title>Worked example: non-equivalent systems of equations</video:title><video:description>Sal analyzes a couple of systems of equations and determines whether they have the same solution as a third given system.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PSDQdwL1T0M.mp4/PSDQdwL1T0M.mp4</video:content_loc><video:duration>270</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/reasoning-system-equations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0fb7b0cb44857460.jpg</video:thumbnail_loc><video:title>Reasoning with systems of equations</video:title><video:description>When we perform operations on a system of equations, some operations produce an equivalent system, while others don&apos;t necessarily produce an equivalent system. When we&apos;re solving a system of equations, we need to use operations that guarantee equivalence.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/s1RB-IgAHr8.mp4/s1RB-IgAHr8.mp4</video:content_loc><video:duration>516</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/graphing-inequalities-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/33752759.jpg</video:thumbnail_loc><video:title>Testing solutions to inequalities</video:title><video:description>Sal checks if the ordered pairs (3,5) and (1,-7) are solutions of the inequality 5x-3y≥25.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2oGsLdAWxlk.mp4/2oGsLdAWxlk.mp4</video:content_loc><video:duration>366</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/testing-solutions-for-a-system-of-inequalities</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/33752767.jpg</video:thumbnail_loc><video:title>Testing solutions to systems of inequalities</video:title><video:description>Sal checks whether the ordered pair (2,5) is a solution of the following system: y≥2x+1 and x&gt;1.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/XzYNh2wpO0A.mp4/XzYNh2wpO0A.mp4</video:content_loc><video:duration>75</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/graphical-system-of-inequalities</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/33752766.jpg</video:thumbnail_loc><video:title>Intro to graphing systems of inequalities</video:title><video:description>Learn how to graph systems of two-variable linear inequalities, like &quot;y&gt;x-8 and y&lt;5-x.&quot;</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/CA4S7S-3Lg4.mp4/CA4S7S-3Lg4.mp4</video:content_loc><video:duration>336</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/graphing-systems-of-inequalities-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26891.jpg</video:thumbnail_loc><video:title>Graphing systems of inequalities</video:title><video:description>Sal graphs the solution set of the system &quot;y≥2x+1 and y&lt;2x-5 and x&gt;1.&quot;</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/YjT3QYfoy4Q.mp4/YjT3QYfoy4Q.mp4</video:content_loc><video:duration>204</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/constructing-two-variable-linear-inequality-word-problem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd477103a.jpg</video:thumbnail_loc><video:title>Writing two-variable inequalities word problem</video:title><video:description>Sal solves a word problem about scores in a chess tournament by creating a two-variable linear inequality.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/MHgi8ZQCG0I.mp4/MHgi8ZQCG0I.mp4</video:content_loc><video:duration>142</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/solving-two-variable-linear-inequality-word-problem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc18c0e7b.jpg</video:thumbnail_loc><video:title>Solving two-variable inequalities word problem</video:title><video:description>Given a two-variable linear inequality that models a context about watering plants, Sal finds how many flowers can be watered.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ysdY1iX_XCs.mp4/ysdY1iX_XCs.mp4</video:content_loc><video:duration>222</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/analyzing-two-variable-linear-inequality</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xecc8be0c.jpg</video:thumbnail_loc><video:title>Interpreting two-variable inequalities word problem</video:title><video:description>Sal analyzes a two-variable linear inequality that models a context about YouTube videos.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TTYDbGXgcCk.mp4/TTYDbGXgcCk.mp4</video:content_loc><video:duration>260</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/u06-l3-t1-we3-graphing-systems-of-inequalities</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/2600587.jpg</video:thumbnail_loc><video:title>Modeling with systems of inequalities</video:title><video:description>Sal models a real-world context into an algebraic system of linear inequalities and graphs it.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/BUmLw5m6F9s.mp4/BUmLw5m6F9s.mp4</video:content_loc><video:duration>585</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/creating-system-of-inequalities-word-problem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x78626c28.jpg</video:thumbnail_loc><video:title>Writing systems of inequalities word problem</video:title><video:description>Sal models a word problem about baking cupcakes and muffins by creating a system of linear inequalities.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jRnkxSfwIpU.mp4/jRnkxSfwIpU.mp4</video:content_loc><video:duration>240</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/interpreting-system-of-inequalities-in-context</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd4f8409b.jpg</video:thumbnail_loc><video:title>Solving systems of inequalities word problem</video:title><video:description>Given a system of linear inequalities that models a context about making chairs and tables, Sal finds how many can be made.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ZTKAn9YNbNY.mp4/ZTKAn9YNbNY.mp4</video:content_loc><video:duration>265</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/graph-of-system-of-inequalities-word-problem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5cab75bc.jpg</video:thumbnail_loc><video:title>Graphs of systems of inequalities word problem</video:title><video:description>Given the graph of a two-variable linear inequality that models a context about chopping vegetables, Sal finds if there&apos;s enough time to chop!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/C_7Tqk9fw4k.mp4/C_7Tqk9fw4k.mp4</video:content_loc><video:duration>215</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/interpreting-visual-linear-inequality-word-problem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7f6281ad.jpg</video:thumbnail_loc><video:title>Graphs of two-variable inequalities word problem</video:title><video:description>Given the graph of a two-variable linear inequality that models a context about dog biscuits, Sal finds if the dog can get enough biscuits.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DhiiGFuUE9I.mp4/DhiiGFuUE9I.mp4</video:content_loc><video:duration>299</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/expand-creative-skills</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x13a6d24bd477485a.jpg</video:thumbnail_loc><video:title>Creativity break: What can we do to expand our creative skills?</video:title><video:description>Experts share their advice on how to expand our creative skills.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/SFUG5KpIf_Q.mp4/SFUG5KpIf_Q.mp4</video:content_loc><video:duration>88</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/evaluate-discrete-function</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5b89a73430127844.jpg</video:thumbnail_loc><video:title>Evaluating discrete functions</video:title><video:description>Given the graph of a discrete function, Sal shows how to evaluate the function for a few different values.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Ddw8u7nNmKs.mp4/Ddw8u7nNmKs.mp4</video:content_loc><video:duration>200</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/evaluating-a-function-expression</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4edf0df7.jpg</video:thumbnail_loc><video:title>Worked example: evaluating expressions with function notation</video:title><video:description>Evaluating -2⋅f(-6)+g(1) given the graphs of f and g.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/uaPm3Tpuxbc.mp4/uaPm3Tpuxbc.mp4</video:content_loc><video:duration>83</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/finding-input-given-function-output-formula</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x19e813a3.jpg</video:thumbnail_loc><video:title>Worked example: matching an input to a function&apos;s output (equation)</video:title><video:description>Sal finds the input value for which f(t)=13, given that f(t)=-2t+5.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tJBQZ3PUkPo.mp4/tJBQZ3PUkPo.mp4</video:content_loc><video:duration>100</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/matching-function-input-to-output-with-graph</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x71621631.jpg</video:thumbnail_loc><video:title>Worked example: matching an input to a function&apos;s output (graph)</video:title><video:description>Sal finds the input value for which g(x)=-2 given the graph of g.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0Rmmynff5Yc.mp4/0Rmmynff5Yc.mp4</video:content_loc><video:duration>67</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/different-inputs-giving-same-value-for-function</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4773a085.jpg</video:thumbnail_loc><video:title>Worked example: two inputs with the same output (graph)</video:title><video:description>Sal finds the input value other than -5 for which f(x)=f(-5), given the graph of f.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qSktOkaW6EA.mp4/qSktOkaW6EA.mp4</video:content_loc><video:duration>108</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/interpreting-function-notation-example-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf396d2ea.jpg</video:thumbnail_loc><video:title>Function notation word problem: bank</video:title><video:description>Learn how to interpret expressions that contain a function within a real-world context. In this video, the function we interpret models an account balance over time.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/HERb3x0aw6c.mp4/HERb3x0aw6c.mp4</video:content_loc><video:duration>204</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/interpreting-function-notation-example-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xeb7c9083.jpg</video:thumbnail_loc><video:title>Function notation word problem: beach</video:title><video:description>Learn how to interpret expressions that contain a function within a real-world context. In this video, the function we interpret models the number of people at the beach over time.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/94Gnto5G1PU.mp4/94Gnto5G1PU.mp4</video:content_loc><video:duration>156</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/introduction-to-interval-notation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbf5f3043.jpg</video:thumbnail_loc><video:title>Intervals and interval notation</video:title><video:description>Introducing intervals, which are bounded sets of numbers and are very useful when describing domain and range. We can use interval notation to show that a value falls between two endpoints. For example, -3≤x≤2, [-3,2], and {x∈ℝ|-3≤x≤2} all mean that x is between -3 and 2 and could be either endpoint.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/UJQkqV2zGv0.mp4/UJQkqV2zGv0.mp4</video:content_loc><video:duration>576</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/domain-of-a-function-intro</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb1c520a6.jpg</video:thumbnail_loc><video:title>What is the domain of a function?</video:title><video:description>Functions assign outputs to inputs. The domain of a function is the set of all possible inputs for the function. For example, the domain of f(x)=x² is all real numbers, and the domain of g(x)=1/x is all real numbers except for x=0. We can also define special functions whose domains are more limited.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-DTMakGDZAw.mp4/-DTMakGDZAw.mp4</video:content_loc><video:duration>405</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/range-of-a-function</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1d008f0a.jpg</video:thumbnail_loc><video:title>What is the range of a function?</video:title><video:description>The range of a function is the set of all possible outputs the function can produce. Some functions (like linear functions) can have a range of all real numbers, but lots of functions have a more limited set of possible outputs.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/96uHMcHWD2E.mp4/96uHMcHWD2E.mp4</video:content_loc><video:duration>399</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/domain-and-range-from-graphs</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1410f50a.jpg</video:thumbnail_loc><video:title>Worked example: domain and range from graph</video:title><video:description>Finding the domain and the range of a function that is given graphically.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/sXP7VhU1gYE.mp4/sXP7VhU1gYE.mp4</video:content_loc><video:duration>214</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/determine-values-domain</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8acbe884682908ed.jpg</video:thumbnail_loc><video:title>Determining whether values are in domain of function</video:title><video:description>Sal shows how to test whether or not a value is or isn&apos;t in the domain of a function.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LdbrNNheFg8.mp4/LdbrNNheFg8.mp4</video:content_loc><video:duration>297</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/find-domain-function</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x034ca9c03c9a9c64.jpg</video:thumbnail_loc><video:title>Examples finding the domain of functions</video:title><video:description>Sal shows how to algebraically find the domain of a few different functions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4ZWbeESjv4M.mp4/4ZWbeESjv4M.mp4</video:content_loc><video:duration>265</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/domain-of-a-modeling-function-example-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3607e05a.jpg</video:thumbnail_loc><video:title>Worked example: determining domain word problem (real numbers)</video:title><video:description>Determining the domain of a function that models the height of a plant over time.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2DnQEaNTd08.mp4/2DnQEaNTd08.mp4</video:content_loc><video:duration>139</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/domain-of-a-modeling-function-example-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9b3adf42.jpg</video:thumbnail_loc><video:title>Worked example: determining domain word problem (positive integers)</video:title><video:description>Determining the domain of a function that models the price of candy bars.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/AiW7syKXfJM.mp4/AiW7syKXfJM.mp4</video:content_loc><video:duration>154</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/domain-of-a-modeling-function-example-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xcba2e3a7.jpg</video:thumbnail_loc><video:title>Worked example: determining domain word problem (all integers)</video:title><video:description>Determining the domain of a function that models going up and down a ladder.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/d1O54EQ1DSE.mp4/d1O54EQ1DSE.mp4</video:content_loc><video:duration>334</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/relative-minima-maxima</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfc106389.jpg</video:thumbnail_loc><video:title>Introducing minimum and maximum points</video:title><video:description>Sal explains all about minimum and maximum points, both absolute and relative.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Hoyv3-BMAGc.mp4/Hoyv3-BMAGc.mp4</video:content_loc><video:duration>330</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/identifying-relative-and-absolute-maxima-and-minima</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8aa33a5c.jpg</video:thumbnail_loc><video:title>Worked example: absolute and relative extrema</video:title><video:description>Extrema is the general name for maximum and minimum points. This video shows how to identify relative and absolute extrema in the graph of a function.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xmrhZ5ySaD0.mp4/xmrhZ5ySaD0.mp4</video:content_loc><video:duration>298</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/increasing-decreasing-positive-and-negative-intervals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbbb7485d.jpg</video:thumbnail_loc><video:title>Increasing, decreasing, positive or negative intervals</video:title><video:description>Function values can be positive or negative, and they can increase or decrease as the input increases. Here we introduce these basic properties of functions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/KxOp3s9ottg.mp4/KxOp3s9ottg.mp4</video:content_loc><video:duration>356</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/when-a-function-is-positive-or-negative</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdf96166c.jpg</video:thumbnail_loc><video:title>Worked example: positive &amp; negative intervals</video:title><video:description>Finding the positive or negative intervals of a function from its graph.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/eDv7dk9uNmM.mp4/eDv7dk9uNmM.mp4</video:content_loc><video:duration>70</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/interpreting-function-graphs-word-problems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xadbc5422.jpg</video:thumbnail_loc><video:title>Graph interpretation word problem: temperature</video:title><video:description>When a function models a real-world context, we can learn a lot about the content from the function&apos;s graph. In this video, we consider a graph that models temperature over time.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/VtBRkjRua0I.mp4/VtBRkjRua0I.mp4</video:content_loc><video:duration>235</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/interpreting-features-of-functions-2-example-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xef8bffa5.jpg</video:thumbnail_loc><video:title>Graph interpretation word problem: basketball</video:title><video:description>When a function models a real-world context, we can learn a lot about the context from the function&apos;s graph. In this video, we interpret the y-intercept of a graph that models a basketball free throw.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/M3PTPN7NH8M.mp4/M3PTPN7NH8M.mp4</video:content_loc><video:duration>230</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/how-creative-in-algebra</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2e1ac5b89b77ae04.jpg</video:thumbnail_loc><video:title>Creativity break: How can people get creative in algebra</video:title><video:description>Experts share how we can get creative in algebra.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DXPz0-HCK80.mp4/DXPz0-HCK80.mp4</video:content_loc><video:duration>67</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/introduction-to-average-rate-of-change</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3beaa235.jpg</video:thumbnail_loc><video:title>Introduction to average rate of change</video:title><video:description>What&apos;s the average rate of change of a function over an interval?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/oT6LclcJ-I8.mp4/oT6LclcJ-I8.mp4</video:content_loc><video:duration>332</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/average-rate-of-change-example-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x50b7170d.jpg</video:thumbnail_loc><video:title>Worked example: average rate of change from graph</video:title><video:description>Finding the interval in a function&apos;s graph where the function has an average rate of change of -4.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TEXSW-o8674.mp4/TEXSW-o8674.mp4</video:content_loc><video:duration>135</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/average-rate-of-change-example-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x765678cf.jpg</video:thumbnail_loc><video:title>Worked example: average rate of change from table</video:title><video:description>Finding the average rate of change of a function over the interval -5&lt;x&lt;-2, given a table of values of the function.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/U1lQbh21y1k.mp4/U1lQbh21y1k.mp4</video:content_loc><video:duration>140</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/average-rate-of-change-from-table-word-problem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfdc54aa7.jpg</video:thumbnail_loc><video:title>Average rate of change word problem: table</video:title><video:description>Average rate of change tells us how much the function changed per a single time unit, over a specific interval. It has many real-world applications. In this video, we compare the average rate of change of temperature over different time periods.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/FBWGRbHf7rU.mp4/FBWGRbHf7rU.mp4</video:content_loc><video:duration>220</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/average-rate-of-change-from-graph-word-problem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8ae36eb0.jpg</video:thumbnail_loc><video:title>Average rate of change word problem: graph</video:title><video:description>Average rate of change tells us how much the function changed per a single time unit, over a specific interval. It has many real-world applications. In this video, we find the average rate of descent of a skydiver over a specific time interval.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-6EqUILZ1yw.mp4/-6EqUILZ1yw.mp4</video:content_loc><video:duration>418</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/introduction-to-function-inverses</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26633.jpg</video:thumbnail_loc><video:title>Intro to inverse functions</video:title><video:description>Sal explains what inverse functions are. Then he explains how to algebraically find the inverse of a function and looks at the graphical relationship between inverse functions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/W84lObmOp8M.mp4/W84lObmOp8M.mp4</video:content_loc><video:duration>545</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/understanding-inverse-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd5d133d9.jpg</video:thumbnail_loc><video:title>Inputs &amp; outputs of inverse functions</video:title><video:description>Sal explains that if f(a)=b, then f ⁻¹(b)=a, or in other words, the inverse function of f outputs a when its input is b.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/KzaPBzFFLRM.mp4/KzaPBzFFLRM.mp4</video:content_loc><video:duration>379</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/understanding-function-inverses-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2835aa81.jpg</video:thumbnail_loc><video:title>Graphing the inverse of a linear function</video:title><video:description>Sal is given a line segment on the coordinate plane, and he graphs the inverse of the function represented by that segment.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/KPeS2gdizhQ.mp4/KPeS2gdizhQ.mp4</video:content_loc><video:duration>137</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/function-inverse-example-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26634.jpg</video:thumbnail_loc><video:title>Finding inverse functions: linear</video:title><video:description>Sal finds the inverses of f(x)=-x+4 and g(x)=-2x-1.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/wSiamij_i_k.mp4/wSiamij_i_k.mp4</video:content_loc><video:duration>404</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/explicit-and-recursive-definitions-of-sequences</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1383721311.jpg</video:thumbnail_loc><video:title>Sequences intro</video:title><video:description>Sequences are ordered lists of numbers (called &quot;terms&quot;), like 2,5,8. Some sequences follow a specific pattern that can be used to extend them indefinitely. For example, 2,5,8 follows the pattern &quot;add 3,&quot; and now we can continue the sequence. Sequences can have formulas that tell us how to find any term in the sequence. For example, 2,5,8,... can be represented by the formula 2+3(n-1).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/KRFiAlo7t1E.mp4/KRFiAlo7t1E.mp4</video:content_loc><video:duration>498</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/arithmetic-sequences</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1383600767.jpg</video:thumbnail_loc><video:title>Intro to arithmetic sequences</video:title><video:description>Sal introduces arithmetic sequences and their main features, the initial term and the common difference. He gives various examples of such sequences, defined explicitly and recursively.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_cooC3yG_p0.mp4/_cooC3yG_p0.mp4</video:content_loc><video:duration>427</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/extending-arithmetic-sequences</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf18f69c4.jpg</video:thumbnail_loc><video:title>Extending arithmetic sequences</video:title><video:description>Sal extends the arithmetic sequences -8, -14, -20, -26,... and 2, -1, -4, -7, -10,... to find their next terms.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/EU0c6qrrevA.mp4/EU0c6qrrevA.mp4</video:content_loc><video:duration>67</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/using-arithmetic-sequences-formulas</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3fb279c6.jpg</video:thumbnail_loc><video:title>Using arithmetic sequences formulas</video:title><video:description>Sal finds terms of arithmetic sequences using their explicit and recursive formulas.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8eSUbi_aYL4.mp4/8eSUbi_aYL4.mp4</video:content_loc><video:duration>218</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/using-recursive-formula-for-arithmetic-sequence</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0ffef60ab9a90d3f.jpg</video:thumbnail_loc><video:title>Worked example: using recursive formula for arithmetic sequence</video:title><video:description>Example finding the 4th term in a recursively defined arithmetic sequence.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/v1ucHH06AxM.mp4/v1ucHH06AxM.mp4</video:content_loc><video:duration>172</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/recursive-formula-for-arithmetic-sequence</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfcb4de1d.jpg</video:thumbnail_loc><video:title>Recursive formulas for arithmetic sequences</video:title><video:description>Sal finds the recursive formula of the arithmetic sequence 4, 3⅘, 3⅗, 3⅖,...</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lBtb30SjU2Q.mp4/lBtb30SjU2Q.mp4</video:content_loc><video:duration>186</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/explicit-formulas-for-arithmetic-sequences</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf3b43d64.jpg</video:thumbnail_loc><video:title>Explicit formulas for arithmetic sequences</video:title><video:description>Sal finds explicit formulas of arithmetic sequences given the first few terms of those sequences. He also explores equivalent forms of such formulas.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ViLt2WI0XSg.mp4/ViLt2WI0XSg.mp4</video:content_loc><video:duration>377</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/finding-the-100th-term-in-a-sequence</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26789.jpg</video:thumbnail_loc><video:title>Arithmetic sequence problem</video:title><video:description>Sal finds the 100th term in the sequence 15, 9, 3, -3...</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/C5titprQAc4.mp4/C5titprQAc4.mp4</video:content_loc><video:duration>357</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/recursive-formulas-for-arithmetic-sequences</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2b3ba86f.jpg</video:thumbnail_loc><video:title>Converting recursive &amp; explicit forms of arithmetic sequences</video:title><video:description>Sal is given an arithmetic sequence in explicit form and he converts it to recursive form. Then he does so the other way around!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/GA_yxxeFYBU.mp4/GA_yxxeFYBU.mp4</video:content_loc><video:duration>368</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/geometric-sequences-introduction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23698.jpg</video:thumbnail_loc><video:title>Intro to geometric sequences</video:title><video:description>Sal introduces geometric sequences and their main features, the initial term and the common ratio.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pXo0bG4iAyg.mp4/pXo0bG4iAyg.mp4</video:content_loc><video:duration>645</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/extending-geometric-sequences</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3a8fd24d.jpg</video:thumbnail_loc><video:title>Extending geometric sequences</video:title><video:description>Sal finds the next term in the geometric sequence -1/32, 1/8, -1/2, 2,...</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/yZ-GufE_uyA.mp4/yZ-GufE_uyA.mp4</video:content_loc><video:duration>134</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/using-explicit-formulas-of-geometric-sequences</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4ebafa27.jpg</video:thumbnail_loc><video:title>Using explicit formulas of geometric sequences</video:title><video:description>Sal finds the 5th term in the geometric sequence whose explicit formula is 3(-¼)^(i-1).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/HODIXLzIMIk.mp4/HODIXLzIMIk.mp4</video:content_loc><video:duration>97</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/using-recursive-formulas-of-geometric-sequences</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0e585ad5.jpg</video:thumbnail_loc><video:title>Using recursive formulas of geometric sequences</video:title><video:description>Sal finds the 4th term in the sequence whose recursive formula is a(1)=-⅛, a(i)=2a(i-1).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/RkJBZALhXRA.mp4/RkJBZALhXRA.mp4</video:content_loc><video:duration>226</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/explicit-and-recursive-formulas-for-geometric-sequences</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0c2d51aa.jpg</video:thumbnail_loc><video:title>Explicit &amp; recursive formulas for geometric sequences</video:title><video:description>Sal finds an explicit formula of a geometric sequence given the first few terms of the sequences. Then he explores equivalent forms the explicit formula and finds the corresponding recursive formula.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8a1a5A3CfdQ.mp4/8a1a5A3CfdQ.mp4</video:content_loc><video:duration>338</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/converting-an-explicit-function-to-a-recursive-function</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9e46afe9.jpg</video:thumbnail_loc><video:title>Converting recursive &amp; explicit forms of geometric sequences</video:title><video:description>Sal solves the following problem: The explicit formula of a geometric sequence is g(x)=9*8^(x-1). Find the recursive formula of the sequence.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Iq7a2vEsT-o.mp4/Iq7a2vEsT-o.mp4</video:content_loc><video:duration>390</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/modeling-situations-with-arithmetic-and-geometric-sequences</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7149cb33.jpg</video:thumbnail_loc><video:title>Sequences word problems</video:title><video:description>Sal solves two word problems about modeling real-world situations with arithmetic and geometric sequences.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/yYGf7xn7TyM.mp4/yYGf7xn7TyM.mp4</video:content_loc><video:duration>343</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/recursive-formulas-for-sequences</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x901988c5.jpg</video:thumbnail_loc><video:title>Evaluating sequences in recursive form</video:title><video:description>Sal shows how to evaluate a sequence that is defined with a recursive formula. This definition gives the base case and then defines how to find the subsequent terms using the base case.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Kjli0Gunkds.mp4/Kjli0Gunkds.mp4</video:content_loc><video:duration>547</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/sequences-and-domain</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0c1b541142bd4db2.jpg</video:thumbnail_loc><video:title>Sequences and domain</video:title><video:description>We can generate the same sequence with different functions and different domains.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TymkzM7J1PY.mp4/TymkzM7J1PY.mp4</video:content_loc><video:duration>376</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/shifting-absolute-value-graphs</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0d6890ee04b473f5.jpg</video:thumbnail_loc><video:title>Shifting absolute value graphs</video:title><video:description>The graph of y=|x-h|+k is the graph of y=|x| shifted h units to the right and k units up. See worked examples practicing this relationship.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Wri26sPEBoI.mp4/Wri26sPEBoI.mp4</video:content_loc><video:duration>372</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/reflecting-and-scaling-absolute-value-function</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9c13b4008f199f84.jpg</video:thumbnail_loc><video:title>Scaling &amp; reflecting absolute value functions: equation</video:title><video:description>The graph of y=k|x| is the graph of y=|x| scaled by a factor of |k|. If k&lt;0, it&apos;s also reflected (or &quot;flipped&quot;) across the x-axis. In this worked example, we find the equation of an absolute value function from a description of the transformation performed on y=|x|.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lPcahMeUYcU.mp4/lPcahMeUYcU.mp4</video:content_loc><video:duration>253</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/scaling-and-reflecting-absolute-value-graphs</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x42691af83250ee2e.jpg</video:thumbnail_loc><video:title>Scaling &amp; reflecting absolute value functions: graph</video:title><video:description>The graph of y=k|x| is the graph of y=|x| scaled by a factor of |k|. If k&lt;0, it&apos;s also reflected (or &quot;flipped&quot;) across the x-axis. In this worked example, we find the equation of an absolute value function from its graph.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Yyfk0rwuZSE.mp4/Yyfk0rwuZSE.mp4</video:content_loc><video:duration>208</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/graphing-absolute-value-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x196b1cad71b2fcb4.jpg</video:thumbnail_loc><video:title>Graphing absolute value functions</video:title><video:description>We can graph any absolute value equation of the form y=k|x-a|+h by thinking about function transformations (horizontal shifts, vertical shifts, reflections, and scalings).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/v6Ct2OEmGNU.mp4/v6Ct2OEmGNU.mp4</video:content_loc><video:duration>371</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/piecewise-function-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x931bced2.jpg</video:thumbnail_loc><video:title>Introduction to piecewise functions</video:title><video:description>A piecewise function is a function built from pieces of different functions over different intervals. For example, we can make a piecewise function f(x) where f(x) = -9 when -9 &lt; x ≤ -5, f(x) = 6 when -5 &lt; x ≤ -1, and f(x) = -7 when -1</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tedzsRH0Jas.mp4/tedzsRH0Jas.mp4</video:content_loc><video:duration>229</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/evaluating-piecewise-functions-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x84b71dc7.jpg</video:thumbnail_loc><video:title>Worked example: evaluating piecewise functions</video:title><video:description>A piecewise function is a function that is defined in separate &quot;pieces&quot; or intervals. For each region or interval, the function may have a different equation or rule that describes it. We can evaluate piecewise functions (find the value of the function) by using their formulas or their graphs.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hg2HR9zJFq4.mp4/hg2HR9zJFq4.mp4</video:content_loc><video:duration>264</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/graphing-piecewise-function</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5db71766.jpg</video:thumbnail_loc><video:title>Worked example: graphing piecewise functions</video:title><video:description>A piecewise function is a function that is defined in separate &quot;pieces&quot; or intervals. For each region or interval, the function may have a different equation or rule that describes it. We can graph a piecewise function by graphing each individual piece.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PQiXRrT_14o.mp4/PQiXRrT_14o.mp4</video:content_loc><video:duration>270</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/domain-and-range-for-piecewise-step-function</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd42a1ea3.jpg</video:thumbnail_loc><video:title>Worked example: domain &amp; range of step function</video:title><video:description>Finding the domain and range of a piecewise function that is constant in each segment. Such functions are called &quot;step functions.&quot;</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4n7TIvRHuDs.mp4/4n7TIvRHuDs.mp4</video:content_loc><video:duration>164</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/domain-and-range-for-piecewise-linear-function</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xae914f2c.jpg</video:thumbnail_loc><video:title>Worked example: domain &amp; range of piecewise linear functions</video:title><video:description>Finding the domain and range of a piecewise function where each segment is linear.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/rpI-X9Gn5a4.mp4/rpI-X9Gn5a4.mp4</video:content_loc><video:duration>445</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/understanding-square-roots</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/2600694.jpg</video:thumbnail_loc><video:title>Understanding square roots</video:title><video:description>Learn how square root means what number multiplied by itself will result in the given number.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ROIfbUQrSY4.mp4/ROIfbUQrSY4.mp4</video:content_loc><video:duration>81</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/5th-roots</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7fb0bb70951d6897.jpg</video:thumbnail_loc><video:title>5th roots</video:title><video:description>5th roots</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8wrtyW1RwNk.mp4/8wrtyW1RwNk.mp4</video:content_loc><video:duration>261</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/simplifying-square-roots-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x18b09b45.jpg</video:thumbnail_loc><video:title>Simplifying square roots</video:title><video:description>Roots are nice, but we prefer dealing with regular numbers as much as possible. So, for example, instead of √4 we prefer dealing with 2. What about roots that aren&apos;t equal to an integer, like √20? Still, we can write 20 as 4⋅5 and then use known properties to write √(4⋅5) as √4⋅√5, which is 2√5. We *simplified* √20.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/cw3mp8oNASk.mp4/cw3mp8oNASk.mp4</video:content_loc><video:duration>189</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/simplifying-square-roots-comment-response</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/126711576.jpg</video:thumbnail_loc><video:title>Simplifying square roots (variables)</video:title><video:description>A worked example of simplifying radical with a variable in it. In this example, we simplify 3√(500x³).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qFFhdLlX220.mp4/qFFhdLlX220.mp4</video:content_loc><video:duration>256</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/simplifying-square-root-expressions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0f8a3173e33fabc3.jpg</video:thumbnail_loc><video:title>Simplifying square-root expressions</video:title><video:description>Worked examples of taking expressions with square roots and taking all of the perfect squares out of the square roots. For example, 2√(7x)⋅3√(14x²) can be written as 42x√(2x).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3MijXB91DVo.mp4/3MijXB91DVo.mp4</video:content_loc><video:duration>510</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/exponential-growth-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23694.jpg</video:thumbnail_loc><video:title>Intro to exponential functions</video:title><video:description>An exponential function represents the relationship between an input and output, where we use repeated multiplication on an initial value to get the output for any given input. Exponential functions can grow or decay very quickly. Exponential functions are often used to model things in the real world, such as populations, radioactive materials, and compound interest.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6WMZ7J0wwMI.mp4/6WMZ7J0wwMI.mp4</video:content_loc><video:duration>461</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/exponential-vs-linear-growth</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe7727adf4e991d4c.jpg</video:thumbnail_loc><video:title>Exponential vs. linear growth</video:title><video:description>For constant increments in x, a linear growth would increase by a constant difference, and an exponential growth would increase by a constant ratio.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_vlXdx-CqM0.mp4/_vlXdx-CqM0.mp4</video:content_loc><video:duration>185</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/linear-exponential-models</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9c757281.jpg</video:thumbnail_loc><video:title>Exponential vs. linear models: verbal</video:title><video:description>Linear growth occurs at a constant rate, with equal increments added or subtracted over time, while exponential growth involves a constant multiplier that drives an increase or decrease over time. We can look at the type of change over time to see if given example represents linear or exponential growth.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8OHEgD6YMBw.mp4/8OHEgD6YMBw.mp4</video:content_loc><video:duration>208</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/exponential-vs-linear-models</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x72dd6e08bd99f9cc.jpg</video:thumbnail_loc><video:title>Exponential vs. linear models: table</video:title><video:description>Determining whether real world model is linear or exponential, where the model is given as a table.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tV0NNJ6ndgk.mp4/tV0NNJ6ndgk.mp4</video:content_loc><video:duration>206</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/exponential-expressions-word-problems-numerical</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7f3f1edc036a1eb0.jpg</video:thumbnail_loc><video:title>Exponential expressions word problems (numerical)</video:title><video:description>Given the description of a real-world context, we write a calculation of a certain measure. The expression is exponential because it involves repeated multiplication.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/L70UJVjc-bc.mp4/L70UJVjc-bc.mp4</video:content_loc><video:duration>296</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/initial-value-and-common-ratio-of-exponential-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x93e0cc1c.jpg</video:thumbnail_loc><video:title>Initial value &amp; common ratio of exponential functions</video:title><video:description>In an exponential function of the form f(x) = a*b^x, the initial value is usually taken to be the value of f(0), or &quot;a&quot;. The common ratio refers to the rate of change in an exponential function. In the form given above, the common ratio is &quot;b&quot;. For example, in the function f(x) = 2*3^x, the initial value is 2 and the common ratio is 3.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/G2WybA4Hf7Y.mp4/G2WybA4Hf7Y.mp4</video:content_loc><video:duration>327</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/exponential-expressions-word-problems-algebraic</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xecc63cbc09fbd99f.jpg</video:thumbnail_loc><video:title>Exponential expressions word problems (algebraic)</video:title><video:description>Given a real-world context that involves repeated multiplication, we model it with an exponential function.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Z3YVZzCEi_A.mp4/Z3YVZzCEi_A.mp4</video:content_loc><video:duration>216</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/interpreting-exponential-expression-word-problem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x178f92593558693f.jpg</video:thumbnail_loc><video:title>Interpreting exponential expression word problem</video:title><video:description>Given an exponential function that models a real-world context, we interpret it to see what each part of the function represents in the real world.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Pud5ygp6H38.mp4/Pud5ygp6H38.mp4</video:content_loc><video:duration>165</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/graphing-exponential-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/364954029.jpg</video:thumbnail_loc><video:title>Exponential function graph</video:title><video:description>We can graph an exponential function, like y=5ˣ, by picking a few inputs (x-values) and finding their corresponding outputs (y-values). We&apos;ll see that an exponential function has a horizontal asymptote in one direction and rapidly changes in the other direction.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9SOSfRNCQZQ.mp4/9SOSfRNCQZQ.mp4</video:content_loc><video:duration>332</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/graphs-of-exponential-growth</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x522467b5f5f47522.jpg</video:thumbnail_loc><video:title>Graphs of exponential growth</video:title><video:description>Identifying which graph represents a given exponential function.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6rX2VNybXEE.mp4/6rX2VNybXEE.mp4</video:content_loc><video:duration>261</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/exponential-vs-linear-growth-over-time</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x068cd70493de8f71.jpg</video:thumbnail_loc><video:title>Exponential vs. linear growth over time</video:title><video:description>If we compare linear and exponential growth, we will see that over time, *any* exponential growth will surpass *any* linear growth, no matter how steep it is.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/cwnke_pjX90.mp4/cwnke_pjX90.mp4</video:content_loc><video:duration>305</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/exponential-decay-intro</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x915aa47aea7bedc6.jpg</video:thumbnail_loc><video:title>Exponential decay intro</video:title><video:description>Both exponential growth and decay functions involve repeated multiplication by a constant factor. However, the difference lies in the size of that factor: - In an exponential growth function, the factor is greater than 1, so the output will increase (or &quot;grow&quot;) over time. - In an exponential decay function, the factor is between 0 and 1, so the output will decrease (or &quot;decay&quot;) over time.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/v4IdaXvyE7U.mp4/v4IdaXvyE7U.mp4</video:content_loc><video:duration>492</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/graphing-basic-exponential-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0c59dbab.jpg</video:thumbnail_loc><video:title>Graphing exponential growth &amp; decay</video:title><video:description>Graphing the exponential functions y=27⋅(⅓)ˣ and y=-30⋅2ˣ.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/RVv0Jgi3Pbw.mp4/RVv0Jgi3Pbw.mp4</video:content_loc><video:duration>246</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/writing-functions-exponential-decay</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9c458523bb3a9600.jpg</video:thumbnail_loc><video:title>Writing functions with exponential decay</video:title><video:description>We can write a function to model exponential decay in a context.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/cgZJU38j8-U.mp4/cgZJU38j8-U.mp4</video:content_loc><video:duration>240</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/writing-exponential-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xcd02b076.jpg</video:thumbnail_loc><video:title>Writing exponential functions</video:title><video:description>Writing the exponential function whose initial value is -2 and common ratio is 1/7.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/UgLfAb_aFt4.mp4/UgLfAb_aFt4.mp4</video:content_loc><video:duration>100</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/constructing-linear-and-exponential-functions-from-data</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6c7009f6.jpg</video:thumbnail_loc><video:title>Writing exponential functions from tables</video:title><video:description>Both linear equations and exponential equations represent relationships between two variables. However, the way that the variables are related to each other in each type of equation is different. A linear equation can be thought of as representing repeated addition on an initial value, while an exponential equation can be thought of as representing repeated multiplication on an initial value.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Qst1UVtq8pE.mp4/Qst1UVtq8pE.mp4</video:content_loc><video:duration>317</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/constructing-linear-and-exponential-functions-from-graph</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x94bf277a.jpg</video:thumbnail_loc><video:title>Writing exponential functions from graphs</video:title><video:description>Given a graph of a line, we can write a linear function in the form y=mx+b by identifying the slope (m) and y-intercept (b) in the graph. GIven a graph of an exponential curve, we can write an exponential function in the form y=ab^x by identifying the common ratio (b) and y-intercept (a) in the graph.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gFdh_rE2XgU.mp4/gFdh_rE2XgU.mp4</video:content_loc><video:duration>445</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/analyzing-tables-of-exponential-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8643e384.jpg</video:thumbnail_loc><video:title>Analyzing tables of exponential functions</video:title><video:description>Here is how we can write an equation for an exponential function from a table of values: 1. Determine the common ratio. For example, if we see that every time x increases by 1, y is multiplied by 2, then the common ratio is 2. 2. Find the initial value of the function, or the y-intercept. This is the y-value when x=0. 3. Write the equation in the form y = ab^x, where a is the initial value and b is the common ratio.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/yOqhKOicqhU.mp4/yOqhKOicqhU.mp4</video:content_loc><video:duration>440</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/analyzing-graph-of-exponential-function</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd6c50c3c.jpg</video:thumbnail_loc><video:title>Analyzing graphs of exponential functions</video:title><video:description>Given the graph of an exponential function, Sal finds the formula of the function and a value that is outside the graph.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/fe1Hsqyetzk.mp4/fe1Hsqyetzk.mp4</video:content_loc><video:duration>246</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/analyzing-exponential-graph-with-negative-initial-value</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe38de1db.jpg</video:thumbnail_loc><video:title>Analyzing graphs of exponential functions: negative initial value</video:title><video:description>Given the graph of an exponential function with a negative initial value, Sal finds the formula of the function and solves an equation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/No1LKevjF6U.mp4/No1LKevjF6U.mp4</video:content_loc><video:duration>367</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/modeling-ticket-fines-with-exponential-function</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd71282d5.jpg</video:thumbnail_loc><video:title>Modeling with basic exponential functions word problem</video:title><video:description>Sal solves a word problem where he models the growth of a speeding ticket fine over time as an exponential function, and then interprets this model.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2iZXFd_ZImA.mp4/2iZXFd_ZImA.mp4</video:content_loc><video:duration>337</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/linear-and-exponential-growth-from-data</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x774a385f.jpg</video:thumbnail_loc><video:title>Linear vs. exponential growth: from data</video:title><video:description>Sal constructs functions that model the growth of trees over time. To do that, he identifies which growth is linear and which is exponential.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/721RrH6auoU.mp4/721RrH6auoU.mp4</video:content_loc><video:duration>357</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/exponential-model-from-data</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe9df159d.jpg</video:thumbnail_loc><video:title>Linear vs. exponential growth: from data (example 2)</video:title><video:description>Sal constructs a function that models cooling water. To do that, he decides whether the function is linear or exponential.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/edwZDu94wNs.mp4/edwZDu94wNs.mp4</video:content_loc><video:duration>416</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/polynomials-intro</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x34127be666be8d0e.jpg</video:thumbnail_loc><video:title>Polynomials intro</video:title><video:description>This introduction to polynomials covers common terminology like terms, degree, standard form, monomial, binomial and trinomial.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Vm7H0VTlIco.mp4/Vm7H0VTlIco.mp4</video:content_loc><video:duration>648</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/multiply-monomials-polynomials-area-model</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0877cbe9e5c706b7.jpg</video:thumbnail_loc><video:title>Multiply monomials by polynomials: Area model</video:title><video:description>We can use an area model to multiply a polynomial by a single term.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/wznE1wlmhR0.mp4/wznE1wlmhR0.mp4</video:content_loc><video:duration>246</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/area-model-for-multiplying-binomials</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x58a3c2e0.jpg</video:thumbnail_loc><video:title>Multiplying binomials: area model</video:title><video:description>Sal expresses the area of a rectangle whose height is x+2 and width is x+3.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/oOTFGdjhqqM.mp4/oOTFGdjhqqM.mp4</video:content_loc><video:duration>235</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/multiplying-simple-binomials</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc1613c4e.jpg</video:thumbnail_loc><video:title>Multiplying binomials intro</video:title><video:description>Sal expresses (x-4)(x+7) as the standard trinomial x²+3x-28 and discusses how the general product (x+a)(x+b) can be written as x²+(a+b)x+a*b.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Xy8NKUoyy98.mp4/Xy8NKUoyy98.mp4</video:content_loc><video:duration>287</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/multiplying-binomials</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179518.jpg</video:thumbnail_loc><video:title>Multiplying binomials</video:title><video:description>Sal expresses the product (3x+2)(5x-7) as 15x²-11x-14.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ZMLFfTX615w.mp4/ZMLFfTX615w.mp4</video:content_loc><video:duration>347</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/factors-and-divisibility-in-algebra</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xef13fe32.jpg</video:thumbnail_loc><video:title>Intro to factors &amp; divisibility</video:title><video:description>Sal explains what it means for a polynomial to be a factor of another polynomial, and what it means for a polynomial to be divisible by another polynomial.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/SjN3_xCJamA.mp4/SjN3_xCJamA.mp4</video:content_loc><video:duration>326</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/factor-by-grouping-and-factoring-completely</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23714.jpg</video:thumbnail_loc><video:title>Intro to grouping</video:title><video:description>Sal introduces the method of grouping, which is very useful in factoring quadratics whose leading coefficient is not 1.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/X7B_tH4O-_s.mp4/X7B_tH4O-_s.mp4</video:content_loc><video:duration>837</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/factoring-trinomials-by-grouping-4</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26986.jpg</video:thumbnail_loc><video:title>Factoring quadratics by grouping</video:title><video:description>Sal factors 4y^2+4y-15 as (2y-3)(2y+5) by grouping.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/u1SAo2GiX8A.mp4/u1SAo2GiX8A.mp4</video:content_loc><video:duration>235</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/factoring-trinomials-by-grouping-5</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26987.jpg</video:thumbnail_loc><video:title>Factoring quadratics: common factor + grouping</video:title><video:description>Sal factors 35k^2+100k-15 as 5(k+3)(7k-1).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/R-rhSQzFJL0.mp4/R-rhSQzFJL0.mp4</video:content_loc><video:duration>286</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/factoring-trinomials-by-grouping-6</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26988.jpg</video:thumbnail_loc><video:title>Factoring quadratics: negative common factor + grouping</video:title><video:description>Sal factors -12f^2-38f+22 as -2(2f-1)(3f+11).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/d-2Lcp0QKfI.mp4/d-2Lcp0QKfI.mp4</video:content_loc><video:duration>317</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/combine-ways-of-thinking-in-problem-solving</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe95b118c5ccddcda.jpg</video:thumbnail_loc><video:title>Creativity break: How can we combine ways of thinking in problem solving?</video:title><video:description>Experts share how they combine ways of thinking to solve complex problems.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jAyqOcNurGU.mp4/jAyqOcNurGU.mp4</video:content_loc><video:duration>151</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/factoring-to-produce-difference-of-squares</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x828e9a9a.jpg</video:thumbnail_loc><video:title>Factoring difference of squares: leading coefficient ≠ 1</video:title><video:description>Sal factors 45x^2-125 as 5(3x+5)(3x-5).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jmbg-DKWuc4.mp4/jmbg-DKWuc4.mp4</video:content_loc><video:duration>143</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/equivalent-expressions-to-differences-of-squares</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x80330a14.jpg</video:thumbnail_loc><video:title>Factoring difference of squares: analyzing factorization</video:title><video:description>Sal analyzes two different factorizations of 16x^2-64 and determines whether they are correct.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TK-U1p9O6Nc.mp4/TK-U1p9O6Nc.mp4</video:content_loc><video:duration>189</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/finding-a-shared-binomial-factor</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5d12a4f8.jpg</video:thumbnail_loc><video:title>Factoring difference of squares: shared factors</video:title><video:description>Sal finds the binomial factor shared by m^2-4m-45 and 6m^2-150.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xYQR2LNZLeU.mp4/xYQR2LNZLeU.mp4</video:content_loc><video:duration>263</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/shared-binomial-factor-between-perfect-square-and-difference-of-squares</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x67daeb72.jpg</video:thumbnail_loc><video:title>Factoring perfect squares: shared factors</video:title><video:description>Sal finds the binomial factor shared by 4x^2+12x+9 and 4x^2-9.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6jZZ6EeE-j0.mp4/6jZZ6EeE-j0.mp4</video:content_loc><video:duration>266</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/strategy-in-factoring-quadratics-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x797baa764c018152.jpg</video:thumbnail_loc><video:title>Strategy in factoring quadratics (part 1 of 2)</video:title><video:description>There are a lot of methods to factor quadratics, which apply on different occasions and conditions. After learning all of them in separate, let&apos;s think strategically about which method is useful for a given quadratic expression we want to factor.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2hHyY1eyHQs.mp4/2hHyY1eyHQs.mp4</video:content_loc><video:duration>432</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/strategy-in-factoring-quadratics-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x82bceac4add1dc85.jpg</video:thumbnail_loc><video:title>Strategy in factoring quadratics (part 2 of 2)</video:title><video:description>There are a lot of methods to factor quadratics, which apply on different occasions and conditions. After learning all of them in separate, let&apos;s think strategically about which method is useful for a given quadratic expression we want to factor.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ahPdiNQGXRA.mp4/ahPdiNQGXRA.mp4</video:content_loc><video:duration>521</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/parabolas-intro</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3ffe2e08365a9116.jpg</video:thumbnail_loc><video:title>Parabolas intro</video:title><video:description>Graphs of quadratic functions all have the same shape which we call &quot;parabola.&quot; All parabolas have shared characteristics. For example, they are all symmetric about a line that passes through their vertex. This video covers this and other basic facts about parabolas.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/BGz3pkoGPag.mp4/BGz3pkoGPag.mp4</video:content_loc><video:duration>494</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/interpret-parabola-context</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x10ab3ee853e280f3.jpg</video:thumbnail_loc><video:title>Interpreting a parabola in context</video:title><video:description>Given a parabola that models a context, we can relate key features of the parabola — like the y-intercept, vertex, and x-intercepts — to what they represent in the given context.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_Bk6XkV9O_0.mp4/_Bk6XkV9O_0.mp4</video:content_loc><video:duration>154</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/interpret-a-quadratic-graph</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfeb705aa7b75cee2.jpg</video:thumbnail_loc><video:title>Interpret a quadratic graph</video:title><video:description>We can interpret what the features of a graph of a quadratic model mean in terms of a given context.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Tqxu53deWCo.mp4/Tqxu53deWCo.mp4</video:content_loc><video:duration>157</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/zero-product-property</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x556b284b8e003b36.jpg</video:thumbnail_loc><video:title>Zero product property</video:title><video:description>The zero product property states that if a⋅b=0 then either a or b equal zero. This basic property helps us solve equations like (x+2)(x-5)=0.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-lWVpoPaPBc.mp4/-lWVpoPaPBc.mp4</video:content_loc><video:duration>437</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/graphing-quadratics-in-factored-form</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8456dafc88a8915f.jpg</video:thumbnail_loc><video:title>Graphing quadratics in factored form</video:title><video:description>An example for a quadratic function in factored form is y=½(x-6)(x+2). We can analyze this form to find the x-intercepts of the graph, as well as find the vertex.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/EV57jv7JKCs.mp4/EV57jv7JKCs.mp4</video:content_loc><video:duration>363</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/quadratic-word-problems-factored-form</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9b8c4618ba35e3de.jpg</video:thumbnail_loc><video:title>Quadratic word problems (factored form)</video:title><video:description>Solving a problem where a quadratic function (given in factored form) models the height of a launched rocket.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xVZA6NOQA7A.mp4/xVZA6NOQA7A.mp4</video:content_loc><video:duration>335</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/simple-quadratic-equation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/150088074.jpg</video:thumbnail_loc><video:title>Solving quadratics by taking square roots</video:title><video:description>Sal solves the equation 2x^2+3=75 by isolating x^2 and taking the square root of both sides.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/RweAgQwLdMs.mp4/RweAgQwLdMs.mp4</video:content_loc><video:duration>138</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/solving-quadratics-by-taking-square-roots</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7a55a0a8.jpg</video:thumbnail_loc><video:title>Solving quadratics by taking square roots examples</video:title><video:description>Sal solves the equation (x+3)²-4=0 and finds the x-intercepts of f(x)=(x-2)²-9.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/VTlvg4wJ1X0.mp4/VTlvg4wJ1X0.mp4</video:content_loc><video:duration>312</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/determining-mistakes-in-steps-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf7eacd77.jpg</video:thumbnail_loc><video:title>Quadratics by taking square roots: strategy</video:title><video:description>Sal analyzes a given solution of a quadratic equation, and finds where and what was the error in that process.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jtPvDycHVQw.mp4/jtPvDycHVQw.mp4</video:content_loc><video:duration>105</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/order-of-steps-exercise-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x947b1dd9.jpg</video:thumbnail_loc><video:title>Solving quadratics by taking square roots: with steps</video:title><video:description>Sal discusses the exact order of steps in the process of solving the equation 3(x+6)^2=75.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/naVFTNWVlQU.mp4/naVFTNWVlQU.mp4</video:content_loc><video:duration>265</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/vertex-form-intro</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x920ee4c2b9181777.jpg</video:thumbnail_loc><video:title>Vertex form introduction</video:title><video:description>One of the common forms for quadratic functions is called vertex form, because it highlights the coordinates of the vertex of the function&apos;s graph.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_QqhuLixNEk.mp4/_QqhuLixNEk.mp4</video:content_loc><video:duration>373</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/graphing-a-parabola-in-vertex-form</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xac1e66a2.jpg</video:thumbnail_loc><video:title>Graphing quadratics: vertex form</video:title><video:description>Learn how to graph any quadratic function that is given in vertex form. Here, Sal graphs y=-2(x-2)²+5.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7QMoNY6FzvM.mp4/7QMoNY6FzvM.mp4</video:content_loc><video:duration>196</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/quadratic-word-problems-in-vertex-form</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6e498f765d2f765d.jpg</video:thumbnail_loc><video:title>Quadratic word problems (vertex form)</video:title><video:description>Given a quadratic function that models the height of an object being launched from a platform, we analyze the function to answer questions like &quot;what is the height of the platform?&quot; or &quot;when does the object reach its maximum height?&quot;</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lUA1LYCoIAg.mp4/lUA1LYCoIAg.mp4</video:content_loc><video:duration>423</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/example-1-solving-a-quadratic-equation-by-factoring</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26992.jpg</video:thumbnail_loc><video:title>Solving quadratics by factoring</video:title><video:description>Sal solves the equation s^2-2s-35=0 by factoring the expression on the left as (s+5)(s-7) and finding the s-values that make each factor equal to zero.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2ZzuZvz33X0.mp4/2ZzuZvz33X0.mp4</video:content_loc><video:duration>382</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/solving-quadratics-by-dividing-and-factoring</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9d3269d7.jpg</video:thumbnail_loc><video:title>Solving quadratics by factoring: leading coefficient ≠ 1</video:title><video:description>Sal solves 6x²-120x+600=0 by first dividing by 6 and then factoring.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/KbFwLvCOBUI.mp4/KbFwLvCOBUI.mp4</video:content_loc><video:duration>275</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/using-structure-to-solve-quadratics</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3579f012.jpg</video:thumbnail_loc><video:title>Solving quadratics using structure</video:title><video:description>Sal solves (2x-3)^2=4x-6 by substituting p for 2x-3 and obtaining the simpler equation p^2=2p.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ZIqW_sXymrM.mp4/ZIqW_sXymrM.mp4</video:content_loc><video:duration>235</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/example-4-solving-a-quadratic-equation-by-factoring</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179588.jpg</video:thumbnail_loc><video:title>Quadratic equations word problem: triangle dimensions</video:title><video:description>Sal solves a geometry problem using a quadratic equation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/STcsaKuW-24.mp4/STcsaKuW-24.mp4</video:content_loc><video:duration>501</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/example-3-solving-a-quadratic-equation-by-factoring</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26994.jpg</video:thumbnail_loc><video:title>Quadratic equations word problem: box dimensions</video:title><video:description>Sal solves a volume problem using a quadratic equation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vl9o9XEfXtw.mp4/vl9o9XEfXtw.mp4</video:content_loc><video:duration>354</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/using-the-quadratic-formula</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23724.jpg</video:thumbnail_loc><video:title>The quadratic formula</video:title><video:description>The quadratic formula helps us solve any quadratic equation. First, we bring the equation to the form ax²+bx+c=0, where a, b, and c are coefficients. Then, we plug these coefficients in the formula: (-b±√(b²-4ac))/(2a) . See examples of using the formula to solve a variety of equations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/i7idZfS8t8w.mp4/i7idZfS8t8w.mp4</video:content_loc><video:duration>992</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/quadratic-formula-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/27003.jpg</video:thumbnail_loc><video:title>Worked example: quadratic formula (example 2)</video:title><video:description>Sal solves the equation -x^2+8x=1 by first bringing it to standard form and then using the quadratic formula.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/CLrImGKeuEI.mp4/CLrImGKeuEI.mp4</video:content_loc><video:duration>400</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/applying-the-quadratic-formula</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/150088073.jpg</video:thumbnail_loc><video:title>Worked example: quadratic formula (negative coefficients)</video:title><video:description>Sal solves -3x^2+10x-3=0 by plugging a=-3, b=10, c=-3 in the quadratic formula. Then he multiplies everything by -1 and solves again. The results are the same!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_E3gx_yQhHQ.mp4/_E3gx_yQhHQ.mp4</video:content_loc><video:duration>291</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/quadratic-formula-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/27004.jpg</video:thumbnail_loc><video:title>Using the quadratic formula: number of solutions</video:title><video:description>Sal determines how many solutions the equation x²+14x+49=0 has by considering its quadratic formula, and more specifically, its discriminant.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/XUvKjC21fYU.mp4/XUvKjC21fYU.mp4</video:content_loc><video:duration>299</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/solving-quadratic-equations-by-completing-the-square</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23722.jpg</video:thumbnail_loc><video:title>Completing the square</video:title><video:description>Some quadratic expressions can be factored as perfect squares. For example, x²+6x+9=(x+3)². However, even if an expression isn&apos;t a perfect square, we can turn it into one by adding a constant number. For example, x²+6x+5 isn&apos;t a perfect square, but if we add 4 we get (x+3)². This, in essence, is the method of *completing the square*</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/bNQY0z76M5A.mp4/bNQY0z76M5A.mp4</video:content_loc><video:duration>846</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/ex1-completing-the-square</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26998.jpg</video:thumbnail_loc><video:title>Worked example: Completing the square (intro)</video:title><video:description>Sal completes x²-44x into a perfect square.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/VvuuRpJbbHE.mp4/VvuuRpJbbHE.mp4</video:content_loc><video:duration>202</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/rewriting-quadratics-as-perfect-squares</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfa51b4a3.jpg</video:thumbnail_loc><video:title>Worked example: Rewriting expressions by completing the square</video:title><video:description>Sal rewrites x²+16x+9 as (x+8)²-55 by completing the square.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/sh-MP-dVhD4.mp4/sh-MP-dVhD4.mp4</video:content_loc><video:duration>182</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/solving-quadratics-by-completing-the-square</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf7adc86f.jpg</video:thumbnail_loc><video:title>Worked example: Rewriting &amp; solving equations by completing the square</video:title><video:description>Sal solves x²-2x-8=0 by rewriting the equation as (x-1)²-9=0 (which is done by completing the square!).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/KouDAzYl_bc.mp4/KouDAzYl_bc.mp4</video:content_loc><video:duration>379</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/solve-completing-square-integer-solutions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x540f247ec7770468.jpg</video:thumbnail_loc><video:title>Solve by completing the square: Integer solutions</video:title><video:description>We can use the strategy of completing the square to solve quadratic equations. If the solutions are integers, we can solve by factoring as well.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/eU41vG9z35M.mp4/eU41vG9z35M.mp4</video:content_loc><video:duration>389</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/solve-completing-square-non-integer-solutions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x22ce3fc5ae0cc6c9.jpg</video:thumbnail_loc><video:title>Solve by completing the square: Non-integer solutions</video:title><video:description>We can use the strategy of completing the square to solve quadratic equations even when the solutions aren&apos;t integers.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Ldp9_K3L4Q8.mp4/Ldp9_K3L4Q8.mp4</video:content_loc><video:duration>242</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/completing-the-square-to-solve-quadratic-equations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/150088071.jpg</video:thumbnail_loc><video:title>Worked example: completing the square (leading coefficient ≠ 1)</video:title><video:description>Sal solves the equation 4x^2+40x-300=0 by completing the square.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TV5kDqiJ1Os.mp4/TV5kDqiJ1Os.mp4</video:content_loc><video:duration>344</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/ex2-completing-the-square</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26999.jpg</video:thumbnail_loc><video:title>Solving quadratics by completing the square: no solution</video:title><video:description>Sal solves the equation 4x^2+40x+280=0 by completing the square, only to find there&apos;s no solution for this equation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6agzj3A9IgA.mp4/6agzj3A9IgA.mp4</video:content_loc><video:duration>324</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/proof-of-quadratic-formula</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23726.jpg</video:thumbnail_loc><video:title>Proof of the quadratic formula</video:title><video:description>Sal proves the quadratic formula using the method of completing the square.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/r3SEkdtpobo.mp4/r3SEkdtpobo.mp4</video:content_loc><video:duration>464</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/strategy-in-solving-quadratic-equations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x75ddcb01a69632a1.jpg</video:thumbnail_loc><video:title>Strategy in solving quadratic equations</video:title><video:description>Based on the initial form of a quadratic equation, we can determine which solution methods are and aren&apos;t appropriate.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_MllyJivas4.mp4/_MllyJivas4.mp4</video:content_loc><video:duration>350</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/ex3-completing-the-square</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/27000.jpg</video:thumbnail_loc><video:title>Finding the vertex of a parabola in standard form</video:title><video:description>Sal rewrites the equation y=-5x^2-20x+15 in vertex form (by completing the square) in order to identify the vertex of the corresponding parabola.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/IbI-l7mbKO4.mp4/IbI-l7mbKO4.mp4</video:content_loc><video:duration>340</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/graphing-a-parabola-using-roots-and-vertex</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe26c2892.jpg</video:thumbnail_loc><video:title>Graphing quadratics: standard form</video:title><video:description>Learn how to graph any quadratic function that is given in standard form. Here, Sal graphs y=5x²-20x+15.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/MQtsRYPx3v0.mp4/MQtsRYPx3v0.mp4</video:content_loc><video:duration>281</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/application-problem-with-quadratic-formula</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/150009952.jpg</video:thumbnail_loc><video:title>Quadratic word problem: ball</video:title><video:description>Sal solves a word problem about a ball being shot in the air. The equation for the height of the ball as a function of time is modeled by a quadratic function.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OZtqz_xw0SQ.mp4/OZtqz_xw0SQ.mp4</video:content_loc><video:duration>353</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/rewriting-a-quadratic-function-to-find-roots-and-vertex</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x96c7edd8.jpg</video:thumbnail_loc><video:title>Forms &amp; features of quadratic functions</video:title><video:description>Different forms of quadratic functions reveal different features of those functions. Here, Sal rewrites f(x)=x²-5x+6 in factored form to reveal its zeros and in vertex form to reveal its vertex.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4Bc5-HRop5Y.mp4/4Bc5-HRop5Y.mp4</video:content_loc><video:duration>509</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/strategy-with-forms-of-quadratics</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xabfbf7e7fd3b373c.jpg</video:thumbnail_loc><video:title>Worked examples: Forms &amp; features of quadratic functions</video:title><video:description>Choosing whether factored form, vertex form or standard form of a quadratic is best in different situations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/eRbgHCaWQQE.mp4/eRbgHCaWQQE.mp4</video:content_loc><video:duration>402</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/quadratic-functions-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26996.jpg</video:thumbnail_loc><video:title>Vertex &amp; axis of symmetry of a parabola</video:title><video:description>Sal rewrites a quadratic equation in vertex form and shows how it reveals the vertex of the corresponding parabola.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/dfoXtodyiIA.mp4/dfoXtodyiIA.mp4</video:content_loc><video:duration>442</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/finding-features-of-quadratic-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb8f6b949.jpg</video:thumbnail_loc><video:title>Finding features of quadratic functions</video:title><video:description>Sal finds the zeros, the vertex, &amp; the line of symmetry of quadratic functions given in vertex form, factored form, &amp; standard form.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/V-BAdpvejTw.mp4/V-BAdpvejTw.mp4</video:content_loc><video:duration>503</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/interpret-quadratic-models-factored-form</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1ba131f975c73839.jpg</video:thumbnail_loc><video:title>Interpret quadratic models: Factored form</video:title><video:description>Given a quadratic function that models a relationship, we can rewrite the function to reveal certain properties of the relationship. Factored form helps us identify the x-intercepts or zeros of the function.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ITBRCLusU1s.mp4/ITBRCLusU1s.mp4</video:content_loc><video:duration>240</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/interpret-quadratic-models</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb055979a96a7ee4e.jpg</video:thumbnail_loc><video:title>Interpret quadratic models: Vertex form</video:title><video:description>Given a quadratic function that models a relationship, we can rewrite the function to reveal certain properties of the relationship.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/JdWEdb90V1s.mp4/JdWEdb90V1s.mp4</video:content_loc><video:duration>353</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/creativity-role-life</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa372f275cca4b470.jpg</video:thumbnail_loc><video:title>Creativity break: How does creativity play a role in your everyday life?</video:title><video:description>Experts share what role creativity plays in their everyday lives.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/eU8IfaoD-v8.mp4/eU8IfaoD-v8.mp4</video:content_loc><video:duration>144</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/comparing-features-of-quadratic-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xae2fb360.jpg</video:thumbnail_loc><video:title>Comparing features of quadratic functions</video:title><video:description>Sal compares the y-intercepts, the zeros, and the concavity of quadratic functions given graphically and algebraically.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/UdLYAqN0gNY.mp4/UdLYAqN0gNY.mp4</video:content_loc><video:duration>251</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/comparing-features-of-functions-2-example-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8d256629.jpg</video:thumbnail_loc><video:title>Comparing maximum points of quadratic functions</video:title><video:description>Given several quadratic functions represented in different forms, Sal finds the one with the lowest maximum value.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4Bx06GFyhUA.mp4/4Bx06GFyhUA.mp4</video:content_loc><video:duration>239</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/shifting-and-scaling-parabolas</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x78bacc55.jpg</video:thumbnail_loc><video:title>Intro to parabola transformations</video:title><video:description>Sal discusses how we can shift and scale the graph of a parabola to obtain any other parabola, and how this affects the equation of the parabola.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/99v51U3HSCU.mp4/99v51U3HSCU.mp4</video:content_loc><video:duration>481</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/example-translating-parabola</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8a38e1f66105044e.jpg</video:thumbnail_loc><video:title>Shifting parabolas</video:title><video:description>The graph of y=(x-k)²+h is the resulting of shifting (or translating) the graph of y=x², k units to the right and h units up. For example, y=(x-3)²-4 is the result of shifting y=x² 3 units to the right and -4 units up, which is the same as 4 units down.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ZmVOR6n_fzY.mp4/ZmVOR6n_fzY.mp4</video:content_loc><video:duration>282</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/scaling-and-reflecting-parabolas</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x510a7b8e94445c84.jpg</video:thumbnail_loc><video:title>Scaling &amp; reflecting parabolas</video:title><video:description>The graph of y=k⋅x² is the graph of y=x² scaled by a factor of |k|. If k&lt;0, it&apos;s also reflected (or &quot;flipped&quot;) across the x-axis. In this worked example, we find the equation of a parabola from its graph.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/AMsbZLxd3lE.mp4/AMsbZLxd3lE.mp4</video:content_loc><video:duration>285</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/sum-and-product-of-rational-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1ff9a2a1.jpg</video:thumbnail_loc><video:title>Proof: sum &amp; product of two rationals is rational</video:title><video:description>Sal proves that the sum, or the product, of any two rational numbers will always be a rational number.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/HKUJkMQsGkM.mp4/HKUJkMQsGkM.mp4</video:content_loc><video:duration>166</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/proof-that-rational-times-irrational-is-irrational</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf3863cc0.jpg</video:thumbnail_loc><video:title>Proof: product of rational &amp; irrational is irrational</video:title><video:description>The product of any rational number and any irrational number will always be an irrational number. This allows us to quickly conclude that 3π is irrational.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/KT32CsdEZEY.mp4/KT32CsdEZEY.mp4</video:content_loc><video:duration>195</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/proof-that-sum-of-rational-and-irrational-is-irrational</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xeb700d9f.jpg</video:thumbnail_loc><video:title>Proof: sum of rational &amp; irrational is irrational</video:title><video:description>The sum of any rational number and any irrational number will always be an irrational number. This allows us to quickly conclude that ½+√2 is irrational.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pPM72fPwIjw.mp4/pPM72fPwIjw.mp4</video:content_loc><video:duration>204</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/sums-and-products-of-irrational-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xda6c575074a2c44a.jpg</video:thumbnail_loc><video:title>Sums and products of irrational numbers</video:title><video:description>The sum of two irrational numbers can be rational and it can be irrational. It depends on which irrational numbers we&apos;re talking about exactly. The same goes for products for two irrational numbers. This video covers this fact with various examples.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/16-GZWi66CI.mp4/16-GZWi66CI.mp4</video:content_loc><video:duration>357</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/recognizing-rational-and-irrational-expressions-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x85d5add2.jpg</video:thumbnail_loc><video:title>Worked example: rational vs. irrational expressions</video:title><video:description>Sal shows how to determine whether the following expressions are rational or irrational: 9 + √(45), √(45)/ (3*√(5)), and 3*√(9).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hTJgK-wZMcE.mp4/hTJgK-wZMcE.mp4</video:content_loc><video:duration>156</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/recognizing-rational-and-irrational-expressions-w-unknowns</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x78710541.jpg</video:thumbnail_loc><video:title>Worked example: rational vs. irrational expressions (unknowns)</video:title><video:description>Sal determines whether expressions with unknown rational/irrational numbers are rational or irrational.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/NC6HXlrH53Y.mp4/NC6HXlrH53Y.mp4</video:content_loc><video:duration>386</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/proof-that-square-root-of-2-is-irrational</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8924c336.jpg</video:thumbnail_loc><video:title>Proof: √2 is irrational</video:title><video:description>Sal proves that the square root of 2 is an irrational number, i.e. it cannot be given as the ratio of two integers.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/mX91_3GQqLY.mp4/mX91_3GQqLY.mp4</video:content_loc><video:duration>467</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/proof-that-square-root-of-prime-number-is-irrational</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5725b03f.jpg</video:thumbnail_loc><video:title>Proof: square roots of prime numbers are irrational</video:title><video:description>Sal proves that the square root of any prime number must be an irrational number. For example, because of this proof we can quickly determine that √3, √5, √7, or √11 are irrational numbers.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/W-Nio466Ek4.mp4/W-Nio466Ek4.mp4</video:content_loc><video:duration>448</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/proof-that-there-is-an-irrational-number-between-any-two-rational-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x04436acf.jpg</video:thumbnail_loc><video:title>Proof: there&apos;s an irrational number between any two rational numbers</video:title><video:description>Sal proves that when given any two rational numbers, no matter how close, we can find an irrational number that lies between them.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hxqo_DiL3pw.mp4/hxqo_DiL3pw.mp4</video:content_loc><video:duration>333</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/creativity-in-algebra</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa0e13c97c9f29692.jpg</video:thumbnail_loc><video:title>Creativity in algebra</video:title><video:description>Hear from professionals as they talk about creativity in algebra and mathematics.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/nOBZM5QYcBc.mp4/nOBZM5QYcBc.mp4</video:content_loc><video:duration>352</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/creative-algebra-at-work</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x55ae315ce1fa0cf6.jpg</video:thumbnail_loc><video:title>Creative algebra at work</video:title><video:description>Hear from experts as they talk about creative algebra and mathematics at work.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Ep7diUpHuhs.mp4/Ep7diUpHuhs.mp4</video:content_loc><video:duration>493</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra/v/the-future-of-creativity-in-algebra</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x90da36ecf98bb584.jpg</video:thumbnail_loc><video:title>The future of creativity in algebra</video:title><video:description>Hear from professionals and students as they talk about the future of creativity in algebra.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Q-apRGBr3Xg.mp4/Q-apRGBr3Xg.mp4</video:content_loc><video:duration>573</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-1-eureka-squared-aligned/v/combining-like-terms-with-negative-coefficients-indian-accent</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x728a776289c36232.jpg</video:thumbnail_loc><video:title>Combining like terms with negative coefficients</video:title><video:description>This example of combining like terms in an expression gets a little hairy. Pay attention.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/WnrV31asOS0.mp4/WnrV31asOS0.mp4</video:content_loc><video:duration>282</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-1-eureka-squared-aligned/v/adding-and-subtracting-polynomials-of-degree-two</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xac21546ae99eca29.jpg</video:thumbnail_loc><video:title>Adding and subtracting polynomials of degree two</video:title><video:description>When given two polynomials of degree two, add or subtract to simplify.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/kieyGh0SDQk.mp4/kieyGh0SDQk.mp4</video:content_loc><video:duration>190</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-1-eureka-squared-aligned/v/equations-with-variables-on-both-sides-20-7x6x-6-indian-accent</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x114c2d766b5ae816.jpg</video:thumbnail_loc><video:title>Equations with variables on both sides: 20-7x=6x-6</video:title><video:description>Solving equations like 20 - 7x = 6x - 6 with the variable on both sides involves a few steps! First, we add or subtract terms from both sides to separate constants and variables to different sides of the equation. Then, we simplify to isolate the variable. Finally, we check our answer by plugging it back into the original equation. Courses on Khan Academy are always 100% free. Start practicing—and saving your progress—now! (add course link here) Khan Academy India is a nonprofit organization with the mission of providing a free, world-class education for anyone, anywhere. We have videos and exercises that have been translated into multiple Indian languages, and 15 million people around the globe learn on Khan Academy every month. Support Us: https://india.khanacademy.org/donate Created by</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0ftMWNI7UGk.mp4/0ftMWNI7UGk.mp4</video:content_loc><video:duration>246</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/example-of-solving-for-a-variable</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/2402503.jpg</video:thumbnail_loc><video:title>Manipulating formulas: perimeter</video:title><video:description>Sal rewrites the formula for the perimeter of a rectangle so it is solved for width.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Aig1hkq3OsU.mp4/Aig1hkq3OsU.mp4</video:content_loc><video:duration>418</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/rearrange-formulas-to-isolate-specific-variables</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179472.jpg</video:thumbnail_loc><video:title>Manipulating formulas: area</video:title><video:description>Sal rewrites the formula for the area of a triangle so it is solved for height.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/eTSVTTg_QZ4.mp4/eTSVTTg_QZ4.mp4</video:content_loc><video:duration>149</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/absolute-value-equations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23668.jpg</video:thumbnail_loc><video:title>Intro to absolute value equations and graphs</video:title><video:description>To solve absolute value equations, find x values that make the expression inside the absolute value positive or negative the constant. To graph absolute value functions, plot two lines for the positive and negative cases that meet at the expression&apos;s zero. The graph is v-shaped.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/u6zDpUL5RkU.mp4/u6zDpUL5RkU.mp4</video:content_loc><video:duration>641</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-1-eureka-squared-aligned/v/solving-absolute-value-equations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x97d9e2fcd70bce73.jpg</video:thumbnail_loc><video:title>Solving absolute value equations</video:title><video:description>Understand why an absolute value equation can have from 0 to 2 solutions. Solve absolute value equations with different numbers of solutions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6KrKv4Z-aH4.mp4/6KrKv4Z-aH4.mp4</video:content_loc><video:duration>406</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/absolute-value-equations-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26785.jpg</video:thumbnail_loc><video:title>Worked example: absolute value equations with one solution</video:title><video:description>To solve absolute value problems with one solution, identify expression in absolute value bars. Recall absolute value is zero only if expression is zero. Make expression equal right-hand side. Use algebra to find x values that satisfy equation. Check solutions by plugging in. Graph solutions on number line. Mark points.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/GwjiR2_7A7Y.mp4/GwjiR2_7A7Y.mp4</video:content_loc><video:duration>156</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/absolute-value-equation-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe7acd9ae.jpg</video:thumbnail_loc><video:title>Worked example: absolute value equation with two solutions</video:title><video:description>Solving the equation 8|x+7|+4 = -6|x+7|+6 which has two possible solutions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/UvtWf4TVawE.mp4/UvtWf4TVawE.mp4</video:content_loc><video:duration>290</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/absolute-value-equation-with-no-solution</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x492a306c.jpg</video:thumbnail_loc><video:title>Worked example: absolute value equations with no solution</video:title><video:description>Solving the equation 4|x+10|+4 = 6|x+10|+10 to find that it has no possible solution.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/15s6B7K9paA.mp4/15s6B7K9paA.mp4</video:content_loc><video:duration>230</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/absolute-value-inequalities</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/4802220.jpg</video:thumbnail_loc><video:title>Intro to absolute value inequalities</video:title><video:description>To solve inequalities with absolute values, use a number line to see how far the absolute value is from zero. Split into two cases: when it is positive or negative. Solve each case with algebra. The answer is both cases together, in intervals or words.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/iI_2Piwn_og.mp4/iI_2Piwn_og.mp4</video:content_loc><video:duration>793</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/absolute-value-inequalities-example-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26816.jpg</video:thumbnail_loc><video:title>Solving absolute value inequalities 1</video:title><video:description>Sal solves the inequality |h|-19.5 &lt; -12.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TvUCe6Bomy4.mp4/TvUCe6Bomy4.mp4</video:content_loc><video:duration>207</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/absolute-value-inequalities-example-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179495.jpg</video:thumbnail_loc><video:title>Solving absolute value inequalities 2</video:title><video:description>Sal solves the inequality |p-12|+4 &lt; 14.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/YKQLZOq4HTA.mp4/YKQLZOq4HTA.mp4</video:content_loc><video:duration>279</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/absolute-value-inequalities-example-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26818.jpg</video:thumbnail_loc><video:title>Solving absolute value inequalities: no solution</video:title><video:description>Sal solves the inequality |y|+22 ≤ 13.5 to find that it has no solution.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/y9MGpOGQVqQ.mp4/y9MGpOGQVqQ.mp4</video:content_loc><video:duration>155</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/population-standard-deviation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4a3e3b6e.jpg</video:thumbnail_loc><video:title>Population standard deviation</video:title><video:description>The population standard deviation is a measure of how much variation there is among individual data points in a population. It&apos;s a way of quantifying how spread out the data is from its mean. A small standard deviation means that the data points are generally close to the mean, while a large standard deviation means that the data is more dispersed.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PWiWkqHmum0.mp4/PWiWkqHmum0.mp4</video:content_loc><video:duration>485</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/comparing-distributions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbb2baca6c0bfe77f.jpg</video:thumbnail_loc><video:title>Example: Comparing distributions</video:title><video:description>Compare distributions using the features of shape, center, spread, and outliers.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lT3LRjtSbJc.mp4/lT3LRjtSbJc.mp4</video:content_loc><video:duration>438</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-1-eureka-squared-aligned/v/two-variable-linear-equations-intro-indian-accent</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd02f9efa5c5542f2.jpg</video:thumbnail_loc><video:title>Two-variable linear equations intro</video:title><video:description>Learn about a class of equations in two variables that&apos;s called &quot;linear equations.&quot; They are called that way because their graph is a line. These are the most basic and probably most useful equations you will ever know! Courses on Khan Academy are always 100% free. Start practicing—and saving your progress—now! Khan Academy India is a nonprofit organization with the mission of providing a free, world-class education for anyone, anywhere. We have videos and exercises that have been translated into multiple Indian languages, and 15 million people around the globe learn on Khan Academy every month. Support Us: https://india.khanacademy.org/donate Created by</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/HKnvMMPiyZw.mp4/HKnvMMPiyZw.mp4</video:content_loc><video:duration>501</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-1-eureka-squared-aligned/v/intro-to-linear-equation-standard-form-indian-accent</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8867b3d8c81527c5.jpg</video:thumbnail_loc><video:title>Intro to linear equation standard form</video:title><video:description>The standard form for linear equations in two variables is Ax+By=C. For example, 2x+3y=5 is a linear equation in standard form. When an equation is given in this form, it&apos;s pretty easy to find both intercepts (x and y). This form is also very useful when solving systems of two linear equations. Courses on Khan Academy are always 100% free. Start practicing—and saving your progress—now! Khan Academy India is a nonprofit organization with the mission of providing a free, world-class education for anyone, anywhere. We have videos and exercises that have been translated into multiple Indian languages, and 15 million people around the globe learn on Khan Academy every month. Support Us: https://india.khanacademy.org/donate Created by</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7L3tm5a2Pus.mp4/7L3tm5a2Pus.mp4</video:content_loc><video:duration>487</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-1-eureka-squared-aligned/v/writing-linear-equations-in-two-variables-given-a-table</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x150cac52890ce0c7.jpg</video:thumbnail_loc><video:title>Writing linear equations in two variables given a table</video:title><video:description>When given a table of values, write the linear equation that represents this data in slope-intercept form.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/v_aEGYeIG9w.mp4/v_aEGYeIG9w.mp4</video:content_loc><video:duration>183</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/calculating-residual-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6cf80c68c23af38d.jpg</video:thumbnail_loc><video:title>Calculating residual example</video:title><video:description>We look at an example scenario that includes understanding least squares regression, interpreting the regression equation, calculating residuals, and interpreting the significance of positive and negative residuals in relation to the regression line.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/50ezMTE_BuA.mp4/50ezMTE_BuA.mp4</video:content_loc><video:duration>292</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/residual-plots</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xec01b05aa4e7daa5.jpg</video:thumbnail_loc><video:title>Residual plots</video:title><video:description>Creating and analyzing residual plots based on regression lines.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/VamMrPZ-8fc.mp4/VamMrPZ-8fc.mp4</video:content_loc><video:duration>372</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/correlation-coefficient-intuition-examples</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf4b1ea36.jpg</video:thumbnail_loc><video:title>Example: Correlation coefficient intuition</video:title><video:description>Sal explains the intuition behind correlation coefficients and does a problem where he matches correlation coefficients to scatter plots.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-Y-M9aD_ccQ.mp4/-Y-M9aD_ccQ.mp4</video:content_loc><video:duration>441</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/calculating-correlation-coefficient-r</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x934981fcf1616c2c.jpg</video:thumbnail_loc><video:title>Calculating correlation coefficient r</video:title><video:description>The most common way to calculate the correlation coefficient (r) is by using technology, but using the formula can help us understand how r measures the direction and strength of the linear association between two quantitative variables.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/u4ugaNo6v1Q.mp4/u4ugaNo6v1Q.mp4</video:content_loc><video:duration>742</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/video-games-and-violence-bivariate-data</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7f0764fa.jpg</video:thumbnail_loc><video:title>Categorical data example</video:title><video:description>We can explore the relationship between two categorical variables with two-way tables to see if there is an association between the variables. In this example, we see if data from a sample suggests an associate between video games and violence.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ahyWUV7AwKw.mp4/ahyWUV7AwKw.mp4</video:content_loc><video:duration>201</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/analyzing-trends-categorical-data</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x49a1fd7f.jpg</video:thumbnail_loc><video:title>Analyzing trends in categorical data</video:title><video:description>Sal solves an example where he is asked to calculate relative frequencies and analyze trends in categorical data.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TXGhMDbbnzQ.mp4/TXGhMDbbnzQ.mp4</video:content_loc><video:duration>534</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/graphical-equations-intro</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x90275c239bedf23d.jpg</video:thumbnail_loc><video:title>Solving equations by graphing: intro</video:title><video:description>Some equations are hard to solve exactly with algebraic tools. We can always solve an equation by graphing it, although the solution might not be exact. This is an example of how to solve a relatively simple equation graphically.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/573yqfOoMwE.mp4/573yqfOoMwE.mp4</video:content_loc><video:duration>267</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/graphically-solving-equations-calculator</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe6aff4650331a1a7.jpg</video:thumbnail_loc><video:title>Solving equations by graphing: graphing calculator</video:title><video:description>We can approximate the solutions to any equation by graphing both sides of the equation and looking for intersection points. If we have a graphing calculator, we can get a very good approximation of the solution.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hlFhHN67ICE.mp4/hlFhHN67ICE.mp4</video:content_loc><video:duration>231</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-1-eureka-squared-aligned/v/determining-the-effects-on-fx-x-when-replaced-by-fx-d-or-fx-c</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe706906e88b5258c.jpg</video:thumbnail_loc><video:title>Determining the effects on f(x) = x when replaced by f(x) + d or f(x - c)</video:title><video:description>Determine the effects on f(x) = x when replaced by f(x) + d or f(x - c).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/AxkLjDmD_oU.mp4/AxkLjDmD_oU.mp4</video:content_loc><video:duration>207</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/reflecting-and-compressing-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x92138f98.jpg</video:thumbnail_loc><video:title>Reflecting &amp; compressing functions</video:title><video:description>Given the graphs of functions f and g, where g is the result of reflecting &amp; compressing f by a factor of 3, Sal finds g(x) in terms of f(x).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Upw1b0EohIM.mp4/Upw1b0EohIM.mp4</video:content_loc><video:duration>261</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-1-eureka-squared-aligned/v/determining-the-effects-on-fx-x-when-replaced-by-afx-or-fbx</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdbd5174755a281cc.jpg</video:thumbnail_loc><video:title>Determining the effects on f(x) = x when replaced by af(x) or f(bx)</video:title><video:description>Determine the effects on f(x) when replaced by af(x) or f(bx).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/nUYbTIAwH8w.mp4/nUYbTIAwH8w.mp4</video:content_loc><video:duration>200</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-1-eureka-squared-aligned/v/determining-the-effects-on-fx-x-multiple-transformations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x81f7ac9cf2f18a4d.jpg</video:thumbnail_loc><video:title>Determining the effects on f(x) = x (multiple transformations)</video:title><video:description>Determine the effects on f(x) = x with multiple transformations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/c26tyBzYnsw.mp4/c26tyBzYnsw.mp4</video:content_loc><video:duration>317</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/line-and-parabola-system</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4af415d1c1bb39db.jpg</video:thumbnail_loc><video:title>Quadratic systems: a line and a parabola</video:title><video:description>A system of equations that contains one linear equation and one quadratic equations can be solved both graphically and algebraically. Each method has its pros and cons. See an example using both methods.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Cy1Pxz_wLfA.mp4/Cy1Pxz_wLfA.mp4</video:content_loc><video:duration>372</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/systems-of-nonlinear-equations-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9e7fad26.jpg</video:thumbnail_loc><video:title>Quadratic systems: a line and a circle</video:title><video:description>Sal solves the system y=x+1 and x^2+y^2=25.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/swFohliPgmQ.mp4/swFohliPgmQ.mp4</video:content_loc><video:duration>254</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-1-eureka-squared-aligned/v/sat-math-p8-easier</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb049a70f.jpg</video:thumbnail_loc><video:title>Linear and quadratic systems — Basic example</video:title><video:description>Watch Sal work through a basic Linear and quadratic systems problem.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/c9H60WSptdE.mp4/c9H60WSptdE.mp4</video:content_loc><video:duration>290</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-1-eureka-squared-aligned/v/sat-math-p8-harder</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0c79f02f.jpg</video:thumbnail_loc><video:title>Linear and quadratic systems — Harder example</video:title><video:description>Watch Sal work through a harder Linear and quadratic systems problem.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OL024xNFuro.mp4/OL024xNFuro.mp4</video:content_loc><video:duration>353</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-1-eureka-squared-aligned/v/writing-a-quadratic-function-to-fit-data-estimate-solutions-and-make-predictions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x855cb8445c50bcfa.jpg</video:thumbnail_loc><video:title>Writing a quadratic function to fit data, estimate solutions, and make predictions</video:title><video:description>Practice writing quadratic functions to fit data, estimate solutions and make predictions from a table of values.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/99XW8CxKzao.mp4/99XW8CxKzao.mp4</video:content_loc><video:duration>449</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/comparing-models-to-fit-data</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x69fec2ac.jpg</video:thumbnail_loc><video:title>Comparing models to fit data example</video:title><video:description>Sal determines if a quadratic or exponential model fits the data better, then uses the model to make a prediction.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2EwTHdg-xgw.mp4/2EwTHdg-xgw.mp4</video:content_loc><video:duration>245</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-1-eureka-squared-aligned/v/recursive-arithmetic-sequence</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe8cb4f7c79e03195.jpg</video:thumbnail_loc><video:title>Recursive formula for arithmetic sequence</video:title><video:description>Find the recursive formula for an arithmetic sequence by using the common difference and solving for the designated initial term.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ddRPUzAXAG4.mp4/ddRPUzAXAG4.mp4</video:content_loc><video:duration>189</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/simplifying-exponent-expression-with-division</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x578b37c4.jpg</video:thumbnail_loc><video:title>Rewriting quotient of powers (rational exponents)</video:title><video:description>Sal rewrites the expression m^(7/9) / m^(1/3) as a single exponential term m^(4/9).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0z-yIFzpunM.mp4/0z-yIFzpunM.mp4</video:content_loc><video:duration>151</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/transforming-exponential-graphs</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0540fde8.jpg</video:thumbnail_loc><video:title>Transforming exponential graphs</video:title><video:description>Given the graph of y=2ˣ, Sal graphs y=2⁻ˣ-5, which is a horizontal reflection and shift of y=2ˣ.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/83gM3ufe1Nw.mp4/83gM3ufe1Nw.mp4</video:content_loc><video:duration>185</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/transforming-exponential-graphs-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x84ac3a80.jpg</video:thumbnail_loc><video:title>Transforming exponential graphs (example 2)</video:title><video:description>Given the graph of y=2ˣ, Sal graphs y=(-1)2ˣ⁺³+4, which is a vertical reflection and a shift of y=2ˣ.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ja4WRZ4DrAw.mp4/ja4WRZ4DrAw.mp4</video:content_loc><video:duration>318</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/graphing-exponential-functions-interactive</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9ee7b980.jpg</video:thumbnail_loc><video:title>Graphing exponential functions</video:title><video:description>Sal graphs y=-2*3ˣ+5 using our interactive graphing widget.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vlSEpdWf2hQ.mp4/vlSEpdWf2hQ.mp4</video:content_loc><video:duration>195</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-1-eureka-squared-aligned/v/identifying-key-features-of-exponential-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6a44d01fdd585c21.jpg</video:thumbnail_loc><video:title>Identifying key features of exponential functions</video:title><video:description>When given an exponential function, identify key features.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/mPxxlOKqPqQ.mp4/mPxxlOKqPqQ.mp4</video:content_loc><video:duration>274</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-1-eureka-squared-aligned/v/determining-and-representing-the-domain-and-range-of-exponential-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfcbcef1d7de4c58c.jpg</video:thumbnail_loc><video:title>Determining and representing the domain and range of exponential functions</video:title><video:description>Given an exponential function of the form f(x) = a*b^x in algebraic or graphed form, determine its domain and range.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/sOLWlpwvfFI.mp4/sOLWlpwvfFI.mp4</video:content_loc><video:duration>390</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-1-eureka-squared-aligned/v/finding-simple-interest-for-one-year-comparing-quantities-class-7-india-khan-aca</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc53bdf431c4bc02a.jpg</video:thumbnail_loc><video:title>Finding simple interest for one year</video:title><video:description>Let&apos;s learn what the &apos;interest rate per annum&apos; means and how we can calculate simple interest for a year using the rate of interest.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qWnEEKqeWL0.mp4/qWnEEKqeWL0.mp4</video:content_loc><video:duration>324</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-1-eureka-squared-aligned/v/finding-simple-interest-for-many-years-comparing-quantities-class-7-india-khan-a</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x341e110afa8ac9c5.jpg</video:thumbnail_loc><video:title>Finding simple interest for many years</video:title><video:description>Have you wondered why we call simple interest &apos;simple&apos;? Also, let&apos;s understand the basics behind the famous formula for calculating simple interest.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/T6wBHgOxUhc.mp4/T6wBHgOxUhc.mp4</video:content_loc><video:duration>484</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/interpreting-time-in-exponential-models</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x720cd5ae.jpg</video:thumbnail_loc><video:title>Interpreting time in exponential models</video:title><video:description>Sal finds the time interval over which a quantity changes by a given factor in various exponential models.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/zFksanIexHI.mp4/zFksanIexHI.mp4</video:content_loc><video:duration>403</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/interpreting-change-in-exponential-models</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2052fba3.jpg</video:thumbnail_loc><video:title>Interpreting change in exponential models</video:title><video:description>Sal finds the factor by which a quantity changes over a single time unit in various exponential models.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/uoN_Ax3dfQo.mp4/uoN_Ax3dfQo.mp4</video:content_loc><video:duration>414</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-1-eureka-squared-aligned/v/writing-exponential-functions-to-fit-data-and-make-predictions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3528ab7725c634e5.jpg</video:thumbnail_loc><video:title>Writing exponential functions to fit data and make predictions</video:title><video:description>When given data, use exponential functions to predict a value.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7E9tV6SL5AU.mp4/7E9tV6SL5AU.mp4</video:content_loc><video:duration>469</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/introduction-to-residuals-and-least-squares-regression</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1dd8ed47d6d9272f.jpg</video:thumbnail_loc><video:title>Introduction to residuals and least squares regression</video:title><video:description>Introduction to residuals and least squares regression</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/yMgFHbjbAW8.mp4/yMgFHbjbAW8.mp4</video:content_loc><video:duration>460</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/perpendicular-lines</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26811.jpg</video:thumbnail_loc><video:title>Perpendicular lines from equation</video:title><video:description>Sal determines which pairs out of a few given linear equations are perpendicular.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0671cRNjeKI.mp4/0671cRNjeKI.mp4</video:content_loc><video:duration>209</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/perpendicular-lines-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26812.jpg</video:thumbnail_loc><video:title>Writing equations of perpendicular lines</video:title><video:description>Given line A and point P, Sal finds the equation of the line perpendicular to A that passes through P.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TsEhZRT16LU.mp4/TsEhZRT16LU.mp4</video:content_loc><video:duration>181</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/find-the-equation-of-a-line</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbded91b9.jpg</video:thumbnail_loc><video:title>Writing equations of perpendicular lines (example 2)</video:title><video:description>Sal finds the equation of a line perpendicular to a line given in slope-intercept form that passes through a specific point.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8m8hFcFJ-JM.mp4/8m8hFcFJ-JM.mp4</video:content_loc><video:duration>105</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/proving-that-parallel-lines-have-the-same-slope</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9e89ebd8.jpg</video:thumbnail_loc><video:title>Proof: parallel lines have the same slope</video:title><video:description>Sal proves that parallel lines have the same slope using triangle similarity.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9ZYoIliBXYE.mp4/9ZYoIliBXYE.mp4</video:content_loc><video:duration>349</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/proof-that-perpendicular-lines-have-negative-reciprocal-slope</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x058b41f0.jpg</video:thumbnail_loc><video:title>Proof: perpendicular lines have opposite reciprocal slopes</video:title><video:description>To prove that perpendicular lines have opposite reciprocal slopes, draw the two lines and label key points. By identifying the two right triangles that are formed, one can use the definition of slope to calculate the slopes of the two lines. Finally, using the properties of similar right triangles, show that the two slopes are indeed opposite reciprocals of each other.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/HyThzLRuqXo.mp4/HyThzLRuqXo.mp4</video:content_loc><video:duration>535</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/bivariate-relationship-linearity-strength-and-direction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd2233b61519abb0d.jpg</video:thumbnail_loc><video:title>Bivariate relationship linearity, strength and direction</video:title><video:description>Describe a bivariate relationship&apos;s linearity, strength, and direction</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/30LcZqRfPRY.mp4/30LcZqRfPRY.mp4</video:content_loc><video:duration>493</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/interpreting-slope-of-regression-line</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x092457deb73afcbe.jpg</video:thumbnail_loc><video:title>Interpreting slope of regression line</video:title><video:description>We look at an example scatter plot showing the relationship between hours studying and test scores. We interpret scatter plots, investigate the relationship between variables, interpret the slope of a trend line, and make predictions based on the trend line&apos;s slope and intercept.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PplggM0KtJ8.mp4/PplggM0KtJ8.mp4</video:content_loc><video:duration>178</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/interpreting-y-intercept-in-regression-model</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe58ed121b4d756b7.jpg</video:thumbnail_loc><video:title>Interpreting y-intercept in regression model</video:title><video:description>Interpreting y-intercept in regression model</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/00YVR5TSZqw.mp4/00YVR5TSZqw.mp4</video:content_loc><video:duration>156</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/probability/v/correlation-and-causality</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/203846247.jpg</video:thumbnail_loc><video:title>Correlation and causality</video:title><video:description>Understanding why correlation does not imply causality (even though many in the press and some researchers often imply otherwise)</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ROpbdO-gRUo.mp4/ROpbdO-gRUo.mp4</video:content_loc><video:duration>645</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/probability/v/regression-residual-intro</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x798e2a79d4b18400.jpg</video:thumbnail_loc><video:title>Introduction to residuals and least-squares regression</video:title><video:description>In linear regression, a residual is the difference between the actual value and the value predicted by the model (y-ŷ) for any given point. A least-squares regression model minimizes the sum of the squared residuals.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/VqD-nf1YUks.mp4/VqD-nf1YUks.mp4</video:content_loc><video:duration>289</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/avg-rate-of-change-of-polynomials</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa25f278a0eb3ede9.jpg</video:thumbnail_loc><video:title>Finding average rate of change of polynomials</video:title><video:description>Learn how to calculate the average rate of change of a function over a specific interval. Discover how changes in the function&apos;s value relate to changes in x. Use tables and visuals to understand the concept better. This is key to mastering polynomial functions in algebra.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/neZeuTgEoMA.mp4/neZeuTgEoMA.mp4</video:content_loc><video:duration>241</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/sign-of-avg-rate-of-change-polynomial</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8198387faa4f2462.jpg</video:thumbnail_loc><video:title>Sign of average rate of change of polynomials</video:title><video:description>Discover how to find the average rate of change in polynomials. Learn to identify intervals with positive average rates of change by comparing function values at different points. See how this concept applies to real-life situations, making math fun and practical!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9COoRE8pc5k.mp4/9COoRE8pc5k.mp4</video:content_loc><video:duration>336</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/basic-fractional-exponents</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x77aefe04.jpg</video:thumbnail_loc><video:title>Intro to rational exponents</video:title><video:description>What does it mean to take a number by a power which is a unit fraction? For example, what is the result of 3 raised to ½?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lZfXc4nHooo.mp4/lZfXc4nHooo.mp4</video:content_loc><video:duration>300</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/rewriting-roots-as-rational-exponents</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7c8829c5.jpg</video:thumbnail_loc><video:title>Rewriting roots as rational exponents</video:title><video:description>Sal solves several problems about the equivalence of expressions with roots and rational exponents. For example, rewrite ⁶√(g⁵) as g^⅚.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gH4IsIEYof0.mp4/gH4IsIEYof0.mp4</video:content_loc><video:duration>259</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/solving-for-a-fractional-exponent</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe5b92d45.jpg</video:thumbnail_loc><video:title>Exponential equation with rational answer</video:title><video:description>A worked example of rewriting a radical as an exponent. In this example, we solve for the unknown in 3ᵃ = ⁵√(3²).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6OFwfxmhtE8.mp4/6OFwfxmhtE8.mp4</video:content_loc><video:duration>242</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/fractional-exponent-expressions-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26914.jpg</video:thumbnail_loc><video:title>Rewriting mixed radical and exponential expressions</video:title><video:description>Sal rewrites (r^(2/3)s^3)^2*√(20r^4s^5), once as an exponential expression and once as a radical expression.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4F6cFLnAAFc.mp4/4F6cFLnAAFc.mp4</video:content_loc><video:duration>451</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/fractional-exponents-with-numerators-other-than-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6f810954.jpg</video:thumbnail_loc><video:title>Evaluating fractional exponents</video:title><video:description>Sal shows how to evaluate 64^(2/3) and (8/27)^(-2/3).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/S34NM0Po0eA.mp4/S34NM0Po0eA.mp4</video:content_loc><video:duration>354</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/negative-fractional-exponent-examples</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x22d2b44c.jpg</video:thumbnail_loc><video:title>Evaluating fractional exponents: negative unit-fraction</video:title><video:description>How to evaluate powers that are negative unit fractions, like 9 raised to -½ and 27 raised to -⅓.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tn53EdOr6Rw.mp4/tn53EdOr6Rw.mp4</video:content_loc><video:duration>182</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/negative-fractional-exponent-examples-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x86a0dd64.jpg</video:thumbnail_loc><video:title>Evaluating fractional exponents: fractional base</video:title><video:description>Sal shows how to evaluate (25/9)^(1/2) and (81/256)^(-1/4).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/bIFdW0NZ9W4.mp4/bIFdW0NZ9W4.mp4</video:content_loc><video:duration>204</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/simplifying-numerical-expression-with-rational-exponents</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf177d976.jpg</video:thumbnail_loc><video:title>Evaluating quotient of fractional exponents</video:title><video:description>Sal simplifies the complicated expression 256^(4/7) / 2^(4/7) until he finds that the expression is equal to 16.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/KGSvigZQKZY.mp4/KGSvigZQKZY.mp4</video:content_loc><video:duration>230</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/simplifying-with-exponent-properties</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf256dbf5.jpg</video:thumbnail_loc><video:title>Evaluating mixed radicals and exponents</video:title><video:description>A worked example of calculating an expression that has both a radical and an exponent. In this example, we evaluate 6^(1/2)⋅(⁵√6)³.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Ht-YXje4R2g.mp4/Ht-YXje4R2g.mp4</video:content_loc><video:duration>171</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/simplifying-an-exponential-expression</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb357b82e.jpg</video:thumbnail_loc><video:title>Rewriting exponential expressions as A⋅Bᵗ</video:title><video:description>Sal simplifies the expression 10*9^(0.5t+2)*5^(3t) as 810*375^t.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Y6wNiYcuCoE.mp4/Y6wNiYcuCoE.mp4</video:content_loc><video:duration>310</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/rewriting-an-exponential-expression-in-a-hairier-way</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc9227a8a.jpg</video:thumbnail_loc><video:title>Equivalent forms of exponential expressions</video:title><video:description>Sal rewrites (1/32)*2^t as 32*1024^(t/10-1).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vSijVSL3ChU.mp4/vSijVSL3ChU.mp4</video:content_loc><video:duration>512</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-basics/v/simplifying-square-root-expressions-no-variables</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc5f2930c.jpg</video:thumbnail_loc><video:title>Simplifying square-root expressions: no variables</video:title><video:description>When square roots have the same value inside the radical, we can combine like terms. First we simplify the radical expressions by removing all factors that are perfect squares from inside the radicals. Then we can see whether we can combine terms or not. If there is only one term, there is nothing to combine.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/74iuGIaBgRc.mp4/74iuGIaBgRc.mp4</video:content_loc><video:duration>380</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/adding-and-simplifying-radicals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/127771046.jpg</video:thumbnail_loc><video:title>Simplifying radical expressions (addition)</video:title><video:description>A worked example of simplifying an expression that is a sum of several radicals. In this example, we simplify √(2x²)+4√8+3√(2x²)+√8.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/egNq4tSfi1I.mp4/egNq4tSfi1I.mp4</video:content_loc><video:duration>281</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/interpreting-change-in-exponential-models-with-manipulation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8c4967da.jpg</video:thumbnail_loc><video:title>Interpreting change in exponential models: with manipulation</video:title><video:description>Sal analyzes the rate of change of various exponential models, where the function that models the situation needs some manipulation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/q20v5ZBsTk8.mp4/q20v5ZBsTk8.mp4</video:content_loc><video:duration>261</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/interpreting-change-in-exponential-models-changing-units</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2501cf19.jpg</video:thumbnail_loc><video:title>Interpreting change in exponential models: changing units</video:title><video:description>Sal analyzes the rate of change of various exponential models for different time units by manipulating the functions that model the situations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/SM6XZj5dPQQ.mp4/SM6XZj5dPQQ.mp4</video:content_loc><video:duration>262</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-1-fl-best/v/intro-to-simple-interest-comparing-quantities-class-7-india-math-khan-academy</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4f1218d729f52396.jpg</video:thumbnail_loc><video:title>Intro to simple interest</video:title><video:description>What is the meaning of paying interest when we borrow money? What is the meaning of the word &quot;principal&quot; here?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Rmol9IzSDXk.mp4/Rmol9IzSDXk.mp4</video:content_loc><video:duration>166</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-2-fl-best/v/intro-to-compound-interest-class-8-india-math-khan-academy</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb5756734b955851f.jpg</video:thumbnail_loc><video:title>Intro to compound interest</video:title><video:description>Let&apos;s understand how compound interest is different from simple interest. Let&apos;s also see how compound interest is simply a special case of percentage increase.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/inayVc1w72M.mp4/inayVc1w72M.mp4</video:content_loc><video:duration>482</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-2-fl-best/v/solving-compound-interest-problems-class-8-india-math-khan-academy</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf9ad53d97701deec.jpg</video:thumbnail_loc><video:title>Solved example: compound interest</video:title><video:description>In a previous video, we learned that compound interest is just a special case of percentage increase. Here, let&apos;s learn how to solve problems involving compound interest by solving an example question.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/cf-Pab4YR40.mp4/cf-Pab4YR40.mp4</video:content_loc><video:duration>889</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/subtracting-polynomials-and-closure</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xaf4f324c.jpg</video:thumbnail_loc><video:title>Polynomial subtraction</video:title><video:description>Learn how to subtract polynomials. Discover how distributing a negative sign changes the signs of all terms in a polynomial. Understand that when you subtract polynomials, you still get a polynomial, showing that the set of polynomials is &apos;closed&apos; under subtraction.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xgoqcc2-RS4.mp4/xgoqcc2-RS4.mp4</video:content_loc><video:duration>170</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/area-model-for-negative-terms</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa5dc6194d8c22038.jpg</video:thumbnail_loc><video:title>Area model for multiplying polynomials with negative terms</video:title><video:description>Discover how to multiply monomials by polynomials using area models. This method works even when dealing with negative terms! By visualizing the process, we can understand why we multiply different terms and how negative areas affect the total area.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_PC1JMBZKUQ.mp4/_PC1JMBZKUQ.mp4</video:content_loc><video:duration>317</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/multiplying-polynomials-using-area-model</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe407348a.jpg</video:thumbnail_loc><video:title>Multiplying binomials by polynomials: area model</video:title><video:description>Discover the magic of multiplying binomials by polynomials using an area model! This method transforms complex algebra into simple rectangles, making it easier to understand. By breaking down the big rectangle into smaller ones, we can find the area and thus the product of the polynomials.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/C9m5VEEyno8.mp4/C9m5VEEyno8.mp4</video:content_loc><video:duration>390</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/more-multiplying-polynomials</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179530.jpg</video:thumbnail_loc><video:title>Multiplying binomials by polynomials</video:title><video:description>Learn how to multiply binomials by polynomials with ease! This lesson breaks down the process into simple steps, using the distributive property to multiply each term. You&apos;ll master combining like terms to simplify expressions, turning complex polynomials into manageable math.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/D6mivA_8L8U.mp4/D6mivA_8L8U.mp4</video:content_loc><video:duration>154</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/polynomial-division-intro</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x45f51d0760a90a0e.jpg</video:thumbnail_loc><video:title>Polynomial division introduction</video:title><video:description>When we divide the polynomial p(x) by q(x) we are basically asking &quot;what should we multiply by q(x) to get p(x)?&quot; If this sounds familiar, it&apos;s because it&apos;s very similar to dividing numbers! In this introduction we see how some quotients end up as a polynomial, while other times we have a remainder and cannot express the quotient as a polynomial. This is very similar to quotients of integers!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3eowXt_LNbg.mp4/3eowXt_LNbg.mp4</video:content_loc><video:duration>327</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/dividing-polynomials-by-x</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfdec982c2246bbeb.jpg</video:thumbnail_loc><video:title>Dividing polynomials by x (no remainders)</video:title><video:description>Discover how to divide polynomials by &apos;x&apos; in two different ways. Finding the quotient (x⁴-2x³+5x)/x is the same as asking &quot;what should we multiply by x to get x⁴-2x³+5x?&quot; First, we distribute &apos;1/x&apos; to each term in the polynomial. Second, we factor out an &apos;x&apos; from each term. Both methods simplify complex expressions,</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/HUdA6LdCRk8.mp4/HUdA6LdCRk8.mp4</video:content_loc><video:duration>269</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/polynomial-divided-by-monomial</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179523.jpg</video:thumbnail_loc><video:title>Divide polynomials by x (with remainders)</video:title><video:description>Learn how to simplify complex expressions by dividing polynomials by &apos;x&apos;. Discover how to break down the numerator, distribute the division, and use exponent properties. Master the art of simplifying fractions and handling negative exponents. Sal demonstrates by dividing (18x^4-3x^2+6x-4) by 6x.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/UquFdMg6Z_U.mp4/UquFdMg6Z_U.mp4</video:content_loc><video:duration>285</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/identifying-individuals-variables-and-categorical-variables-in-a-data-set</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6b023a43115966cd.jpg</video:thumbnail_loc><video:title>Identifying individuals, variables and categorical variables in a data set</video:title><video:description>The concept of variables in data sets comes to life through an exploration of categorical and quantitative variables. Using nutritional data from a coffee shop as an example, the lesson highlights how variables can represent diverse aspects of a data set, such as drink type, calorie count, sugar content, and caffeine amount.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/EqeVXI4WNHM.mp4/EqeVXI4WNHM.mp4</video:content_loc><video:duration>160</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/median-histogram</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa3c51d8e2fcf899f.jpg</video:thumbnail_loc><video:title>Median in a histogram</video:title><video:description>Worked example from Khan Academy finding the interval in a histogram containing the media of a data set.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xTwDmnEEb9E.mp4/xTwDmnEEb9E.mp4</video:content_loc><video:duration>148</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/estimating-mean-median-displays</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xec8235ec63b789f8.jpg</video:thumbnail_loc><video:title>Estimating mean and median in data displays</video:title><video:description>Estimating mean and median in data displays</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/rb-T5ppxJk0.mp4/rb-T5ppxJk0.mp4</video:content_loc><video:duration>275</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/example-describing-a-distribution</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf2e81b25614f71f5.jpg</video:thumbnail_loc><video:title>Example: Describing a distribution</video:title><video:description>Learn how to describe a distribution of quantitative data by discussing its shape, center, spread, and potential outliers.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/XLNAkLuokzY.mp4/XLNAkLuokzY.mp4</video:content_loc><video:duration>341</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/types-studies-ap</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xeaaf31ee356c9c79.jpg</video:thumbnail_loc><video:title>Types of studies</video:title><video:description>We can distinguish between experiments and observational studies, and further describe types of observational studies: retrospective, prospective, and sample surveys.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/zmXBbHDUgY4.mp4/zmXBbHDUgY4.mp4</video:content_loc><video:duration>319</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/worked-example-identifying-observational-study</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa69c3c6076363b1a.jpg</video:thumbnail_loc><video:title>Worked example identifying observational study</video:title><video:description>Worked example identifying observational study</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tHFyaoIrV14.mp4/tHFyaoIrV14.mp4</video:content_loc><video:duration>404</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/probability/v/invalid-conclusions-studies-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x88df25b9f097e577.jpg</video:thumbnail_loc><video:title>Invalid conclusions from studies example</video:title><video:description>Example understanding when a conclusion about causality can be made from a study. Discussion of experimental and observational studies.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xSvvjdZjgl8.mp4/xSvvjdZjgl8.mp4</video:content_loc><video:duration>219</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/probability/v/causality-from-study</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x93ca171b7d55cf2c.jpg</video:thumbnail_loc><video:title>Can causality be established from this study?</video:title><video:description>Thinking about whether a causal relationship can be established or if there are confounding variables.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/yWva9DtV0Rk.mp4/yWva9DtV0Rk.mp4</video:content_loc><video:duration>214</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/marginal-distribution-and-conditional-distribution</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4e33fc0d5833c2a8.jpg</video:thumbnail_loc><video:title>Marginal and conditional distributions</video:title><video:description>We investigate distributions using a two-way table and then explain the concept of marginal distribution, both in counts and percentages, to understand the distribution of each variable individually. Finally, we cover conditional distribution, where we look at the relationship between variables and understand how one variable impacts the distribution of another.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Iw9fEYIpPMA.mp4/Iw9fEYIpPMA.mp4</video:content_loc><video:duration>317</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math-1-illustrative-math-aligned/v/numerical-and-categorical-data</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe16ed34fb60b2f1f.jpg</video:thumbnail_loc><video:title>Numerical and categorical data</video:title><video:description>Learn how to tell whether data is numerical or categorical by looking at the types of answers a statistical question produces.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/EYMfpriHkcg.mp4/EYMfpriHkcg.mp4</video:content_loc><video:duration>136</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/classifying-distributions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xccf3bee87725bcf8.jpg</video:thumbnail_loc><video:title>Classifying shapes of distributions</video:title><video:description>When we describe shapes of distributions, we commonly use words like symmetric, left-skewed, right-skewed, bimodal, and uniform. Not every distribution fits one of these descriptions, but they are still a useful way to summarize the overall shape of many distributions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Y53_8WRrPzg.mp4/Y53_8WRrPzg.mp4</video:content_loc><video:duration>268</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math-1-illustrative-math-aligned/v/using-iqr-and-mad-to-compare-variability</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x25ab550a46da6fad.jpg</video:thumbnail_loc><video:title>Using IQR and MAD to compare variability</video:title><video:description>Compare two data sets with nearly the same measure of center and use IQR and MAD to determine which has greater variability.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6_Pmwrx_kg0.mp4/6_Pmwrx_kg0.mp4</video:content_loc><video:duration>248</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/range-variance-and-standard-deviation-as-measures-of-dispersion</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23764.jpg</video:thumbnail_loc><video:title>Measures of spread: range, variance &amp; standard deviation</video:title><video:description>Range, variance, and standard deviation all measure the spread or variability of a data set in different ways. The range is easy to calculate—it&apos;s the difference between the largest and smallest data points in a set. Standard deviation is the square root of the variance. Standard deviation is a measure of how spread out the data is from its mean.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/E4HAYd0QnRc.mp4/E4HAYd0QnRc.mp4</video:content_loc><video:duration>754</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/variance-of-a-population</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1162004491.jpg</video:thumbnail_loc><video:title>Variance of a population</video:title><video:description>Population variance is a measure of how spread out a group of data points is. Specifically, it quantifies the average squared deviation from the mean. So, if all data points are very close to the mean, the variance will be small; if data points are spread out over a wide range, the variance will be larger.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/dvoHB9djouc.mp4/dvoHB9djouc.mp4</video:content_loc><video:duration>485</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/how-parameters-change-as-data-is-shifted-and-scaled</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x025cb6ad95d9c9b9.jpg</video:thumbnail_loc><video:title>How parameters change as data is shifted and scaled</video:title><video:description>See how transforming a data set by adding, subtracting, multiplying, or dividing a constant affects measures of center and spread.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/JFlI4Vxtzxo.mp4/JFlI4Vxtzxo.mp4</video:content_loc><video:duration>438</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math-1-illustrative-math-aligned/v/standard-deviation-in-context</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc0f44e2b009a2e71.jpg</video:thumbnail_loc><video:title>Standard deviation in context</video:title><video:description>Interpret the standard deviation in the context of a problem.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/nNhzI4GdcKg.mp4/nNhzI4GdcKg.mp4</video:content_loc><video:duration>154</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/judging-outliers-in-a-dataset</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc73e4b612b2ff150.jpg</video:thumbnail_loc><video:title>Judging outliers in a dataset</video:title><video:description>Using the inter-quartile range (IQR) to judge outliers in a dataset.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/FRlTh5HQORA.mp4/FRlTh5HQORA.mp4</video:content_loc><video:duration>501</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math-1-illustrative-math-aligned/v/investigating-outliers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa4491f7c15cda491.jpg</video:thumbnail_loc><video:title>Investigating outliers</video:title><video:description>Determine when values are considered outliers, investigate their source, and determine if they should be excluded from the data.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/BT5x_BEib-4.mp4/BT5x_BEib-4.mp4</video:content_loc><video:duration>172</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/mean-and-standard-deviation-versus-median-and-iqr</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe556bac7306cc461.jpg</video:thumbnail_loc><video:title>Mean and standard deviation versus median and IQR</video:title><video:description>Learn to choose the &quot;preferred&quot; measures of center and spread when outliers are present in a set of data.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qNKOi08NxHs.mp4/qNKOi08NxHs.mp4</video:content_loc><video:duration>479</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math-1-illustrative-math-aligned/v/graphs-of-linear-equations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23634.jpg</video:thumbnail_loc><video:title>Graphing a linear equation: y=2x+7</video:title><video:description>Learn how to create a graph of the linear equation y = 2x + 7.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/rgvysb9emcQ.mp4/rgvysb9emcQ.mp4</video:content_loc><video:duration>790</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math-1-illustrative-math-aligned/v/interpreting-linear-equations-in-different-forms</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3b2e1939604a1ab1.jpg</video:thumbnail_loc><video:title>Interpreting linear equations in different forms</video:title><video:description>Explore what standard form and slope-intercept form each tell us about a linear relationship and its graph.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-cRbQpUmj6Q.mp4/-cRbQpUmj6Q.mp4</video:content_loc><video:duration>301</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math-1-illustrative-math-aligned/v/using-technology-to-graph-and-evaluate-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0723159c0026881f.jpg</video:thumbnail_loc><video:title>Using technology to graph and evaluate functions</video:title><video:description>Use technology to graph and evaluate functions given in function notation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lMiWwRukSKY.mp4/lMiWwRukSKY.mp4</video:content_loc><video:duration>176</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math-1-illustrative-math-aligned/v/comparing-graphs</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd3e962be04eb2402.jpg</video:thumbnail_loc><video:title>Comparing graphs</video:title><video:description>Analyze and interpret functions, using graphs, equations (such as f(x)=g(x)), and function notation, to compare their key features and understand what their relationships mean in context.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/t-LuEry9P3o.mp4/t-LuEry9P3o.mp4</video:content_loc><video:duration>176</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math-1-illustrative-math-aligned/v/exploring-key-features-of-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x00f13c460a3f890d.jpg</video:thumbnail_loc><video:title>Exploring key features of functions</video:title><video:description>Interpret key features of a graph.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PYJdiguNWKQ.mp4/PYJdiguNWKQ.mp4</video:content_loc><video:duration>222</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math-1-illustrative-math-aligned/v/interpreting-a-piecewise-function-graph</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd37f8ac55ee5c7d8.jpg</video:thumbnail_loc><video:title>Interpreting a piecewise function graph</video:title><video:description>Learn how to read a piecewise function graph by interpreting movie ticket prices for different age ranges, including what the open and closed circles mean at each boundary.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/G1SH5MJvfoM.mp4/G1SH5MJvfoM.mp4</video:content_loc><video:duration>128</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math-1-illustrative-math-aligned/v/comparing-guesses-and-absolute-errors</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6669803dc09ebb97.jpg</video:thumbnail_loc><video:title>Comparing guesses and absolute errors</video:title><video:description>Analyze and interpret a scatter plot of numerical guesses versus their absolute errors, calculating the errors from a target value and generalizing the relationship in words and/or equations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Y3oJbKTnVXQ.mp4/Y3oJbKTnVXQ.mp4</video:content_loc><video:duration>280</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math-1-illustrative-math-aligned/v/finding-and-interpreting-inverse-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3e530684eb6dc77a.jpg</video:thumbnail_loc><video:title>Finding and interpreting inverse functions</video:title><video:description>Find and interpret an inverse function in terms of situations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/fvJZWSrdSOM.mp4/fvJZWSrdSOM.mp4</video:content_loc><video:duration>178</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math-1-illustrative-math-aligned/v/comparing-linear-and-exponential-relationships</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2a9416c840661655.jpg</video:thumbnail_loc><video:title>Comparing linear and exponential relationships</video:title><video:description>Analyze and compare linear and exponential relationships using numerical calculations and by interpreting graphs that illustrate their respective growth patterns.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/exCgXqE6ZF0.mp4/exCgXqE6ZF0.mp4</video:content_loc><video:duration>212</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math-1-illustrative-math-aligned/v/modeling-car-value-over-time-with-exponential-decay</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1ef7795a0dac7d4b.jpg</video:thumbnail_loc><video:title>Modeling car value over time with exponential decay</video:title><video:description>Interpret an exponential decay graph that models the value of a car over time, including what the graph suggests about the car’s value in the long run and what the y-intercept represents.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/no0tMoIHLwg.mp4/no0tMoIHLwg.mp4</video:content_loc><video:duration>152</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math-1-illustrative-math-aligned/v/exploring-exponential-situations-as-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2d16e879f950a45e.jpg</video:thumbnail_loc><video:title>Exploring exponential situations as functions</video:title><video:description>Decide if a relationship is a function by looking at descriptions, tables, equations, or graphs, and use function notation to write equations for exponential relationships.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/YhEBIHPG9cM.mp4/YhEBIHPG9cM.mp4</video:content_loc><video:duration>96</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math-1-illustrative-math-aligned/v/interpreting-exponential-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5ce936490527bc26.jpg</video:thumbnail_loc><video:title>Interpreting exponential functions</video:title><video:description>Analyze exponential functions by interpreting and describing exponential relationships using function notation and using graphing technology to explore domains and behaviors of exponential functions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8XicDs22wlw.mp4/8XicDs22wlw.mp4</video:content_loc><video:duration>206</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math-1-illustrative-math-aligned/v/calculating-and-interpreting-rates-of-change-for-exponential-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0e03a55d2202170c.jpg</video:thumbnail_loc><video:title>Calculating and interpreting rates of change for exponential functions</video:title><video:description>Calculate the average rate of change over intervals to explain how it reflects the behavior of exponential functions and to understand how exponential growth differs from the constant rate of change in linear functions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/FQtcvJiVmWQ.mp4/FQtcvJiVmWQ.mp4</video:content_loc><video:duration>268</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math-1-illustrative-math-aligned/v/comparing-exponential-functions-with-the-same-growth-factor</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfd210b64fd74cdc4.jpg</video:thumbnail_loc><video:title>Comparing exponential functions with the same growth factor</video:title><video:description>Use equations and graphs to compare exponential functions and explore how changing the parameters a and b in an exponential function affects its graph.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3-BIGCWr8Ow.mp4/3-BIGCWr8Ow.mp4</video:content_loc><video:duration>119</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math-1-illustrative-math-aligned/v/comparing-exponential-functions-with-the-same-initial-value</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8e1f7b837fa993ce.jpg</video:thumbnail_loc><video:title>Comparing exponential functions with the same initial value</video:title><video:description>Use equations and graphs to compare exponential functions and explore how changing the parameters a and b in an exponential function affects its graph.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6UwuYpY9IxY.mp4/6UwuYpY9IxY.mp4</video:content_loc><video:duration>121</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/graphically-solving-equations-word-problems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0e2500ebf3a509df.jpg</video:thumbnail_loc><video:title>Solving equations by graphing: word problems</video:title><video:description>We can approximate the solutions of any equation by graphing both sides of the equation and looking for intersection point. See how we apply this idea to solve some word problems.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/wlhuoE56t3c.mp4/wlhuoE56t3c.mp4</video:content_loc><video:duration>510</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/word-problem-solving-exponential-growth-and-decay</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23700.jpg</video:thumbnail_loc><video:title>Exponential growth &amp; decay word problems</video:title><video:description>How do you solve word problems involving exponential growth and decay? In this video, you will learn how to use a table and a formula to find the percentage of a radioactive substance that remains after a certain time. You will also see how a common ratio, which is the factor by which the quantity changes every time period, determines the rate of change. You will use a calculator to apply the formula and get the answers.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/m5Tf6vgoJtQ.mp4/m5Tf6vgoJtQ.mp4</video:content_loc><video:duration>441</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math-1-illustrative-math-aligned/v/exploring-different-compounding-intervals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xda3b77e9fa084729.jpg</video:thumbnail_loc><video:title>Exploring different compounding intervals</video:title><video:description>Calculate and compare the effects of different interest rates and compounding intervals to determine the better investment option.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/VordmbxdG3A.mp4/VordmbxdG3A.mp4</video:content_loc><video:duration>479</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math-1-illustrative-math-aligned/v/exploring-changes-over-equal-intervals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf78b0afe30e02c95.jpg</video:thumbnail_loc><video:title>Exploring changes over equal intervals</video:title><video:description>Compare how functions change over equal input intervals to determine whether a situation is linear or exponential. Linear functions change by equal differences over equal intervals, while exponential functions change by equal factors.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/JcN8Dl1Y1tg.mp4/JcN8Dl1Y1tg.mp4</video:content_loc><video:duration>255</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-1-illustrative-math/v/analyzing-data-to-model-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x95d791bff4888b71.jpg</video:thumbnail_loc><video:title>Analyzing data to model functions</video:title><video:description>Sal demonstrates the process of matching a table of values to a specific function type: linear, quadratic, or exponential.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/v7gmPAARnSw.mp4/v7gmPAARnSw.mp4</video:content_loc><video:duration>362</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-1-illustrative-math/v/building-quadratic-functions-from-geometric-patterns</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7cc9cdb35759333d.jpg</video:thumbnail_loc><video:title>Building quadratic functions from geometric patterns</video:title><video:description>Represent growing patterns of squares using expressions and functions. Compare different expressions that represent the same pattern and match quadratic rules to the patterns they create.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DrrYX7VhGLE.mp4/DrrYX7VhGLE.mp4</video:content_loc><video:duration>86</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/comparing-exponentials-quadratics</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x51b990d2.jpg</video:thumbnail_loc><video:title>Comparing growth of exponential &amp; quadratic models</video:title><video:description>Sal discusses two functions that model the shipment rate of cars. One function is quadratic and the other is exponential. Which one will eventually exceed the other?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/EuwKjpUpkhs.mp4/EuwKjpUpkhs.mp4</video:content_loc><video:duration>420</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-1-illustrative-math/v/comparing-quadratic-and-exponential-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x197842e5ebe3db0b.jpg</video:thumbnail_loc><video:title>Comparing quadratic and exponential functions</video:title><video:description>Compare quadratic and exponential functions using tables, graphs, calculations, and growth factors to understand how each type of function grows. Identify when an exponential becomes greater and explain why exponential growth eventually surpasses quadratic growth.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/RDkH6qG-E6U.mp4/RDkH6qG-E6U.mp4</video:content_loc><video:duration>310</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-1-illustrative-math/v/modeling-free-fall-with-quadratic-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa4d18f6766eb393f.jpg</video:thumbnail_loc><video:title>Modeling free fall with quadratic functions</video:title><video:description>Use equations, tables, and graphs to model free-fall situations. Interpret and write quadratic functions that describe height over time.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/kPzBt5gUFuY.mp4/kPzBt5gUFuY.mp4</video:content_loc><video:duration>155</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/domain-and-range-of-a-function-given-a-formula</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/364981333.jpg</video:thumbnail_loc><video:title>Domain and range of quadratic functions</video:title><video:description>Sal finds the domain and the range of f(x)=3x^2+6x-2.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/za0QJRZ-yQ4.mp4/za0QJRZ-yQ4.mp4</video:content_loc><video:duration>487</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-1-illustrative-math/v/choosing-an-appropriate-domain-for-a-quadratic-function</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe4e43c7908c4f531.jpg</video:thumbnail_loc><video:title>Choosing an appropriate domain for a quadratic function</video:title><video:description>Choose an appropriate domain for a quadratic function that represents a context, and explain why it was selected.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/aEBI6aO9-1E.mp4/aEBI6aO9-1E.mp4</video:content_loc><video:duration>240</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-1-illustrative-math/v/interpreting-graphs-of-quadratic-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x52c2f1eaf0167721.jpg</video:thumbnail_loc><video:title>Interpreting graphs of quadratic functions</video:title><video:description>Connect how a quadratic expression in factored form corresponds to the x- and y-intercepts of its graph.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/t_pzO1ydVbo.mp4/t_pzO1ydVbo.mp4</video:content_loc><video:duration>136</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-1-illustrative-math/v/graphing-quadratics-in-factored-form-when-a-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1f6bbfe9480d8c91.jpg</video:thumbnail_loc><video:title>Graphing quadratics in factored form when a=1</video:title><video:description>Graph quadratic functions written in factored form, f(x) = a(x-p)(x-q), when a = 1, and identify the vertex and y-intercept.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Mk_hLTGabTQ.mp4/Mk_hLTGabTQ.mp4</video:content_loc><video:duration>241</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-1-illustrative-math/v/sat-math-p10-easier</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2708bc6f.jpg</video:thumbnail_loc><video:title>Interpreting nonlinear expressions — Basic example</video:title><video:description>Watch Sal work through a basic Interpreting nonlinear expressions problem.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/YfYiS2Bfx20.mp4/YfYiS2Bfx20.mp4</video:content_loc><video:duration>127</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-1-illustrative-math/v/quadratic-equation-from-geometric-context</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xafa3561c1c8ad6b8.jpg</video:thumbnail_loc><video:title>Quadratic equation from geometric context</video:title><video:description>Write a quadratic equation from a situation and interpret what a solution means in context.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/au5T5cznr5k.mp4/au5T5cznr5k.mp4</video:content_loc><video:duration>188</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-1-illustrative-math/v/determining-the-number-of-solutions-of-a-quadratic-graphically</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x617210543009ae91.jpg</video:thumbnail_loc><video:title>Determining the number of solutions of a quadratic graphically</video:title><video:description>Use graphs to determine whether quadratic equations have two solutions, one solution, or no real solutions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/EQwrOE86YPw.mp4/EQwrOE86YPw.mp4</video:content_loc><video:duration>195</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-1-illustrative-math/v/why-you-cant-divide-by-a-variable-when-solving-quadratics</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4c421a9807140240.jpg</video:thumbnail_loc><video:title>Why you can&apos;t divide by a variable when solving quadratics</video:title><video:description>Learn why dividing both sides of a quadratic equation by a variable can eliminate solutions, and see how factoring reveals all solutions instead.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PL9X7Ww8aFU.mp4/PL9X7Ww8aFU.mp4</video:content_loc><video:duration>223</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-1-illustrative-math/v/solving-by-completing-the-square-rational-solutions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc9a4c925512f4e2a.jpg</video:thumbnail_loc><video:title>Solving by completing the square: rational solutions</video:title><video:description>Express a quadratic equation in the form (x+p)^2=q, and use completing the square to solve quadratic equations in which the squared term has a coefficient of 1.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/wupekgmKRbA.mp4/wupekgmKRbA.mp4</video:content_loc><video:duration>283</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-1-illustrative-math/v/exact-vs-approximate-solutions-to-quadratic-equations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x056ab8790eaecae5.jpg</video:thumbnail_loc><video:title>Exact vs. approximate solutions to quadratic equations</video:title><video:description>Solve a quadratic equation by completing the square and by graphing, then compare the exact and approximate solutions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qsk_5WCPEy8.mp4/qsk_5WCPEy8.mp4</video:content_loc><video:duration>336</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-1-illustrative-math/v/rewriting-a-quadratic-function-from-vertex-form-to-standard-form</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdb2a02453900a4cc.jpg</video:thumbnail_loc><video:title>Rewriting a quadratic function from vertex form to standard form</video:title><video:description>Given a quadratic function in vertex form, rewrite it in standard form.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/NbNfSIG65Qc.mp4/NbNfSIG65Qc.mp4</video:content_loc><video:duration>170</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/terms-coefficients-and-exponents-in-a-polynomial</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179510.jpg</video:thumbnail_loc><video:title>The parts of polynomial expressions</video:title><video:description>Discover the magic of polynomials! Learn to identify terms, coefficients, and exponents in a polynomial. Understand that terms are the parts being added, coefficients are the numbers multiplying the powers of x, and exponents are the powers to which x is raised. Dive into the world of polynomials and make math fun!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/REiDXCN0lGU.mp4/REiDXCN0lGU.mp4</video:content_loc><video:duration>156</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/interpreting-expressions-with-multiple-variables-resistors</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa067e8a28a42697f.jpg</video:thumbnail_loc><video:title>Interpreting expressions with multiple variables: Resistors</video:title><video:description>Given the expression for the total resistance in an electric circuit with two resistors, analyze the expression to tell what happens to the total resistance when the resistance of one resistor increases and the resistance of the other resistor stays the same.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8ffMjFXiW9A.mp4/8ffMjFXiW9A.mp4</video:content_loc><video:duration>207</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/interpreting-expressions-with-multiple-variables-cylinder</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1bc6c490b5f36156.jpg</video:thumbnail_loc><video:title>Interpreting expressions with multiple variables: Cylinder</video:title><video:description>Given the vale and the expression for the radius of a cylinder, find the radius of a cylinder with the same volume and 100 times the height. This involves analyzing the expression for the radius to see how changing the height affects the radius.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/k00KEcYijo8.mp4/k00KEcYijo8.mp4</video:content_loc><video:duration>215</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-1-tx/v/adding-and-subtracting-polynomials-of-degree-one</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3a2560f8a6da50d7.jpg</video:thumbnail_loc><video:title>Adding and subtracting polynomials of degree one</video:title><video:description>Expand previous knowledge of combining like terms to this new context with more than one variable.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4MRaGUNKw8U.mp4/4MRaGUNKw8U.mp4</video:content_loc><video:duration>293</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-1-tx/v/dividing-polynomials-of-degree-one</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x953db4fde352a6b6.jpg</video:thumbnail_loc><video:title>Dividing polynomials of degree one</video:title><video:description>Expand previous knowledge of division to this new context involving more than one term. With and without remainders are in the exercise, so the video should cover remainders.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LtCd09uHFnc.mp4/LtCd09uHFnc.mp4</video:content_loc><video:duration>407</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-1-tx/v/domain-and-range-of-lines-segments-and-rays</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xefb4ca8a30451db2.jpg</video:thumbnail_loc><video:title>Domain and range of lines, segments, and rays</video:title><video:description>Compare and contrast domain and range given graphs of line segment and line.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/wd19aPWRRKA.mp4/wd19aPWRRKA.mp4</video:content_loc><video:duration>267</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-1-tx/v/domain-and-range-from-graphs-of-quadratic-and-exponential-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe722bfcbf46256ce.jpg</video:thumbnail_loc><video:title>Domain and range from graphs of quadratic and exponential functions</video:title><video:description>Compare and contrast domain and range given graphs of partial quadratic and exponential functions, where the ends of the shown graph vary among points, and arrows.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jArkTYaZuek.mp4/jArkTYaZuek.mp4</video:content_loc><video:duration>207</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/direct-and-inverse-variation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/62754976.jpg</video:thumbnail_loc><video:title>Intro to direct &amp; inverse variation</video:title><video:description>Sal explains what it means for quantities to vary directly or inversely, and gives many examples of both types of variation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/92U67CUy9Gc.mp4/92U67CUy9Gc.mp4</video:content_loc><video:duration>594</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/proportionality-constant-for-direct-variation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/124291560.jpg</video:thumbnail_loc><video:title>Proportionality constant for direct variation</video:title><video:description>Worked example: y is directly proportional to x, and y=30 when x=6. Find the value of x when y=45.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/c6-FJRda_Vc.mp4/c6-FJRda_Vc.mp4</video:content_loc><video:duration>104</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/direct-variation-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26794.jpg</video:thumbnail_loc><video:title>Direct variation word problem: filling gas</video:title><video:description>Worked example: Model a context about filling gas with a direct variation equation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/rSadG6EtJmY.mp4/rSadG6EtJmY.mp4</video:content_loc><video:duration>219</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-1-tx/v/writing-equations-of-parallel-lines</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x431a7475d4b78eb4.jpg</video:thumbnail_loc><video:title>Writing equations of parallel lines</video:title><video:description>Write the equation of a line that passes through a given point and is parallel to a given line.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/i3Jsfn8dd80.mp4/i3Jsfn8dd80.mp4</video:content_loc><video:duration>278</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/probability/v/statistical-significance-experiment</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfcac80a7.jpg</video:thumbnail_loc><video:title>Statistical significance of experiment</video:title><video:description>Sal determines if the results of an experiment about advertising are statistically significant.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jLFeqQxGtOc.mp4/jLFeqQxGtOc.mp4</video:content_loc><video:duration>484</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-1-tx/v/writing-a-system-of-linear-equations-from-tables</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9fac2e33fa41b85f.jpg</video:thumbnail_loc><video:title>Writing a system of linear equations from tables</video:title><video:description>Write a system of two linear equations from tables.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/B86zMf0u864.mp4/B86zMf0u864.mp4</video:content_loc><video:duration>329</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-1-tx/v/writing-a-system-of-linear-equations-from-a-graph</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6af67034e0e70150.jpg</video:thumbnail_loc><video:title>Writing a system of linear equations from a graph</video:title><video:description>Write a system of two linear equations from a graph.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ODYSynkDNnQ.mp4/ODYSynkDNnQ.mp4</video:content_loc><video:duration>261</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-1-tx/v/estimating-graphically-with-systems-in-real-world-problems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0ee2551fa79974fd.jpg</video:thumbnail_loc><video:title>Estimating graphically with systems in real world problems</video:title><video:description>Estimate the solution to a real-world system of linear equations by graphing both equations, identifying the intersection point, and comparing costs using the graph.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9p7sVDEof5Q.mp4/9p7sVDEof5Q.mp4</video:content_loc><video:duration>190</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/polynomial-division</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23780.jpg</video:thumbnail_loc><video:title>Intro to long division of polynomials</video:title><video:description>Learn how to divide polynomials, also known as algebraic long division. This video starts with simple examples and gradually moves to more complex ones, demonstrating how to divide quadratics by linear factors. The process involves looking at the highest degree terms, dividing, and subtracting to simplify expressions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/FXgV9ySNusc.mp4/FXgV9ySNusc.mp4</video:content_loc><video:duration>729</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/quad-div-by-linear-no-remainder</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdfd8519b61001565.jpg</video:thumbnail_loc><video:title>Dividing quadratics by linear expressions (no remainders)</video:title><video:description>We can divide polynomials similarly to how we divide integers. For example, when we divide (x²+7x+10) by (x+2), we are asking &quot;what can we multiply by (x+2) to get (x²+7x+10)?&quot; We can answer this question in many ways. One is with using factorization, and another one is long division.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/dRvLVdQ8cw4.mp4/dRvLVdQ8cw4.mp4</video:content_loc><video:duration>244</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/quad-div-by-linear-with-remainder</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe8d44657d914ffe9.jpg</video:thumbnail_loc><video:title>Dividing quadratics by linear expressions with remainders</video:title><video:description>Learn how to simplify complex math problems by dividing quadratics by linear factors with remainders. Discover two methods for simplifying these kinds of math problems: factoring the numerator or using algebraic long division. This process helps break down tricky equations, making them easier to solve.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-veSAbfer7Q.mp4/-veSAbfer7Q.mp4</video:content_loc><video:duration>296</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/quad-div-by-linear-missing-x-term</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0c9165d8371b07d6.jpg</video:thumbnail_loc><video:title>Dividing quadratics by linear expressions with remainders: missing x-term</video:title><video:description>An interesting case in polynomial division is when one of the terms is missing. The video explains how to divide a quadratic expression, like (x²+1), by a linear one, such as (x+2). It shows two methods: re-expressing the numerator and using algebraic long division. Both methods lead to the same answer.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/CDJGU9P_pGU.mp4/CDJGU9P_pGU.mp4</video:content_loc><video:duration>283</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-1-tx/v/rewriting-expressions-with-exponents-challenge-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf0e2b4b0fb9b9a03.jpg</video:thumbnail_loc><video:title>Rewriting expressions with exponents challenge 1</video:title><video:description>Expand previous knowledge of isolated exponent rules to rewriting expressions using multiple rules in the same problem.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/NsNhpzljMFE.mp4/NsNhpzljMFE.mp4</video:content_loc><video:duration>308</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-1-tx/v/exponent-rule-challenge-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf6979f999f54ef2f.jpg</video:thumbnail_loc><video:title>Rewriting expressions with exponents challenge 2</video:title><video:description>Expand previous knowledge of isolated exponent rules to rewriting expressions using multiple rules in the same problem.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Ne8_dXWjeeU.mp4/Ne8_dXWjeeU.mp4</video:content_loc><video:duration>290</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-2-tx/v/writing-a-quadratic-when-given-the-vertex-and-another-point</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa1dbf5a2e76e1c1a.jpg</video:thumbnail_loc><video:title>Writing a quadratic when given the vertex and another point</video:title><video:description>Given the vertex of a quadratic function and another point on the graph, write the equation for that function in vertex form.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/04vzdWS3Q7k.mp4/04vzdWS3Q7k.mp4</video:content_loc><video:duration>318</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-1-tx/v/writing-a-quadratic-function-from-a-graph</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xac2455cfda81760a.jpg</video:thumbnail_loc><video:title>Writing a quadratic function from a graph</video:title><video:description>When given a graph of a quadratic function, write its equation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xUtzpjM4xyE.mp4/xUtzpjM4xyE.mp4</video:content_loc><video:duration>317</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-1-tx/v/writing-a-quadratic-function-from-solutions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xaf44af9711632f18.jpg</video:thumbnail_loc><video:title>Writing a quadratic function from solutions</video:title><video:description>When given the real solutions of a quadratic function, write its equation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Wv-SiowM4M8.mp4/Wv-SiowM4M8.mp4</video:content_loc><video:duration>283</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-1-tx/v/graphing-arithmetic-sequences</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3ec74f2d88ba92f9.jpg</video:thumbnail_loc><video:title>Graphing arithmetic sequences</video:title><video:description>Connecting existing knowledge of arithmetic sequences expressed in recursive function form to their representation graphically.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2OU-pb7CCT0.mp4/2OU-pb7CCT0.mp4</video:content_loc><video:duration>263</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-1-tx/v/graphing-geometric-sequences</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x30bbcb43daaab271.jpg</video:thumbnail_loc><video:title>Graphing geometric sequences</video:title><video:description>Connecting existing knowledge of geometric sequences expressed in recursive function form to their representation graphically.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/a37pYSmcU7c.mp4/a37pYSmcU7c.mp4</video:content_loc><video:duration>235</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-1-tx-teks-imra-2026-publisher-initiated-changes/v/horizontal-and-vertical-lines-equations-and-slope</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd5310b991eb3872d.jpg</video:thumbnail_loc><video:title>Horizontal and vertical lines: equations and slope (IMRA 2026 publisher-initiated change)</video:title><video:description>Write the equation of a horizontal and vertical line, and determine whether its slope is zero or undefined. IMRA 2026 publisher-initiated change</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gKG2fKmeEY4.mp4/gKG2fKmeEY4.mp4</video:content_loc><video:duration>270</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-1-tx-teks-imra-2026-publisher-initiated-changes/v/finding-the-zero-of-a-linear-function</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x56432438250b9bdf.jpg</video:thumbnail_loc><video:title>Finding the zero of a linear function (IMRA 2026 publisher-initiated change)</video:title><video:description>Find the zero of a linear function, also called the x-intercept, by reading it from a graph and by solving the equation algebraically.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DVObvLWb720.mp4/DVObvLWb720.mp4</video:content_loc><video:duration>271</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-1-tx-teks-imra-2026-publisher-initiated-changes/v/interpreting-the-zero-of-a-linear-function-in-a-real-world-problem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb53a0b68d5c3bda8.jpg</video:thumbnail_loc><video:title>Interpreting the zero of a linear function in a real world problem (IMRA 2026 publisher-initiated change)</video:title><video:description>Find the zero of a linear function that models a real-world situation,, and explain what it means in context.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/o58Du_cErSI.mp4/o58Du_cErSI.mp4</video:content_loc><video:duration>110</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-1-tx-teks-imra-2026-publisher-initiated-changes/v/fitting-a-line-to-data-using-a-graphing-calculator</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa32348d946651ecf.jpg</video:thumbnail_loc><video:title>Fitting a line to data using a graphing calculator (IMRA 2026 publisher-initiated change)</video:title><video:description>Sal uses a graphing calculator (Desmos) to fit a line to a person&apos;s weekly walking distance using linear regression, then uses the model to make a prediction. IMRA 2026 publisher-initiated change.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Bnzg9wtyCq8.mp4/Bnzg9wtyCq8.mp4</video:content_loc><video:duration>373</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-1-tx-teks-imra-2026-publisher-initiated-changes/v/worked-example-rewriting-and-solving-equations-by-completing-the-square</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7ec99b7dc5aca17c.jpg</video:thumbnail_loc><video:title>Worked example: Rewriting and solving equations by completing the square (IMRA 2026 publisher-initiated change)</video:title><video:description>Rewrite and solve quadratic equations by completing the square. IMRA 2026 publisher-initiated change</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Q0rT65JxXjo.mp4/Q0rT65JxXjo.mp4</video:content_loc><video:duration>378</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/introduction-to-i-and-imaginary-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/145918385.jpg</video:thumbnail_loc><video:title>Intro to the imaginary numbers</video:title><video:description>Learn about the imaginary unit, &quot;i&quot;, a unique number defined as the square root of -1. It&apos;s a key part of complex numbers, which are in the form a + bi. The powers of &quot;i&quot; cycle through a set of values.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ysVcAYo7UPI.mp4/ysVcAYo7UPI.mp4</video:content_loc><video:duration>320</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/imaginary-roots-of-negative-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/150088079.jpg</video:thumbnail_loc><video:title>Simplifying roots of negative numbers</video:title><video:description>Discover the magic of the imaginary unit &apos;i&apos;! This lesson dives into simplifying the square root of negative numbers using &apos;i&apos;, the principal square root of -1. We&apos;ll explore how to rewrite negative numbers as products, and use prime factorization to simplify roots.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/s03qez-6JMA.mp4/s03qez-6JMA.mp4</video:content_loc><video:duration>244</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/calculating-i-raised-to-arbitrary-exponents</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/145918384.jpg</video:thumbnail_loc><video:title>Powers of the imaginary unit</video:title><video:description>The imaginary unit i is defined such that i²=-1. So what&apos;s i³? i³=i²⋅i=-i. What&apos;s i⁴? i⁴=i²⋅i²=(-1)²=1. What&apos;s i⁵? i⁵=i⁴⋅i=1⋅i=i. Discover how the powers of &apos;i&apos; cycle through values, making it possible to calculate high exponents of &apos;i&apos; easily.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/QiwfF83NWNA.mp4/QiwfF83NWNA.mp4</video:content_loc><video:duration>380</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/i-as-the-principal-root-of-1-a-little-technical</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/148079183.jpg</video:thumbnail_loc><video:title>i as the principal root of -1</video:title><video:description>The video explores the intriguing concept of imaginary numbers, specifically the imaginary unit &apos;i&apos;. &apos;i&apos; is equal to the square root of -1, and every complex number can be expressed as a + bi, where a and b are real numbers. This video clarifies misconceptions about square roots of negative numbers.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/rYG1D5lUE4I.mp4/rYG1D5lUE4I.mp4</video:content_loc><video:duration>404</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/complex-number-intro</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe9c076b5.jpg</video:thumbnail_loc><video:title>Intro to complex numbers</video:title><video:description>Sal explains how we obtain complex numbers by adding real numbers and imaginary numbers.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/SP-YJe7Vldo.mp4/SP-YJe7Vldo.mp4</video:content_loc><video:duration>284</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/adding-complex-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/150088080.jpg</video:thumbnail_loc><video:title>Adding complex numbers</video:title><video:description>Learn how to break down the process of adding complex numbers into simple steps. First, add the real parts. Then, do the same with the imaginary parts. The result? A new complex number! Learn and try some examples with Sal.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/SfbjqVyQljk.mp4/SfbjqVyQljk.mp4</video:content_loc><video:duration>71</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/subtracting-complex-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/150088077.jpg</video:thumbnail_loc><video:title>Subtracting complex numbers</video:title><video:description>Learn how to break down the process of subtracting complex numbers into simple steps. Distribute the negative sign to get rid of parentheses, then add up the real and imaginary parts separately. Voila! You&apos;ve got your answer in the form of a + bi.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tvXRaZbIjO8.mp4/tvXRaZbIjO8.mp4</video:content_loc><video:duration>113</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/multiplying-complex-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/150088076.jpg</video:thumbnail_loc><video:title>Multiplying complex numbers</video:title><video:description>Discover how to multiply complex numbers! Just like multiplying regular numbers, you can use the distributive property or FOIL method. Remember, the imaginary unit &apos;i&apos; squared equals -1. So, when you multiply complex numbers like 1-3i and 2+5i, you get a new complex number: 17-i.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/cWn6g8Qqvs4.mp4/cWn6g8Qqvs4.mp4</video:content_loc><video:duration>332</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/complex-roots-from-the-quadratic-formula</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/150088081.jpg</video:thumbnail_loc><video:title>Solving quadratic equations: complex roots</video:title><video:description>Solving quadratic equations can lead to complex solutions. Listen to Sal break down the process using the quadratic formula and standard form. Then, learn how to verify these complex solutions, ensuring you&apos;ve got the right answer. It&apos;s all about turning tricky problems into solvable equations!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/dnjK4DPqh0k.mp4/dnjK4DPqh0k.mp4</video:content_loc><video:duration>615</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/factor-high-deg-poly-intro</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xcb872f1c2aba4146.jpg</video:thumbnail_loc><video:title>Introduction to factoring higher degree polynomials</video:title><video:description>Unpack the process of factoring monomials in algebra. Learn to simplify third-degree polynomials and tackle fourth-degree monomials. Understand the structure of introductory algebra and apply it to higher degree polynomials. Explore the concept of factoring multiple times and delve into the difference of squares. It&apos;s all about breaking down complex expressions into simpler parts!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7y_2jQlnKag.mp4/7y_2jQlnKag.mp4</video:content_loc><video:duration>353</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/algebraic-factoring-by-greatest-common-monomial-factor</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xaae59186.jpg</video:thumbnail_loc><video:title>Taking common factor from binomial</video:title><video:description>Explore the process of factoring polynomials using the greatest common monomial factor. This involves breaking down coefficients and powers of variables to find the largest common factor, and then rewriting the expression with this common factor factored out. It&apos;s an essential skill for simplifying and solving algebraic expressions</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/iTn3TTF0IXk.mp4/iTn3TTF0IXk.mp4</video:content_loc><video:duration>298</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/factoring-and-the-distributive-property-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26982.jpg</video:thumbnail_loc><video:title>Taking common factor from trinomial</video:title><video:description>Break down the process of taking common factors from trinomials. Learn how to identify the greatest common factor of a trinomial expression and use it to simplify the expression. Follow along as Sal factors 4x⁴y-8x³y-2x² as 2x²(2x²y-4xy-1) by taking the greatest common factor.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/MZl6Mna0leQ.mp4/MZl6Mna0leQ.mp4</video:content_loc><video:duration>354</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/factoring-polynomial-with-area-model</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5424a175.jpg</video:thumbnail_loc><video:title>Taking common factor: area model</video:title><video:description>The video explores taking common factors in algebra using an area model. It demonstrates how to find the greatest common monomial factor of terms and uses the area of a rectangle as a visual aid. By factoring out the length and width, you can better grasp the process of factoring polynomials.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tYknkDjp-bQ.mp4/tYknkDjp-bQ.mp4</video:content_loc><video:duration>327</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/factor-high-deg-poly</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc1951d0a2ffae6d9.jpg</video:thumbnail_loc><video:title>Factoring higher degree polynomials</video:title><video:description>Factoring higher degree polynomials involves breaking down complex expressions into simpler parts. This process includes identifying common factors, using the distributive property, and recognizing perfect squares. Sal demonstrates how to factor a partially factored polynomial and how to factor a third degree polynomial by grouping.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/AUBX_aHStQY.mp4/AUBX_aHStQY.mp4</video:content_loc><video:duration>238</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/factoring-perfect-square-polynomial</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1520bb8a.jpg</video:thumbnail_loc><video:title>Factoring higher degree polynomials: Common factor</video:title><video:description>Discover the art of factoring higher degree polynomials. We start by pulling out common factors, then spot perfect squares. The key is seeing patterns and using them to simplify complex expressions. Sal demonstrates by factoring 16x^3+24x^2+9x as (x)(4x+3)^2.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/BFW2lHobO4E.mp4/BFW2lHobO4E.mp4</video:content_loc><video:duration>219</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/id-quad-patterns</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x91cf610e0c621e01.jpg</video:thumbnail_loc><video:title>Identifying quadratic patterns</video:title><video:description>Factoring using structure involves recognizing patterns in expressions, like the difference of squares or perfect square trinomials, and using these patterns to break down complex expressions into simpler ones. As an example, you’ll determine whether the polynomial 9x⁸+6x⁴y+y² can be factored using the perfect square pattern or the difference of squares pattern (or neither).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OcavJJA8Uyg.mp4/OcavJJA8Uyg.mp4</video:content_loc><video:duration>350</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/factor-w-substitution</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd2d2ed4ed28d8978.jpg</video:thumbnail_loc><video:title>Factorization with substitution</video:title><video:description>Unravel the mystery of algebraic expressions with factorization using substitution! This lesson explores how to simplify complex expressions by identifying patterns and substituting variables. By using U+V² and U+V x U-V structures, you can easily transform and factor expressions!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/js5cP-rq0FI.mp4/js5cP-rq0FI.mp4</video:content_loc><video:duration>313</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/factoring-special-products-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26990.jpg</video:thumbnail_loc><video:title>Factoring using the perfect square pattern</video:title><video:description>Sal factors 25x^4-30x^2+9 as (5x^2-3)^2.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/o-ZbdYVGehI.mp4/o-ZbdYVGehI.mp4</video:content_loc><video:duration>145</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/factoring-difference-of-squares</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179583.jpg</video:thumbnail_loc><video:title>Factoring using the difference of squares pattern</video:title><video:description>If we expand (a+b)(a-b) we will get a²-b². Factorization goes the other way: suppose we have an expression that is the difference of two squares, like x²-25 or 49x²-y², then we can factor is using the roots of those squares. For example, x²-25 can be factored as (x+5)(x-5). This is an extremely useful method that is used throughout math.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tvnOWIoeeaU.mp4/tvnOWIoeeaU.mp4</video:content_loc><video:duration>109</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/geo-series-intro</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5b09b14bc0585679.jpg</video:thumbnail_loc><video:title>Geometric series introduction</video:title><video:description>Learn how money grows in a bank account with geometric series! Discover how each deposit grows by a fixed percentage every year, creating a pattern. This pattern forms a geometric series, a useful concept in finance and business. Keep depositing and watch your money multiply!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/BdsURIUQ04k.mp4/BdsURIUQ04k.mp4</video:content_loc><video:duration>377</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/deriving-formula-for-sum-of-finite-geometric-series</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x59f9c2a4.jpg</video:thumbnail_loc><video:title>Finite geometric series formula</video:title><video:description>A finite geometric series can be solved using the formula a(1-rⁿ)/(1-r). Sal demonstrates how to derive a formula for the sum of the first &apos;n&apos; terms of such a series, emphasizing the importance of understanding the number of terms being summed.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Cf0-6ngH2gs.mp4/Cf0-6ngH2gs.mp4</video:content_loc><video:duration>435</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/three-examples-of-evaluating-finite-geometric-series</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe9cd3f25.jpg</video:thumbnail_loc><video:title>Worked examples: finite geometric series</video:title><video:description>Get a front row seat to Sal&apos;s step-by-step solutions to finite geometric series. Learn how to find the sum of the first 50 terms of a series by multiplying each term by a common ratio. Discover how to apply the formula for the sum of a finite geometric series. Plus, explore how to handle series with a change in sign.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DY9Q3qNmZnw.mp4/DY9Q3qNmZnw.mp4</video:content_loc><video:duration>415</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/poly-div-by-linear</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x97920bb5395034a1.jpg</video:thumbnail_loc><video:title>Dividing polynomials by linear expressions</video:title><video:description>Learn how to divide polynomials by linear factors! This tutorial guides you through the process of algebraic long division, focusing on highest degree terms first. You&apos;ll master the art of subtracting polynomials, handling remainders, and rewriting expressions in different forms.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/G2VBRwXq1q4.mp4/G2VBRwXq1q4.mp4</video:content_loc><video:duration>204</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/poly-div-by-linear-missing-term</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe64842d7cab9c7d2.jpg</video:thumbnail_loc><video:title>Dividing polynomials by linear expressions: missing term</video:title><video:description>This lesson guides you through the process of dividing polynomials by linear factors, showing you how to neatly organize your work and avoid common errors. You&apos;ll learn how to handle missing degree terms and ensure correct subtraction. The result? You&apos;ll confidently simplify and rewrite complex rational expressions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/QTZ5Dn0t6M4.mp4/QTZ5Dn0t6M4.mp4</video:content_loc><video:duration>272</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/factor-w-poly-div</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0b2e705bd9a9e53b.jpg</video:thumbnail_loc><video:title>Factoring using polynomial division</video:title><video:description>This video breaks down the process of dividing polynomials by linear factors. It starts with a given polynomial and a known factor, then uses polynomial division to rewrite the expression as a product of linear factors.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/I9PiXAbjnMQ.mp4/I9PiXAbjnMQ.mp4</video:content_loc><video:duration>358</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/factor-w-poly-div-missing-term</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2e3087588cbe3086.jpg</video:thumbnail_loc><video:title>Factoring using polynomial division: missing term</video:title><video:description>If we know one linear factor of a higher degree polynomial, we can use polynomial division to find other factors of the polynomial. For example, we can use the fact that (x+6) is a factor of (x³+9x²-108) in order to completely factor the polynomial. We just need to be careful because the polynomial has no x-term.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/AkY3DGzrvk8.mp4/AkY3DGzrvk8.mp4</video:content_loc><video:duration>238</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/polynomial-remainder-theorem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdb4ca463.jpg</video:thumbnail_loc><video:title>Intro to the Polynomial Remainder Theorem</video:title><video:description>The Polynomial Remainder Theorem allows us to determine whether a linear expression is a factor of a polynomial expression easily. It tells us the remainder when a polynomial is divided by \[x - a\] is \[f(a)\]. This means if \[x - a\] is a factor of the polynomial, the remainder is zero. It&apos;s a neat trick to quickly find remainders without doing long division!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/MwG6QD352yc.mp4/MwG6QD352yc.mp4</video:content_loc><video:duration>403</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/polynomial-remainder-theorem-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x908ffb83.jpg</video:thumbnail_loc><video:title>Remainder theorem: finding remainder from equation</video:title><video:description>The Polynomial Remainder Theorem simplifies the process of finding the remainder when dividing a polynomial by \[x - a\]. Instead of long division, you just evaluate the polynomial at \[a\]. This method saves time and space, making polynomial division more manageable.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/MHtTP6vc4RU.mp4/MHtTP6vc4RU.mp4</video:content_loc><video:duration>212</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/remainder-theorem-examples</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4fb30cebf726e2c3.jpg</video:thumbnail_loc><video:title>Remainder theorem examples</video:title><video:description>The polynomial remainder theorem says that for a polynomial p(x) and a number a, the remainder on division by (x-a) is p(a). This might not be very clear right now, but you will understand this much better after watching these examples.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/dBOpC_-PDTA.mp4/dBOpC_-PDTA.mp4</video:content_loc><video:duration>332</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/polynomial-remainder-theorem-to-test-factor</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd36a1a36.jpg</video:thumbnail_loc><video:title>Remainder theorem: checking factors</video:title><video:description>Learn how to determine if an expression is a factor of a polynomial by dividing the polynomial by the expression. If the remainder is zero, the expression is a factor. The video also demonstrates how to quickly calculate the remainder using the theorem.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/JAdNNJynWM4.mp4/JAdNNJynWM4.mp4</video:content_loc><video:duration>206</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/constructing-a-polynomial-that-has-a-certain-factor</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7ea74388.jpg</video:thumbnail_loc><video:title>Remainder theorem: finding coefficients</video:title><video:description>Learn how to find the value of &apos;c&apos; that makes &apos;x - 5&apos; a factor of a polynomial &apos;p(x)&apos;. Understand how setting &apos;p(5)&apos; equal to zero and solving for &apos;c&apos; unveils the mystery. Grasp the concept of the Polynomial Remainder Theorem with a real example.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/e0lBUViss8E.mp4/e0lBUViss8E.mp4</video:content_loc><video:duration>219</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/polynomial-remainder-theorem-proof</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1f4eea1e.jpg</video:thumbnail_loc><video:title>Proof of the Polynomial Remainder Theorem</video:title><video:description>The PRT (Polynomial Remainder Theorem) may seem crazy to prove, but Sal shows how you can do it in less than six minutes!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/NIazpCER9oM.mp4/NIazpCER9oM.mp4</video:content_loc><video:duration>342</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/polynomial-zeros-introduction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xeb690eddfd61151c.jpg</video:thumbnail_loc><video:title>Zeros of polynomials introduction</video:title><video:description>The zeros of a polynomial p(x) are all the x-values that make the polynomial equal to zero. They are interesting to us for many reasons, one of which is that they tell us about the x-intercepts of the polynomial&apos;s graph. We will also see that they are directly related to the factors of the polynomial.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/EtzwLlkoAnM.mp4/EtzwLlkoAnM.mp4</video:content_loc><video:duration>309</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/plot-polynomial-zeros</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa02384672e2b08f2.jpg</video:thumbnail_loc><video:title>Zeros of polynomials: plotting zeros</video:title><video:description>When we are given a polynomial in factored form, we can quickly find the polynomial&apos;s zeros. Then, we can represent them as the x-intercepts of the polynomial&apos;s graph.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5qQUN1fugXQ.mp4/5qQUN1fugXQ.mp4</video:content_loc><video:duration>199</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/polynomial-equation-from-zeros</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7d23b9c4dae7643b.jpg</video:thumbnail_loc><video:title>Zeros of polynomials: matching equation to zeros</video:title><video:description>When we are given a list of the zeros of a polynomial, we can conclude the polynomial must have certain factors, which gives us information about the equation of the polynomial.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/CtqwiX4wHEY.mp4/CtqwiX4wHEY.mp4</video:content_loc><video:duration>231</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/polynomial-equation-from-graph</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6274b6e74d5b6e77.jpg</video:thumbnail_loc><video:title>Zeros of polynomials: matching equation to graph</video:title><video:description>When we are given the graph of a polynomial, we can deduce what its zeros are, which helps us determine a few factors the polynomial&apos;s equation must include.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/f-xluUaAfwo.mp4/f-xluUaAfwo.mp4</video:content_loc><video:duration>181</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/polynomial-zeros-grouping</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x394e49d04a8e1912.jpg</video:thumbnail_loc><video:title>Zeros of polynomials (with factoring): grouping</video:title><video:description>When a polynomial is given in factored form, we can quickly find its zeros. When its given in expanded form, we can factor it, and then find the zeros! Here is an example of a 3rd degree polynomial we can factor using the method of grouping.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/w0vTAHIS5B4.mp4/w0vTAHIS5B4.mp4</video:content_loc><video:duration>295</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/polynomial-zeros-common-factor</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdd574d3d4e28f785.jpg</video:thumbnail_loc><video:title>Zeros of polynomials (with factoring): common factor</video:title><video:description>When a polynomial is given in factored form, we can quickly find its zeros. When it&apos;s given in expanded form, we can factor it, and then find the zeros! Here is an example of a 3rd degree polynomial we can factor by first taking a common factor and then using the sum-product pattern.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/SONskIMkYdU.mp4/SONskIMkYdU.mp4</video:content_loc><video:duration>212</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/polynomial-zero-multiplicity</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x453d8f1967753c96.jpg</video:thumbnail_loc><video:title>Multiplicity of zeros of polynomials</video:title><video:description>The polynomial p(x)=(x-1)(x-3)² is a 3rd degree polynomial, but it has only 2 distinct zeros. This is because the zero x=3, which is related to the factor (x-3)², repeats twice. This is called multiplicity. It means that x=3 is a zero of multiplicity 2, and x=1 is a zero of multiplicity 1. Multiplicity is a fascinating concept, and it is directly related to graphical behavior of the polynomial around the zero.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jrFLb9ZoZH0.mp4/jrFLb9ZoZH0.mp4</video:content_loc><video:duration>396</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/polynomial-multiplicity-examples</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xea0e9844108ab8f1.jpg</video:thumbnail_loc><video:title>Zeros of polynomials (multiplicity)</video:title><video:description>Given the graph of a polynomial and looking at its x-intercepts, we can determine the factors the polynomial must have. Additionally, we can determine whether those factors are raised to an odd power or to an even power (this is called the multiplicity of the factors).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1ke_xceCevk.mp4/1ke_xceCevk.mp4</video:content_loc><video:duration>300</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/solving-exponential-equations-with-exponent-properties</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x73e71236.jpg</video:thumbnail_loc><video:title>Solving exponential equations using exponent properties</video:title><video:description>Sal solves equations like 26^(9x+5) = 1 and 2^(3x+5) = 64^(x-7).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/etl9KKf6se0.mp4/etl9KKf6se0.mp4</video:content_loc><video:duration>296</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/solving-exponential-equations-with-exponent-properties-advanced</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbe4a3f78.jpg</video:thumbnail_loc><video:title>Solving exponential equations using exponent properties (advanced)</video:title><video:description>Sal solves equations like 32^(x/3) = 8^(x-12) and 5^(4x+3) / 25^(9-x) = 5^(2x+5).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/mGSn-qR6k-g.mp4/mGSn-qR6k-g.mp4</video:content_loc><video:duration>422</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/constructing-exponential-models</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd0ae5341.jpg</video:thumbnail_loc><video:title>Constructing exponential models</video:title><video:description>Sal models the distribution of a chain letter using an exponential function.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/FRW7SINSYco.mp4/FRW7SINSYco.mp4</video:content_loc><video:duration>228</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/constructing-exponential-models-half-life</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x085dfeba.jpg</video:thumbnail_loc><video:title>Constructing exponential models: half life</video:title><video:description>Sal models the decay of a Carbon-14 sample using an exponential function.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/kaxfCiP9d0w.mp4/kaxfCiP9d0w.mp4</video:content_loc><video:duration>258</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/constructing-exponential-models-percent-change</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x017b71e8.jpg</video:thumbnail_loc><video:title>Constructing exponential models: percent change</video:title><video:description>Sal models a population of narwhals using an exponential function.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/x9a73iHv06U.mp4/x9a73iHv06U.mp4</video:content_loc><video:duration>292</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/logarithms</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1242982964.jpg</video:thumbnail_loc><video:title>Intro to logarithms</video:title><video:description>Sal explains what logarithms are and gives a few examples of finding logarithms.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Z5myJ8dg_rM.mp4/Z5myJ8dg_rM.mp4</video:content_loc><video:duration>422</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/fancier-logarithm-expressions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1243193209.jpg</video:thumbnail_loc><video:title>Evaluating logarithms (advanced)</video:title><video:description>Sal evaluates log₂(8), log₈(2), log₂(⅛), and log₈(½).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/eTWCARmrzJ0.mp4/eTWCARmrzJ0.mp4</video:content_loc><video:duration>260</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/exponential-to-logarithmic-form</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x19c7ee10.jpg</video:thumbnail_loc><video:title>Relationship between exponentials &amp; logarithms</video:title><video:description>Sal rewrites 100=10^2 as a logarithmic equation and log_5(1/125)=-3 as an exponential equation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Obch1OP5QyA.mp4/Obch1OP5QyA.mp4</video:content_loc><video:duration>102</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/plotting-exponential-logarithm</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x07bc9727.jpg</video:thumbnail_loc><video:title>Relationship between exponentials &amp; logarithms: graphs</video:title><video:description>Given a few points on the graph of an exponential function, Sal plots the corresponding points on the graph of the corresponding logarithmic function.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DhW9pz5Vfwo.mp4/DhW9pz5Vfwo.mp4</video:content_loc><video:duration>250</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/logarithm-exponential-deductions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xce641b55.jpg</video:thumbnail_loc><video:title>Relationship between exponentials &amp; logarithms: tables</video:title><video:description>Given incomplete tables of values of b^x and its corresponding inverse function, log_b(y), Sal uses the inverse relationship of the functions to fill in the missing values.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Iz6IVf8frjw.mp4/Iz6IVf8frjw.mp4</video:content_loc><video:duration>359</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/natural-logarithm-with-a-calculator</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/367722961.jpg</video:thumbnail_loc><video:title>Evaluating natural logarithm with calculator</video:title><video:description>Sal evaluates log_e(67) (which is more commonly written as ln(67) ) using a calculator.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Dpo_-GrMpNE.mp4/Dpo_-GrMpNE.mp4</video:content_loc><video:duration>217</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/introduction-to-logarithm-properties</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25781.jpg</video:thumbnail_loc><video:title>Intro to logarithm properties (1 of 2)</video:title><video:description>Sal introduces the logarithm identities for addition and subtraction of logarithms.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PupNgv49_WY.mp4/PupNgv49_WY.mp4</video:content_loc><video:duration>556</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/introduction-to-logarithm-properties-part-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25783.jpg</video:thumbnail_loc><video:title>Intro to logarithm properties (2 of 2)</video:title><video:description>Sal introduces the logarithm identities for multiplication of logarithm by a constant, and the change of base rule.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TMmxKZaCqe0.mp4/TMmxKZaCqe0.mp4</video:content_loc><video:duration>604</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/sum-of-logarithms-with-same-base</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/367722960.jpg</video:thumbnail_loc><video:title>Using the logarithmic product rule</video:title><video:description>Sal rewrites log₃(27x) as log₃(27)+log_3(x), which is simplified as 3+log₃(x).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pkGrXzakRFs.mp4/pkGrXzakRFs.mp4</video:content_loc><video:duration>304</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/logarithm-of-a-power</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/367723734.jpg</video:thumbnail_loc><video:title>Using the logarithmic power rule</video:title><video:description>Sal rewrites log₅(x³) as 3log₅(x).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Pb9V374iOas.mp4/Pb9V374iOas.mp4</video:content_loc><video:duration>289</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/using-multiple-logarithm-properties-to-simplify</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/367723732.jpg</video:thumbnail_loc><video:title>Using the properties of logarithms: multiple steps</video:title><video:description>Sal rewrites log_5([25^x]/y) as 2x-log_5(y) by using both the log subtraction property and the log multiplied by a constant property.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/RhzXX5PbsuQ.mp4/RhzXX5PbsuQ.mp4</video:content_loc><video:duration>130</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/proof-log-a-log-b-log-ab</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23514.jpg</video:thumbnail_loc><video:title>Proof of the logarithm product rule</video:title><video:description>Sal proves the logarithm addition property, log(a) + log(b) = log(ab).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/FP2arCfAfBY.mp4/FP2arCfAfBY.mp4</video:content_loc><video:duration>428</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/proof-a-log-b-log-b-a-log-a-log-b-log-a-b</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23516.jpg</video:thumbnail_loc><video:title>Proof of the logarithm quotient and power rules</video:title><video:description>Sal proves the logarithm quotient rule, log(a) - log(b) = log(a/b), and the power rule, k⋅log(a) = log(aᵏ).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/yEAxG_D1HDw.mp4/yEAxG_D1HDw.mp4</video:content_loc><video:duration>479</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/change-of-base-formula</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/367721779.jpg</video:thumbnail_loc><video:title>Evaluating logarithms: change of base rule</video:title><video:description>Sal approximates log₅(100) by rewriting it as log(100)/log(5) using the change of base rule, then evaluates with a calculator.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OkFdDqW9xxM.mp4/OkFdDqW9xxM.mp4</video:content_loc><video:duration>452</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/rewriting-logarithmic-expressions-change-of-base</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x97b1cfa7.jpg</video:thumbnail_loc><video:title>Using the logarithm change of base rule</video:title><video:description>Sal rewrites logarithmic expressions like 1/(logₐ4) or logₐ(16)*log₂(a) using the change of base rule.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qtsMgdZ98Yg.mp4/qtsMgdZ98Yg.mp4</video:content_loc><video:duration>403</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/change-of-base-formula-proof</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1335425394.jpg</video:thumbnail_loc><video:title>Proof of the logarithm change of base rule</video:title><video:description>Sal proves the logarithmic change of base rule, logₐ(b)=logₓ(b)/logₓ(a).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1reblXFlM6I.mp4/1reblXFlM6I.mp4</video:content_loc><video:duration>299</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/exponential-equation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1030e61c.jpg</video:thumbnail_loc><video:title>Solving exponential equations using logarithms: base-10</video:title><video:description>Sal solves the equation 10^(2t-3)=7.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/R443Db-wJ5o.mp4/R443Db-wJ5o.mp4</video:content_loc><video:duration>171</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/shifting-functions-intro</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6e84edb65f8627f7.jpg</video:thumbnail_loc><video:title>Shifting functions introduction</video:title><video:description>The graph of y=f(x)+k (where k is a real number) is the same as the graph of y=f(x) only it&apos;s shifted up (when k&gt;0) or down (when k&lt;0). Similarly, the graph of y=f(x-h) (where h is a real number) is the same as the graph of y=f(x) only it&apos;s shifted to the right (when h&gt;0) or to the left (when h&lt;0)</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/RttvubuBhAE.mp4/RttvubuBhAE.mp4</video:content_loc><video:duration>338</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/shifting-functions-examples</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9389c47e.jpg</video:thumbnail_loc><video:title>Shifting functions examples</video:title><video:description>Sal analyzes two cases where functions f and g are given graphically, and g is a result of shifting f. He writes formulas for g in terms of f and in terms of x.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/MDav5OMpCto.mp4/MDav5OMpCto.mp4</video:content_loc><video:duration>462</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/graphing-shifted-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc28ac02f.jpg</video:thumbnail_loc><video:title>Graphing shifted functions</video:title><video:description>Given the graph of f(x)=x², Sal graphs g(x)=(x-2)²-4, which is the graph of f shifted 2 units to the right and 4 units down.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5DLkB-g8Rr8.mp4/5DLkB-g8Rr8.mp4</video:content_loc><video:duration>168</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/reflecting-functions-intro</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa07bf13a87f45a4f.jpg</video:thumbnail_loc><video:title>Reflecting functions introduction</video:title><video:description>We can reflect the graph of y=f(x) over the x-axis by graphing y=-f(x) and over the y-axis by graphing y=f(-x). See this in action and understand why it happens.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/mR2y_kohZIw.mp4/mR2y_kohZIw.mp4</video:content_loc><video:duration>430</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/reflecting-functions-examples</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x840d7bd27c963978.jpg</video:thumbnail_loc><video:title>Reflecting functions: examples</video:title><video:description>We can reflect the graph of any function f about the x-axis by graphing y=-f(x) and we can reflect it about the y-axis by graphing y=f(-x). We can even reflect it about both axes by graphing y=-f(-x). See how this is applied to solve various problems.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0QOnEoQHZ1k.mp4/0QOnEoQHZ1k.mp4</video:content_loc><video:duration>393</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/scaling-functions-intro</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3f4f68f86bcdb75a.jpg</video:thumbnail_loc><video:title>Scaling functions introduction</video:title><video:description>The graph y=k⋅f(x) (where k is a real number) is similar to the graph y=f(x), but each point&apos;s distance from the x-axis is multiplied by k. A similar thing happens when we graph y=f(k⋅x), only now the distance from the y-axis changes. These operations are called &quot;scaling.&quot;</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1lt6a77OmLU.mp4/1lt6a77OmLU.mp4</video:content_loc><video:duration>363</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/vert-function-scaling</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb5a485b436f48633.jpg</video:thumbnail_loc><video:title>Scaling functions vertically: examples</video:title><video:description>The function k⋅f(x) is a vertical scaling of f. See multiple examples of how we relate the two functions and their graphs, and determine the value of k.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tRCEBtKLqEw.mp4/tRCEBtKLqEw.mp4</video:content_loc><video:duration>309</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/scaling-functions-horizontally</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x65945a460335704b.jpg</video:thumbnail_loc><video:title>Scaling functions horizontally: examples</video:title><video:description>The function f(k⋅x) is a horizontal scaling of f. See multiple examples of how we relate the two functions and their graphs, and determine the value of k.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/npMMbXm9sR0.mp4/npMMbXm9sR0.mp4</video:content_loc><video:duration>489</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/compressing-functions-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf63087fc.jpg</video:thumbnail_loc><video:title>Identifying horizontal squash from graph</video:title><video:description>Given the graphs of functions f and g, where g is the result of compressing f by a factor of 2, Sal finds g(x) in terms of f(x).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4H5JZnytOfE.mp4/4H5JZnytOfE.mp4</video:content_loc><video:duration>196</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/shifting-and-reflecting-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb05fec98.jpg</video:thumbnail_loc><video:title>Identifying function transformations</video:title><video:description>Sal walks through several examples of how to write g(x) implicitly in terms of f(x) when g(x) is a shift or a reflection of f(x).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ENFNyNPYfZU.mp4/ENFNyNPYfZU.mp4</video:content_loc><video:duration>400</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/graphing-square-and-cube-root</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9762d161485e0a98.jpg</video:thumbnail_loc><video:title>Graphing square and cube root functions</video:title><video:description>We can graph various square root and cube root functions by thinking of them as transformations of the parent graphs y=√x and y=∛x.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PI6IV7K3DbM.mp4/PI6IV7K3DbM.mp4</video:content_loc><video:duration>408</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/comparing-exponential-logarithmic-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd6ac565c.jpg</video:thumbnail_loc><video:title>Graphical relationship between 2ˣ and log₂(x)</video:title><video:description>Sal graphs y=2ˣ and y=log₂(x) on the same coordinate plane, showing how they relate as graphs of inverse functions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/K_PiPfYxtao.mp4/K_PiPfYxtao.mp4</video:content_loc><video:duration>342</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/graphing-logarithmic-functions-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6573016191db84e6.jpg</video:thumbnail_loc><video:title>Graphing logarithmic functions (example 1)</video:title><video:description>We can graph y=2log₂(-x-3) by viewing it as a transformation of y=log₂(x).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/GpBSbNoon1E.mp4/GpBSbNoon1E.mp4</video:content_loc><video:duration>327</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/graphing-logarithmic-functions-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf8b2301cb608d79f.jpg</video:thumbnail_loc><video:title>Graphing logarithmic functions (example 2)</video:title><video:description>We can graph y=4log₂(x+6)-7 by viewing it as a transformation of y=log₂(x).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/f_BJC6UwDTE.mp4/f_BJC6UwDTE.mp4</video:content_loc><video:duration>226</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/rational-equation-intro</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1242890488.jpg</video:thumbnail_loc><video:title>Rational equations intro</video:title><video:description>When we have an equation where the variable is in the denominator of a quotient, that&apos;s a rational equation. We can solve it by multiplying both sides by the denominator, but we have to look out for extraneous solutions in the process.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3RdNPrNUi4s.mp4/3RdNPrNUi4s.mp4</video:content_loc><video:duration>192</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/equations-with-two-rational-expressions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x62e31296.jpg</video:thumbnail_loc><video:title>Equations with rational expressions</video:title><video:description>Sal solves (x²-10x+21)/(3x-12)=(x-5)/(x-4), which has one real solution and one extraneous solution.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/McOMtxI_Jzs.mp4/McOMtxI_Jzs.mp4</video:content_loc><video:duration>312</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/equations-with-two-rational-expressions-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9985bba7.jpg</video:thumbnail_loc><video:title>Equations with rational expressions (example 2)</video:title><video:description>Sal solves (-2x+4)/(x-1)=3/(x+1)-1.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/CBlSsy1eslw.mp4/CBlSsy1eslw.mp4</video:content_loc><video:duration>432</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/rational-function-inverse</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x479fdc23.jpg</video:thumbnail_loc><video:title>Finding inverses of rational functions</video:title><video:description>The inverse of a function ƒ is a function that maps every output in ƒ&apos;s range to its corresponding input in ƒ&apos;s domain. We can find an expression for the inverse of ƒ by solving the equation 𝘹=ƒ(𝘺) for the variable 𝘺. See how it&apos;s done with a rational function.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/YI30Ecfl4tc.mp4/YI30Ecfl4tc.mp4</video:content_loc><video:duration>257</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/extraneous-solutions-to-radical-equations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23748.jpg</video:thumbnail_loc><video:title>Intro to square-root equations &amp; extraneous solutions</video:title><video:description>Sal explains what square-root equations are, and shows an example of solving such an equation and checking for extraneous solutions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/711pdW8TbbY.mp4/711pdW8TbbY.mp4</video:content_loc><video:duration>670</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/extraneous-solutions-of-radical-equations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfaa88068.jpg</video:thumbnail_loc><video:title>Square-root equations intro</video:title><video:description>Sal gives an example of how an extraneous solution arises when solving 2x-1=√(8-x).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/m4eiYHL3PP8.mp4/m4eiYHL3PP8.mp4</video:content_loc><video:duration>323</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/solving-radical-equations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/127771048.jpg</video:thumbnail_loc><video:title>Solving square-root equations: one solution</video:title><video:description>Sal solves the equation 3+√(5x+6)=12.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pFFoAGIEyJc.mp4/pFFoAGIEyJc.mp4</video:content_loc><video:duration>191</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/solving-square-root-equations-w-two-solutions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe1ea042e.jpg</video:thumbnail_loc><video:title>Solving square-root equations: two solutions</video:title><video:description>Sal solves the equation 6+3w=√(2w+12)+2w which has two solutions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/wt6XqG59t5U.mp4/wt6XqG59t5U.mp4</video:content_loc><video:duration>329</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/solving-square-root-equations-w-no-solution</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x91409da4.jpg</video:thumbnail_loc><video:title>Solving square-root equations: no solution</video:title><video:description>Sal solves the equation √(3x-7)+√(2x-1)=0, only to find out that the single solution is extraneous, which means the equation has no solution.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ibeyn2QGjCM.mp4/ibeyn2QGjCM.mp4</video:content_loc><video:duration>239</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/extraneous-solutions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc87f4bd4f8e58a14.jpg</video:thumbnail_loc><video:title>Extraneous solutions</video:title><video:description>Extraneous solutions are values that we get when solving equations that aren&apos;t really solutions to the equation. In this video, we explain how and why we get extraneous solutions, by understanding the logic behind the process of solving equations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Hz3vkU3gTeI.mp4/Hz3vkU3gTeI.mp4</video:content_loc><video:duration>475</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/finding-radical-equation-with-given-extraneous-solution</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x194f0296.jpg</video:thumbnail_loc><video:title>Equation that has a specific extraneous solution</video:title><video:description>Sal finds the value of d for which √(3x+25)=d+2x has an extraneous solution at x=-3.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/HRVrbJzXxdM.mp4/HRVrbJzXxdM.mp4</video:content_loc><video:duration>297</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/unit-circle-definition-of-trig-functions-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1159990979.jpg</video:thumbnail_loc><video:title>Unit circle</video:title><video:description>Learn how to use the unit circle to define sine, cosine, and tangent for all real numbers.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1m9p9iubMLU.mp4/1m9p9iubMLU.mp4</video:content_loc><video:duration>544</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/matching-ratios-trig-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdcacd12a.jpg</video:thumbnail_loc><video:title>The trig functions &amp; right triangle trig ratios</video:title><video:description>Sal shows how, for acute angles, the two different definitions of the trigonometric values (SOH CAH TOA and the unit circle definition) result in the same values.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/WffVdYETdng.mp4/WffVdYETdng.mp4</video:content_loc><video:duration>417</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/introduction-to-radians</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1159577071.jpg</video:thumbnail_loc><video:title>Intro to radians</video:title><video:description>Sal explains the definition and motivation for radians and the relationship between radians and degrees.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/EnwWxMZVBeg.mp4/EnwWxMZVBeg.mp4</video:content_loc><video:duration>651</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/radian-and-degree-conversion-practice</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1159451550.jpg</video:thumbnail_loc><video:title>Radians &amp; degrees</video:title><video:description>Sal discusses the general approach to converting between radians and degrees and vice versa.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/z8vj8tUCkxY.mp4/z8vj8tUCkxY.mp4</video:content_loc><video:duration>432</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/we-converting-degrees-to-radians</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1153849058.jpg</video:thumbnail_loc><video:title>Degrees to radians</video:title><video:description>To convert from degrees to radians, multiply the number of degrees by π/180. This will give you the measurement in radians. If you have an angle that&apos;s 90 degrees, and you want to know what it is in radians, you multiply 90 by π/180. This gives you π/2.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/O3jvUZ8wvZs.mp4/O3jvUZ8wvZs.mp4</video:content_loc><video:duration>422</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/we-converting-radians-to-degrees</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1153727649.jpg</video:thumbnail_loc><video:title>Radians to degrees</video:title><video:description>To change from radians to degrees, you need to multiply the number of radians by 180/π. This number will help you switch between the two units. For example, if you multiply π/2 radians by 180/π, you will get 90 degrees.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/z0-1gBy1ykE.mp4/z0-1gBy1ykE.mp4</video:content_loc><video:duration>200</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/rotation-by-radians-and-quadrants</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x81df7889.jpg</video:thumbnail_loc><video:title>Radian angles &amp; quadrants</video:title><video:description>Sal determines the quadrant at which a ray falls after a rotation by a certain measure of radians.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/fYQ3GRSu4JU.mp4/fYQ3GRSu4JU.mp4</video:content_loc><video:duration>231</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/we-graph-domain-and-range-of-sine-function</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1153456927.jpg</video:thumbnail_loc><video:title>Graph of y=sin(x)</video:title><video:description>The graph of y=sin(x) is like a wave that forever oscillates between -1 and 1, in a shape that repeats itself every 2π units. Specifically, this means that the domain of sin(x) is all real numbers, and the range is [-1,1]. See how we find the graph of y=sin(x) using the ​unit-circle definition of sin(x).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/sjUhr0HkLUg.mp4/sjUhr0HkLUg.mp4</video:content_loc><video:duration>562</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/we-graphs-of-sine-and-cosine-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1153664550.jpg</video:thumbnail_loc><video:title>Intersection points of y=sin(x) and y=cos(x)</video:title><video:description>Sal draws the graphs of the sine and the cosine functions and analyzes their intersection points.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/08zHioOVTd4.mp4/08zHioOVTd4.mp4</video:content_loc><video:duration>667</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/tangent-graph</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9267c937.jpg</video:thumbnail_loc><video:title>Graph of y=tan(x)</video:title><video:description>Sal draws the graph of the tangent function based on the unit circle definition of the function.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/FK6-tZ5D7xM.mp4/FK6-tZ5D7xM.mp4</video:content_loc><video:duration>612</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/example-graphing-y-3sin-x-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x70280d50ff5ef21c.jpg</video:thumbnail_loc><video:title>Example: Graphing y=3⋅sin(½⋅x)-2</video:title><video:description>Sal graphs y=3⋅sin(½⋅x)-2 by thinking about the graph of y=sin(x) and analyzing how the graph (including the midline, amplitude, and period) changes as we perform function transformations to get from y=sin(x) to y=3⋅sin(½⋅x)-2.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-Si4W4KyeMw.mp4/-Si4W4KyeMw.mp4</video:content_loc><video:duration>203</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/example-graphing-y-cos-x-1-5</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x77b9a0f0a63cfc2e.jpg</video:thumbnail_loc><video:title>Example: Graphing y=-cos(π⋅x)+1.5</video:title><video:description>Sal graphs y=-cos(π⋅x)+1.5 by thinking about the graph of y=cos(x) and analyzing how the graph (including the midline, amplitude, and period) changes as we perform function transformations to get from y=cos(x) to y=-cos(π⋅x)+1.5.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9XtCWJmKF28.mp4/9XtCWJmKF28.mp4</video:content_loc><video:duration>190</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/trig-function-equation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdaccbc0b.jpg</video:thumbnail_loc><video:title>Sinusoidal function from graph</video:title><video:description>Sal finds the equation of a sinusoidal function from its graph where the minimum point (-2,-5) and the maximum point (2,1) are highlighted.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/yHo0CcDVHsk.mp4/yHo0CcDVHsk.mp4</video:content_loc><video:duration>322</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/interpreting-trig-graphs-in-context</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc07920a8b52ac0c2.jpg</video:thumbnail_loc><video:title>Interpreting trigonometric graphs in context</video:title><video:description>When a trigonometric function models a real-world relationship, we can assign meaning to its midline, amplitude and period.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7q9eHwP2Smw.mp4/7q9eHwP2Smw.mp4</video:content_loc><video:duration>334</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/modeling-with-combined-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9e853ab5.jpg</video:thumbnail_loc><video:title>Modeling with function combination</video:title><video:description>Sal models the height of a tree on top of a tower, by adding the functions that model the growth of the tree and the tower separately.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2IWhknVzeJM.mp4/2IWhknVzeJM.mp4</video:content_loc><video:duration>188</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/periodicity-of-algebraic-models</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x19dc89e1.jpg</video:thumbnail_loc><video:title>Periodicity of algebraic models</video:title><video:description>Sal analyzes the periodicity of graphs that model real world situations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/zHS9ZVXw_Z0.mp4/zHS9ZVXw_Z0.mp4</video:content_loc><video:duration>201</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/end-behavior-word-problems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5ae6fb8c.jpg</video:thumbnail_loc><video:title>End behavior of algebraic models</video:title><video:description>Sal analyzes the end behavior of graphs that model real world situations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/kmzBGnniH2w.mp4/kmzBGnniH2w.mp4</video:content_loc><video:duration>180</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/interpreting-features-of-functions-2-example-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x62250c60.jpg</video:thumbnail_loc><video:title>Symmetry of algebraic models</video:title><video:description>Sal interprets the significance of modeling function being even.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ynIq9IxbVso.mp4/ynIq9IxbVso.mp4</video:content_loc><video:duration>198</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/function-symmetry</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/62754978.jpg</video:thumbnail_loc><video:title>Function symmetry introduction</video:title><video:description>Functions can be symmetrical about the y-axis, which means that if we reflect their graph about the y-axis we will get the same graph. There are other functions that we can reflect about both the x- and y-axis and get the same graph. These are two types of symmetry we call even and odd functions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4dOQePLgqxE.mp4/4dOQePLgqxE.mp4</video:content_loc><video:duration>322</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/recognizing-features-of-functions-2-example-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x09a49d09.jpg</video:thumbnail_loc><video:title>Even and odd functions: Graphs</video:title><video:description>Sal picks the function that is odd among three functions given by their graphs.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/zltgXTlUVLw.mp4/zltgXTlUVLw.mp4</video:content_loc><video:duration>233</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/even-and-odd-functions-tables</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6219cabb7ec1daa4.jpg</video:thumbnail_loc><video:title>Even and odd functions: Tables</video:title><video:description>Even functions are symmetrical about the y-axis: f(x)=f(-x). Odd functions are symmetrical about the x- and y-axis: f(x)=-f(-x). Let&apos;s use these definitions to determine if a function given as a table is even, odd, or neither.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/eKwJlJUM_d0.mp4/eKwJlJUM_d0.mp4</video:content_loc><video:duration>249</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/even-and-odd-functions-equations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc67b21d48f754599.jpg</video:thumbnail_loc><video:title>Even and odd functions: Equations</video:title><video:description>When we are given the equation of a function f(x), we can check whether the function is even, odd, or neither by evaluating f(-x). If we get an expression that is equivalent to f(x), we have an even function; if we get an expression that is equivalent to -f(x), we have an odd function; and if neither happens, it is neither!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/fTeO-V_VgEc.mp4/fTeO-V_VgEc.mp4</video:content_loc><video:duration>236</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/even-and-odd-functions-find-the-mistake</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd2801e92243d7dbc.jpg</video:thumbnail_loc><video:title>Even and odd functions: Find the mistake</video:title><video:description>See another student&apos;s work when trying to determine whether a function is even, odd, or either, and decide whether they made a mistake, and if so, where.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/RAksvTJWgxo.mp4/RAksvTJWgxo.mp4</video:content_loc><video:duration>215</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/comparing-features-of-functions-2-example-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x37888c41.jpg</video:thumbnail_loc><video:title>Comparing functions: x-intercepts</video:title><video:description>Given several functions represented in different forms (as a formula, as a graph, and as a table of values), Sal finds the one with that has no x-intercepts.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/w2BN2AJ4fOI.mp4/w2BN2AJ4fOI.mp4</video:content_loc><video:duration>167</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/comparing-features-of-functions-2-example-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbb39e37a.jpg</video:thumbnail_loc><video:title>Comparing functions: shared features</video:title><video:description>Sal is given the formula of one function and the graph of the other, and he determines which features are shared by both functions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/H1H0xmjZMPA.mp4/H1H0xmjZMPA.mp4</video:content_loc><video:duration>270</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/equations-by-graphing</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4b838d2059b027eb.jpg</video:thumbnail_loc><video:title>Solving equations by graphing</video:title><video:description>You probably already solved a system of equations by graphing the equations and looking for intersection points. This method can actually be used to solve (or find an approximate solution to) any single equation, no matter what kind! This is a very exciting tool.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7JkY19bYF28.mp4/7JkY19bYF28.mp4</video:content_loc><video:duration>259</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/complex-conjugates</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187550.jpg</video:thumbnail_loc><video:title>Intro to complex number conjugates</video:title><video:description>Learn about the conjugate of complex numbers, how to add and divide using conjugates, and the key property that multiplying a complex number by its conjugate produces a real number. Conjugates are very useful for simplifying division of complex numbers.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/BZxZ_eEuJBM.mp4/BZxZ_eEuJBM.mp4</video:content_loc><video:duration>483</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/complex-conjugates-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/150088078.jpg</video:thumbnail_loc><video:title>Complex number conjugates</video:title><video:description>Through a guided example with 7 - 5i, this video explains how to find the conjugate of a complex number, which is simply changing the sign of the imaginary part. Multiplying a complex number by its conjugate results in a real number. This is useful for simplifying complex numbers and is similar to the difference of squares.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/dbxJ6LD0344.mp4/dbxJ6LD0344.mp4</video:content_loc><video:duration>241</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/dividing-complex-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/150088083.jpg</video:thumbnail_loc><video:title>Dividing complex numbers</video:title><video:description>Sal divides (6+3i) by (7-5i).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Z8j5RDOibV4.mp4/Z8j5RDOibV4.mp4</video:content_loc><video:duration>298</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/non-linear-systems-of-equations-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/27010.jpg</video:thumbnail_loc><video:title>Quadratic system with no solutions</video:title><video:description>Sal solves a system of two quadratic equations algebraically and finds the system has no solutions. He then graphs the equations to show that this is true.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/FksgVpM_iXs.mp4/FksgVpM_iXs.mp4</video:content_loc><video:duration>416</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/polynomial-intervals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1eca5b5935d679c0.jpg</video:thumbnail_loc><video:title>Positive and negative intervals of polynomials</video:title><video:description>If we know all the zeros of a polynomial, then we can determine the intervals over which the polynomial is positive and negative. This is because the polynomial has the same sign between consecutive zeros. So all we need to do is check each interval that is between two consecutive zeros (or before the smallest zero and after the largest zero).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/z3faK7OV3Ew.mp4/z3faK7OV3Ew.mp4</video:content_loc><video:duration>520</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/polynomial-end-behavior</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb79a4102.jpg</video:thumbnail_loc><video:title>Intro to end behavior of polynomials</video:title><video:description>Sal explains what &quot;end behavior&quot; is and what affects the end behavior of polynomial functions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tZKzaF28sOk.mp4/tZKzaF28sOk.mp4</video:content_loc><video:duration>490</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/example-adding-polynomials-with-multiple-variables</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1159107679.jpg</video:thumbnail_loc><video:title>Adding polynomials: two variables (intro)</video:title><video:description>Sal simplifies (4x²y - 3x² - 2y) + (8xy - 3x² + 2x²y + 4).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jroamh6SIo0.mp4/jroamh6SIo0.mp4</video:content_loc><video:duration>150</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/subtracting-polynomials-with-multiple-variables</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179529.jpg</video:thumbnail_loc><video:title>Subtracting polynomials: two variables (intro)</video:title><video:description>Sal simplifies (4x²y - 3xy + 25) - (9y²x + 7xy - 20).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/AqMT_zB9rP8.mp4/AqMT_zB9rP8.mp4</video:content_loc><video:duration>130</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/example-of-error-when-subtracting-polynomials</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x23cf0821.jpg</video:thumbnail_loc><video:title>Finding an error in polynomial subtraction</video:title><video:description>Sal analyzes a polynomial subtraction process to find the step that has an error.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ZBDiMLAQU-8.mp4/ZBDiMLAQU-8.mp4</video:content_loc><video:duration>147</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/poly-diff-of-squares</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x08cd42d946762f26.jpg</video:thumbnail_loc><video:title>Polynomial special products: difference of squares</video:title><video:description>Dive into the exciting world of special products of polynomials, focusing on the difference of squares. We explore how to expand and simplify algebraic expressions. We also tackle more complex expressions, applying the same principles to make math magic happen!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/uNweU6I4Icw.mp4/uNweU6I4Icw.mp4</video:content_loc><video:duration>246</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/poly-perfect-square</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xce2df43c40bb1be6.jpg</video:thumbnail_loc><video:title>Polynomial special products: perfect square</video:title><video:description>Squaring binomials is a breeze when you recognize patterns! The perfect square pattern tells us that (a+b)²=a²+2ab+b². The video shows how to square more complex binomials. It&apos;s all about applying what we know about simple binomials to these trickier ones.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hw5DE8HSZk0.mp4/hw5DE8HSZk0.mp4</video:content_loc><video:duration>310</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/factoring-sums-of-squares</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe59b0d49.jpg</video:thumbnail_loc><video:title>Complex numbers &amp; sum of squares factorization</video:title><video:description>Learn how expressions of the form x^2+y^2 can be factored into linear factors. This would not be possible without the aid of complex numbers!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8TPofjGXDR4.mp4/8TPofjGXDR4.mp4</video:content_loc><video:duration>291</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/factoring-sum-of-squares</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbe367cd0.jpg</video:thumbnail_loc><video:title>Factoring sum of squares</video:title><video:description>Sal factors 36a^8+2b^6 as (6a^4-i*√2b^3)(6a^4+i*√2b^3).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/C3QPTCwpIZo.mp4/C3QPTCwpIZo.mp4</video:content_loc><video:duration>152</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/factoring-polynomials-using-complex-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1328ad6348f733b1.jpg</video:thumbnail_loc><video:title>Factoring polynomials using complex numbers</video:title><video:description>Sal shows how to factor a fourth degree polynomial into linear factors using the sum-product rule and the sum of squares identity.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9NhTVXhfqzU.mp4/9NhTVXhfqzU.mp4</video:content_loc><video:duration>190</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/intro-to-polynomial-synthetic-division-precalculus-khan-academy</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb2853877f3e1c452.jpg</video:thumbnail_loc><video:title>Intro to polynomial synthetic division</video:title><video:description>Learn how to use synthetic division as another approach to solve polynomials.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/z7JiQ5etCZs.mp4/z7JiQ5etCZs.mp4</video:content_loc><video:duration>299</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/why-synthetic-division-works</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/948944478.jpg</video:thumbnail_loc><video:title>Why synthetic division works</video:title><video:description>Sal explains why synthetic division gives you the same result as traditional algebraic long division.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-nlMXVrgtjw.mp4/-nlMXVrgtjw.mp4</video:content_loc><video:duration>420</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/factoring-5th-degree-polynomial-to-find-real-zeros</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2e519607.jpg</video:thumbnail_loc><video:title>Factoring higher-degree polynomials</video:title><video:description>Sal factors p(x)=2x^5+x^4-2x-1 as (2x+1)(x^4-1) using grouping. Then he further factors (x^4-1) as (x^2+1)(x+1)(x-1) using the special product form of difference of squares.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/mekBhhFWC9c.mp4/mekBhhFWC9c.mp4</video:content_loc><video:duration>482</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/factoring-sum-of-cubes</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179584.jpg</video:thumbnail_loc><video:title>Factoring sum of cubes</video:title><video:description>Sal factors 27x^6+125 as (3x^2+5)(9x^4-15x^2+25) using a special product form for a sum of cubes.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Touv2APcBRw.mp4/Touv2APcBRw.mp4</video:content_loc><video:duration>286</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/difference-of-cubes-factoring</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/466052139.jpg</video:thumbnail_loc><video:title>Factoring difference of cubes</video:title><video:description>Sal factors 40c^3-5d^3 as 5(2x-d)(4c^2+2cd+d^2) using a special product form for a difference of cubes.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/CxcP4ylUP5w.mp4/CxcP4ylUP5w.mp4</video:content_loc><video:duration>252</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/function-composition</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2114d642.jpg</video:thumbnail_loc><video:title>Intro to composing functions</video:title><video:description>This video is about composing functions, which is the process of building up a function by composing it from other functions. It explains how to evaluate the composition of functions step by step, using examples with three different function definitions: f (x), g(t), and h(x).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/wUNWjd4bMmw.mp4/wUNWjd4bMmw.mp4</video:content_loc><video:duration>375</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/evaluating-composite-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x10ca4f8b.jpg</video:thumbnail_loc><video:title>Evaluating composite functions</video:title><video:description>Sal evaluates (h⚬g)(-6) for g(x)=x²+5x-3 and h(y)=3(y-1)²-5.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lxtlwnCV-HM.mp4/lxtlwnCV-HM.mp4</video:content_loc><video:duration>250</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/evaluating-composite-functions-using-tables</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x19ec1112.jpg</video:thumbnail_loc><video:title>Evaluating composite functions: using tables</video:title><video:description>Given tables of values of the functions f and g, Sal evaluates f(g(0)) and g(f(0)).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/FR8JH6IldsE.mp4/FR8JH6IldsE.mp4</video:content_loc><video:duration>250</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/evaluating-composite-functions-using-graphs</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4dd841a1.jpg</video:thumbnail_loc><video:title>Evaluating composite functions: using graphs</video:title><video:description>Given the graphs of the functions f and g, Sal evaluates g(f(-5)).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/oORnGaJp1pk.mp4/oORnGaJp1pk.mp4</video:content_loc><video:duration>182</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/new-function-from-composition</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb73f4bfe.jpg</video:thumbnail_loc><video:title>Finding composite functions</video:title><video:description>Through a worked example involving f(x)=√(x²-1) and g(x)=x/(1+x), learn about function composition: the process of combining two functions to create a new function. This involves replacing the input of one function with the output of another function. Also note that the composition of two functions is typically not the same as their composition in the reverse order.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_b-2rZpX5z4.mp4/_b-2rZpX5z4.mp4</video:content_loc><video:duration>177</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/evaluating-composite-functions-example-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf6ad0f67.jpg</video:thumbnail_loc><video:title>Evaluating composite functions (advanced)</video:title><video:description>Given that h(x)=3x and g(t)=-2t-2-h(t), Sal finds h(g(8)).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jlID_mIJXi4.mp4/jlID_mIJXi4.mp4</video:content_loc><video:duration>251</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/determining-if-a-function-is-invertible</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x88678122.jpg</video:thumbnail_loc><video:title>Determining if a function is invertible</video:title><video:description>Learn how to build a mapping diagram for a finite function, and how to use this diagram to determine if the function is invertible. An invertible function has a one-to-one mapping between its domain and range. Functions that map multiple domain elements to the same range element are not invertible.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/dqCTAHHza10.mp4/dqCTAHHza10.mp4</video:content_loc><video:duration>244</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/restricting-trig-function-domain</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5679daee.jpg</video:thumbnail_loc><video:title>Restricting domains of functions to make them invertible</video:title><video:description>Sal is given the graph of a trigonometric function, and he discusses ways in which he can change the function to make it invertible.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tCV9VyIIaw0.mp4/tCV9VyIIaw0.mp4</video:content_loc><video:duration>360</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/reading-inverse-values-from-a-graph</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9cd44c3726ddbc92.jpg</video:thumbnail_loc><video:title>Reading inverse values from a graph</video:title><video:description>Learn how to find the inverse of a function and how to graph it in this video. The inverse function swaps the x and y values of the original function, and the graph of this inverse function is a reflection of the original function about the line y=x.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/nEWYKpTCX-U.mp4/nEWYKpTCX-U.mp4</video:content_loc><video:duration>254</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/reading-inverse-values-from-a-table</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd20cb95991e2c2f7.jpg</video:thumbnail_loc><video:title>Reading inverse values from a table</video:title><video:description>An inverse function takes the output from the original function and gives us the input. Given a table of inputs and outputs for a function, evaluate the inverse function for a certain input.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ygVpyyASavk.mp4/ygVpyyASavk.mp4</video:content_loc><video:duration>128</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/verify-inverse-functions-from-tables</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xda04e060cb055b5a.jpg</video:thumbnail_loc><video:title>Verifying inverse functions from tables</video:title><video:description>Inverse functions undo each other. Functions s and t are inverses if and only if s(t(x))=x and t(s(x))=x for every x-value in the domains.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/UTUuyCXFAs4.mp4/UTUuyCXFAs4.mp4</video:content_loc><video:duration>272</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/using-specific-values-to-test-for-inverses</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x741d01745ab2e2c1.jpg</video:thumbnail_loc><video:title>Using specific values to test for inverses</video:title><video:description>Are two functions inverses? Even one counterexample can show that they are not. How many examples would it take to show that they really are inverses?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/EYv2EoEFRbo.mp4/EYv2EoEFRbo.mp4</video:content_loc><video:duration>213</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/verifying-function-inverses-by-composition</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x365d0a93.jpg</video:thumbnail_loc><video:title>Verifying inverse functions by composition</video:title><video:description>Sal composes f(x)=(x+7)³-1 and g(x)=∛(x+1)-7, and finds that f(g(x))=g(f(x))=x, which means the functions are inverses!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8GEGnSEJA2s.mp4/8GEGnSEJA2s.mp4</video:content_loc><video:duration>401</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/composing-non-inverse-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe665f62f.jpg</video:thumbnail_loc><video:title>Verifying inverse functions by composition: not inverse</video:title><video:description>Sal composes f(x)=2x-3 and g(x)=½x+3, and finds that f(g(x)) ≠ g(f(x)) ≠ x, which means the functions are not inverses.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PJIL0kRHND0.mp4/PJIL0kRHND0.mp4</video:content_loc><video:duration>252</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/solving-radical-equations-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26908.jpg</video:thumbnail_loc><video:title>Solving cube-root equations</video:title><video:description>Sal solves the equation -∛y=4∛y+5.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/b6WtwQddAcY.mp4/b6WtwQddAcY.mp4</video:content_loc><video:duration>214</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/solve-exponentials</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xad64718b.jpg</video:thumbnail_loc><video:title>Solving exponential equations using logarithms: base-2</video:title><video:description>We can use logarithms to solve *any* exponential equation of the form a⋅bᶜˣ=d. For example, this is how you can solve 3⋅10²ˣ=7: 1. Divide by 3: 10²ˣ=7/3 2. Use the definition of logarithm: 2x=log(7/3) 3. Divide by 2: x=log(7/3)/2 Now you can use a calculator to find the solution of the equation as a rounded decimal number ​</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7Ig6kVZaWoU.mp4/7Ig6kVZaWoU.mp4</video:content_loc><video:duration>312</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/solving-exponential-model-word-problems-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6edba13f.jpg</video:thumbnail_loc><video:title>Exponential model word problem: medication dissolve</video:title><video:description>Sal solves an exponential equation in order to answer a question about an exponential model.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/HnHCQ2X_meg.mp4/HnHCQ2X_meg.mp4</video:content_loc><video:duration>245</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/solving-exponential-model-word-problems-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x472204e4.jpg</video:thumbnail_loc><video:title>Exponential model word problem: bacteria growth</video:title><video:description>Sal evaluates an exponential function at a specific value in order to answer a question about an exponential model.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/IpXL9HIkqUQ.mp4/IpXL9HIkqUQ.mp4</video:content_loc><video:duration>94</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math3/v/simplifying-rational-expressions-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/27012.jpg</video:thumbnail_loc><video:title>Simplifying rational expressions: grouping</video:title><video:description>Sal simplifies and states the domain of (2x^2+13x+20)/(2x^2+17x+30).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/dstNU7It-Ro.mp4/dstNU7It-Ro.mp4</video:content_loc><video:duration>402</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math3/v/simplifying-rational-expressions-w-higher-degree-terms</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc35049aa.jpg</video:thumbnail_loc><video:title>Simplifying rational expressions: higher degree terms</video:title><video:description>Sal simplifies &amp; states the domain of (x⁴+8x²+7)/(3x⁵-3x).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/yPZ7In2tdOQ.mp4/yPZ7In2tdOQ.mp4</video:content_loc><video:duration>353</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math3/v/simplifying-rational-expressions-w-two-variables</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x27b04c23.jpg</video:thumbnail_loc><video:title>Simplifying rational expressions: two variables</video:title><video:description>Sal simplifies &amp; states the domain of (5x²+20xy+20y²)/(x²-xy-6y²).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/e7vA_S7abSY.mp4/e7vA_S7abSY.mp4</video:content_loc><video:duration>371</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/end-behavior-of-rational-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4f467034.jpg</video:thumbnail_loc><video:title>End behavior of rational functions</video:title><video:description>Sal analyzes the end behavior of several rational functions, that together cover all cases types of end behavior.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Vtcmyr5IGYY.mp4/Vtcmyr5IGYY.mp4</video:content_loc><video:duration>607</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/discontinuities-of-rational-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc81ec0b8.jpg</video:thumbnail_loc><video:title>Discontinuities of rational functions</video:title><video:description>Sal analyzes two rational functions to find their vertical asymptotes &amp; removable discontinuities. He distinguishes those from the zeros of the functions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qoMimDT7D8w.mp4/qoMimDT7D8w.mp4</video:content_loc><video:duration>406</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/finding-asymptotes-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0149f708.jpg</video:thumbnail_loc><video:title>Graphing rational functions according to asymptotes</video:title><video:description>Learn how to find removable discontinuities, horizontal asymptotes, and vertical asymptotes of rational functions. This video explores the specific example f(x)=(3x^2-18x-81)/(6x^2-54) before generalizing findings to all rational functions. Don&apos;t forget that not every zero of the denominator is a vertical asymptote!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/P0ZgqB44Do4.mp4/P0ZgqB44Do4.mp4</video:content_loc><video:duration>682</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/graphs-of-rational-functions-y-intercept</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc5366e26.jpg</video:thumbnail_loc><video:title>Graphs of rational functions: y-intercept</video:title><video:description>Sal picks the graph that matches f(x)=(ax^m+bx+12)/(cx^m+dx+12) based on its y-intercept.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/YElHmwdbkzQ.mp4/YElHmwdbkzQ.mp4</video:content_loc><video:duration>188</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/graphs-of-rational-functions-horizontal-asymptote</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x06669d97.jpg</video:thumbnail_loc><video:title>Graphs of rational functions: horizontal asymptote</video:title><video:description>Sal picks the graph that matches f(x)=(-x²+ax+b)/(x²+cx+d) based on its horizontal asymptote.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qAfETdORmcw.mp4/qAfETdORmcw.mp4</video:content_loc><video:duration>196</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/graphs-of-rational-functions-vertical-asymptotes</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xcb7ef0f1.jpg</video:thumbnail_loc><video:title>Graphs of rational functions: vertical asymptotes</video:title><video:description>Sal picks the graph that matches f(x)=g(x)/(x²-x-6) (where g(x) is a polynomial) based on its discontinuities.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-jXk1gl_sEo.mp4/-jXk1gl_sEo.mp4</video:content_loc><video:duration>333</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/graphs-of-rational-functions-zeros</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x70aa392a.jpg</video:thumbnail_loc><video:title>Graphs of rational functions: zeros</video:title><video:description>Sal picks the graph that matches f(x)=(2x²-18)/g(x) (where g(x) is a polynomial) based on its zeros.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TX_mx3qULpw.mp4/TX_mx3qULpw.mp4</video:content_loc><video:duration>467</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/dogs-cats-and-bears-in-a-pet-store-visual-argument</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x65947499.jpg</video:thumbnail_loc><video:title>Analyzing structure word problem: pet store (1 of 2)</video:title><video:description>Sal solves a word problem about the unknown number of bears, cats, and dogs in a pet store. This is part 1 where Sal uses a visual reasoning.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/glEP04Pzap8.mp4/glEP04Pzap8.mp4</video:content_loc><video:duration>354</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/dogs-cats-and-bears-in-a-pet-store-analytic-argument</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd2f9789a.jpg</video:thumbnail_loc><video:title>Analyzing structure word problem: pet store (2 of 2)</video:title><video:description>Sal solves a word problem about the unknown number of bears, cats, and dogs in a pet store. This is part 2 where Sal uses an algebraic reasoning.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/mpHMuaVW0DI.mp4/mpHMuaVW0DI.mp4</video:content_loc><video:duration>164</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/combining-mixtures-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x210e0e3e0fe45fe7.jpg</video:thumbnail_loc><video:title>Combining mixtures example</video:title><video:description>Figure out how much of two gasoline mixtures to combine to get gasoline with a certain concentration of ethanol.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xMADEddxSEo.mp4/xMADEddxSEo.mp4</video:content_loc><video:duration>348</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/applying-rational-equations-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187347.jpg</video:thumbnail_loc><video:title>Rational equations word problem: combined rates</video:title><video:description>Sal solves a word problem about the combined leaf-bagging rates of Ian and Kyandre, by creating a rational equation that models the situation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gD7A1LA4jO8.mp4/gD7A1LA4jO8.mp4</video:content_loc><video:duration>326</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/applying-rational-equations-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/27075.jpg</video:thumbnail_loc><video:title>Rational equations word problem: combined rates (example 2)</video:title><video:description>Sal solves a word problem about the combined deck-staining rates of Anya and Bill, by creating a rational equation that models the situation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/E1j8W64NQ0Y.mp4/E1j8W64NQ0Y.mp4</video:content_loc><video:duration>360</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/applying-rational-equations-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/27076.jpg</video:thumbnail_loc><video:title>Rational equations word problem: eliminating solutions</video:title><video:description>Sal solves a word problem about the combined pool-filling rates of two water hoses, by creating a rational equation that models the situation. The equation has a solution that is eliminated due to the context.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/B0Z4s38YIgQ.mp4/B0Z4s38YIgQ.mp4</video:content_loc><video:duration>479</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/reasoning-through-inequality-expressions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf89c9064.jpg</video:thumbnail_loc><video:title>Reasoning about unknown variables</video:title><video:description>Sal solves the following challenge: Given that a&gt;0, b&lt;0, and a/b&gt;a*b, what further can we learn about the variables?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0_VaUYoNV7Y.mp4/0_VaUYoNV7Y.mp4</video:content_loc><video:duration>367</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/using-expressions-to-understand-relationships</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xec00e95f.jpg</video:thumbnail_loc><video:title>Reasoning about unknown variables: divisibility</video:title><video:description>Sal solves the following challenge: Given the positive integers a, b, and c, where a is a multiple of c and (a+b)/c is an integer. Is b necessarily a multiple of c?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/zTLxxezKUT8.mp4/zTLxxezKUT8.mp4</video:content_loc><video:duration>218</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/structure-in-rational-expression</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9a692344.jpg</video:thumbnail_loc><video:title>Structure in rational expression</video:title><video:description>Analyzing an elaborate rational expression to determine what&apos;s bigger: the value of that expression at some unknown c, or the number of times the expression is equal to 0? This is algebraic reasoning at its best!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/mNgW6SAQLhk.mp4/mNgW6SAQLhk.mp4</video:content_loc><video:duration>281</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/multiplying-rational-expressions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x90ca5af3f8374426.jpg</video:thumbnail_loc><video:title>Multiplying rational expressions</video:title><video:description>When we multiply rational expressions, we multiply both numerators and multiply both denominators. We can also see if we can reduce the product to lowest terms. This is very similar to multiplying fractions, only we also have to think about the domain while we do it.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/fjJ0C7-N-xU.mp4/fjJ0C7-N-xU.mp4</video:content_loc><video:duration>334</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/dividing-rational-expressions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb2c6a8969d9d3f67.jpg</video:thumbnail_loc><video:title>Dividing rational expressions</video:title><video:description>When we divide rational expressions, we multiply the dividend (the first expression) by the reciprocal of the divisor (the second expression). We can also see if we can reduce the quotient to lowest terms. This is very similar to dividing fractions, only we also have to think about the domain while we do it.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0cmhBgQNGDI.mp4/0cmhBgQNGDI.mp4</video:content_loc><video:duration>384</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/least-common-multiples-of-polynomials</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x58140338.jpg</video:thumbnail_loc><video:title>Least common multiple of polynomials</video:title><video:description>Sal finds the least common multiple (LCM) of 3z³-6z²-9z and 7z⁴+21z³+14z².</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Ws03IbNrjfM.mp4/Ws03IbNrjfM.mp4</video:content_loc><video:duration>412</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/adding-and-subtracting-rational-expressions-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/27019.jpg</video:thumbnail_loc><video:title>Subtracting rational expressions</video:title><video:description>Sal subtracts and simplifies (a-2)/(a+2) - (a-3)/(a²+4a+4).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/IKsi-DQU2zo.mp4/IKsi-DQU2zo.mp4</video:content_loc><video:duration>276</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-2-tx/v/domain-and-range-of-parent-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfd6e995c5d95cd0a.jpg</video:thumbnail_loc><video:title>Domain and range of parent functions</video:title><video:description>This video reviews domain and range in the context of parent functions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6Paqbr7CyO8.mp4/6Paqbr7CyO8.mp4</video:content_loc><video:duration>195</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-2-tx/v/formulating-absolute-value-linear-equations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe2b49e4b9ca02c83.jpg</video:thumbnail_loc><video:title>Formulating absolute value linear equations</video:title><video:description>Sal solves an example problem about formulating an absolute value equation that matches a real-world context.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lLRm1kUgIzc.mp4/lLRm1kUgIzc.mp4</video:content_loc><video:duration>281</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/absolute-inequalities-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26817.jpg</video:thumbnail_loc><video:title>Solving absolute value inequalities: fractions</video:title><video:description>Sal solves the inequality |2r-3 1/4| &lt; 2 1/2.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/x5EJG_rAtkY.mp4/x5EJG_rAtkY.mp4</video:content_loc><video:duration>450</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/writing-and-using-inequalities</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26819.jpg</video:thumbnail_loc><video:title>Absolute value inequalities word problem</video:title><video:description>Sal solves a word problem about a carpenter by writing an appropriate absolute value inequality and solving it.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/RHe9X2HDEjA.mp4/RHe9X2HDEjA.mp4</video:content_loc><video:duration>278</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/representing-systems-of-equations-with-matrices</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa9a6ec209a5d8147.jpg</video:thumbnail_loc><video:title>Representing systems of equations with matrices</video:title><video:description>Given a system of 3 linear equations with 3 variables, we can represent it with the equation Ax=b, where A is a 3x3 matrix, x is a 3D vector with the variables, and b is a constant 3D vector. Why is this useful? We can solve the system by solving the equation, which in many cases is much more efficient.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/V8lIpRHjthk.mp4/V8lIpRHjthk.mp4</video:content_loc><video:duration>410</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/representing-systems-of-any-number-of-equations-with-matrices</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x623f12621cbc424b.jpg</video:thumbnail_loc><video:title>Representing systems of any number of equations with matrices</video:title><video:description>In a previous videos, we saw how to represent a system with 3 equations and variables as a single matrix equation. It turns out we can do the same for a system of n equations and variables. The resulting equation will be Ax=b, where A is an nXn matrix, x is an nX1 unknown vector, and b is the nX1 constant vector.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lVle8hJTZAk.mp4/lVle8hJTZAk.mp4</video:content_loc><video:duration>289</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-2-tx/v/solving-systems-of-three-linear-equations-in-three-variables-substitution</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb5c5b1e8baed6ca5.jpg</video:thumbnail_loc><video:title>Solving systems of three linear equations in three variables: substitution</video:title><video:description>Sal demonstrates how to solve a system of three linear equations in three variables using substitution.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/umCBMJI_nNU.mp4/umCBMJI_nNU.mp4</video:content_loc><video:duration>372</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/matrices-reduced-row-echelon-form-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25257.jpg</video:thumbnail_loc><video:title>Solving linear systems with matrices</video:title><video:description>Sal solves a linear system with 3 variables by representing it with an augmented matrix and bringing the matrix to reduced row-echelon form.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lP1DGtZ8Wys.mp4/lP1DGtZ8Wys.mp4</video:content_loc><video:duration>457</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/synthetic-division-example-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/948968139.jpg</video:thumbnail_loc><video:title>Dividing polynomials: synthetic division</video:title><video:description>Sal divides (2x^5-x^3+3x^2-2x+7) by (x-3) using synthetic division.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3Ee_huKclEQ.mp4/3Ee_huKclEQ.mp4</video:content_loc><video:duration>300</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-2-tx/v/solving-equations-with-rational-exponents</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf6c818e2d8c41803.jpg</video:thumbnail_loc><video:title>Solving equations with rational exponents</video:title><video:description>Sal solves two equations with rational exponents, one with a decimal exponent and one using radical notation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/dopR7YdndHE.mp4/dopR7YdndHE.mp4</video:content_loc><video:duration>277</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-2-tx/v/writing-quadratic-functions-given-3-points</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfbc119fa3f61f75f.jpg</video:thumbnail_loc><video:title>Writing quadratic functions given 3 points</video:title><video:description>Sal shows how to use the general form quadratic equation to write the equation of a parabola given any three points on it.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tirQoI10a1A.mp4/tirQoI10a1A.mp4</video:content_loc><video:duration>427</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/equation-for-parabola-from-focus-and-directrix</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf4347fc5.jpg</video:thumbnail_loc><video:title>Equation of a parabola from focus &amp; directrix</video:title><video:description>The equation of a parabola is derived from the focus and directrix, and then the general formula is used to solve an example.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/okXVhDMuGFg.mp4/okXVhDMuGFg.mp4</video:content_loc><video:duration>588</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/quadratic-inequality-word-problem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8b9f273d.jpg</video:thumbnail_loc><video:title>Quadratic inequality word problem</video:title><video:description>Sal models a context that concerns a candy vending machine. The model turns out to be a quadratic inequality.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/GDppV18XDCs.mp4/GDppV18XDCs.mp4</video:content_loc><video:duration>600</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/introduction-to-complex-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc316d3f4.jpg</video:thumbnail_loc><video:title>Classifying complex numbers</video:title><video:description>Dive into expressions involving the imaginary unit &apos;i&apos;, simplifying them to reveal the real and imaginary components. Learn how real and imaginary numbers are subsets of complex numbers and study how to classify numbers as real, pure imaginary, or complex.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/A_ESfuN1Pkg.mp4/A_ESfuN1Pkg.mp4</video:content_loc><video:duration>279</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-2-tx/v/formulating-quadratic-and-square-root-equations-using-graphs-part-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf497f0f853f8c779.jpg</video:thumbnail_loc><video:title>Formulating quadratic and square-root equations using graphs - Part 1</video:title><video:description>Sal demonstrates how to use vertex form to write the equation of a quadratic function given a table of values.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3Puz8m-vLUc.mp4/3Puz8m-vLUc.mp4</video:content_loc><video:duration>275</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-2-tx/v/formulating-quadratic-and-square-root-equations-using-graphs-part-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6748db709c9b2f74.jpg</video:thumbnail_loc><video:title>Formulating quadratic and square-root equations using graphs - Part 2</video:title><video:description>Sal demonstrates how to use vertex form to write the equation of a quadratic function given a table of values, and how to use this equation to write the equation of the inverse square root function.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/r_s4NIjFXmA.mp4/r_s4NIjFXmA.mp4</video:content_loc><video:duration>396</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-2-tx/v/transforming-a-cubic-function</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5f12a1bf136d6717.jpg</video:thumbnail_loc><video:title>Graphing cubic function transformations</video:title><video:description>Sal demonstrates the relationship between changes to the equation of the parent function x^3 and transformations of its original graph.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gpaRJMGFmyI.mp4/gpaRJMGFmyI.mp4</video:content_loc><video:duration>183</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-precalculus/v/transforming-rational-function</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x36793f71389bbd37.jpg</video:thumbnail_loc><video:title>Graphing rational function transformations</video:title><video:description>Sal demonstrates the relationship between changes to the equation of the parent function 1/x and transformations of its original graph.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/GsOBAUUNzQg.mp4/GsOBAUUNzQg.mp4</video:content_loc><video:duration>277</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/making-more-pizzas-to-spread-cost-per-pizza</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5d5d623c.jpg</video:thumbnail_loc><video:title>Rational equation word problem</video:title><video:description>Sal models a context that concerns the number and price of pizza slices. The model turns out to be a rational equation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jQ15tkoXZoA.mp4/jQ15tkoXZoA.mp4</video:content_loc><video:duration>540</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-2-tx/v/intro-to-direct-inverse-variation-indian-accent</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc2941f2cee8c6163.jpg</video:thumbnail_loc><video:title>Intro to direct &amp; inverse variation</video:title><video:description>This video explains what it means for quantities to vary directly or inversely, and gives many examples of both types of variation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OXF_xaAIjf4.mp4/OXF_xaAIjf4.mp4</video:content_loc><video:duration>593</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/recognizing-direct-and-inverse-variation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/62754977.jpg</video:thumbnail_loc><video:title>Recognizing direct &amp; inverse variation</video:title><video:description>Sal gives many examples of two-variable equations where the variables vary directly, inversely, or neither.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3_DxJwDTbyQ.mp4/3_DxJwDTbyQ.mp4</video:content_loc><video:duration>425</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/direct-inverse-and-joint-variation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/124291559.jpg</video:thumbnail_loc><video:title>Recognizing direct &amp; inverse variation: table</video:title><video:description>Sal is given a table with a few values of the variables x and y, and determines whether the variables vary directly or inversely.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/v-k5L0BPOmc.mp4/v-k5L0BPOmc.mp4</video:content_loc><video:duration>330</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/inverse-variation-application</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/124291567.jpg</video:thumbnail_loc><video:title>Inverse variation word problem: string vibration</video:title><video:description>Sal models a context about lengths of strings and the frequency of their vibrations! with an inverse variation equation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lkP-E2LUnjA.mp4/lkP-E2LUnjA.mp4</video:content_loc><video:duration>282</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/constructing-an-exponential-equation-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x45286516.jpg</video:thumbnail_loc><video:title>Exponential equation word problem</video:title><video:description>Sal models a context that concerns a bank savings account. The model turns out to be an exponential equation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/IlFD0LzAZeo.mp4/IlFD0LzAZeo.mp4</video:content_loc><video:duration>528</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/college-algebra/v/solving-logarithmic-equations-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe2ac1cd0b3c5ed9a.jpg</video:thumbnail_loc><video:title>Solving logarithmic equations</video:title><video:description>Sal solves a logarithmic equation with a fractional argument.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ZQUuhYgjqmw.mp4/ZQUuhYgjqmw.mp4</video:content_loc><video:duration>125</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/college-algebra/v/solving-real-world-logarithmic-equations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x44947ec1ef9ad4a3.jpg</video:thumbnail_loc><video:title>Solving real world logarithmic equations</video:title><video:description>Sal solves a real world example of a logarithmic equation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/cZUpKBALvTU.mp4/cZUpKBALvTU.mp4</video:content_loc><video:duration>135</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-basics/v/absolute-value-and-number-lines</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/2344592.jpg</video:thumbnail_loc><video:title>Absolute value and number lines</video:title><video:description>One easy way to think of absolute value is the distance it is from zero. To do that, a number line comes in handy. Watch and learn.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/frBJEYvyd-8.mp4/frBJEYvyd-8.mp4</video:content_loc><video:duration>339</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-basics/v/understanding-exponents-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/2600693.jpg</video:thumbnail_loc><video:title>Exponent example 1</video:title><video:description>Sal explains the difference between 5 × 3 and 5 to the third power</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5qfOViJda_g.mp4/5qfOViJda_g.mp4</video:content_loc><video:duration>75</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-basics/v/understanding-exponents</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/2600692.jpg</video:thumbnail_loc><video:title>Exponent example 2</video:title><video:description>We can write a number multiplied by itself multiple times in exponential notation. 6 to the 8th power means we have 8 factors of 6, not that we multiply 6 by 8. 6 to the 8th power is a much larger number than 6 times 8.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/mJ1P4A-KA8k.mp4/mJ1P4A-KA8k.mp4</video:content_loc><video:duration>115</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-basics/v/rewriting-square-root-of-fraction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1918d185.jpg</video:thumbnail_loc><video:title>Simplifying square roots of fractions</video:title><video:description>We can simplify the √(1/200) by finding perfect squares that are factors of 200. We could either look directly for the largest perfect square factor or break 200 into smaller factors and find repeated factors. If we have √2 in the denominator, we can multiply by √2/√2 to make an equivalent fraction.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/s9ppnjgmiyk.mp4/s9ppnjgmiyk.mp4</video:content_loc><video:duration>281</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-basics/v/converting-decimals-to-fractions-2-ex-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/915110987.jpg</video:thumbnail_loc><video:title>Converting decimals to fractions 2 (ex 1)</video:title><video:description>To convert a decimal to a fraction, we need to figure out the smallest place value of the digits. In this case, the smallest place is the ten-thousandths place, so the fraction will have a denominator of 10,000. The numerator will be the decimal number without the decimal point. Then we check for common factors to simplify.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/EGr3KC55sfU.mp4/EGr3KC55sfU.mp4</video:content_loc><video:duration>74</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-basics/v/multiplying-decimals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1812.jpg</video:thumbnail_loc><video:title>Multiplying decimals example</video:title><video:description>To multiply decimals, we multiply them just like whole numbers. We count the number of digits behind the decimal in both numbers we&apos;re multiplying, and make sure our answer has the same number of digits after the decimal. - We can check our answer by thinking about what it means to multiply by 0.5 (or one half).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/JEHejQphIYc.mp4/JEHejQphIYc.mp4</video:content_loc><video:duration>172</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-basics/v/algebraic-expressions-with-fraction-division</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa376e0ea.jpg</video:thumbnail_loc><video:title>Nested fractions</video:title><video:description>Sal starts with a simple case of multiplying two fractions and proceeds to simplifying a nested fraction expression.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_BFaxpf35sY.mp4/_BFaxpf35sY.mp4</video:content_loc><video:duration>346</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-basics/v/proportions-2-exercise-examples</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8802e219.jpg</video:thumbnail_loc><video:title>Solving tricky proportions</video:title><video:description>Sal solves the equation (x-9)/12=2/3.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qzsR7cChujg.mp4/qzsR7cChujg.mp4</video:content_loc><video:duration>264</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-basics/v/slope-and-rate-of-change</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23636.jpg</video:thumbnail_loc><video:title>Slope (more examples)</video:title><video:description>Given two points on a line, you can find the slope of the line. Watch Sal doing a bunch of examples.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Iqws-qzyZwc.mp4/Iqws-qzyZwc.mp4</video:content_loc><video:duration>822</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-basics/v/factoring-a-common-binomial-factor</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb16e9511.jpg</video:thumbnail_loc><video:title>Factoring polynomials: common binomial factor</video:title><video:description>Sal factors n(n-1)+3(n-1) as (n+3)(n-1) by noticing that (n-1) is a common factor.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tDlzWNtRzS8.mp4/tDlzWNtRzS8.mp4</video:content_loc><video:duration>102</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-basics/v/factoring-difference-of-squares-exercise-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe909c411.jpg</video:thumbnail_loc><video:title>Factoring difference of squares: missing values</video:title><video:description>Sal analyzes the factorization of 3y^3-100y as 4y(My+g)(My-g) to find the possible values for the missing coefficient g.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/IRmv-Z--3LA.mp4/IRmv-Z--3LA.mp4</video:content_loc><video:duration>350</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-basics/v/segment-addition</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf0270049.jpg</video:thumbnail_loc><video:title>Equation practice with segment addition</video:title><video:description>If we split a line segment into two segments, the length of the total segment equals the sums of the lengths of the two smaller segments. We can make an equation out of the given information. After we solve for the value of x, we can substitute that value back into the expression for the length we are seeking.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/YFqeMzfcyg4.mp4/YFqeMzfcyg4.mp4</video:content_loc><video:duration>221</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-basics/v/midpoint-of-a-segment</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x73a3d40c.jpg</video:thumbnail_loc><video:title>Equation practice with midpoints</video:title><video:description>Given an information about the distance of a segment&apos;s midpoint from its endpoints, Sal forms and solves an equation in order to find the length of the segment.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/E0TNh9uWesw.mp4/E0TNh9uWesw.mp4</video:content_loc><video:duration>199</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-basics/v/pythagorean-theorem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23754.jpg</video:thumbnail_loc><video:title>Intro to the Pythagorean theorem 2</video:title><video:description>Sal introduces the famous and super important Pythagorean theorem!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/AEIzy1kNRqo.mp4/AEIzy1kNRqo.mp4</video:content_loc><video:duration>783</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/dependent-and-independent-variables-exercise-example-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x063b5c9e.jpg</video:thumbnail_loc><video:title>Dependent &amp; independent variables</video:title><video:description>Identifying the dependent and the independent variables in a word problem.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/i9j_VUMq5yg.mp4/i9j_VUMq5yg.mp4</video:content_loc><video:duration>130</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/square-roots-and-real-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23610.jpg</video:thumbnail_loc><video:title>Square roots and real numbers (old)</video:title><video:description>An old video of Sal where he simplifies square roots in order to determine whether they represent rational or irrational numbers.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/BpBh8gvMifs.mp4/BpBh8gvMifs.mp4</video:content_loc><video:duration>619</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/number-systems-introduction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x00087af5.jpg</video:thumbnail_loc><video:title>Introduction to number systems and binary</video:title><video:description>The base 10 (decimal) system is the most common number system used by humans, but there are other important and useful number systems. For example, base 2, called binary system, is the basis of modern computing. We can convert between the decimal form and binary form of a number to solve different problems.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ku4KOFQ-bB4.mp4/ku4KOFQ-bB4.mp4</video:content_loc><video:duration>600</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/hexadecimal-number-system</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3ba7f09a.jpg</video:thumbnail_loc><video:title>Hexadecimal number system</video:title><video:description>The hexadecimal number system is a way of counting that uses 16 different symbols instead of just the ten we&apos;re used to. It uses the numbers 0-9 like we do, but it also uses the letters A-F to represent the numbers 10-15. This system is useful in computer science because it can represent large numbers in a shorter, more compact way.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4EJay-6Bioo.mp4/4EJay-6Bioo.mp4</video:content_loc><video:duration>454</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/decimal-to-binary</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x47887da0.jpg</video:thumbnail_loc><video:title>Converting from decimal to binary</video:title><video:description>To convert a number from decimal to binary, we need to figure out which combination of 0s and 1s will represent the number. Start by finding the largest power of 2 that fits into the number, write down a &quot;1&quot; to represent that power of 2, and subtract it from the number. We keep going until we reach the smallest power of 2, which is 1.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/H4BstqvgBow.mp4/H4BstqvgBow.mp4</video:content_loc><video:duration>232</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/large-number-decimal-to-binary</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x72738886.jpg</video:thumbnail_loc><video:title>Converting larger number from decimal to binary</video:title><video:description>To convert a number from decimal to binary, we need to figure out which combination of 0s and 1s will represent the number. Start by finding the largest power of 2 that fits into the number, write down a &quot;1&quot; to represent that power of 2, and subtract it from the number. We keep going until we reach the smallest power of 2, which is 1.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/bvcXEJbEzSs.mp4/bvcXEJbEzSs.mp4</video:content_loc><video:duration>252</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/decimal-to-hexadecimal</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x86cfb88f.jpg</video:thumbnail_loc><video:title>Converting from decimal to hexadecimal representation</video:title><video:description>To convert a decimal number to hexadecimal, you need to break it down into powers of 16. Start by finding the largest power of 16 that is less than or equal to the decimal number. Once the decimal number is expressed as the sum of powers of 16, you can write it in hexadecimal form using place values. Remember that in hexadecimal, the digits A-F represent the numbers 10-15.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/NFmDz1dQyPU.mp4/NFmDz1dQyPU.mp4</video:content_loc><video:duration>223</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/binary-addition</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfe57d10d.jpg</video:thumbnail_loc><video:title>Adding in binary</video:title><video:description>When we add two numbers in binary, the key is that we can only use the digits zero and one. When we add two ones together, the result is two, but we have to write it as &quot;10&quot; in binary. Sometimes we have to &quot;carry&quot; a one over just like in regular addition.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/RgklPQ8rbkg.mp4/RgklPQ8rbkg.mp4</video:content_loc><video:duration>168</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/binary-multiplication</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbf936360.jpg</video:thumbnail_loc><video:title>Multiplying in binary</video:title><video:description>To multiply numbers in base 2, we can use the same process as we would in base 10, but with only two digits: 0 and 1. Start by multiplying the rightmost digit of one number by each digit of the other number, working left. Keep track of any &quot;carries&quot; (when the product is 2, carry over a 1 to the next column). Finally, add up all the partial products.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xHWKYFhhtJQ.mp4/xHWKYFhhtJQ.mp4</video:content_loc><video:duration>260</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/binary-to-hexadecimal</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8e9be1be.jpg</video:thumbnail_loc><video:title>Converting directly from binary to hexadecimal</video:title><video:description>To convert from binary to hexadecimal, we can split the binary number into groups of four digits. Each group of four binary digits can be converted into one hexadecimal digit. We can use a table or chart to figure out which hexadecimal digit matches each group of four binary digits. Once we have converted each group, we put the hexadecimal digits together to get the final answer.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8T4F7WboWPQ.mp4/8T4F7WboWPQ.mp4</video:content_loc><video:duration>327</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/mixture-problems-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26888.jpg</video:thumbnail_loc><video:title>Linear equation word problem: saline</video:title><video:description>Sal solves the following word problem: You have 50 ounces of a 25% saline solution. How many ounces of a 10% saline solution must you add to make a solution that is 15% saline?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OBVGQt1Eeug.mp4/OBVGQt1Eeug.mp4</video:content_loc><video:duration>403</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/mixture-problems-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26889.jpg</video:thumbnail_loc><video:title>Linear equation word problem: sugary drinks</video:title><video:description>Sal solves the following problem: Drink A with 40% sugar is mixed with Drink B to obtain Drink C which has 25% sugar. What is the percentage of sugar of Drink B?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/JVlfQEhzLMM.mp4/JVlfQEhzLMM.mp4</video:content_loc><video:duration>247</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/algebra-linear-equations-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23426.jpg</video:thumbnail_loc><video:title>Linear equations 1</video:title><video:description>To solve linear equations, find the value of the variable that makes the equation true. Use the inverse of the number that multiplies the variable, and multiply or divide both sides by it. Simplify the result to get the variable value. Check your answer by plugging it back into the equation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/bAerID24QJ0.mp4/bAerID24QJ0.mp4</video:content_loc><video:duration>447</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/algebra-linear-equations-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23428.jpg</video:thumbnail_loc><video:title>Linear equations 2</video:title><video:description>solving equations of the form AX+B=C</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DopnmxeMt-s.mp4/DopnmxeMt-s.mp4</video:content_loc><video:duration>367</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/algebra-linear-equations-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23430.jpg</video:thumbnail_loc><video:title>Linear equations 3</video:title><video:description>Linear equations with multiple variable and constant terms</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Zn-GbH2S0Dk.mp4/Zn-GbH2S0Dk.mp4</video:content_loc><video:duration>405</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/algebra-linear-equations-4</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23432.jpg</video:thumbnail_loc><video:title>Linear equations 4</video:title><video:description>Solving linear equations with variable expressions in the denominators of fractions</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9IUEk9fn2Vs.mp4/9IUEk9fn2Vs.mp4</video:content_loc><video:duration>458</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/averages</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23450.jpg</video:thumbnail_loc><video:title>Averages</video:title><video:description>We can calculate an average by adding up all the numbers in a group and dividing by the number of numbers. We can also use algebra to solve problems involving averages, and figure out how well we need to do on exams to get a good grade in a class.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9VZsMY15xeU.mp4/9VZsMY15xeU.mp4</video:content_loc><video:duration>516</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/taking-percentages</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23454.jpg</video:thumbnail_loc><video:title>Taking percentages</video:title><video:description>Taking a percentage of a number.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_SpE4hQ8D_o.mp4/_SpE4hQ8D_o.mp4</video:content_loc><video:duration>596</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/more-percent-problems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23460.jpg</video:thumbnail_loc><video:title>More percent problems</video:title><video:description>Slightly harder percent problems</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4oeoIOan_h4.mp4/4oeoIOan_h4.mp4</video:content_loc><video:duration>545</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/solving-for-a-variable</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/124291556.jpg</video:thumbnail_loc><video:title>Solving an equation for a variable</video:title><video:description>The perimeter of a rectangle is equal to 2 times the length plus 2 times the width. We can solve for the length by isolating it on one side of the equation. We do this by subtracting 2 times the width from both sides, and then dividing both sides by 2. This gives us the formula for the length.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/fnuIT7EhAvs.mp4/fnuIT7EhAvs.mp4</video:content_loc><video:duration>84</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/solving-and-graphing-linear-inequalities-in-two-variables-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26822.jpg</video:thumbnail_loc><video:title>Solving and graphing linear inequalities</video:title><video:description>How to graph on a number line and coordinate plane.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/EoCeL4SPIcA.mp4/EoCeL4SPIcA.mp4</video:content_loc><video:duration>135</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/ordered-pair-solutions-of-equations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/561901044.jpg</video:thumbnail_loc><video:title>Solutions to 2-variable equations: substitution (old)</video:title><video:description>An old video of Sal checking whether (3,-4) is a solution of 5x+2y=7 by substituting x=3 and y=-4.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/HUn4XwV7o9I.mp4/HUn4XwV7o9I.mp4</video:content_loc><video:duration>89</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/ordered-pair-solutions-of-equations-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/466056216.jpg</video:thumbnail_loc><video:title>Solutions to 2-variable equations: graphical (old)</video:title><video:description>An old video of Sal checking whether (3,-4) is a solution of 5x+2y=7 by graphing the equation and checking if (3,-4) is on the line.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/SSNA9gaAOVc.mp4/SSNA9gaAOVc.mp4</video:content_loc><video:duration>306</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/graphing-using-x-and-y-intercepts</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/33752748.jpg</video:thumbnail_loc><video:title>Graphing using intercepts (old)</video:title><video:description>An old video of Sal where he draws the line y=3x-9 by finding its x- and y-intercetps.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6m642-2D3V4.mp4/6m642-2D3V4.mp4</video:content_loc><video:duration>238</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/equation-of-a-line-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/33752755.jpg</video:thumbnail_loc><video:title>Slope-intercept equation from slope &amp; point (old)</video:title><video:description>An old video where Sal finds the slope-intercept form of a line that has a slope of 7 and goes through the point (-4,-11).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/MxiqyE2uMCo.mp4/MxiqyE2uMCo.mp4</video:content_loc><video:duration>237</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/equation-of-a-line-hairier-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/466052138.jpg</video:thumbnail_loc><video:title>Slope-intercept equation from slope &amp; point: fractions (old)</video:title><video:description>An old video where Sal finds the slope-intercept form of a line that has a slope of ⅓ and goes through the point (-12,-14/3).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/k8EfLFvUI5U.mp4/k8EfLFvUI5U.mp4</video:content_loc><video:duration>204</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/finding-y-intercept-given-slope-and-point</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x81716b8c.jpg</video:thumbnail_loc><video:title>Finding y intercept given slope &amp; point (old)</video:title><video:description>An old video where Sal finds the y-intercept of the line y=17/13x+b given that the line passes through (5,8).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/KV_XLL4K2Fw.mp4/KV_XLL4K2Fw.mp4</video:content_loc><video:duration>120</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/interpreting-linear-formulas-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf811a89f.jpg</video:thumbnail_loc><video:title>Linear equations word problem: marbles</video:title><video:description>Sal finds the y-intercept and the slope of a linear relationship representing someone filling a glass tank with marbles. He then interprets what the y-intercept and the slope mean in that context.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/deKCm28TkRo.mp4/deKCm28TkRo.mp4</video:content_loc><video:duration>160</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/interpreting-linear-formulas-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x43f08c7b.jpg</video:thumbnail_loc><video:title>Linear equations word problem: file transfer</video:title><video:description>Sal finds the y-intercept and the slope of a linear relationship representing a top secret file transfer. He then interprets what the y-intercept and the slope mean in that context.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/AY8ldIEi3fU.mp4/AY8ldIEi3fU.mp4</video:content_loc><video:duration>155</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/linear-models-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1b99677b.jpg</video:thumbnail_loc><video:title>Linear models word problem: book</video:title><video:description>Sal solves a word problem about a person reading a book. The solution involves the modeling of the situation as a linear function.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/W3flX500w5g.mp4/W3flX500w5g.mp4</video:content_loc><video:duration>532</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/linear-models-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x922ace72.jpg</video:thumbnail_loc><video:title>Linear models word problem: marbles</video:title><video:description>Sal solves a word problem about a person filling a glass tank with marbles. The solution involves the modeling of the situation as a linear function.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Rq56-OJR964.mp4/Rq56-OJR964.mp4</video:content_loc><video:duration>337</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/solving-systems-of-equations-by-elimination</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23678.jpg</video:thumbnail_loc><video:title>Solving systems of equations by elimination (old)</video:title><video:description>An old video where Sal introduces the elimination method for systems of linear equations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vA-55wZtLeE.mp4/vA-55wZtLeE.mp4</video:content_loc><video:duration>764</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/solving-linear-systems-by-substitution</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23676.jpg</video:thumbnail_loc><video:title>Solving linear systems by substitution (old)</video:title><video:description>An old video where Sal introduces the substitution method for systems of linear equations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/V7H1oUHXPkg.mp4/V7H1oUHXPkg.mp4</video:content_loc><video:duration>561</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/manipulating-expressions-with-unknown-variables-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf33e100e.jpg</video:thumbnail_loc><video:title>Manipulating expressions using structure</video:title><video:description>Given that a+b=0, Sal finds an expression equivalent to a*b.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ZYn8MhrwHr4.mp4/ZYn8MhrwHr4.mp4</video:content_loc><video:duration>95</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/manipulating-expressions-with-unknown-variables-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf778691f.jpg</video:thumbnail_loc><video:title>Manipulating expressions using structure (example 2)</video:title><video:description>Given that a+b=2a, Sal finds an expression equivalent to b-a.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DF5MkPVjnCc.mp4/DF5MkPVjnCc.mp4</video:content_loc><video:duration>161</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/interpreting-equations-graphically-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6bfe3d09.jpg</video:thumbnail_loc><video:title>Interpreting equations graphically</video:title><video:description>Sal interprets the intersection point of the graphs of functions f and g as the solution of the equation f(x)=g(x).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LyVqwJkI5jg.mp4/LyVqwJkI5jg.mp4</video:content_loc><video:duration>245</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/interpreting-equations-graphically-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xad6730ce.jpg</video:thumbnail_loc><video:title>Interpreting equations graphically (example 2)</video:title><video:description>Sal finds the coordinates of points on a graph that are solutions to a given equation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/R446VpTeOU8.mp4/R446VpTeOU8.mp4</video:content_loc><video:duration>157</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/estimating-a-solution-to-nonlinear-system-with-calculator</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x16a2de2b.jpg</video:thumbnail_loc><video:title>Solving equations graphically (1 of 2)</video:title><video:description>Sal solves the equation e^x=1/[x(x-1)(x-2)] by considering the graphs of y=e^x and y=1/[x(x-1)(x-2)].</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/mXsn-YYUN4Y.mp4/mXsn-YYUN4Y.mp4</video:content_loc><video:duration>483</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/estimating-a-solution-to-nonlinear-system-with-calculator-part-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x364f568c.jpg</video:thumbnail_loc><video:title>Solving equations graphically (2 of 2)</video:title><video:description>Sal solves the equation e^x=1/[x(x-1)(x-2)] by considering the graphs of y=e^x and y=1/[x(x-1)(x-2)].</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/wUb7tWgv49U.mp4/wUb7tWgv49U.mp4</video:content_loc><video:duration>265</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/systems-of-three-variables</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/33752776.jpg</video:thumbnail_loc><video:title>Intro to linear systems with 3 variables</video:title><video:description>Sal discusses how we approach solving systems of three variables algebraically, and how we visualize it graphically.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pANZpI9sOYg.mp4/pANZpI9sOYg.mp4</video:content_loc><video:duration>503</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/systems-of-three-variables-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/33752777.jpg</video:thumbnail_loc><video:title>Solving linear systems with 3 variables</video:title><video:description>Sal solves a system of three variables using elimination.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/f7cX-Ar2cEM.mp4/f7cX-Ar2cEM.mp4</video:content_loc><video:duration>420</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/solutions-to-three-variable-system-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/465991886.jpg</video:thumbnail_loc><video:title>Solving linear systems with 3 variables: no solution</video:title><video:description>Sal solves a system with three variables that turns out to have no solution.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/145zOBT0LD4.mp4/145zOBT0LD4.mp4</video:content_loc><video:duration>306</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/three-equation-application-problem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/33752778.jpg</video:thumbnail_loc><video:title>3-variable linear system word problem</video:title><video:description>Sal solves a word problem about the angles of a given triangle by modeling the given information as a system of three equations and variables.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TJaHNxJk5-4.mp4/TJaHNxJk5-4.mp4</video:content_loc><video:duration>496</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/constraining-solutions-to-two-variable-linear-inequalities</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1849794a.jpg</video:thumbnail_loc><video:title>Constraining solutions of two-variable inequalities</video:title><video:description>Sal determines which x-values make the ordered pair (x,-7) a solution of 2x-7y&lt;25, both algebraically and graphically.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/a5YZ7-JRSUE.mp4/a5YZ7-JRSUE.mp4</video:content_loc><video:duration>252</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/constraining-solutions-of-systems-of-inequalities</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x66f6081c.jpg</video:thumbnail_loc><video:title>Constraining solutions of systems of inequalities</video:title><video:description>Given the graph of a system of inequalities, Sal finds the x-values that make the ordered pair (x,-2) a solution of the system.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/BGyrSuW3GCg.mp4/BGyrSuW3GCg.mp4</video:content_loc><video:duration>348</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/graphing-inequalities-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/33752760.jpg</video:thumbnail_loc><video:title>Graphing two-variable inequalities (old)</video:title><video:description>An old video where Sal graphs the inequality y-4x&lt;-3.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-aTy1ED1m5I.mp4/-aTy1ED1m5I.mp4</video:content_loc><video:duration>320</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math1/v/analyzing-structure-with-linear-inequalities-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x182dfd3b87d8eecf.jpg</video:thumbnail_loc><video:title>Analyzing structure with linear inequalities: fruits</video:title><video:description>Given a real-world context about the number of fruits bought, we find a linear inequality that correctly depicts the situation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/JeIwsn-EWZU.mp4/JeIwsn-EWZU.mp4</video:content_loc><video:duration>233</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math1/v/analyzing-structure-with-linear-inequalities-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc92fb1665aa8ac6e.jpg</video:thumbnail_loc><video:title>Analyzing structure with linear inequalities: balls</video:title><video:description>Given a real-world context about the number of balls in a bag, we find a linear inequality that correctly depicts the situation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Pfi_chISQbg.mp4/Pfi_chISQbg.mp4</video:content_loc><video:duration>140</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/domain-of-a-radical-function</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/364967637.jpg</video:thumbnail_loc><video:title>Domain of a radical function</video:title><video:description>Finding the domain of f(x)=√(2x-8).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4h54s7BBPpA.mp4/4h54s7BBPpA.mp4</video:content_loc><video:duration>107</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/domain-of-algebraic-function-examples</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x43141392.jpg</video:thumbnail_loc><video:title>Worked example: domain of algebraic functions</video:title><video:description>Many examples of determining the domains of functions according to mathematical limitations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/n17q8CBiMtQ.mp4/n17q8CBiMtQ.mp4</video:content_loc><video:duration>434</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/average-rate-of-change-when-function-defined-by-equation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4f2e6d3a.jpg</video:thumbnail_loc><video:title>Worked example: average rate of change from equation</video:title><video:description>Finding the interval where a function has an average rate of change of ½ given its equation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6n0yxfWNFR4.mp4/6n0yxfWNFR4.mp4</video:content_loc><video:duration>304</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/average-rate-of-change-with-function-notation-word-problem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x33e4fdd9.jpg</video:thumbnail_loc><video:title>Average rate of change word problem: equation</video:title><video:description>Average rate of change tells us how much the function changed per a single time unit, over a specific interval. It has many real-world applications. In this video, we represent the average rate of water draining with an algebraic expression.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/wmQdFLdxLYc.mp4/wmQdFLdxLYc.mp4</video:content_loc><video:duration>273</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/sum-of-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/364981332.jpg</video:thumbnail_loc><video:title>Adding functions</video:title><video:description>Given that f(x)=9-x^2 and g(x)=5x^2+2x+1, Sal finds (f+g)(x).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/n34dqyVCXs4.mp4/n34dqyVCXs4.mp4</video:content_loc><video:duration>153</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/difference-of-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/364967636.jpg</video:thumbnail_loc><video:title>Subtracting functions</video:title><video:description>Given that f(x)=2x√5-4 and g(x)=x^2+2x√5-1, Sal finds (g-f)(x).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6arI8XhLZ9o.mp4/6arI8XhLZ9o.mp4</video:content_loc><video:duration>136</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/product-of-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/364954028.jpg</video:thumbnail_loc><video:title>Multiplying functions</video:title><video:description>Sal solves the following problem: given that f(x)=7x-5 and g(x)=x^3+4x, find (f*g)(x). He explains that generally, (f*g)(x)=f(x)*g(x).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/JKvmAexeMgY.mp4/JKvmAexeMgY.mp4</video:content_loc><video:duration>180</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/quotient-of-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/364954027.jpg</video:thumbnail_loc><video:title>Dividing functions</video:title><video:description>Sal solves the following problem: given that f(x)=2x^2+15x-8 and g(x)=x^2+10x+16, find (f/g)(x). He explains that generally, (f/g)(x)=f(x)/g(x).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/u9v_bakOIcU.mp4/u9v_bakOIcU.mp4</video:content_loc><video:duration>378</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/modeling-with-composite-functions-examples</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x11595a4f.jpg</video:thumbnail_loc><video:title>Modeling with composite functions</video:title><video:description>Sal determines the correct functions to compose (and the correct order) in order to model a given relationship, and vice versa.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pIMfRbznxKA.mp4/pIMfRbznxKA.mp4</video:content_loc><video:duration>403</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/modeling-with-composite-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7cd69a43.jpg</video:thumbnail_loc><video:title>Modeling with composite functions: skydiving</video:title><video:description>Sal models the maximum speed of a skydiver, by using composing given formulas for the maximum speed as a function of parachute area and parachute area as a function of width.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/UMTeKCLvv9E.mp4/UMTeKCLvv9E.mp4</video:content_loc><video:duration>208</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/function-inverses-example-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26635.jpg</video:thumbnail_loc><video:title>Finding inverse functions: quadratic</video:title><video:description>Sal finds the inverse of f(x)=(x+2)^2+1.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/aeyFb2eVH1c.mp4/aeyFb2eVH1c.mp4</video:content_loc><video:duration>432</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/function-inverses-example-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26636.jpg</video:thumbnail_loc><video:title>Finding inverse functions: quadratic (example 2)</video:title><video:description>Sal finds the inverse of f(x)=(x-1)^2-2.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Bq9cq9FZuNM.mp4/Bq9cq9FZuNM.mp4</video:content_loc><video:duration>455</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/finding-inverse-functions-radical</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8af4cad8.jpg</video:thumbnail_loc><video:title>Finding inverse functions: radical</video:title><video:description>Sal finds the inverse of h(x)=-∛(3x-6)+12.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/JBqYTuA_WgE.mp4/JBqYTuA_WgE.mp4</video:content_loc><video:duration>277</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/domain-of-a-function</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23512.jpg</video:thumbnail_loc><video:title>Domain of advanced functions</video:title><video:description>Sal covers many different kinds of functions and shows how to determine their domain.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/U-k5N1WPk4g.mp4/U-k5N1WPk4g.mp4</video:content_loc><video:duration>599</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/finding-a-piecewise-function-definition-from-graph</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3af6a8cc.jpg</video:thumbnail_loc><video:title>Graphs of nonlinear piecewise functions</video:title><video:description>Sal is given the graph of a piecewise function and several possible formulas. He determines which is the correct formula.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/IJWDyPFXGyM.mp4/IJWDyPFXGyM.mp4</video:content_loc><video:duration>263</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/new-operator-definitions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/185730830.jpg</video:thumbnail_loc><video:title>New operator definitions 1</video:title><video:description>Sal solves a few problems where a new operator is defined and Sal evaluates some expression with it.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ND-Bbp_q46s.mp4/ND-Bbp_q46s.mp4</video:content_loc><video:duration>410</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/new-definitions-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1254312875.jpg</video:thumbnail_loc><video:title>New operator definitions 2</video:title><video:description>Worked examples of working with more newly defined operators.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/soUmhhuF08Y.mp4/soUmhhuF08Y.mp4</video:content_loc><video:duration>133</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/solving-quadratic-equations-by-square-roots</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23720.jpg</video:thumbnail_loc><video:title>Solving quadratics by taking square roots: challenge</video:title><video:description>Sal solves challenging quadratic equations like (4x+1)²-8=0 by taking the square root of both sides.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/55G8037gsKY.mp4/55G8037gsKY.mp4</video:content_loc><video:duration>663</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/factoring-special-products</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23712.jpg</video:thumbnail_loc><video:title>Solving quadratic equations by factoring (old)</video:title><video:description>An old video where Sal solves a bunch of quadratic equations by using factorization methods.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/BI_jmI4xRus.mp4/BI_jmI4xRus.mp4</video:content_loc><video:duration>608</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/quadratic-formula-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/27002.jpg</video:thumbnail_loc><video:title>Using the quadratic formula</video:title><video:description>Sal solves the equation -7q^2+2q+9=0 by using the quadratic formula.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/iulx0z1lz8M.mp4/iulx0z1lz8M.mp4</video:content_loc><video:duration>334</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/quadratic-equations-in-standard-form</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/150088075.jpg</video:thumbnail_loc><video:title>Worked example: quadratic formula</video:title><video:description>Solving 6x²+3=2x-6 by rewriting in standard form and identifying the parameters a, b, and c, that can be used within the quadratic formula.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ty4Ohya4hdE.mp4/ty4Ohya4hdE.mp4</video:content_loc><video:duration>141</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/non-linear-systems-of-equations-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/27008.jpg</video:thumbnail_loc><video:title>Quadratic systems: graphical solution</video:title><video:description>Sal solves a system of a quadratic equation and a linear equation by graphing both equations and looking for their intersections, and then checks the solution algebraically.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hjigR_rHKDI.mp4/hjigR_rHKDI.mp4</video:content_loc><video:duration>344</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/systems-of-nonlinear-equations-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0698a8ee.jpg</video:thumbnail_loc><video:title>Quadratic systems: both variables are squared</video:title><video:description>Sal solves the system y=0.5x and 2x^2-y^2=7.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/GQf1vjfxuo8.mp4/GQf1vjfxuo8.mp4</video:content_loc><video:duration>214</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/quadratic-inequality-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x63a87fa0.jpg</video:thumbnail_loc><video:title>Quadratic inequalities</video:title><video:description>Sal solves x^2+3x&gt;10.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OP91XWBRI1w.mp4/OP91XWBRI1w.mp4</video:content_loc><video:duration>461</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/quadratic-inequality-example-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3de63390.jpg</video:thumbnail_loc><video:title>Quadratic inequalities (example 2)</video:title><video:description>Sal solves -x(2x-14)≥24.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/YS_3XRj74oo.mp4/YS_3XRj74oo.mp4</video:content_loc><video:duration>474</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/quadratic-inequalities-visual-explanation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23502.jpg</video:thumbnail_loc><video:title>Quadratic inequalities: graphical approach</video:title><video:description>Sal solves a few quadratic inequalities by moving all terms to one side of the inequality and graphing the resulting expression.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xdiBjypYFRQ.mp4/xdiBjypYFRQ.mp4</video:content_loc><video:duration>593</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/evaluating-a-polynomial-at-a-given-value</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179511.jpg</video:thumbnail_loc><video:title>Evaluating polynomials</video:title><video:description>Evaluating 3x²-8x+7 when x=-2.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/03yq7XsErqo.mp4/03yq7XsErqo.mp4</video:content_loc><video:duration>69</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/simply-a-polynomial</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179512.jpg</video:thumbnail_loc><video:title>Simplifying polynomials</video:title><video:description>Simplifying the polynomial 3x²-8x+7+2x³-x²+8x-3 by combining like terms.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vN0aL-_vIKM.mp4/vN0aL-_vIKM.mp4</video:content_loc><video:duration>217</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/adding-and-subtracting-polynomials-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26922.jpg</video:thumbnail_loc><video:title>Adding &amp; subtracting multiple polynomials</video:title><video:description>Sal simplifies (x³ + 3x - 6) + (-2x² + x - 2) - (3x - 4).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DMyhUb1pZT0.mp4/DMyhUb1pZT0.mp4</video:content_loc><video:duration>147</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/adding-polynomials</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179513.jpg</video:thumbnail_loc><video:title>Adding polynomials (old)</video:title><video:description>An old video where Sal adds (5x²+8x-3) + (2x² - 7x + 13x).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Oe1PKI_6-38.mp4/Oe1PKI_6-38.mp4</video:content_loc><video:duration>130</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/subtracting-polynomials-in-two-variables</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x206d2842.jpg</video:thumbnail_loc><video:title>Subtracting polynomials: two variables</video:title><video:description>Sal subtracts -6x⁴-3x²y²+5y⁴ from 2x⁴-8x²y²-y⁴.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/G9C7uz3XOh0.mp4/G9C7uz3XOh0.mp4</video:content_loc><video:duration>224</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/addition-and-subtraction-of-polynomials</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23702.jpg</video:thumbnail_loc><video:title>Polynomials review</video:title><video:description>Quickly review what polynomials are, common related terms (e.g. degree, coefficient, binomial, etc.), addition &amp; subtraction of polynomials, and modeling area with polynomials.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ZgFXL6SEUiI.mp4/ZgFXL6SEUiI.mp4</video:content_loc><video:duration>959</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/special-products-of-polynomials-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187338.jpg</video:thumbnail_loc><video:title>Special products of binomials: two variables</video:title><video:description>Sal finds the area of a square with side (6x-5y).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4fQeHtSdw80.mp4/4fQeHtSdw80.mp4</video:content_loc><video:duration>312</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/special-products-of-binomials</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23706.jpg</video:thumbnail_loc><video:title>More examples of special products</video:title><video:description>Sal gives numerous examples of the two special binomial product forms: perfect squares and the difference of two squares.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/bFtjG45-Udk.mp4/bFtjG45-Udk.mp4</video:content_loc><video:duration>636</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/special-products-of-polynomials-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26976.jpg</video:thumbnail_loc><video:title>Squaring a binomial (old)</video:title><video:description>An old video where Sal expands and simplifies (7x+10)².</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4GcNzvILqtM.mp4/4GcNzvILqtM.mp4</video:content_loc><video:duration>199</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/missing-coefficients-in-binomial-product</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe2571c46.jpg</video:thumbnail_loc><video:title>Multiplying binomials by polynomials challenge</video:title><video:description>Sal finds the values of coefficients a and b that make (2x+4)(5x-9)=ax²+bx-46 true for all x-values.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ieC5LgoGJVg.mp4/ieC5LgoGJVg.mp4</video:content_loc><video:duration>283</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/multiplication-of-polynomials</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23704.jpg</video:thumbnail_loc><video:title>Multiplying binomials by polynomials (old)</video:title><video:description>An old video where Sal gives several examples of polynomial multiplication.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/fGThIRpWEE4.mp4/fGThIRpWEE4.mp4</video:content_loc><video:duration>589</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/multiplying-binomials-with-radicals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/127771049.jpg</video:thumbnail_loc><video:title>Multiplying binomials with radicals (old)</video:title><video:description>An old video Where Sal multiplies and simplifies (x²-√6)(x²+√2).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/yAH3722GrP8.mp4/yAH3722GrP8.mp4</video:content_loc><video:duration>364</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/multiplying-polynomials-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26975.jpg</video:thumbnail_loc><video:title>Polynomial multiplication word problem</video:title><video:description>Sal finds the volume of a tank whose base has an area of 3x² + 30x + 5 square feet and whose height is 8x - 5 feet.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/bamcYQDzVTw.mp4/bamcYQDzVTw.mp4</video:content_loc><video:duration>259</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/polynomials1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187332.jpg</video:thumbnail_loc><video:title>Polynomial word problem: rectangle and circle area</video:title><video:description>Sal writes a binomial to express the difference between the area of a rectangle and the area of a circle.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/EvvxBdNIUeQ.mp4/EvvxBdNIUeQ.mp4</video:content_loc><video:duration>277</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/polynomials-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26919.jpg</video:thumbnail_loc><video:title>Polynomial word problem: total value of bills</video:title><video:description>Sal writes a polynomial to express the total value of p twenty dollar bills, q ten dollar bills, and r five dollar bills.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/IGs7IB48Fvg.mp4/IGs7IB48Fvg.mp4</video:content_loc><video:duration>84</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/multiplying-polynomials-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26974.jpg</video:thumbnail_loc><video:title>Polynomial word problem: area of a window</video:title><video:description>Sal writes a polynomial expression that represents the total area of a window made of wood and glass.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/J1HAY8E3gms.mp4/J1HAY8E3gms.mp4</video:content_loc><video:duration>288</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/ways-to-factor-a-monomial</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x846ba409.jpg</video:thumbnail_loc><video:title>Which monomial factorization is correct?</video:title><video:description>Factoring monomials involves breaking down an expression into two parts. This process shows that there are multiple correct ways to factor a monomial. By multiplying coefficients and powers, you can verify if the factorization is accurate. It&apos;s a fun exploration of the many ways to dissect monomials!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_MCPV8CQzf8.mp4/_MCPV8CQzf8.mp4</video:content_loc><video:duration>126</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/finding-algebraic-factor-of-a-monomial</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa5ca219a.jpg</video:thumbnail_loc><video:title>Worked example: finding the missing monomial factor</video:title><video:description>Follow along as Sal works an example to show you how to factor monomials by isolating variables in equations. Learn how to use exponent properties to rewrite complex expressions and get a firm grasp on the crucial role that coefficients and exponents play in this process. This knowledge will empower you to solve for unknown factors in any monomial equation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/kkrF9X6Fycg.mp4/kkrF9X6Fycg.mp4</video:content_loc><video:duration>199</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/dimensions-of-rectangle-for-algebraically-described-area</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x498ab758.jpg</video:thumbnail_loc><video:title>Worked example: finding missing monomial side in area model</video:title><video:description>Learn how to find the length of a rectangle using algebraic expressions, as Sal finds the length of a rectangle whose area is 42xy^3 and whose height is 14xy. Dive into dividing coefficients and variables to solve for length and uncover how dividing powers of &apos;y&apos; can simplify your equation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/UYh7Sj_yR8c.mp4/UYh7Sj_yR8c.mp4</video:content_loc><video:duration>129</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/monomial-greatest-common-factor</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179576.jpg</video:thumbnail_loc><video:title>Greatest common factor of monomials</video:title><video:description>Follow along as Sal finds the greatest common factor of 10cd^2 and 25c^3d^2 and discover the secret to finding the greatest common factor of monomials! Dive into prime factorization and variable parts, and learn how to break down monomials into their simplest forms. Uncover the common factors and master the art of algebraic expressions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_01wqwsb66E.mp4/_01wqwsb66E.mp4</video:content_loc><video:duration>193</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/factoring-and-the-distributive-property-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26981.jpg</video:thumbnail_loc><video:title>Factoring polynomials: common factor (old)</video:title><video:description>An old video where Sal factors 20u²v - 10uv² as 10uv(2u-v).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/499MvHFrqUU.mp4/499MvHFrqUU.mp4</video:content_loc><video:duration>286</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/factor-polynomials-using-the-gcf</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179577.jpg</video:thumbnail_loc><video:title>Factoring polynomials: common factor (old)</video:title><video:description>An old video where Sal factors 4x⁴y+8x³y as 4x³y(x+2).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_sIuZHYrdWM.mp4/_sIuZHYrdWM.mp4</video:content_loc><video:duration>328</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/evaluating-expressions-where-individual-variable-values-are-unknown</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1242712428.jpg</video:thumbnail_loc><video:title>Worked example: evaluating expressions using structure</video:title><video:description>Sal solved a few examples where we need to evaluate an expression, but we don&apos;t know the individual variable values.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TIwGXn4NalM.mp4/TIwGXn4NalM.mp4</video:content_loc><video:duration>279</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/evaluating-expressions-with-unknown-variables-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1242747382.jpg</video:thumbnail_loc><video:title>Worked example: evaluating expressions using structure (more examples)</video:title><video:description>A few more examples where Sal evaluates expressions with multiple unknown variables.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/CLQRZ2UbQ4Q.mp4/CLQRZ2UbQ4Q.mp4</video:content_loc><video:duration>180</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/factoring-quadratics-with-two-variables</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd24800c6.jpg</video:thumbnail_loc><video:title>Factoring two-variable quadratics</video:title><video:description>Sal factors x^2+4xy-5y^2 as (x-y)(x+5y).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DRpdoZQtvOM.mp4/DRpdoZQtvOM.mp4</video:content_loc><video:duration>371</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/factoring-quadratics-with-two-variables-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x97900f0f.jpg</video:thumbnail_loc><video:title>Factoring two-variable quadratics: rearranging</video:title><video:description>Sal rearranges 30x^2+11xy+y^2 as y^2+11xy+30x^2 and then factors it as (y+5x)(y+6x).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0xrvRKHoO2g.mp4/0xrvRKHoO2g.mp4</video:content_loc><video:duration>166</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/factoring-trinomials-by-grouping-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26983.jpg</video:thumbnail_loc><video:title>Factoring two-variable quadratics: grouping</video:title><video:description>Sal factors 5rs+25r-3s-15 as (s+5)(5r-3).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/HXIj16mjfgk.mp4/HXIj16mjfgk.mp4</video:content_loc><video:duration>226</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/factoring-trinomials-with-a-common-factor</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179580.jpg</video:thumbnail_loc><video:title>Factoring quadratics with common factor (old)</video:title><video:description>An old video where Sal factors 8k²-24k-144 by first taking out a common factor of 8 and then using the sum-product pattern.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/GMoqg_s4Dl4.mp4/GMoqg_s4Dl4.mp4</video:content_loc><video:duration>301</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/u09-l2-t1-we3-factoring-special-products-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26991.jpg</video:thumbnail_loc><video:title>Factoring difference of squares: two variables (example 2)</video:title><video:description>Sal factors 49x^2-49y^2 as (7x+7y)(7x-7y) or as 49(x+y)(x-y).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/YahJQvY396o.mp4/YahJQvY396o.mp4</video:content_loc><video:duration>150</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/dividing-polynomials-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179524.jpg</video:thumbnail_loc><video:title>Dividing polynomials: long division</video:title><video:description>Sal divides (x^2-3x+2) by (x-2) and then checks the solution.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8Wxw9bpKEGQ.mp4/8Wxw9bpKEGQ.mp4</video:content_loc><video:duration>200</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/dividing-polynomials-with-remainders-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4278b219.jpg</video:thumbnail_loc><video:title>Divide polynomials by monomials (with remainders)</video:title><video:description>Sal divides (7x^6+x^3+2x+1) by x^2, and writes the solution as q(x)+r(x)/x^2, where the degree of the remainder, r(x), is less than the degree of x^2.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/WqNc6My1aNU.mp4/WqNc6My1aNU.mp4</video:content_loc><video:duration>161</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/dividing-polynomials-with-remainders</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179525.jpg</video:thumbnail_loc><video:title>Dividing polynomials with remainders</video:title><video:description>Sal divides (x^3+5x-4) by (x^2-x+1) using long division.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pLCmwHsDYqo.mp4/pLCmwHsDYqo.mp4</video:content_loc><video:duration>383</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/binomial-theorem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x143f944b.jpg</video:thumbnail_loc><video:title>Intro to the Binomial Theorem</video:title><video:description>The Binomial theorem tells us how to expand expressions of the form (a+b)ⁿ, for example, (x+y)⁷. The larger the power is, the harder it is to expand expressions like this directly. But with the Binomial theorem, the process is relatively fast!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/iPwrDWQ7hPc.mp4/iPwrDWQ7hPc.mp4</video:content_loc><video:duration>795</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/pascals-triangle-binomial-theorem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x87dcb8c9.jpg</video:thumbnail_loc><video:title>Pascal&apos;s triangle and binomial expansion</video:title><video:description>Sal introduces Pascal&apos;s triangle, and shows how we can use it to figure out the coefficients in binomial expansions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/v9Evg2tBdRk.mp4/v9Evg2tBdRk.mp4</video:content_loc><video:duration>500</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/coefficient-in-binomial-expansion</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x69d9ce4e.jpg</video:thumbnail_loc><video:title>Expanding binomials</video:title><video:description>Sal expands (3y^2+6x^3)^5 using the binomial theorem and Pascal&apos;s triangle.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ojFuf9RYmzI.mp4/ojFuf9RYmzI.mp4</video:content_loc><video:duration>521</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/binomial-expansion-algorithm</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x10480fb9.jpg</video:thumbnail_loc><video:title>Expanding binomials w/o Pascal&apos;s triangle</video:title><video:description>Sal gives a &quot;trick&quot; for expanding large powers of binomials, without using Pascal&apos;s triangle.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2IFItASxDVo.mp4/2IFItASxDVo.mp4</video:content_loc><video:duration>299</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/binomial-theorem-and-combinatorics-intuition</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5fbb948e.jpg</video:thumbnail_loc><video:title>Binomial expansion &amp; combinatorics</video:title><video:description>Sal explains why we use the combinatorial formula for (n choose k) to expand binomial expressions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_hrN4rVCOfI.mp4/_hrN4rVCOfI.mp4</video:content_loc><video:duration>255</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/binomial-theorem-intuition</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x18e9abfd.jpg</video:thumbnail_loc><video:title>Pascal&apos;s triangle &amp; combinatorics</video:title><video:description>Sal shows how generating the values in Pascal&apos;s triangle is related to the combinatorial formula (n choose k).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/x-N76NrMDNE.mp4/x-N76NrMDNE.mp4</video:content_loc><video:duration>246</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/binomial-theorem-part-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25810.jpg</video:thumbnail_loc><video:title>Binomial expansion &amp; combinatorics (old)</video:title><video:description>An old video of Sal explaining why we use the combinatorial formula for (n choose k) to expand binomial expressions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xF_hJaXUNfE.mp4/xF_hJaXUNfE.mp4</video:content_loc><video:duration>719</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/analyzing-polynomial-manipulations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa96fc7d0.jpg</video:thumbnail_loc><video:title>Analyzing polynomial identities</video:title><video:description>The video focuses on the critical analysis of polynomial manipulations, emphasizing the importance of checking each step for errors. It provides practice on identifying valid polynomial identities and highlights the significance of correct algebraic multiplication in solving polynomial equations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-6qiO49Q180.mp4/-6qiO49Q180.mp4</video:content_loc><video:duration>459</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/fundamental-theorem-of-algebra-intro</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd72bdb29.jpg</video:thumbnail_loc><video:title>The Fundamental theorem of Algebra</video:title><video:description>Sal introduces the Fundamental Theorem of Algebra, which, as is reflected in its name, is a very important theorem about polynomials.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/d8-LO6FCna0.mp4/d8-LO6FCna0.mp4</video:content_loc><video:duration>334</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/fundamental-theorem-algebra-quadratic</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6d4fe289.jpg</video:thumbnail_loc><video:title>Quadratics &amp; the Fundamental Theorem of Algebra</video:title><video:description>The proof of the Fundamental Theorem of Algebra for any degree of polynomial is really tough. For now, let&apos;s note that it indeed holds for polynomials of the second degree (i.e. quadratics).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/zNxEVaRbdus.mp4/zNxEVaRbdus.mp4</video:content_loc><video:duration>395</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/possible-real-roots</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf74e2e33.jpg</video:thumbnail_loc><video:title>Number of possible real roots of a polynomial</video:title><video:description>The Fundamental Theorem of Algebra can be used in order to determine how many real roots a given polynomial has. Check it out!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_HFTRQRpzFM.mp4/_HFTRQRpzFM.mp4</video:content_loc><video:duration>226</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/finding-roots-or-zeros-of-polynomial-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc9beaa62.jpg</video:thumbnail_loc><video:title>Finding zeros of polynomials (1 of 2)</video:title><video:description>Sal finds all the zeros (which is the same as the roots) of p(x)=x⁵+9x³-2x³-18x=0.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/x9lb_frpkH0.mp4/x9lb_frpkH0.mp4</video:content_loc><video:duration>549</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/finding-roots-or-zeros-of-polynomial-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x19e2704e.jpg</video:thumbnail_loc><video:title>Finding zeros of polynomials (2 of 2)</video:title><video:description>Sal uses an alternative method to find the zeros of p(x)=x⁵+9x³-2x³-18x=0.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/HJgjAZ7JkHQ.mp4/HJgjAZ7JkHQ.mp4</video:content_loc><video:duration>180</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/finding-roots-or-zeros-of-polynomial-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0ef1472a.jpg</video:thumbnail_loc><video:title>Finding zeros of polynomials (example 2)</video:title><video:description>Sal finds all the zeros (which is the same as the roots) of p(x)=(3x⁴-8x³+15x-40)(3x-8)².</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9zreFD3T0qY.mp4/9zreFD3T0qY.mp4</video:content_loc><video:duration>405</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/identifying-graph-based-on-roots</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x64e707f0.jpg</video:thumbnail_loc><video:title>Zeros of polynomials &amp; their graphs</video:title><video:description>Sal uses the zeros of y=x^3+3x^2+x+3 to determine its corresponding graph.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/uFZvWYPfOmw.mp4/uFZvWYPfOmw.mp4</video:content_loc><video:duration>327</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/recognizing-features-of-functions-example-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x88f83ee2.jpg</video:thumbnail_loc><video:title>End behavior of functions &amp; their graphs</video:title><video:description>Sal picks a function that has a given end behavior based on its graph.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hpBBuaiIkrg.mp4/hpBBuaiIkrg.mp4</video:content_loc><video:duration>143</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/connection-between-even-and-odd-numbers-and-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/62754979.jpg</video:thumbnail_loc><video:title>Even/odd functions &amp; numbers</video:title><video:description>The connection between even and odd functions to even and odd numbers.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jFazrvLodrA.mp4/jFazrvLodrA.mp4</video:content_loc><video:duration>248</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/identifying-even-and-odd-polynomials</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd705e9ac.jpg</video:thumbnail_loc><video:title>Even &amp; odd polynomials</video:title><video:description>Sal analyzes three different polynomials to see if they are even, odd, or neither.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/bOsNS3FsCPs.mp4/bOsNS3FsCPs.mp4</video:content_loc><video:duration>442</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/radical-expressions-with-higher-roots</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23742.jpg</video:thumbnail_loc><video:title>Simplifying higher-index roots</video:title><video:description>Multiple examples of simplifications of higher-index radicals. For example, simplifying ⁵√96 as 2⁵√3.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/iX7ivCww2ws.mp4/iX7ivCww2ws.mp4</video:content_loc><video:duration>526</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/multiply-and-simplify-a-radical-expression-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/127771044.jpg</video:thumbnail_loc><video:title>Simplifying cube root expressions</video:title><video:description>A worked example of simplifying elaborate expressions that contain radicals. In this example, we simplify 5∛(2x²)⋅3∛(4x⁴).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/GEeKOeGHddY.mp4/GEeKOeGHddY.mp4</video:content_loc><video:duration>265</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/rational-exponents-and-exponent-laws</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/126711577.jpg</video:thumbnail_loc><video:title>Simplifying cube root expressions (two variables)</video:title><video:description>Sal simplifies ∛(125x⁶y³) as 5x²y.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/NuccqpiUHrk.mp4/NuccqpiUHrk.mp4</video:content_loc><video:duration>136</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/radical-equivalent-to-rational-exponents-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/126711575.jpg</video:thumbnail_loc><video:title>Simplifying higher-index root expressions</video:title><video:description>How to rewrite a radical with variables in it as an exponent and then simplify it using exponent properties. In this example, we simplify ∜(5a⁴b¹²).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/zlRKO21qEpQ.mp4/zlRKO21qEpQ.mp4</video:content_loc><video:duration>144</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/simplifying-mixed-exponent-and-radical-expressions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3472e447.jpg</video:thumbnail_loc><video:title>Simplifying rational exponent expressions: mixed exponents and radicals</video:title><video:description>Sal simplifies v^(-6/5)* ⁵√v as v^(-1).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/95KX0dNZXAA.mp4/95KX0dNZXAA.mp4</video:content_loc><video:duration>159</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/simplifying-square-root-expressions-no-variables-advanced</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7cc704b6.jpg</video:thumbnail_loc><video:title>Simplifying square-root expressions: no variables (advanced)</video:title><video:description>Sal simplifies elaborate expressions with square roots. For example, he simplifies (4√20-3√45)/√35 as -√(1/7).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/suwJmCrSDI8.mp4/suwJmCrSDI8.mp4</video:content_loc><video:duration>283</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/how-to-rationalize-a-denominator</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23746.jpg</video:thumbnail_loc><video:title>Intro to rationalizing the denominator</video:title><video:description>When we have a fraction with a root in the denominator, like 1/√2, it&apos;s often desirable to manipulate it so the denominator doesn&apos;t have roots. To do that, we can multiply both the numerator and the denominator by the same root, that will get rid of the root in the denominator. For example, we can multiply 1/√2 by √2/√2 to get √2/2</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gY5TvlHg4Vk.mp4/gY5TvlHg4Vk.mp4</video:content_loc><video:duration>618</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/rationalizing-denominators-of-expressions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/127771045.jpg</video:thumbnail_loc><video:title>Worked example: rationalizing the denominator</video:title><video:description>Sal rationalizes the denominator of the expression (16+2x²)/(√8).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Z3db5itCIiQ.mp4/Z3db5itCIiQ.mp4</video:content_loc><video:duration>298</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/subtracting-and-simplifying-radicals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/127771043.jpg</video:thumbnail_loc><video:title>Simplifying radical expressions (subtraction)</video:title><video:description>Sal simplifies 4∜(81x⁵)-2∜(81x⁵)-√(x³).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qH4IQfDD1Nw.mp4/qH4IQfDD1Nw.mp4</video:content_loc><video:duration>345</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/multiply-and-simplify-a-radical-expression-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/127771042.jpg</video:thumbnail_loc><video:title>Simplifying radical expressions: two variables</video:title><video:description>A worked example of simplifying elaborate expressions that contain radicals with two variables. In this example, we simplify √(60x²y)/√(48x).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/sBvRJUwXJPo.mp4/sBvRJUwXJPo.mp4</video:content_loc><video:duration>187</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/simplifying-cube-roots</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/126711579.jpg</video:thumbnail_loc><video:title>Simplifying radical expressions: three variables</video:title><video:description>A worked example of simplifying the cube root of 27a²b⁵c³ using the properties of exponents.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/c-wtvEdEoVs.mp4/c-wtvEdEoVs.mp4</video:content_loc><video:duration>325</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/simplifying-rational-exponent-expressions-advanced</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4753d1a9.jpg</video:thumbnail_loc><video:title>Simplifying hairy expression with fractional exponents</video:title><video:description>Sal simplifies hairy expressions with rational exponents. For example, he simplifies (125^-⅛*125^⅝)/(5^½) as 5.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1BRXCIvt9e0.mp4/1BRXCIvt9e0.mp4</video:content_loc><video:duration>367</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/decay-of-cesium-137-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5621b10d.jpg</video:thumbnail_loc><video:title>Constructing exponential models (old example)</video:title><video:description>Sal constructs a function to model the decay of a radioactive element.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/polop-89aIA.mp4/polop-89aIA.mp4</video:content_loc><video:duration>553</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/structure-in-exponential-expression</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7de74d32.jpg</video:thumbnail_loc><video:title>Structure in exponential expression</video:title><video:description>Analyzing an elaborate exponential function to determine its value at t=0 and whether it increases or decreases with t. This is algebraic reasoning at its best!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gR8-vRg6Yp0.mp4/gR8-vRg6Yp0.mp4</video:content_loc><video:duration>439</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/solving-logarithmic-equations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/370262996.jpg</video:thumbnail_loc><video:title>Logarithmic equations: variable in the argument</video:title><video:description>Sal solves the equation log(x)+log(3)=2log(4)-log(2).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Kv2iHde7Xgw.mp4/Kv2iHde7Xgw.mp4</video:content_loc><video:duration>253</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/solving-logarithmic-equations-dup-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/367722962.jpg</video:thumbnail_loc><video:title>Logarithmic equations: variable in the base</video:title><video:description>Sal solves the equation 4=log_b(81).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/oqAYqT70EBQ.mp4/oqAYqT70EBQ.mp4</video:content_loc><video:duration>208</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/matching-exponential-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9061c6c9.jpg</video:thumbnail_loc><video:title>Graphs of exponential functions (old example)</video:title><video:description>Sal matches the following four functions to their appropriate graphs: y=2^x, y=-3^x, y=2-(1/3)^x, y=(1/2)^x-2.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/EwEbZI57P1o.mp4/EwEbZI57P1o.mp4</video:content_loc><video:duration>442</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/graphing-logarithmic-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/367721780.jpg</video:thumbnail_loc><video:title>Shape of a logarithmic parent graph</video:title><video:description>Sal graphs y=log₅(x).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DuYgVVU_BwY.mp4/DuYgVVU_BwY.mp4</video:content_loc><video:duration>550</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/logarithmic-function-graphs</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x74c0eb39.jpg</video:thumbnail_loc><video:title>Graphs of logarithmic functions</video:title><video:description>The graph of y=log base 2 of x looks like a curve that increases at an ever-decreasing rate as x gets larger. It becomes very negative as x approaches 0 from the right. The graph of y=-log base 2 of x is the same as the first graph, but flipped over the x-axis. The graph of y=-log base 2 of (x+2) is the same as the first graph, but shifted to the left by 2.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LqyA96oYtwE.mp4/LqyA96oYtwE.mp4</video:content_loc><video:duration>388</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/vertical-asymptote-natural-log</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbd675271.jpg</video:thumbnail_loc><video:title>Vertical asymptote of natural log</video:title><video:description>What happens to ln(x) as x approaches 0?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/78tnNYNISOc.mp4/78tnNYNISOc.mp4</video:content_loc><video:duration>420</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/vi-and-sal-explore-how-we-think-about-scale</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/214235936.jpg</video:thumbnail_loc><video:title>Logarithmic scale (with Vi Hart)</video:title><video:description>Vi Hart and Sal talk about how we humans perceive things nonlinearly</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4xfOq00BzJA.mp4/4xfOq00BzJA.mp4</video:content_loc><video:duration>416</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/logarithmic-scale</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/214235939.jpg</video:thumbnail_loc><video:title>Logarithmic scale</video:title><video:description>Sal discusses the differences between linear and logarithmic scale.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/sBhEi4L91Sg.mp4/sBhEi4L91Sg.mp4</video:content_loc><video:duration>675</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/richter-scale</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/231149553.jpg</video:thumbnail_loc><video:title>Richter scale</video:title><video:description>Sal explains the basics of the Richter scale (Moment magnitude scale) and uses this to compare the magnitude of 4 famous earthquakes.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/RFn-IGlayAg.mp4/RFn-IGlayAg.mp4</video:content_loc><video:duration>679</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/vi-and-sal-talk-about-the-mysteries-of-benford-s-law</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/214235938.jpg</video:thumbnail_loc><video:title>Benford&apos;s law (with Vi Hart, 1 of 2)</video:title><video:description>Vi Hart visits Khan Academy and talks about the mysteries of Benford&apos;s Law with Sal</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6KmeGpjeLZ0.mp4/6KmeGpjeLZ0.mp4</video:content_loc><video:duration>485</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/benford-s-law-explanation-sequel-to-mysteries-of-benford-s-law</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/214235937.jpg</video:thumbnail_loc><video:title>Benford&apos;s law (with Vi Hart, 2 of 2)</video:title><video:description>Vi Hart visits Khan Academy and talks about the mysteries of Benford&apos;s Law with Sal</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/SZUDoEdjTzg.mp4/SZUDoEdjTzg.mp4</video:content_loc><video:duration>387</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/flipping-shifting-radical-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x463eded6.jpg</video:thumbnail_loc><video:title>Transforming the square-root function</video:title><video:description>Sal shows various examples of functions and their graphs that are a result of shifting and/or flipping y=√x.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/t5ry2rasWvI.mp4/t5ry2rasWvI.mp4</video:content_loc><video:duration>435</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/graphs-of-square-root-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23740.jpg</video:thumbnail_loc><video:title>Graphs of square-root functions</video:title><video:description>Sal graphs y=√x. Then, he shows a few examples of how we can shift and stretch the graphs of y=√x and y=x^2, and how the equations of those graphs look.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/outcfkh69U0.mp4/outcfkh69U0.mp4</video:content_loc><video:duration>901</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/radical-function-graphs-exercise</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc7be7cc7.jpg</video:thumbnail_loc><video:title>Square-root functions &amp; their graphs</video:title><video:description>Sal is given a drawing with four graphs and four formulas of square-root functions. He uses transformations to match each formula with its appropriate graph.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Uteoh0PtWwI.mp4/Uteoh0PtWwI.mp4</video:content_loc><video:duration>222</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math3/v/simplifying-rational-expressions-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187340.jpg</video:thumbnail_loc><video:title>Simplifying rational expressions: common binomial factors</video:title><video:description>Given a rectangle with length a²+6a+27 and width a²-9, Sal writes the ratio of the width to the length as a simplified rational expression.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/XChok8XlF90.mp4/XChok8XlF90.mp4</video:content_loc><video:duration>251</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math3/v/simplifying-rational-expressions-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/27013.jpg</video:thumbnail_loc><video:title>Simplifying rational expressions: opposite common binomial factors</video:title><video:description>Sal simplifies and states the domain of (x^2-36)/(6-x).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ey_b3aPsRl8.mp4/ey_b3aPsRl8.mp4</video:content_loc><video:duration>233</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/solving-rational-equations-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/27022.jpg</video:thumbnail_loc><video:title>Equations with one rational expression (advanced)</video:title><video:description>Sal solves the following equation by first simplifying the rational expression: x^2-(x^2-4)/(x-2)=4.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5wUJLMWZ5Fw.mp4/5wUJLMWZ5Fw.mp4</video:content_loc><video:duration>272</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/rational-equations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/124291561.jpg</video:thumbnail_loc><video:title>Equation with two rational expressions (old example)</video:title><video:description>Sal solves the equation 4/(p-1)=5/(p+3).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/bRwJ-QCz9XU.mp4/bRwJ-QCz9XU.mp4</video:content_loc><video:duration>256</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/solving-rational-equations-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/27021.jpg</video:thumbnail_loc><video:title>Equation with two rational expressions (old example 2)</video:title><video:description>Sal solves the equation 5/(2x)-4/(3x)=7/18 by first finding the LCM (least common multiple) of 2x and 3x.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/RdYA8ZpqdJE.mp4/RdYA8ZpqdJE.mp4</video:content_loc><video:duration>248</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/extraneous-solutions-to-rational-equations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/124291568.jpg</video:thumbnail_loc><video:title>Equation with two rational expressions (old example 3)</video:title><video:description>Sal solves the following equation and eliminates the resulting extraneous solution: (x^2)/(x+2)=4/(x+2).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/bml74_PsfwA.mp4/bml74_PsfwA.mp4</video:content_loc><video:duration>183</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/direct-variation-application</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/124291558.jpg</video:thumbnail_loc><video:title>Direct variation word problem: space travel</video:title><video:description>Sal models a context about space travel with a direct variation equation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ZsjfUUJUq9s.mp4/ZsjfUUJUq9s.mp4</video:content_loc><video:duration>122</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math3/v/analyzing-vertical-asymptotes-of-rational-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdf0aa09d.jpg</video:thumbnail_loc><video:title>Analyzing vertical asymptotes of rational functions</video:title><video:description>Sal analyzes the behavior of q(x)=(x²+3x+2)/(x+3) around its vertical asymptote at x=-3.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/X8B4Fi7wadc.mp4/X8B4Fi7wadc.mp4</video:content_loc><video:duration>426</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math3/v/example-rational-functions-graphs</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6d96b6fe.jpg</video:thumbnail_loc><video:title>Graphs of rational functions (old example)</video:title><video:description>Sal matches three graphs of rational functions to three formulas of such functions by considering asymptotes and intercepts.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/onmNaDrxwmo.mp4/onmNaDrxwmo.mp4</video:content_loc><video:duration>367</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math3/v/horizontal-vertical-asymptotes</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc5653fa0.jpg</video:thumbnail_loc><video:title>Graphing rational functions 1</video:title><video:description>Sal graphs f(x)=(2x+10)/(5x-15).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/fvC0dm2wzIo.mp4/fvC0dm2wzIo.mp4</video:content_loc><video:duration>664</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math3/v/another-rational-function-graph-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23776.jpg</video:thumbnail_loc><video:title>Graphing rational functions 2</video:title><video:description>Sal graphs y=(2x)/(x+1).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ReEMqdZEEX0.mp4/ReEMqdZEEX0.mp4</video:content_loc><video:duration>500</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math3/v/asymptotes-of-rational-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23774.jpg</video:thumbnail_loc><video:title>Graphing rational functions 3</video:title><video:description>Sal graphs y=(x^2)/(x^2-16).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2N62v_63SBo.mp4/2N62v_63SBo.mp4</video:content_loc><video:duration>1266</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math3/v/a-third-example-of-graphing-a-rational-function</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23778.jpg</video:thumbnail_loc><video:title>Graphing rational functions 4</video:title><video:description>Sal graphs y=(x)/(x^2-x-6).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/p7ycTWq6BFk.mp4/p7ycTWq6BFk.mp4</video:content_loc><video:duration>691</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/rational-inequalities</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23568.jpg</video:thumbnail_loc><video:title>Rational inequalities: one side is zero</video:title><video:description>Sal shows two ways to solve the inequality (x-1)/(x+2)&gt;0.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ZjeMdXV0QMg.mp4/ZjeMdXV0QMg.mp4</video:content_loc><video:duration>709</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/rational-inequalities-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23570.jpg</video:thumbnail_loc><video:title>Rational inequalities: both sides are not zero</video:title><video:description>Sal solves the rational inequality (x-3)/(x+4)≥2.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2RnS3fSHVV8.mp4/2RnS3fSHVV8.mp4</video:content_loc><video:duration>795</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/partial-fraction-expansion-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23546.jpg</video:thumbnail_loc><video:title>Intro to partial fraction expansion</video:title><video:description>Sal explains what partial fraction expansion is by rewriting (x²-2x-37)/(x²-3x-40) as the sum of 1 and two rational expressions with linear denominators.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/S-XKGBesRzk.mp4/S-XKGBesRzk.mp4</video:content_loc><video:duration>688</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/partial-fraction-expansion-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23548.jpg</video:thumbnail_loc><video:title>Partial fraction expansion</video:title><video:description>Sal performs partial fraction expansion upon (10x²+12x+20)/(x³-8).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6FrPLJY0rqM.mp4/6FrPLJY0rqM.mp4</video:content_loc><video:duration>782</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/partial-fraction-expansion-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23550.jpg</video:thumbnail_loc><video:title>Partial fraction expansion: repeated factors</video:title><video:description>Sal performs partial fraction expansion upon (6x²-19x+15)/(x-1)(x-2)².</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/A52fEdPn9lg.mp4/A52fEdPn9lg.mp4</video:content_loc><video:duration>635</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/trigonometry-unit-circle-symmetry</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa88b4a7e.jpg</video:thumbnail_loc><video:title>Sine &amp; cosine identities: symmetry</video:title><video:description>Sal finds several trigonometric identities for sine and cosine by considering horizontal and vertical symmetries of the unit circle.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tzQ7arA917E.mp4/tzQ7arA917E.mp4</video:content_loc><video:duration>478</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/tan-symmetries-unit-circle</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2cb52cc7.jpg</video:thumbnail_loc><video:title>Tangent identities: symmetry</video:title><video:description>Sal finds several trigonometric identities for tangent by considering horizontal and vertical symmetries of the unit circle.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/k_wJsio68D4.mp4/k_wJsio68D4.mp4</video:content_loc><video:duration>435</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/trig-angle-rotations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5e52b073.jpg</video:thumbnail_loc><video:title>Sine &amp; cosine identities: periodicity</video:title><video:description>Sal finds trigonometric identities for sine and cosine by considering angle rotations on the unit circle.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/h-TPSylHrvE.mp4/h-TPSylHrvE.mp4</video:content_loc><video:duration>373</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/tan-periodicity</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa5a398fc.jpg</video:thumbnail_loc><video:title>Tangent identities: periodicity</video:title><video:description>Sal solves a problem by considering the periodicity of the tangent function.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/C3HFAyigqoY.mp4/C3HFAyigqoY.mp4</video:content_loc><video:duration>242</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/solving-triangle-unit-circle</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8f71dac4.jpg</video:thumbnail_loc><video:title>Trig values of π/4</video:title><video:description>Sal finds the trigonometric values of π/4 using the unit-circle definition.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/KoYZErFpZ5Q.mp4/KoYZErFpZ5Q.mp4</video:content_loc><video:duration>474</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/pythagorean-trig-identity-from-unit-circle</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x952a1f00.jpg</video:thumbnail_loc><video:title>Proof of the Pythagorean trig identity</video:title><video:description>The Pythagorean identity tells us that no matter what the value of θ is, sin²θ+cos²θ is equal to 1. We can prove this identity using the Pythagorean theorem in the unit circle with x²+y²=1.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/n0DLSIOYBsQ.mp4/n0DLSIOYBsQ.mp4</video:content_loc><video:duration>372</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/using-the-pythagorean-trig-identity</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xda6daf69.jpg</video:thumbnail_loc><video:title>Using the Pythagorean trig identity</video:title><video:description>The Pythagorean identity tells us that no matter what the value of θ is, sin²θ+cos²θ is equal to 1. This follows from the Pythagorean theorem, which is why it&apos;s called the Pythagorean identity! We can use this identity to solve various problems.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/soIt2TwV6Xk.mp4/soIt2TwV6Xk.mp4</video:content_loc><video:duration>375</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/midline-amplitude-period</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2f235e5a.jpg</video:thumbnail_loc><video:title>Features of sinusoidal functions</video:title><video:description>Sal introduces the main features of sinusoidal functions: midline, amplitude, &amp; period. He shows how these can be found from a sinusoidal function&apos;s graph.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/s4cLM0l1gd4.mp4/s4cLM0l1gd4.mp4</video:content_loc><video:duration>298</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/we-amplitude-and-period</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1153684694.jpg</video:thumbnail_loc><video:title>Amplitude &amp; period of sinusoidal functions from equation</video:title><video:description>Sal finds the amplitude and the period of y=-0.5cos(3x).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/SBqnRja4CW4.mp4/SBqnRja4CW4.mp4</video:content_loc><video:duration>501</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/example-amplitude-and-period-transformations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1153830189.jpg</video:thumbnail_loc><video:title>Transforming sinusoidal graphs: vertical stretch &amp; horizontal reflection</video:title><video:description>Sal graphs y=2*sin(-x) by considering it as a vertical stretch and a horizontal reflection of y=sin(x).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0zCcFSO8ouE.mp4/0zCcFSO8ouE.mp4</video:content_loc><video:duration>772</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/amplitude-and-period-cosine-transformations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1153825235.jpg</video:thumbnail_loc><video:title>Transforming sinusoidal graphs: vertical &amp; horizontal stretches</video:title><video:description>Sal graphs y=-2.5*cos(1/3*x) by considering it as a vertical stretch and reflection, and a horizontal stretch, of y=cos(x).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/uBVhtGL9y88.mp4/uBVhtGL9y88.mp4</video:content_loc><video:duration>643</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/modeling-with-shifted-trig-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd667e103.jpg</video:thumbnail_loc><video:title>Trig word problem: modeling daily temperature</video:title><video:description>Sal solves a word problem about the daily change in temperature by modeling it with a sinusoidal function.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/RX0DY9eRp8g.mp4/RX0DY9eRp8g.mp4</video:content_loc><video:duration>655</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/modeling-temperature-fluxtuations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x02d93c3e.jpg</video:thumbnail_loc><video:title>Trig word problem: modeling annual temperature</video:title><video:description>Sal solves a word problem about the annual change in temperature by modeling it with a sinusoidal function.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/mVlCXkht6hg.mp4/mVlCXkht6hg.mp4</video:content_loc><video:duration>406</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/inverse-trig-functions-arcsin</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26269.jpg</video:thumbnail_loc><video:title>Intro to arcsine</video:title><video:description>Sal introduces arcsine, which is the inverse function of sine, and discusses its principal range.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/JGU74wbZMLg.mp4/JGU74wbZMLg.mp4</video:content_loc><video:duration>636</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/inverse-trig-functions-arctan</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26271.jpg</video:thumbnail_loc><video:title>Intro to arctangent</video:title><video:description>Sal introduces arctangent, which is the inverse function of tangent, and discusses its principal range.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Idxeo49szW0.mp4/Idxeo49szW0.mp4</video:content_loc><video:duration>606</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/inverse-trig-functions-arccos</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26273.jpg</video:thumbnail_loc><video:title>Intro to arccosine</video:title><video:description>Sal introduces arccosine, which is the inverse function of cosine, and discusses its principal range.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/eTDaJ4ebK28.mp4/eTDaJ4ebK28.mp4</video:content_loc><video:duration>818</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/inverse-tan-domain</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7988ecbb.jpg</video:thumbnail_loc><video:title>Domain &amp; range of inverse tangent function</video:title><video:description>Sal finds the formula for the inverse function of g(x)=tan(x-3π/2)+6, and then determines the domain of that inverse function.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/QGfdhqbilY8.mp4/QGfdhqbilY8.mp4</video:content_loc><video:duration>584</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/inverse-tan-scenario</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x793351da.jpg</video:thumbnail_loc><video:title>Using inverse trig functions with a calculator</video:title><video:description>Sal discusses the appropriate way to use the calculator in order to find an angle when its tangent value is given.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/MABWdzmZFIQ.mp4/MABWdzmZFIQ.mp4</video:content_loc><video:duration>215</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/sine-solutions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdbe9f9c2.jpg</video:thumbnail_loc><video:title>Solving sinusoidal equations of the form sin(x)=d</video:title><video:description>Sal finds the expressions that together represent all possible solutions to the equation sin(x)=1/3.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/NC7iWEQ9Kug.mp4/NC7iWEQ9Kug.mp4</video:content_loc><video:duration>370</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/we-graph-of-cosine-function</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1153795385.jpg</video:thumbnail_loc><video:title>Solving cos(θ)=1 and cos(θ)=-1</video:title><video:description>Sal solves the equations cos(θ)=1 and cos(θ)=-1 using the graph of y=cos(θ).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/SdHwokUU8xI.mp4/SdHwokUU8xI.mp4</video:content_loc><video:duration>318</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/inverse-trig-with-model</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x42b7ba00.jpg</video:thumbnail_loc><video:title>Trig word problem: solving for temperature</video:title><video:description>Sal solves a word problem about the annual change in temperature by solving a sinusoidal equation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2pwnr_soZEU.mp4/2pwnr_soZEU.mp4</video:content_loc><video:duration>503</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/trigonometry-identity-review-fun</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26275.jpg</video:thumbnail_loc><video:title>Trig angle addition identities</video:title><video:description>Sal reviews 6 related trigonometric angle addition identities: sin(a+b), sin(a-c), cos(a+b), cos(a-b), cos(2a), and sin(2a).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/a70-dYvDJZY.mp4/a70-dYvDJZY.mp4</video:content_loc><video:duration>667</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/cosine-addition-identity-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfb68005e.jpg</video:thumbnail_loc><video:title>Using the cosine angle addition identity</video:title><video:description>Sal evaluates the cosine of the sum of 60° and another angle whose right triangle is given. To do this, he must use the cosine angle addition formula.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/h0SNEO25vIw.mp4/h0SNEO25vIw.mp4</video:content_loc><video:duration>314</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/double-angle-formula-for-cosine-example-c</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5368b1c4.jpg</video:thumbnail_loc><video:title>Using the cosine double-angle identity</video:title><video:description>The cosine double angle formula tells us that cos(2θ) is always equal to cos²θ-sin²θ. For example, cos(60) is equal to cos²(30)-sin²(30). We can use this identity to rewrite expressions or solve problems. See some examples in this video.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/D_smr0GBPvA.mp4/D_smr0GBPvA.mp4</video:content_loc><video:duration>208</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/proof-angle-addition-sine</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8c2e47e4.jpg</video:thumbnail_loc><video:title>Proof of the sine angle addition identity</video:title><video:description>Sal proves the identity sin(x+y) = sin(x)*cos(y) + cos(x)*sin(y).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/R0EQg9vgbQw.mp4/R0EQg9vgbQw.mp4</video:content_loc><video:duration>506</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/proof-angle-addition-cosine</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9472d9c4.jpg</video:thumbnail_loc><video:title>Proof of the cosine angle addition identity</video:title><video:description>Sal proves the identity cos(x+y) = cos(x)*cos(y) - sin(x)*sin(y).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0VBQnR2h8XM.mp4/0VBQnR2h8XM.mp4</video:content_loc><video:duration>362</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/sine-angle-addition-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd0dcedae.jpg</video:thumbnail_loc><video:title>Finding trig values using angle addition identities</video:title><video:description>Sal finds the value of sin(7π/12) by rewriting it as sin(π/3+π/4) and then using the sine angle addition formula.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2RbKfRfzD-M.mp4/2RbKfRfzD-M.mp4</video:content_loc><video:duration>515</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/sin-angle-addition</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdf09400e.jpg</video:thumbnail_loc><video:title>Using trig angle addition identities: finding side lengths</video:title><video:description>Sal is given a drawing with two triangles and some side lengths, and he uses the sine angle addition identity in order to find a missing side length.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/sI789G6FBb4.mp4/sI789G6FBb4.mp4</video:content_loc><video:duration>320</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/cosine-angle-addition</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3448aa45.jpg</video:thumbnail_loc><video:title>Using trig angle addition identities: manipulating expressions</video:title><video:description>Sal is given that cos(2θ)=C and he uses the cosine double-angle identity in order to find an expression for sin(θ).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/yV4Xa8Xtmrc.mp4/yV4Xa8Xtmrc.mp4</video:content_loc><video:duration>372</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/examples-using-pythagorean-identities-to-simplify-trigonometric-expressions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x756fc164.jpg</video:thumbnail_loc><video:title>Using trigonometric identities</video:title><video:description>Trigonometric identities like sin²θ+cos²θ=1 can be used to rewrite expressions in a different, more convenient way. For example, (1-sin²θ)(cos²θ) can be rewritten as (cos²θ)(cos²θ), and then as cos⁴θ.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4OEeVLo5V1o.mp4/4OEeVLo5V1o.mp4</video:content_loc><video:duration>187</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/parametric-equations-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25825.jpg</video:thumbnail_loc><video:title>Parametric equations intro</video:title><video:description>In this video, we learn about parametric equations using the example of a car driving off a cliff. Parametric equations define x and y as functions of a third parameter, t (time). They help us find the path, direction, and position of an object at any given time.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/m6c6dlmUT1c.mp4/m6c6dlmUT1c.mp4</video:content_loc><video:duration>668</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/parametric-equations-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25827.jpg</video:thumbnail_loc><video:title>Removing the parameter in parametric equations</video:title><video:description>Sal starts with parametric equations that give x and y as functions of t, and he manipulates the equations to get y as a function of x.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/wToSIQJ2o_8.mp4/wToSIQJ2o_8.mp4</video:content_loc><video:duration>585</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/parametric-equations-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25829.jpg</video:thumbnail_loc><video:title>Removing the parameter in parametric equations (example 2)</video:title><video:description>Sal is given x=3cost and y=2sint and he finds an equation that gives the relationship between x and y (spoiler: it&apos;s an ellipse!).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/57BiI_iD3-U.mp4/57BiI_iD3-U.mp4</video:content_loc><video:duration>772</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/parametric-equations-4</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25831.jpg</video:thumbnail_loc><video:title>Parametric equations with the same graph</video:title><video:description>Sal shows how different parametric equations can result in the same relationship between x and y (and therefore with the same graph).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/IReD6c_njOY.mp4/IReD6c_njOY.mp4</video:content_loc><video:duration>784</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/can-a-squirrel-avoid-getting-run-over</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdfd94c1b.jpg</video:thumbnail_loc><video:title>Worked example: Rate problem</video:title><video:description>Sal solves two related proportion word problems about a squirrel crossing the road and a car that approaches it. He does that using dimensional analysis.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/F0LLR7bs7Qo.mp4/F0LLR7bs7Qo.mp4</video:content_loc><video:duration>253</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/unit-conversion-exercise-example-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbabf89be.jpg</video:thumbnail_loc><video:title>Multiple units word problem: road trip</video:title><video:description>Sal solves a word problem where he finds the cost of gas in a road trip given the car&apos;s fuel efficiency, length of the trip, and price of gas.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xpzt0wqMT6Y.mp4/xpzt0wqMT6Y.mp4</video:content_loc><video:duration>227</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/plotting-complex-numbers-on-the-complex-plane</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x21268ed3.jpg</video:thumbnail_loc><video:title>Plotting numbers on the complex plane</video:title><video:description>Understand the roles of real and imaginary parts in forming coordinates. Learn how to plot complex numbers on a unique two-dimensional grid known as the complex plane. Discover the real and imaginary parts of complex numbers, and see how they correspond to the horizontal and vertical axes.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/kGzXIbauGQk.mp4/kGzXIbauGQk.mp4</video:content_loc><video:duration>74</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/absolute-value-of-a-complex-number</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x49eee15a.jpg</video:thumbnail_loc><video:title>Absolute value of complex numbers</video:title><video:description>Sal finds the absolute value of (3-4i).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/yvzyC4VBpUU.mp4/yvzyC4VBpUU.mp4</video:content_loc><video:duration>213</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/basic-complex-analysis</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187548.jpg</video:thumbnail_loc><video:title>Absolute value &amp; angle of complex numbers</video:title><video:description>Sal finds the modulus (which is the absolute value) and the argument (which is the angle) of √3/2+1/2*i.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/FwuPXchH2rA.mp4/FwuPXchH2rA.mp4</video:content_loc><video:duration>784</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/complex-plane-distance-midpoint</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd622f44d.jpg</video:thumbnail_loc><video:title>Distance &amp; midpoint of complex numbers</video:title><video:description>Sal finds the distance between (2+3i) and (-5-i) and then he finds their midpoint on the complex plane.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Efoeqb6tC88.mp4/Efoeqb6tC88.mp4</video:content_loc><video:duration>371</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/polar-form-complex-number</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5cb8c70a.jpg</video:thumbnail_loc><video:title>Polar &amp; rectangular forms of complex numbers</video:title><video:description>Learn how to convert a complex number from rectangular form to polar form. This video covers how to find the distance (r) and direction (theta) of the complex number on the complex plane, and how to use trigonometric functions and the Pythagorean theorem to make the conversion.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8RasCV_Lggg.mp4/8RasCV_Lggg.mp4</video:content_loc><video:duration>736</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/complex-polar-form-intuition</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x039d8d9ed24bc35c.jpg</video:thumbnail_loc><video:title>Complex number polar form intuition</video:title><video:description>Learn how to convert a complex number from rectangular form to polar form. We find the distance (r) and direction (theta) of the complex number on the complex plane, and use trigonometric functions, special right triangles, and the Pythagorean theorem to make the conversion.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/YZRzt_AsuVs.mp4/YZRzt_AsuVs.mp4</video:content_loc><video:duration>361</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/complex-number-division</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7818ca14.jpg</video:thumbnail_loc><video:title>Dividing complex numbers: polar &amp; exponential form</video:title><video:description>Sal shows how complex division affects the modulus and the argument of the divisor and the dividend.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xOa-l_tXgWA.mp4/xOa-l_tXgWA.mp4</video:content_loc><video:duration>430</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/powers-of-complex-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf6a4f54a.jpg</video:thumbnail_loc><video:title>Powers of complex numbers</video:title><video:description>Sal simplifies the 20th power of a complex number given in polar form.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/dl_9NC_J6yo.mp4/dl_9NC_J6yo.mp4</video:content_loc><video:duration>385</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/exponential-form-to-find-complex-roots</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187549.jpg</video:thumbnail_loc><video:title>Complex number equations: x³=1</video:title><video:description>Sal finds all complex solutions to the equation x^3=1.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/N0Y8ia57C24.mp4/N0Y8ia57C24.mp4</video:content_loc><video:duration>713</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/iit-jee-complex-numbers-part-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187445.jpg</video:thumbnail_loc><video:title>Challenging complex numbers problem (1 of 3)</video:title><video:description>Paper 1 Problem 39 from the challenging 2010 IIT JEE exam, about complex numbers.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_5ei_I02huY.mp4/_5ei_I02huY.mp4</video:content_loc><video:duration>441</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/iit-jee-complex-numbers-part-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187446.jpg</video:thumbnail_loc><video:title>Challenging complex numbers problem (2 of 3)</video:title><video:description>Paper 1 Problem 39 from the challenging 2010 IIT JEE exam, about complex numbers.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pQwoBOpVoWw.mp4/pQwoBOpVoWw.mp4</video:content_loc><video:duration>446</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/iit-jee-complex-numbers-part-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187447.jpg</video:thumbnail_loc><video:title>Challenging complex numbers problem (3 of 3)</video:title><video:description>Paper 1 Problem 39 from the challenging 2010 IIT JEE exam, about complex numbers.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/FwA_UZkI-JM.mp4/FwA_UZkI-JM.mp4</video:content_loc><video:duration>189</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/complex-determinant-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187468.jpg</video:thumbnail_loc><video:title>Challenging complex numbers problem: complex determinant</video:title><video:description>Paper 1 Problem 53 from the challenging 2010 IIT JEE exam, about determinant of a complex numbers matrix.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/E7OkUomRq1Q.mp4/E7OkUomRq1Q.mp4</video:content_loc><video:duration>778</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/introduction-to-conic-sections</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23522.jpg</video:thumbnail_loc><video:title>Intro to conic sections</video:title><video:description>Sal introduces the four conic sections and shows how they are derived by intersecting planes with cones in certain ways.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0A7RR0oy2ho.mp4/0A7RR0oy2ho.mp4</video:content_loc><video:duration>658</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/graphing-circles-from-features</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa6159ffd.jpg</video:thumbnail_loc><video:title>Graphing circles from features</video:title><video:description>How to graph a circle given the center and either the radius or another point on the circle.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LDjMDIuTWtM.mp4/LDjMDIuTWtM.mp4</video:content_loc><video:duration>129</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/center-and-radius-of-circle-from-graph</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x48f9959e.jpg</video:thumbnail_loc><video:title>Features of a circle from its graph</video:title><video:description>Given a circle on the coordinate plane, Sal finds its center and its radius.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/SLyM_-sQwMM.mp4/SLyM_-sQwMM.mp4</video:content_loc><video:duration>230</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/radius-and-center-for-a-circle-equation-in-standard-form</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xca06c2ed.jpg</video:thumbnail_loc><video:title>Features of a circle from its standard equation</video:title><video:description>Sal finds the center and the radius of the circle whose equation is (x+3)^2+(y-4)^2=49.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/JvDpYlyKkNU.mp4/JvDpYlyKkNU.mp4</video:content_loc><video:duration>231</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/graphing-a-circle-from-standard-equation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x64f04a47.jpg</video:thumbnail_loc><video:title>Graphing a circle from its standard equation</video:title><video:description>Sal graphs the circle whose equation is (x+5)²+(y-5)²=4.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/thDrJvWNI8M.mp4/thDrJvWNI8M.mp4</video:content_loc><video:duration>314</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/writing-standard-equation-of-circle</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6415cfbc.jpg</video:thumbnail_loc><video:title>Writing standard equation of a circle</video:title><video:description>Given a circle on the coordinate plane, Sal finds its standard equation, which is an equation in the form (x-a)²+(y-b)²=r².</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/iX5UgArMyiI.mp4/iX5UgArMyiI.mp4</video:content_loc><video:duration>340</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/completing-the-square-to-write-equation-in-standard-form-of-a-circle</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x577fb2f2.jpg</video:thumbnail_loc><video:title>Features of a circle from its expanded equation</video:title><video:description>Sal finds the center and the radius of a circle whose equation is x^2+y^2+4x-4y-17=0, and then he graphs the circle.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/XyDMsotfJhE.mp4/XyDMsotfJhE.mp4</video:content_loc><video:duration>260</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/conic-sections-intro-to-ellipses</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23526.jpg</video:thumbnail_loc><video:title>Intro to ellipses</video:title><video:description>Learn all about ellipses in this video. The standard form for an ellipse centered at the origin is x²/a² + y²/b² = 1. The semi-major axis is the longest radius and the semi-minor axis is the shortest radius. The video also explains how to shift an ellipse.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lvAYFUIEpFI.mp4/lvAYFUIEpFI.mp4</video:content_loc><video:duration>854</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/ellipse-standard-equation-from-graph</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf0e7990c.jpg</video:thumbnail_loc><video:title>Ellipse standard equation from graph</video:title><video:description>Given an ellipse on the coordinate plane, Sal finds its standard equation, which is an equation in the form (x-h)²/a²+(y-k)²/b²=1.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_JrQF8Rkaio.mp4/_JrQF8Rkaio.mp4</video:content_loc><video:duration>215</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/ellipse-graph-from-standard-equation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb04ef9af.jpg</video:thumbnail_loc><video:title>Ellipse graph from standard equation</video:title><video:description>This video explains how to graph an ellipse when given its equation in standard form. The center of this ellipse is (4,1), the horizontal radius is 4, and the vertical radius is 7. The key definitions are center, horizontal radius, and vertical radius.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/h5dIVNjVjXg.mp4/h5dIVNjVjXg.mp4</video:content_loc><video:duration>100</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/foci-of-an-ellipse</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23540.jpg</video:thumbnail_loc><video:title>Foci of an ellipse from equation</video:title><video:description>Sal explains how the radii and the foci of an ellipse relate to each other, and how we can use this relationship in order to find the foci from the equation of an ellipse.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/QR2vxfwiHAU.mp4/QR2vxfwiHAU.mp4</video:content_loc><video:duration>829</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/focus-and-directrix-introduction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0abb5ff2.jpg</video:thumbnail_loc><video:title>Intro to focus &amp; directrix</video:title><video:description>A parabola is the set of all points equidistant from a point (called the &quot;focus&quot;) and a line (called the &quot;directrix&quot;). See this video to learn more about this.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pe8Dm_FUpdU.mp4/pe8Dm_FUpdU.mp4</video:content_loc><video:duration>247</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math2/v/finding-focus-and-directrix-from-vertex</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x009570c6.jpg</video:thumbnail_loc><video:title>Focus &amp; directrix of a parabola from equation</video:title><video:description>Given the parabola equation y-23/4=-1/3(x-1)^2, Sal finds the parabola&apos;s focus and directrix using the general formula for a parabola whose focus is (a,b) and directrix is y=k.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/w56Vuf9tHfA.mp4/w56Vuf9tHfA.mp4</video:content_loc><video:duration>689</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/conic-sections-intro-to-hyperbolas</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23528.jpg</video:thumbnail_loc><video:title>Intro to hyperbolas</video:title><video:description>Sal introduces the standard equation for hyperbolas, and how it can be used in order to determine the direction of the hyperbola and its vertices.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pzSyOTkAsY4.mp4/pzSyOTkAsY4.mp4</video:content_loc><video:duration>814</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/vertices-and-direction-of-a-hyperbola</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x16b23523.jpg</video:thumbnail_loc><video:title>Vertices &amp; direction of a hyperbola</video:title><video:description>Sal picks the graph of y²/9-x²/4=1 based on the hyperbola&apos;s center, direction, &amp; vertices.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/oO3nWnJppqg.mp4/oO3nWnJppqg.mp4</video:content_loc><video:duration>315</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/vertices-and-direction-of-a-hyperbola-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb9aa106e.jpg</video:thumbnail_loc><video:title>Vertices &amp; direction of a hyperbola (example 2)</video:title><video:description>Sal matches an equation to a given graph of a hyperbola, based on the hyperbola&apos;s direction &amp; vertices.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hnVFThmLW5Q.mp4/hnVFThmLW5Q.mp4</video:content_loc><video:duration>141</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/conic-sections-hyperbolas-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23530.jpg</video:thumbnail_loc><video:title>Graphing hyperbolas (old example)</video:title><video:description>Given the hyperbola equation y^2/4-x^2/9=1, Sal determines the direction to which it opens and its vertices in order to draw its graph.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hl58vTCqVIY.mp4/hl58vTCqVIY.mp4</video:content_loc><video:duration>450</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/foci-of-a-hyperbola</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23542.jpg</video:thumbnail_loc><video:title>Foci of a hyperbola from equation</video:title><video:description>Sal discusses the foci of hyperbolas and shows how they relate to hyperbola equations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/S0Fd2Tg2v7M.mp4/S0Fd2Tg2v7M.mp4</video:content_loc><video:duration>924</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/proof-hyperbola-foci</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23544.jpg</video:thumbnail_loc><video:title>Proof of the hyperbola foci formula</video:title><video:description>Sal proves why, for the general hyperbola equation x^2/a^2-y^2/b^2=1, the focal length f forms the equation f^2=a^2+b^2 with the parameters a and b.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/HPRFmu7JsKU.mp4/HPRFmu7JsKU.mp4</video:content_loc><video:duration>890</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/conic-sections-hyperbolas-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23532.jpg</video:thumbnail_loc><video:title>Equation of a hyperbola not centered at the origin</video:title><video:description>Sal analyzes the hyperbola whose equation is (x-1)^2/16-(y+1)^2/4=1, and graphs it.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lGQw-W1PxBE.mp4/lGQw-W1PxBE.mp4</video:content_loc><video:duration>629</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/conic-identification-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23538.jpg</video:thumbnail_loc><video:title>Conic section from expanded equation: circle &amp; parabola</video:title><video:description>Sal manipulates the equation x^2+y^2-3x+4y=4 in order to find that it represents a circle, and the equation 2x^2+y+12x+16=0 in order to find it represents a parabola.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Dru0RHgfp2g.mp4/Dru0RHgfp2g.mp4</video:content_loc><video:duration>694</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/identifying-conics-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23534.jpg</video:thumbnail_loc><video:title>Conic section from expanded equation: ellipse</video:title><video:description>Sal manipulates the equation 9x^2+4y^2+54x-8y+49=0 in order to find that it represents an ellipse.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LSJuu4Qm2qQ.mp4/LSJuu4Qm2qQ.mp4</video:content_loc><video:duration>551</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/identifying-conics-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23536.jpg</video:thumbnail_loc><video:title>Conic section from expanded equation: hyperbola</video:title><video:description>Sal manipulates the equation 4y^2-50x=25x^2+16y+109 in order to find that it represents a hyperbola.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/cvA4VN1dpuY.mp4/cvA4VN1dpuY.mp4</video:content_loc><video:duration>688</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/tangent-line-hyperbola-relationship-very-optional</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187463.jpg</video:thumbnail_loc><video:title>Representing a line tangent to a hyperbola</video:title><video:description>How a tangent line relates to a hyperbola. Might be useful for some competitive exams where there isn&apos;t time to derive (like we are doing in this video).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/c_8QQbVQKU0.mp4/c_8QQbVQKU0.mp4</video:content_loc><video:duration>604</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/iit-jee-circle-hyperbola-common-tangent-part-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187454.jpg</video:thumbnail_loc><video:title>Common tangent of circle &amp; hyperbola (1 of 5)</video:title><video:description>2010 IIT JEE Paper 1 Problem 45: Find the equation of a tangent common a given circle and a given hyperbola.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/MhLfun2Vask.mp4/MhLfun2Vask.mp4</video:content_loc><video:duration>376</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/iit-jee-circle-hyperbola-common-tangent-part-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187455.jpg</video:thumbnail_loc><video:title>Common tangent of circle &amp; hyperbola (2 of 5)</video:title><video:description>2010 IIT JEE Paper 1 Problem 45 Circle Hyperbola Common Tangent Part 2</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0imeUgSxR10.mp4/0imeUgSxR10.mp4</video:content_loc><video:duration>645</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/iit-jee-circle-hyperbola-common-tangent-part-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187456.jpg</video:thumbnail_loc><video:title>Common tangent of circle &amp; hyperbola (3 of 5)</video:title><video:description>2010 IIT JEE Paper 1 Problem 45 Circle Hyperbola Common Tangent Part 3</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/RomnHMWSLoE.mp4/RomnHMWSLoE.mp4</video:content_loc><video:duration>535</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/iit-jee-circle-hyperbola-common-tangent-part-4</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187457.jpg</video:thumbnail_loc><video:title>Common tangent of circle &amp; hyperbola (4 of 5)</video:title><video:description>2010 IIT JEE Paper 1 Problem 45 Circle Hyperbola Common Tangent Part 4</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/eGo8C2Jshzs.mp4/eGo8C2Jshzs.mp4</video:content_loc><video:duration>636</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/iit-jee-circle-hyperbola-common-tangent-part-5</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187458.jpg</video:thumbnail_loc><video:title>Common tangent of circle &amp; hyperbola (5 of 5)</video:title><video:description>2010 IIT JEE Paper 1 Problem 45 Circle Hyperbola Common Tangent Part 5</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/rPoqpQcgNv4.mp4/rPoqpQcgNv4.mp4</video:content_loc><video:duration>737</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/iit-jee-circle-hyperbola-intersection</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187453.jpg</video:thumbnail_loc><video:title>Intersection of circle &amp; hyperbola</video:title><video:description>2010 IIT JEE Paper 1 Problem 46: Find the equation of a circle whose diameter is defined by the two intersection points of given circle and hyperbola.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6g3DPg2HqGw.mp4/6g3DPg2HqGw.mp4</video:content_loc><video:duration>764</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/sigma-notation-sum</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xea358b4a.jpg</video:thumbnail_loc><video:title>Understanding summation notation</video:title><video:description>Sigma notation is the standard notation for writing long sums. Learn how it is used in this video.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5jwXThH6fg4.mp4/5jwXThH6fg4.mp4</video:content_loc><video:duration>267</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/sum-of-arithmetic-sequence-arithmetic-series</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1393162637.jpg</video:thumbnail_loc><video:title>Arithmetic series intro</video:title><video:description>Sal explains the formula for the sum of a finite arithmetic series</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/cYw4MFWsB6c.mp4/cYw4MFWsB6c.mp4</video:content_loc><video:duration>236</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/evaluating-finite-arithmetic-series</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc323fdc4.jpg</video:thumbnail_loc><video:title>Worked example: arithmetic series (sigma notation)</video:title><video:description>Sal evaluates the arithmetic series Σ(2k+50) for k=1 to 550. He does that using the arithmetic series formula (a₁+aₙ)*n/2.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/RM644gFKo_g.mp4/RM644gFKo_g.mp4</video:content_loc><video:duration>422</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/evaluating-arithmetic-sum-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x75e479bb.jpg</video:thumbnail_loc><video:title>Worked example: arithmetic series (sum expression)</video:title><video:description>Sal evaluates the arithmetic sum (-50)+(-44)+(-38)+...+2044. He does that by finding the number of terms and using the arithmetic series formula (a₁+aₙ)*n/2.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0-wa7voc0uM.mp4/0-wa7voc0uM.mp4</video:content_loc><video:duration>407</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/finding-sum-from-recursive-definition-of-sequence</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x779f2dfd.jpg</video:thumbnail_loc><video:title>Worked example: arithmetic series (recursive formula)</video:title><video:description>Sal evaluates the sum of the first 650 terms in the sequence defined recursively as {aᵢ=aᵢ₋₁+11, a₁=4}. He does that by finding the 650th term and using the arithmetic series formula (a₁+aₙ)*n/2.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pIO34mrW_Ro.mp4/pIO34mrW_Ro.mp4</video:content_loc><video:duration>321</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/alternate-proof-to-induction-for-integer-sum</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/193202563.jpg</video:thumbnail_loc><video:title>Proof of finite arithmetic series formula</video:title><video:description>Watch Sal prove the expression for the sum of all positive integers up to and including n.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1wnIsgUivEQ.mp4/1wnIsgUivEQ.mp4</video:content_loc><video:duration>212</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/geometric-sequences</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1383732207.jpg</video:thumbnail_loc><video:title>Intro to geometric sequences (advanced)</video:title><video:description>Sal introduces geometric sequences and gives a few examples. Notation used in this video is relatively advanced.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/dIGLhLMsy2U.mp4/dIGLhLMsy2U.mp4</video:content_loc><video:duration>399</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/series-as-sum-of-sequence</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1393021992.jpg</video:thumbnail_loc><video:title>Geometric series intro</video:title><video:description>A geometric series is the sum of the terms of a geometric sequence. Learn more about it here.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/rcRg_gO7-7E.mp4/rcRg_gO7-7E.mp4</video:content_loc><video:duration>173</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/geometric-series-introduction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8bcd35c6.jpg</video:thumbnail_loc><video:title>Geometric series with sigma notation</video:title><video:description>A geometric series is the sum of the terms of a geometric sequence. Learn about geometric series and how they can be written in general terms and using sigma notation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/CecgFWTg9pQ.mp4/CecgFWTg9pQ.mp4</video:content_loc><video:duration>268</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/example-finding-sum-of-finite-geometric-series</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9a2ad65d.jpg</video:thumbnail_loc><video:title>Worked example: finite geometric series (sigma notation)</video:title><video:description>Sal evaluates the geometric series Σ2(3ᵏ) for k=0 to 99 using the finite geometric series formula a(1-rⁿ)/(1-r).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/AXP5PGSaaYk.mp4/AXP5PGSaaYk.mp4</video:content_loc><video:duration>168</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/geometric-series-word-problem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9ba70b9b.jpg</video:thumbnail_loc><video:title>Finite geometric series word problem: social media</video:title><video:description>Watch Sal solve an example of using a geometric series to answer a fun word problem.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/aIjzkiijGnA.mp4/aIjzkiijGnA.mp4</video:content_loc><video:duration>483</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/writing-arithmetic-series-in-sigma-notation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8ebd01f2.jpg</video:thumbnail_loc><video:title>Arithmetic series in sigma notation</video:title><video:description>Sal writes the arithmetic sum 7+9+11+...+403+405 in sigma notation. There are actually two common ways of doing this.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/XArCfFaOhoo.mp4/XArCfFaOhoo.mp4</video:content_loc><video:duration>248</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/writing-geometric-series-in-sigma-notation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xeebb3f52.jpg</video:thumbnail_loc><video:title>Finite geometric series in sigma notation</video:title><video:description>Sal writes the geometric sum 2+6+18+54 in sigma notation. There are actually two common ways of doing this.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/bT_0pn1lHiY.mp4/bT_0pn1lHiY.mp4</video:content_loc><video:duration>194</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/properties-to-find-sum</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9235e839.jpg</video:thumbnail_loc><video:title>Evaluating series using the formula for the sum of n squares</video:title><video:description>Using properties of sigma notation to rewrite an elaborate sum as a combination of simpler sums, which we know the formula for.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LwhJVURumAA.mp4/LwhJVURumAA.mp4</video:content_loc><video:duration>414</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/partial-sum-notation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x59079628.jpg</video:thumbnail_loc><video:title>Partial sums intro</video:title><video:description>This video introduces partial sums, which are sums of a certain number of terms in an infinite series. It explains the notation S sub n (Sₙ) and shows how to calculate partial sums using a formula.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/k9MEOgcc5KY.mp4/k9MEOgcc5KY.mp4</video:content_loc><video:duration>369</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/term-from-partial-sum</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbb49a4841e6d74b5.jpg</video:thumbnail_loc><video:title>Partial sums: formula for nth term from partial sum</video:title><video:description>This video shows how to find a rule for the nth term (aₙ) in a series. We start with the formula for the sum of the first n terms (sₙ). Then, we subtract the sum of the first n-1 terms (sₙ₋₁) from sₙ to get aₙ. Finally, we simplify the expression.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Ppuj5gw78Vc.mp4/Ppuj5gw78Vc.mp4</video:content_loc><video:duration>245</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/finding-term-value-from-sum-formula</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x67de3ad3908c900b.jpg</video:thumbnail_loc><video:title>Partial sums: term value from partial sum</video:title><video:description>The partial sum of a sequence gives us the sum of the first n terms in the sequence. If we know the formula for the partial sums of a sequence, we can find the value of any term in the sequence.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qmWJ3nLII1M.mp4/qmWJ3nLII1M.mp4</video:content_loc><video:duration>249</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/deriving-geometric-series-sum-formula</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x16f67abe.jpg</video:thumbnail_loc><video:title>Infinite geometric series formula intuition</video:title><video:description>In the video, we learn about the sum of an infinite geometric series. The sum converges (has a finite value) when the common ratio (r) is between -1 and 1. The formula for the sum is S = a / (1 - r), where a is the first term.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/wqnpSzEzq1w.mp4/wqnpSzEzq1w.mp4</video:content_loc><video:duration>474</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/infinite-geometric-series</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc809ee47.jpg</video:thumbnail_loc><video:title>Proof of infinite geometric series as a limit</video:title><video:description>The video provides a proof for the sum of an infinite geometric series using limits. When the absolute value of the common ratio (r) is between 0 and 1, the limit of the series converges to a finite sum. The formula for the sum is a / (1 - r), where a is the first term.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/b-7kCymoUpg.mp4/b-7kCymoUpg.mp4</video:content_loc><video:duration>286</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/evaluating-infinite-geometric-series</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5b3f5531.jpg</video:thumbnail_loc><video:title>Worked example: convergent geometric series</video:title><video:description>Sal evaluates the infinite geometric series 8+8/3+8/9+... Because the common ratio&apos;s absolute value is less than 1, the series converges to a finite number.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Sify7Bp7BmI.mp4/Sify7Bp7BmI.mp4</video:content_loc><video:duration>230</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/infinite-geometric-series-not-converging</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6ee026a1.jpg</video:thumbnail_loc><video:title>Worked example: divergent geometric series</video:title><video:description>Sal evaluates the infinite geometric series -0.5+1.5-4.5+... Because the common ratio&apos;s absolute value is greater than 1, the series doesn&apos;t converge.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Gk1mWXIpasE.mp4/Gk1mWXIpasE.mp4</video:content_loc><video:duration>194</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/bouncing-ball-distance</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb23a1b53.jpg</video:thumbnail_loc><video:title>Infinite geometric series word problem: bouncing ball</video:title><video:description>Watch Sal determine the total vertical distance a bouncing ball moves using an infinite geometric series.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tqTJZEglrvc.mp4/tqTJZEglrvc.mp4</video:content_loc><video:duration>310</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/repeating-decimal-geometric-series</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9a32c336.jpg</video:thumbnail_loc><video:title>Infinite geometric series word problem: repeating decimal</video:title><video:description>See how we can write a repeating decimal as an infinite geometric series.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2BgWWsypzLA.mp4/2BgWWsypzLA.mp4</video:content_loc><video:duration>482</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/deductive-reasoning-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/27088.jpg</video:thumbnail_loc><video:title>Inductive &amp; deductive reasoning</video:title><video:description>Sal discusses the difference between inductive and deductive reasoning by considering a word problem.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/GEId0GonOZM.mp4/GEId0GonOZM.mp4</video:content_loc><video:duration>120</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/deductive-reasoning-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/27089.jpg</video:thumbnail_loc><video:title>Deductive reasoning</video:title><video:description>Sal analyzes a solution of a mathematical problem to determine whether it uses deductive reasoning.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/VMEV__2wW3E.mp4/VMEV__2wW3E.mp4</video:content_loc><video:duration>237</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/deductive-reasoning-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/27090.jpg</video:thumbnail_loc><video:title>Using deductive reasoning</video:title><video:description>Sal uses deductive reasoning to prove an algebraic identity.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lYLaaMObgkw.mp4/lYLaaMObgkw.mp4</video:content_loc><video:duration>251</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/inductive-reasoning-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/27086.jpg</video:thumbnail_loc><video:title>Inductive reasoning</video:title><video:description>Sal analyzes a solution of a mathematical problem to determine whether it uses inductive reasoning.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ZSsBh4Ybbj8.mp4/ZSsBh4Ybbj8.mp4</video:content_loc><video:duration>141</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/inductive-reasoning-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/27087.jpg</video:thumbnail_loc><video:title>Inductive reasoning (example 2)</video:title><video:description>Sal analyzes a solution of a mathematical problem to determine whether it uses inductive reasoning.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pgfWkaySFGY.mp4/pgfWkaySFGY.mp4</video:content_loc><video:duration>183</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/u12-l1-t3-we1-inductive-reasoning-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/27085.jpg</video:thumbnail_loc><video:title>Using inductive reasoning</video:title><video:description>Sal uses inductive reasoning to find an expression for the nth number in the sequence 6, 9, 12, 15,....</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/MnQ7Lizkpqk.mp4/MnQ7Lizkpqk.mp4</video:content_loc><video:duration>127</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/u03-l1-t1-we2-inductive-patterns</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/2600591.jpg</video:thumbnail_loc><video:title>Using inductive reasoning (example 2)</video:title><video:description>Sal uses inductive reasoning in order to find the 50th element of a pattern toothpick shapes.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/GvbrtnEYRpY.mp4/GvbrtnEYRpY.mp4</video:content_loc><video:duration>394</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/proof-by-induction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/193202564.jpg</video:thumbnail_loc><video:title>Proof of finite arithmetic series formula by induction</video:title><video:description>Proving an expression for the sum of all positive integers up to and including n by induction</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/wblW_M_HVQ8.mp4/wblW_M_HVQ8.mp4</video:content_loc><video:duration>563</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/sum-of-n-squares-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe115b9a9.jpg</video:thumbnail_loc><video:title>Sum of n squares (part 1)</video:title><video:description>What is the sum of the first n squares, 1 + 4 + 9 + 16 + ... + n²? In this video we begin the journey towards finding a formula for this sum.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/i7iKLZQ-vCk.mp4/i7iKLZQ-vCk.mp4</video:content_loc><video:duration>376</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/sum-n-squares-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4f4861b7.jpg</video:thumbnail_loc><video:title>Sum of n squares (part 2)</video:title><video:description>What is the sum of the first n squares, 1 + 4 + 9 + 16 + ... + n²? In this video we find one possible formula for this sum.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/MkGXR8umLco.mp4/MkGXR8umLco.mp4</video:content_loc><video:duration>312</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/alternate-sum-of-n-squares-formula</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x463bbd8a.jpg</video:thumbnail_loc><video:title>Sum of n squares (part 3)</video:title><video:description>The sum of the first n squares, 1 + 4 + 9 + 16 + ... + n², is given by the formula ⅙n(n+1)(2n+1). In this video we factor and rewrite the formula that we found in the previous video and obtain the common formula given above.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/KvvFTPsZxU4.mp4/KvvFTPsZxU4.mp4</video:content_loc><video:duration>291</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/introduction-to-vectors-and-scalars</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/113633126.jpg</video:thumbnail_loc><video:title>Intro to vectors and scalars</video:title><video:description>Scalars and vectors are two kinds of quantities that are used in physics and math. Scalars are quantities that only have magnitude (or size), while vectors have both magnitude and direction. Explore some examples of scalars and vectors, including distance, displacement, speed, and velocity.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ihNZlp7iUHE.mp4/ihNZlp7iUHE.mp4</video:content_loc><video:duration>519</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/vector-representations-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x88dbd3d7.jpg</video:thumbnail_loc><video:title>Recognizing vectors</video:title><video:description>Watch Sal figure out which of a few options could be represented by a vector. Remember that vectors have both magnitude and direction!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/n8Ic2Oj-zvA.mp4/n8Ic2Oj-zvA.mp4</video:content_loc><video:duration>156</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/equivalent-vectors-examples</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf0d96e10.jpg</video:thumbnail_loc><video:title>Equivalent vectors</video:title><video:description>Sal determines if two vectors shown on a graph are equivalent by seeing if they have the same magnitude and direction.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/v_W-aaB1irs.mp4/v_W-aaB1irs.mp4</video:content_loc><video:duration>397</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/example-finding-components-of-a-vector</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x014bbaf1.jpg</video:thumbnail_loc><video:title>Finding the components of a vector</video:title><video:description>Sal finds the x and y-components of a vector given its graph.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/BmDph4uNfPI.mp4/BmDph4uNfPI.mp4</video:content_loc><video:duration>198</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/example-comparing-x-components-of-vectors</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1e25ccda.jpg</video:thumbnail_loc><video:title>Comparing the components of vectors</video:title><video:description>Sal figures out which vectors have the same x-component given the graphs of 4 different vectors.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/v7ZZ1ctT1k0.mp4/v7ZZ1ctT1k0.mp4</video:content_loc><video:duration>175</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/example-calcuating-magnitude-of-vector-from-graph</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7e3752a9.jpg</video:thumbnail_loc><video:title>Vector magnitude from graph</video:title><video:description>Sal finds the magnitude of a vector given its graph.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-U53eHKCLcg.mp4/-U53eHKCLcg.mp4</video:content_loc><video:duration>218</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/finding-vector-magnitude-from-components</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x79bdd17f.jpg</video:thumbnail_loc><video:title>Vector magnitude from components</video:title><video:description>Sal finds the magnitude of a vector given its components of (5, -3).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qMZnsj4ZO9g.mp4/qMZnsj4ZO9g.mp4</video:content_loc><video:duration>186</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/vector-magnitude-from-initial-and-terminal-points</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x904d03e1b40a61f2.jpg</video:thumbnail_loc><video:title>Vector magnitude from initial &amp; terminal points</video:title><video:description>Example of finding the magnitude of a vector when what we&apos;re given about the vector is where it starts and where it ends.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jfaSZhNFEOE.mp4/jfaSZhNFEOE.mp4</video:content_loc><video:duration>323</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/understanding-multiplying-vectors-by-scalars</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd8f11403.jpg</video:thumbnail_loc><video:title>Scalar multiplication: component form</video:title><video:description>Sal explains what happens graphically and to the components of a vector when we multiply it by a scalar.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/JuTvjQgpUMQ.mp4/JuTvjQgpUMQ.mp4</video:content_loc><video:duration>342</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/examples-from-understanding-scalar-multiplication-exercise</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa8a0effa.jpg</video:thumbnail_loc><video:title>Scalar multiplication: magnitude and direction</video:title><video:description>Sal analyzes the magnitude and direction of vectors that are a result of scalar multiplication of a vector whose magnitude is given.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/kLLsJXc1E1E.mp4/kLLsJXc1E1E.mp4</video:content_loc><video:duration>293</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/adding-and-subtracting-vectors</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa1f61db1.jpg</video:thumbnail_loc><video:title>Adding &amp; subtracting vectors</video:title><video:description>Sal shows how to add vectors by adding their components, then explains the intuition behind adding vectors using a graph.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/VgqsM-XdBD0.mp4/VgqsM-XdBD0.mp4</video:content_loc><video:duration>462</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/visually-adding-and-subtracting-vectors</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdccf8d66.jpg</video:thumbnail_loc><video:title>Adding &amp; subtracting vectors end-to-end</video:title><video:description>Build intuition behind adding and subtracting vectors visually and the &quot;end-to-end&quot; method.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/BsBH8nAv5l4.mp4/BsBH8nAv5l4.mp4</video:content_loc><video:duration>382</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/subtracting-vectors-exercise-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x12b923fb.jpg</video:thumbnail_loc><video:title>Subtracting vectors end-to-end</video:title><video:description>Watch Sal determine which diagram represents vector subtraction graphically.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/coDfeoi2zcQ.mp4/coDfeoi2zcQ.mp4</video:content_loc><video:duration>104</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/adding-vectors</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6bc2f1ae.jpg</video:thumbnail_loc><video:title>Adding vectors algebraically &amp; graphically</video:title><video:description>To add the vectors (x₁,y₁) and (x₂,y₂), we add the corresponding components from each vector: (x₁+x₂,y₁+y₂). Here&apos;s a concrete example: the sum of (2,4) and (1,5) is (2+1,4+5), which is (3,9). There&apos;s also a nice graphical way to add vectors, and the two ways will always result in the same vector.​​</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8QihetGj3pg.mp4/8QihetGj3pg.mp4</video:content_loc><video:duration>432</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/combined-vector-operations-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xea5f084d.jpg</video:thumbnail_loc><video:title>Combined vector operations</video:title><video:description>Watch Sal find new vector 3u + 1/5w when u = (2, -1) and w = (-5, 5).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TdhbEonaHrc.mp4/TdhbEonaHrc.mp4</video:content_loc><video:duration>359</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/unit-vector-intro</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb1784845.jpg</video:thumbnail_loc><video:title>Worked example: finding unit vector with given direction</video:title><video:description>Learn what a unit vector is and how to find a unit vector in the direction of a given vector.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jCkhbKFZgLk.mp4/jCkhbKFZgLk.mp4</video:content_loc><video:duration>302</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/intro-unit-vector-notation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xad013660.jpg</video:thumbnail_loc><video:title>Unit vectors intro</video:title><video:description>Unit vectors are vectors whose magnitude is exactly 1 unit. They are very useful for different reasons. Specifically, the unit vectors [0,1] and [1,0] can form together any other vector.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9ylUcCOTH8Y.mp4/9ylUcCOTH8Y.mp4</video:content_loc><video:duration>479</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/scaling-unit-vector</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x95ab94f3.jpg</video:thumbnail_loc><video:title>Worked example: Scaling unit vectors</video:title><video:description>Watch Sal scale up a unit vector to have a magnitude greater than 1.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OFBI_rNDZE0.mp4/OFBI_rNDZE0.mp4</video:content_loc><video:duration>173</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/angles-of-vectors-from-components</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xadedc828.jpg</video:thumbnail_loc><video:title>Direction of vectors from components: 1st &amp; 2nd quadrants</video:title><video:description>Sal first finds the direction angle of a vector in the first quadrant, then moves onto a trickier one in the second quadrant.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/A3OuFLHum6w.mp4/A3OuFLHum6w.mp4</video:content_loc><video:duration>541</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/more-examples-finding-vector-angles</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x06688cbf.jpg</video:thumbnail_loc><video:title>Direction of vectors from components: 3rd &amp; 4th quadrants</video:title><video:description>Sal finds the direction angle of a vector in the third quadrant and a vector in the fourth quadrant.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/EX0Ha42WQ24.mp4/EX0Ha42WQ24.mp4</video:content_loc><video:duration>402</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/vector-components-from-magnitude-and-direction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa3355657.jpg</video:thumbnail_loc><video:title>Vector components from magnitude &amp; direction</video:title><video:description>Sal finds the components of a couple of vectors given in magnitude and direction form.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/MkFbisCyjFc.mp4/MkFbisCyjFc.mp4</video:content_loc><video:duration>616</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/mag-dir-vec-sums</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb581cb7c.jpg</video:thumbnail_loc><video:title>Adding vectors in magnitude &amp; direction form (1 of 2)</video:title><video:description>Watch Sal add two vectors given in magnitude and direction form by breaking them down into components first.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6Kw2nIwWYL0.mp4/6Kw2nIwWYL0.mp4</video:content_loc><video:duration>562</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/mag-dir-vec-sums-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6d0446b8.jpg</video:thumbnail_loc><video:title>Adding vectors in magnitude &amp; direction form (2 of 2)</video:title><video:description>Watch Sal finish the problem he started in part 1 by converting the sum back to magnitude and direction form.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/SjY5UytlTTs.mp4/SjY5UytlTTs.mp4</video:content_loc><video:duration>487</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/mag-vec-sums</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5a2e610c.jpg</video:thumbnail_loc><video:title>Vector addition &amp; magnitude</video:title><video:description>Sal explains some interesting properties of the magnitude of vector sums.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0t8W4JFpP2M.mp4/0t8W4JFpP2M.mp4</video:content_loc><video:duration>330</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/vector-component-in-direction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xff91329c.jpg</video:thumbnail_loc><video:title>Vector components from magnitude &amp; direction: word problem</video:title><video:description>Given the magnitudes and directions of the forces two people are applying to a box, find the overall force that is applied in the direction of the target.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9A8wM1UMLyo.mp4/9A8wM1UMLyo.mp4</video:content_loc><video:duration>536</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/adding-three-vectors</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf3e77364.jpg</video:thumbnail_loc><video:title>Vectors word problem: tug of war</video:title><video:description>Sal solves a word problem where three vector forces act upon a ring in different magnitudes &amp; directions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/KNklNvGof8o.mp4/KNklNvGof8o.mp4</video:content_loc><video:duration>524</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/adding-displacement-vectors</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8e6a40ba.jpg</video:thumbnail_loc><video:title>Vector word problem: hiking</video:title><video:description>Sal solves a word problem with vectors where he finds the total straight-line distance traveled over a few days.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/cf1-CwrDwrA.mp4/cf1-CwrDwrA.mp4</video:content_loc><video:duration>416</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/introduction-to-the-matrix</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1400915680.jpg</video:thumbnail_loc><video:title>Intro to matrices</video:title><video:description>Take the red pill and enter the Matrix!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0oGJTQCy4cQ.mp4/0oGJTQCy4cQ.mp4</video:content_loc><video:duration>269</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/matrix-addition-and-subtraction-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1401149467.jpg</video:thumbnail_loc><video:title>Adding matrices (with -1 scalar also)</video:title><video:description>Sal defines what it means to add or subtract matrices. He shows a few examples and discusses some important properties of matrix addition and subtraction.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/WR9qCSXJlyY.mp4/WR9qCSXJlyY.mp4</video:content_loc><video:duration>335</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/scalar-multiplication</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1400835599.jpg</video:thumbnail_loc><video:title>Multiplying matrices by scalars</video:title><video:description>Sal defines what it means to multiply a matrix by a scalar (in the world of matrices, a scalar is simply a regular number).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TbaltFbJ3wE.mp4/TbaltFbJ3wE.mp4</video:content_loc><video:duration>138</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/matrix-multiplication-intro</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe9bce422.jpg</video:thumbnail_loc><video:title>Intro to matrix multiplication</video:title><video:description>Sal explains what it means to multiply two matrices, and gives an example.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/kT4Mp9EdVqs.mp4/kT4Mp9EdVqs.mp4</video:content_loc><video:duration>386</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/multiplying-a-matrix-by-a-matrix</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x07e01747.jpg</video:thumbnail_loc><video:title>Multiplying matrices</video:title><video:description>Sal gives an example of a multiplication of two matrices that don&apos;t have the same dimensions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OMA2Mwo0aZg.mp4/OMA2Mwo0aZg.mp4</video:content_loc><video:duration>330</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/defined-and-undefined-matrix-operations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x044ecd2f.jpg</video:thumbnail_loc><video:title>Defined matrix operations</video:title><video:description>Sal discusses the conditions of matrix dimensions for which addition or multiplication are defined.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/O1-9f1g0OsI.mp4/O1-9f1g0OsI.mp4</video:content_loc><video:duration>212</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/identity-matrix</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x45df6c9a.jpg</video:thumbnail_loc><video:title>Intro to identity matrix</video:title><video:description>Just as any number remains the same when multiplied by 1, any matrix remains the same when multiplied by the identity matrix. Learn more from Sal.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3cnIa0fYJkY.mp4/3cnIa0fYJkY.mp4</video:content_loc><video:duration>479</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/identity-matrix-dimensions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xcb707bb1.jpg</video:thumbnail_loc><video:title>Dimensions of identity matrix</video:title><video:description>Sal explains why the identity matrix is always a square matrix, even though it works with non-square matrices.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/l7p1X5pdDoc.mp4/l7p1X5pdDoc.mp4</video:content_loc><video:duration>224</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/commutative-property-matrix-multiplication</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe5c8c1bb.jpg</video:thumbnail_loc><video:title>Is matrix multiplication commutative?</video:title><video:description>Sal checks whether the commutative property applies for matrix multiplication. In other words, he checks whether for any two matrices A and B, A*B=B*A (the answer is NO, by the way).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/z-SU7P-gIoQ.mp4/z-SU7P-gIoQ.mp4</video:content_loc><video:duration>452</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/associative-property-matrix-multiplication</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa56c25c1.jpg</video:thumbnail_loc><video:title>Associative property of matrix multiplication</video:title><video:description>Sal shows that matrix multiplication is associative. Mathematically, this means that for any three matrices A, B, and C, (A*B)*C=A*(B*C).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8Ryfe82DTcM.mp4/8Ryfe82DTcM.mp4</video:content_loc><video:duration>517</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/zero-matrix</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x04b88473.jpg</video:thumbnail_loc><video:title>Zero matrix &amp; matrix multiplication</video:title><video:description>Just as any number multiplied by zero is zero, there is a zero matrix such that any matrix multiplied by it results in that zero matrix. Learn more from Sal.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LOf8bfjiLow.mp4/LOf8bfjiLow.mp4</video:content_loc><video:duration>282</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/matrix-expressions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6ed8fca0.jpg</video:thumbnail_loc><video:title>Using properties of matrix operations</video:title><video:description>Sal determines which of a few optional matrix expressions is equivalent to the matrix expression A*B*C. This is done using what we know about the properties of matrix addition and multiplication.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OjF765iVuF8.mp4/OjF765iVuF8.mp4</video:content_loc><video:duration>210</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/identity-zero-matrix-equation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x620f2504.jpg</video:thumbnail_loc><video:title>Using identity &amp; zero matrices</video:title><video:description>Sal solves a problem where he has to determine whether unknown matrices are zero or identity to make an equation true.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ikadoCpDNT8.mp4/ikadoCpDNT8.mp4</video:content_loc><video:duration>238</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/transforming-position-vector</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x181bbe4e.jpg</video:thumbnail_loc><video:title>Transforming vectors using matrices</video:title><video:description>Sal transforms a 2-dimensional vector using a 2x2 matrix, and draws the original vector and its image on the plane.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Kh8HKAxdEyw.mp4/Kh8HKAxdEyw.mp4</video:content_loc><video:duration>283</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/matrix-transformation-triangle</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe4b9c0d5.jpg</video:thumbnail_loc><video:title>Transforming polygons using matrices</video:title><video:description>Sal transforms a triangle using a 2x2 matrix.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/RKBSX-6pKgY.mp4/RKBSX-6pKgY.mp4</video:content_loc><video:duration>435</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/matrix-transformation-quadrilateral</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x723c8dfd.jpg</video:thumbnail_loc><video:title>Visual representation of transformation from matrix</video:title><video:description>Sal finds the drawing that appropriately represents the effect of a given 2x2 transformation matrix on the plane.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3tyM_M3FQNM.mp4/3tyM_M3FQNM.mp4</video:content_loc><video:duration>368</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/finding-the-determinant-of-a-2x2-matrix</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1128184016.jpg</video:thumbnail_loc><video:title>Determinant of a 2x2 matrix</video:title><video:description>Sal shows how to find the determinant of a 2x2 matrix.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OU9sWHk_dlw.mp4/OU9sWHk_dlw.mp4</video:content_loc><video:duration>70</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/inverse-matrix-part-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25203.jpg</video:thumbnail_loc><video:title>Intro to matrix inverses</video:title><video:description>Sal introduces the concept of an inverse matrix.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/iUQR0enP7RQ.mp4/iUQR0enP7RQ.mp4</video:content_loc><video:duration>854</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/singular-matrices</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25213.jpg</video:thumbnail_loc><video:title>Determining invertible matrices</video:title><video:description>Sal shows why a matrix is invertible if and only if its determinant is not 0.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/UqyN7-tRS00.mp4/UqyN7-tRS00.mp4</video:content_loc><video:duration>867</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/inverse-of-a-2x2-matrix</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1128298896.jpg</video:thumbnail_loc><video:title>Finding inverses of 2x2 matrices</video:title><video:description>Sal gives an example of how to find the inverse of a given 2x2 matrix.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/01c12NaUQDw.mp4/01c12NaUQDw.mp4</video:content_loc><video:duration>168</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/finding-the-determinant-of-a-3x3-matrix-method-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1128472045.jpg</video:thumbnail_loc><video:title>Determinant of a 3x3 matrix: standard method (1 of 2)</video:title><video:description>Sal shows the standard method for finding the determinant of a 3x3 matrix.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/u00I3MCrspU.mp4/u00I3MCrspU.mp4</video:content_loc><video:duration>237</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/finding-the-determinant-of-a-3x3-matrix-method-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1128416416.jpg</video:thumbnail_loc><video:title>Determinant of a 3x3 matrix: shortcut method (2 of 2)</video:title><video:description>Sal shows a &quot;shortcut&quot; method for finding the determinant of a 3x3 matrix.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/v4MenooI1J0.mp4/v4MenooI1J0.mp4</video:content_loc><video:duration>159</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/inverting-matrices-part-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25207.jpg</video:thumbnail_loc><video:title>Inverting a 3x3 matrix using Gaussian elimination</video:title><video:description>Sal explains how we can find the inverse of a 3x3 matrix using Gaussian elimination.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/obts_JDS6_Q.mp4/obts_JDS6_Q.mp4</video:content_loc><video:duration>816</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/inverting-3x3-part-1-calculating-matrix-of-minors-and-cofactor-matrix</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1128367509.jpg</video:thumbnail_loc><video:title>Inverting a 3x3 matrix using determinants Part 1: Matrix of minors and cofactor matrix</video:title><video:description>Sal shows how to find the inverse of a 3x3 matrix using its determinant. In Part 1 we learn how to find the matrix of minors of a 3x3 matrix and its cofactor matrix.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xZBbfLLfVV4.mp4/xZBbfLLfVV4.mp4</video:content_loc><video:duration>527</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/inverting-3x3-part-2-determinant-and-adjugate-of-a-matrix</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1128279750.jpg</video:thumbnail_loc><video:title>Inverting a 3x3 matrix using determinants Part 2: Adjugate matrix</video:title><video:description>Sal shows how to find the inverse of a 3x3 matrix using its determinant. In Part 2 we complete the process by finding the determinant of the matrix and its adjugate matrix.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ArcrdMkEmKo.mp4/ArcrdMkEmKo.mp4</video:content_loc><video:duration>383</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/matrix-equations-systems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x41cbb463.jpg</video:thumbnail_loc><video:title>Representing linear systems with matrix equations</video:title><video:description>Sal shows how a system of two linear equations can be represented with the equation A*x=b where A is the coefficient matrix, x is the variable vector, and b is the constant vector.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/EC2mgUZyzoA.mp4/EC2mgUZyzoA.mp4</video:content_loc><video:duration>595</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/solving-matrix-equation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x516a2c36.jpg</video:thumbnail_loc><video:title>Solving linear systems with matrices</video:title><video:description>Sal solves that matrix equation using the inverse of the coefficient matrix.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0_DYEFtlCiM.mp4/0_DYEFtlCiM.mp4</video:content_loc><video:duration>398</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/matrices-to-solve-a-vector-combination-problem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25211.jpg</video:thumbnail_loc><video:title>Matrix word problem: vector combination</video:title><video:description>Sal finds the appropriate combination of two given vectors in order to obtain a third given vector. This is done by representing the problem with a single matrix equation and solving that equation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gsNgdVdAT1o.mp4/gsNgdVdAT1o.mp4</video:content_loc><video:duration>860</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra-home/v/data-in-matrices</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf6a9994c.jpg</video:thumbnail_loc><video:title>Matrix word problem: prices</video:title><video:description>Sal shows how matrices can be used to efficiently represent data about the prices of toilet paper and toothpaste in two different cities.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PPOIlLhsT6s.mp4/PPOIlLhsT6s.mp4</video:content_loc><video:duration>343</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/factor-high-deg-monomials</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7af1edb2cc92a08b.jpg</video:thumbnail_loc><video:title>Introduction to factoring higher degree monomials</video:title><video:description>Factoring monomials involves breaking down a single term into the product of other terms. This video explores how to factor monomials, like 6x to the 7th power, into simpler parts. It also introduces the concept of prime factorization, which is useful for factoring higher degree expressions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Kze7cw30F60.mp4/Kze7cw30F60.mp4</video:content_loc><video:duration>283</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/polynomial-identities-intro</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1534feedace1666e.jpg</video:thumbnail_loc><video:title>Polynomial identities introduction</video:title><video:description>Polynomial identities are equal expressions involving polynomials. We can prove these identities through algebraic manipulation, like expanding and simplifying. This helps us see if two expressions are the same for all values of a variable, making them true polynomial identities.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/EvNKKyhLSpQ.mp4/EvNKKyhLSpQ.mp4</video:content_loc><video:duration>296</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/relationships-w-poly-identities</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbc8b185cf7a1a65b.jpg</video:thumbnail_loc><video:title>Describing numerical relationships with polynomial identities</video:title><video:description>Explore numerical relationships in polynomial identities, demonstrating how they can reveal patterns in sequences of integer squares. Learn how algebra can prove that the difference between successive terms in a sequence of integer squares is always an increasing odd number.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/uJwq67y5wAY.mp4/uJwq67y5wAY.mp4</video:content_loc><video:duration>274</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/geo-series-word-problem-swing</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xabd79ca6fc794e36.jpg</video:thumbnail_loc><video:title>Geometric series word problems: swing</video:title><video:description>The length a monkey passes when swinging from a tree can be modeled by a geometric series! We learn that each swing&apos;s length is half the previous one, forming a finite geometric series. By applying the sum formula, we calculate the total distance the monkey swings.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/NlzK79p3QDQ.mp4/NlzK79p3QDQ.mp4</video:content_loc><video:duration>352</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/geo-series-word-problem-hike</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe4bdeef0a16ce982.jpg</video:thumbnail_loc><video:title>Geometric series word problems: hike</video:title><video:description>Can a finite geometric series help us plan a hiking trip? Sloan embarks on a four-day hiking trip, increasing her distance by 20% each day. To figure out her first day&apos;s distance, we use the finite geometric series formula. This math tool helps us solve Sloan&apos;s hiking puzzle.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9jxd1EUfQnc.mp4/9jxd1EUfQnc.mp4</video:content_loc><video:duration>390</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/modeling-periodic-function-with-shift</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x049abc7f.jpg</video:thumbnail_loc><video:title>Trig word problem: length of day (phase shift)</video:title><video:description>Sal solves a word problem about the annual change in the length of day by modeling it with a sinusoidal function that has a phase shift.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/MJBjGnR6vlk.mp4/MJBjGnR6vlk.mp4</video:content_loc><video:duration>463</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/graph-labels-and-scales</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x338c6e3dc24cbc11.jpg</video:thumbnail_loc><video:title>Graph labels and scales</video:title><video:description>When graphing a real-world relationship, we need to pick labels and axis scales that are appropriate for the purpose of our model.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/IoPQtvXkde0.mp4/IoPQtvXkde0.mp4</video:content_loc><video:duration>273</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/modeling-with-multiple-variables-pancakes</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4bde56bfed975b68.jpg</video:thumbnail_loc><video:title>Modeling with multiple variables: Pancakes</video:title><video:description>Modeling the relationship between three quantities (or more) isn&apos;t that different from modeling the relationship between two quantities. Here is an example of a model that relates different quantities in the context of making pancakes.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/bp29Cf4xCqU.mp4/bp29Cf4xCqU.mp4</video:content_loc><video:duration>145</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/modeling-with-multiple-variables-roller-coaster</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x056b41d61dd7068a.jpg</video:thumbnail_loc><video:title>Modeling with multiple variables: Roller coaster</video:title><video:description>Modeling the relationship between three quantities (or more) isn&apos;t that different from modeling the relationship between two quantities. Here is an example of a model that relates different quantities in the context of roller coaster rides.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hANm5-51ywk.mp4/hANm5-51ywk.mp4</video:content_loc><video:duration>140</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/modeling-with-multiple-variables-taco-stand</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb64563073b5a7e70.jpg</video:thumbnail_loc><video:title>Modeling with multiple variables: Taco stand</video:title><video:description>Modeling the relationship between three quantities (or more) isn&apos;t that different from modeling the relationship between two quantities. Here is an example of a model that relates different quantities related to the daily profits of a taco stand.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/YvuW40fpptI.mp4/YvuW40fpptI.mp4</video:content_loc><video:duration>196</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/algebra2/v/modeling-with-multiple-variables-ice-cream</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xaa312f986d971d09.jpg</video:thumbnail_loc><video:title>Modeling with multiple variables: Ice cream</video:title><video:description>Modeling the relationship between three quantities (or more) isn&apos;t that different from modeling the relationship between two quantities. Here is an example of a model that relates different quantities related to two people walking to the same ice cream shop.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_auAZcmJF3M.mp4/_auAZcmJF3M.mp4</video:content_loc><video:duration>208</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/khan-academy-in-the-classroom-bill-scott</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xec0c91221a4cd607.jpg</video:thumbnail_loc><video:title>Khan Academy in the classroom</video:title><video:description>Bill Scott uses Khan Academy to teach AP Calculus at Phillips Academy in Andover, Massachusetts, and he&apos;s part of the teaching team that helped develop Khan Academy&apos;s AP lessons. Phillips Academy was one of the first schools to teach AP nearly 60 years ago.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Tx-AtZOJYfE.mp4/Tx-AtZOJYfE.mp4</video:content_loc><video:duration>206</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/sal-interviews-the-ap-calculus-lead-at-college-board</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc8a53bbe.jpg</video:thumbnail_loc><video:title>Sal interviews the AP Calculus Lead at College Board</video:title><video:description>In this video, Sal interviews Ben Hedrick, the AP Calculus Lead at College Board. They discuss the AP Calculus exam&apos;s focus on conceptual understanding, the importance of mastering core topics like derivatives and integrals, and the value of practicing with past exams. Ben also advises students to relax and approach the exam as just another test.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_3VKtPGbSzk.mp4/_3VKtPGbSzk.mp4</video:content_loc><video:duration>597</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/introduction-to-limits-hd</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/91852634.jpg</video:thumbnail_loc><video:title>Introducing limits</video:title><video:description>In this video, we learn about limits, a fundamental concept in calculus. Limits help us understand what a function approaches as the input gets closer to a certain value, even when the function is undefined at that point. The video demonstrates this concept using two examples with different functions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/riXcZT2ICjA.mp4/riXcZT2ICjA.mp4</video:content_loc><video:duration>692</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/limits-from-graphs</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbb039ef35482481d.jpg</video:thumbnail_loc><video:title>Estimating limit values from graphs</video:title><video:description>In this video, we learn to estimate limit values from graphs by observing the function&apos;s behavior as x approaches a value from both left and right sides. If the function approaches the same value from both sides, the limit exists. If it approaches different values or is unbounded, the limit doesn&apos;t exist.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/mols6pMKrto.mp4/mols6pMKrto.mp4</video:content_loc><video:duration>361</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/unbounded-limits</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xedd08d5c288f2e21.jpg</video:thumbnail_loc><video:title>Examining unbounded limits</video:title><video:description>This video discusses estimating limit values from graphs, focusing on two functions: y = 1/x² and y = 1/x. For y = 1/x², the limit is unbounded as x approaches 0, since the function increases without bound. For y = 1/x, the limit doesn&apos;t exist as x approaches 0, since it&apos;s unbounded in opposite directions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/56qtGRCd8bE.mp4/56qtGRCd8bE.mp4</video:content_loc><video:duration>152</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/one-sided-limits-from-graphs</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0aee8ec3.jpg</video:thumbnail_loc><video:title>Estimating one-sided limits from graphs</video:title><video:description>A one-sided limit is the value the function approaches as the x-values approach the limit from *one side only*. For example, f(x)=|x|/x returns -1 for negative numbers, 1 for positive numbers, and isn&apos;t defined for 0. The one-sided *right* limit of f at x=0 is 1, and the one-sided *left* limit at x=0 is -1.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/nOnd3SiYZqM.mp4/nOnd3SiYZqM.mp4</video:content_loc><video:duration>551</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/one-sided-limits-from-graphs-asymptote</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc8975421.jpg</video:thumbnail_loc><video:title>Estimating one-sided limits from graphs: asymptote</video:title><video:description>This video explores estimating one-sided limit values from graphs. As x approaches 6 from the left, the function becomes unbounded with an asymptote, making the left-sided limit nonexistent. However, when approaching 6 from the right, the function approaches -3, indicating that the right-handed limit exists. Sal&apos;s analysis highlights the importance of understanding limits from both sides.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5f1-Rg3MmKs.mp4/5f1-Rg3MmKs.mp4</video:content_loc><video:duration>147</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/connecting-limits-and-graphical-behavior</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x38f5a88c7c08b6ed.jpg</video:thumbnail_loc><video:title>Connecting limits and graphical behavior</video:title><video:description>Usually when we analyze a function&apos;s limits from its graph, we are looking at the more &quot;interesting&quot; points. It&apos;s important to remember that you can talk about the function&apos;s value at any point. Also, a description of a limit can apply to multiple different functions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/l6FX_r_Tkls.mp4/l6FX_r_Tkls.mp4</video:content_loc><video:duration>303</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/missing-function-detail-when-zoomed-out</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x07fe160200ec1a22.jpg</video:thumbnail_loc><video:title>Missing function detail when zoomed out</video:title><video:description>Understand because of issues of scale, graphical representations of functions may miss important function behavior.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/oCfQz8BcJN4.mp4/oCfQz8BcJN4.mp4</video:content_loc><video:duration>209</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/missing-function-features-when-zoomed-in</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x35f7d4dfe4c31d89.jpg</video:thumbnail_loc><video:title>Missing function features when zoomed in</video:title><video:description>Understand because of issues of scale, graphical representations of functions may miss important function behavior.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Nfdu6x4vJuQ.mp4/Nfdu6x4vJuQ.mp4</video:content_loc><video:duration>198</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/finding-limit-of-an-oscillating-function</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbaf15f030d45a687.jpg</video:thumbnail_loc><video:title>Finding limit of an oscillating function</video:title><video:description>A limit might not exist if the function is oscillating near a value of x.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vyWni0VxLao.mp4/vyWni0VxLao.mp4</video:content_loc><video:duration>75</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/approximating-limit-from-table</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x91d9e677c75da969.jpg</video:thumbnail_loc><video:title>Approximating limits using tables</video:title><video:description>In this video, we learn about estimating limit values from tables. The main points are approximating the limit from the left (values less than the target) and the right (values greater than the target). By getting closer to the target value from both sides, we can estimate the limit even if the expression is not defined at the target value.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1tn0vd2835k.mp4/1tn0vd2835k.mp4</video:content_loc><video:duration>267</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/estimating-limit-from-table</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xba5a348d6c1f4a1e.jpg</video:thumbnail_loc><video:title>Estimating limits from tables</video:title><video:description>When given a table of values for a function, we can estimate the limit at a certain point by observing the values the function approaches from both sides. The limit is the value the function converges to, even if the function&apos;s value at that point is different.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/zX49LocrXbg.mp4/zX49LocrXbg.mp4</video:content_loc><video:duration>204</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/one-sided-limits-from-tables</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x618f6823de234d0f.jpg</video:thumbnail_loc><video:title>Estimating one-sided limits from tables</video:title><video:description>In this video, we explore one-sided limits using tables, focusing on estimating the value a function approaches from either the left or right. We emphasize the importance of understanding the negative and positive superscripts, which indicate the direction we&apos;re approaching the limit from.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9geXUOXTJJQ.mp4/9geXUOXTJJQ.mp4</video:content_loc><video:duration>380</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/limit-properties</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1313230441.jpg</video:thumbnail_loc><video:title>Introducing properties of limits</video:title><video:description>This video introduces limit properties, which are intuitive rules that help simplify limit problems. The main properties covered are the sum, difference, product, quotient, and exponent rules. These properties allow you to break down complex limits into simpler components, making it easier to find the limit of a function.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lSwsAFgWqR8.mp4/lSwsAFgWqR8.mp4</video:content_loc><video:duration>308</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/limits-of-combined-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf598b75a.jpg</video:thumbnail_loc><video:title>Determining limits of combined functions</video:title><video:description>In this video, we learn how to find the limit of combined functions using algebraic properties of limits. The main ideas are that the limit of a product is the product of the limits, and that the limit of a quotient is the quotient of the limits, provided the denominator&apos;s limit isn&apos;t zero.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/AhnJtTI_DMM.mp4/AhnJtTI_DMM.mp4</video:content_loc><video:duration>249</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/limits-of-combined-functions-piecewise</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb8e7508a99eac58f.jpg</video:thumbnail_loc><video:title>Determining limits of combined functions: piecewise functions</video:title><video:description>This video demonstrates that even when individual limits of functions f(x) and g(x) don&apos;t exist, the limit of their sum or product might still exist. By analyzing left and right-hand limits, we can determine if the limit of the combined functions exists and find its value.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Xo49w4DDEfQ.mp4/Xo49w4DDEfQ.mp4</video:content_loc><video:duration>253</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/limits-of-composite-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xce616e87.jpg</video:thumbnail_loc><video:title>Examining the theorem for limits of composite functions</video:title><video:description>This video focuses on finding the limit of composite functions, specifically the limit as &apos;x&apos; approaches &apos;a&apos; of f(g(x)). It explains that this limit equals f(limit as &apos;x&apos; approaches &apos;a&apos; of g(x)) if two conditions are met: the limit of g(x) exists, and f(x) is continuous at that limit.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9Z3ngNi-12k.mp4/9Z3ngNi-12k.mp4</video:content_loc><video:duration>193</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/theorem-for-limits-of-composite-functions-when-conditions-aren-t-met</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x747e37f92542c9b6.jpg</video:thumbnail_loc><video:title>Examining the theorem for limits of composite functions: when conditions aren&apos;t met</video:title><video:description>This video focuses on determining limits of composite functions using algebraic properties of limits. It explains that if the theorem for limits of composite functions doesn&apos;t apply, the limit might still exist. The video demonstrates this through examples and analyzing graphs of functions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/eK8T3CcSvwE.mp4/eK8T3CcSvwE.mp4</video:content_loc><video:duration>202</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/limits-of-composite-functions-internal-limit-doesn-t-exist</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x73e09706aab6477d.jpg</video:thumbnail_loc><video:title>Determining limits of composite functions: internal limit doesn&apos;t exist</video:title><video:description>This video focuses on finding the limit of composite functions, even when the limit of the internal function does not exist. It demonstrates how to use right-handed and left-handed limits to determine if the composite function&apos;s limit exists by analyzing the graphs of the functions involved.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/XYaZgRQdV3g.mp4/XYaZgRQdV3g.mp4</video:content_loc><video:duration>257</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/limits-of-composite-functions-external-limit-doesn-t-exist</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6300390872f3a878.jpg</video:thumbnail_loc><video:title>Determining limits of composite functions: external limit doesn&apos;t exist</video:title><video:description>Finding the limit of g(h(x)) at x=1 when the limit of h(x) at x=1 is 2 and the limit of g(x) at x=2 doesn&apos;t exist. Does it mean that the composite limit doesn&apos;t exist? Not necessarily! See how we analyze it.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/VAk50-zIes8.mp4/VAk50-zIes8.mp4</video:content_loc><video:duration>205</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/limit-by-substitution</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc6cdef6f.jpg</video:thumbnail_loc><video:title>Finding limits by direct substitution</video:title><video:description>Sal explains how you can easily find limits of functions at points where the functions are continuous: simply plug in the x-value into the function! Later we will learn how to find limits even when the function isn&apos;t continuous.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/cfOcOgr0E7U.mp4/cfOcOgr0E7U.mp4</video:content_loc><video:duration>127</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/undefined-limit-by-substitution</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xcb791a87.jpg</video:thumbnail_loc><video:title>Examining undefined limits by direct substitution</video:title><video:description>Sal gives an example of a limit where direct substitution ends in a quotient with 0 in the denominator and non-0 in the numerator. Such limits are undefined. What about limits where substitution ends in 0/0? Keep going and you&apos;ll see!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/JlOyb_RTejo.mp4/JlOyb_RTejo.mp4</video:content_loc><video:duration>134</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/limits-of-trigonometric-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2e2de15b2bd817a2.jpg</video:thumbnail_loc><video:title>Determining limits of trigonometric functions</video:title><video:description>This video covers limits of trigonometric functions, focusing on sine, cosine, and tangent. It emphasizes that sine and cosine are continuous and defined for all real numbers, so their limits can be found using direct substitution. For tangent and cotangent, limits depend on whether the point is in their domain.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5_zxtSyTfOY.mp4/5_zxtSyTfOY.mp4</video:content_loc><video:duration>366</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/limits-of-piecewise-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc5697551683ca362.jpg</video:thumbnail_loc><video:title>Determining limits of piecewise functions</video:title><video:description>In this video, we explore limits of piecewise functions using algebraic properties of limits and direct substitution. We learn that to find one-sided and two-sided limits, we need to consider the function definition for the specific interval we&apos;re approaching and substitute the value of x accordingly.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2xdh0yKopB8.mp4/2xdh0yKopB8.mp4</video:content_loc><video:duration>229</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/limit-at-a-point-of-discontinuity</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1313337273.jpg</video:thumbnail_loc><video:title>Determining limits of piecewise functions: absolute value</video:title><video:description>This video focuses on finding the limit of |x-3|/(x-3) at x=3 by rewriting it and examining it as a piecewise function. This approach helps us understand the behavior of the function for x values greater or less than 3, revealing that the limit doesn&apos;t exist.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Y7sqB1e4RBI.mp4/Y7sqB1e4RBI.mp4</video:content_loc><video:duration>380</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/limit-example-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1313161995.jpg</video:thumbnail_loc><video:title>Determining limits by factoring</video:title><video:description>In this video, we explore the limit of (x²+x-6)/(x-2) as x approaches 2. By factoring and simplifying the expression, we discover that the function is undefined at x = 2, but its limit from both sides as x approaches 2 is in fact 5.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/EAa3J_nDkoI.mp4/EAa3J_nDkoI.mp4</video:content_loc><video:duration>344</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/limits-by-rationalizing</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x626f2630.jpg</video:thumbnail_loc><video:title>Determining limits by rationalizing</video:title><video:description>In this video, we explore how to find the limit of a function as x approaches -1. The function is (x+1)/(√(x+5)-2). To tackle the indeterminate form 0/0, we &quot;rationalize the denominator&quot; by multiplying the numerator and denominator by the conjugate of the denominator. This simplifies the expression, allowing us to evaluate the limit.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/yVWxxQ7SMOw.mp4/yVWxxQ7SMOw.mp4</video:content_loc><video:duration>572</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/trig-limit-using-pythagorean-identity</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb48ac8d7.jpg</video:thumbnail_loc><video:title>Using the Pythagorean identity to determine trig limits</video:title><video:description>In this video, we explore finding the limit as θ approaches 0 for the expression (1-cosθ)/(2sin²θ). By using the Pythagorean identity, we rewrite the expression to simplify it and avoid the indeterminate form 0/0. This allows us to evaluate the limit and find the answer, 1/4.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/d8qtbGMB2gI.mp4/d8qtbGMB2gI.mp4</video:content_loc><video:duration>422</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/trig-limit-using-double-angle-identity</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x44aa2481.jpg</video:thumbnail_loc><video:title>Using double angle identities to determine trig limits</video:title><video:description>In this video, we dive into finding the limit at θ=-π/4 of (1+√2sinθ)/(cos2θ) by employing trigonometric identities. We use the cosine double angle identity to rewrite the expression, allowing us to simplify and cancel terms. This approach helps us overcome the indeterminate form and find the limit, showcasing the power of trig identities in solving limit problems.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lXShNH1G6Pk.mp4/lXShNH1G6Pk.mp4</video:content_loc><video:duration>631</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/flow-chart-of-limit-strategies</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x32b0695e0ad9fefa.jpg</video:thumbnail_loc><video:title>Exploring strategies to find limits</video:title><video:description>In this video we explore strategies for determining which technique to use when finding limits. We also highlight the importance of understanding various methods, such as direct substitution, factoring, multiplying by conjugates, and using trig identities. By knowing when to apply each technique, we can effectively tackle different types of limit problems and enhance our problem-solving skills.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ZaLw1cunN3s.mp4/ZaLw1cunN3s.mp4</video:content_loc><video:duration>751</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/squeeze-sandwich-theorem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1006b0c1.jpg</video:thumbnail_loc><video:title>Introducing the squeeze theorem</video:title><video:description>The squeeze (or sandwich) theorem states that if f(x)≤g(x)≤h(x) for all numbers, and at some point x=k we have f(k)=h(k), then g(k) must also be equal to them. We can use the theorem to find tricky limits like sin(x)/x at x=0, by &quot;squeezing&quot; sin(x)/x between two nicer functions and ​using them to find the limit at x=0.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/WvxKwRcHGHg.mp4/WvxKwRcHGHg.mp4</video:content_loc><video:duration>431</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/sinx-over-x-as-x-approaches-0</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x55458aa544b67d20.jpg</video:thumbnail_loc><video:title>Determining the limit of sin(x)/x as x approaches 0</video:title><video:description>In this video, we prove that the limit of sin(θ)/θ as θ approaches 0 is equal to 1. We use a geometric construction involving a unit circle, triangles, and trigonometric functions. By comparing the areas of these triangles and applying the squeeze theorem, we demonstrate that the limit is indeed 1. This proof helps clarify a fundamental concept in calculus.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5xitzTutKqM.mp4/5xitzTutKqM.mp4</video:content_loc><video:duration>556</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/1-cosx-over-x-as-x-approaches-0</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6b5ae9affbc7334e.jpg</video:thumbnail_loc><video:title>Determining the limit of (1-cos(x))/x as x approaches 0</video:title><video:description>In this video, we explore the limit of (1-cos(x))/x as x approaches 0 and show that it equals 0. We use the Pythagorean trigonometric identity, algebraic manipulation, and the known limit of sin(x)/x as x approaches 0 to prove this result. This concept is helpful for understanding the derivative of sin(x).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Ojtwh8XDF8M.mp4/Ojtwh8XDF8M.mp4</video:content_loc><video:duration>245</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/types-of-discontinuities</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe1171210a532febe.jpg</video:thumbnail_loc><video:title>Exploring types of discontinuities</video:title><video:description>This video discusses three discontinuity types: point/removable, jump, and asymptotic/infinite. Point/removable occurs when the two-sided limit exists but differs from the function&apos;s value. Jump arises when one-sided limits aren&apos;t equal, and asymptotic/infinite happens when the two-sided limit is unbounded. Continuity requires the two-sided limit to match the function&apos;s value.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/NVGBq_V-F6U.mp4/NVGBq_V-F6U.mp4</video:content_loc><video:duration>436</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/continuity-at-a-point</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc3f8ab9b4556a5fd.jpg</video:thumbnail_loc><video:title>Exploring continuity at a point</video:title><video:description>A function f is continuous at a point x=c if we can draw its graph at that point without lifting our pencil. To define this rigorously, f is continuous at x=c if the two-sided limit of f(x) as x approaches c exists and matches the value of f(c).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3KMqU5j7irw.mp4/3KMqU5j7irw.mp4</video:content_loc><video:duration>496</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/continuity-at-a-point-graphically</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0db3f6a2.jpg</video:thumbnail_loc><video:title>Working an example: Continuity at a point (graphical)</video:title><video:description>In this video, we explore the necessary conditions for continuity at a point using graphical representations of functions. We analyze two examples to determine if the left-hand and right-hand limits exist, if the function is defined at the point, and then we use these observations to determine if the function is continuous at that point.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jzn4rTPajT0.mp4/jzn4rTPajT0.mp4</video:content_loc><video:duration>439</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/limit-of-piecewise-function-that-is-defined</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x05e1dd0f.jpg</video:thumbnail_loc><video:title>Working an example: point where a function is continuous</video:title><video:description>In this video, we explore the limit of a piecewise function at the point where two cases of the function meet. By finding the left-hand and right-hand limits, we can determine if they&apos;re equal. If so, the limit exists at that point, and we&apos;ve successfully analyzed the function&apos;s behavior.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TdVDqWOR3dU.mp4/TdVDqWOR3dU.mp4</video:content_loc><video:duration>239</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/limit-of-piecewise-function-that-is-undefined</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x42e9592b.jpg</video:thumbnail_loc><video:title>Working an example: point where a function isn&apos;t continuous</video:title><video:description>Discover how to determine the limit of a piecewise function at the boundary between two distinct cases. By examining one-sided limits approaching from the left and right, we reveal that unequal values result in a non-existent limit for this particular function.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LVqv8PBR1is.mp4/LVqv8PBR1is.mp4</video:content_loc><video:duration>243</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/continuity-over-an-interval</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xedde6ebaf1ab032d.jpg</video:thumbnail_loc><video:title>Exploring continuity over an interval</video:title><video:description>A function ƒ is continuous over the open interval (a,b) if and only if it&apos;s continuous on every point in (a,b). ƒ is continuous over the closed interval [a,b] if and only if it&apos;s continuous on (a,b), the right-sided limit of ƒ at x=a is ƒ(a) and the left-sided limit of ƒ at x=b is ƒ(b).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ENIQiqxFpBc.mp4/ENIQiqxFpBc.mp4</video:content_loc><video:duration>540</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/functions-continuous-on-all-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x83a5cb78.jpg</video:thumbnail_loc><video:title>Determining if functions are continuous on all real numbers</video:title><video:description>Discover how to determine if a function is continuous on all real numbers by examining two examples: eˣ and √x. Generally, common functions exhibit continuity within their domain. Explore the concept of continuity, including asymptotic and jump discontinuities, and learn how to identify continuous functions in various scenarios.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DCWeH62w-NA.mp4/DCWeH62w-NA.mp4</video:content_loc><video:duration>197</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/functions-continuous-on-specific-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x27857f00.jpg</video:thumbnail_loc><video:title>Determining if functions are continuous at specific x-values</video:title><video:description>Determine the continuity of two functions, ln(x-3) and e^(x-3), at x=3. Explore the concept of continuity, highlighting that common functions are continuous within their domain. Discover that ln(x-3) is not continuous at x=3, while e^(x-3) is continuous for all real numbers, including x=3.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/X51CaI4tfQg.mp4/X51CaI4tfQg.mp4</video:content_loc><video:duration>262</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/defining-a-function-at-a-point-to-make-it-continuous</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf8a1e5c8.jpg</video:thumbnail_loc><video:title>Removing discontinuities (factoring)</video:title><video:description>Discover how to make a function continuous by determining the appropriate value for a discontinuous point. In this example, we explore the function f(x) = (6x² + 18x + 12) / (x² - 4) and find the value it should have at x = -2 to ensure continuity.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/oUgDaEwMbiU.mp4/oUgDaEwMbiU.mp4</video:content_loc><video:duration>297</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/fancy-algebra-to-find-a-limit-and-make-a-function-continuous</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0f1bf7aa.jpg</video:thumbnail_loc><video:title>Removing discontinuities (rationalization)</video:title><video:description>Discover how to determine the value of the function f(x) = (√(x+4) - 3) / (x - 5) at x = 5 to ensure continuity. By employing algebraic techniques like rationalization and factoring, we can find the limit as x approaches 5 and identify the value that makes the function continuous.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/P1DJxuG7U9A.mp4/P1DJxuG7U9A.mp4</video:content_loc><video:duration>320</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/introduction-to-infinite-limits</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x03359d4283dfc6fd.jpg</video:thumbnail_loc><video:title>Introducing infinite limits</video:title><video:description>We will now explore infinite limits in calculus, focusing on the notation used for unbounded limits. Learn how to determine if a limit approaches positive or negative infinity, or if it doesn&apos;t exist. Dive into one-sided limits and practice with examples using graphs of rational functions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/WS-76fFFICY.mp4/WS-76fFFICY.mp4</video:content_loc><video:duration>263</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/infinite-limits-and-asymptotes</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2a99dc091edd63c8.jpg</video:thumbnail_loc><video:title>Exploring infinite limits and asymptotes</video:title><video:description>Exploring unbounded limits and limits at infinity, this video delves into the relationship between vertical and horizontal asymptotes. Vertical asymptotes signify undefined limits, while horizontal asymptotes can have existing limits as x approaches infinity or negative infinity. The video highlights key differences and demonstrates how functions can cross horizontal asymptotes.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6BwDYdfw9NQ.mp4/6BwDYdfw9NQ.mp4</video:content_loc><video:duration>254</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/unbounded-limits-algebraic-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3b574f8c.jpg</video:thumbnail_loc><video:title>Analyzing unbounded limits: rational function</video:title><video:description>Explore one-sided limits of the function f(x) = -1/(x-1)² as it approaches x=1. By evaluating f(x) from both the right and left sides, we discover that the function tends towards negative infinity in both cases. This analysis helps us understand the behavior of functions around asymptotes.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_ZGHGDKWpp8.mp4/_ZGHGDKWpp8.mp4</video:content_loc><video:duration>303</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/unbounded-limits-algebraic-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x650d767e.jpg</video:thumbnail_loc><video:title>Analyzing unbounded limits: mixed function</video:title><video:description>Explore the fascinating behavior of the function f(x) = x / (1 - cos(x - 2)) around its asymptote at x = 2. Dive into one-sided limits and discover how the function approaches positive infinity from both the left and right sides. Unravel the properties of the cosine function and learn to evaluate limits using algebraic and graphical methods.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/AI3aOkafYFw.mp4/AI3aOkafYFw.mp4</video:content_loc><video:duration>377</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/introduction-to-limits-at-infinity</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3e64d63d151a2eb6.jpg</video:thumbnail_loc><video:title>Introducing limits at infinity</video:title><video:description>Discover the concept of limits at infinity in calculus, where functions approach a finite value as x approaches positive or negative infinity. This notation helps identify horizontal asymptotes and understand the behavior of functions as x gets larger or smaller, providing insight into the graph&apos;s structure.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/eh_ATp0hbB0.mp4/eh_ATp0hbB0.mp4</video:content_loc><video:duration>166</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/functions-with-same-limit-at-inifinity</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x417fbfe644109072.jpg</video:thumbnail_loc><video:title>Exploring functions with same limit at infinity</video:title><video:description>Exploring limits at infinity reveals that various functions can share the same limit as x approaches infinity. By examining diverse functions, including those with oscillations and natural logs, we can appreciate the infinite possibilities of functions converging to a common limit as x grows infinitely large.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/H_Nm3qGE65s.mp4/H_Nm3qGE65s.mp4</video:content_loc><video:duration>226</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/limits-at-positive-and-negative-infinity</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1313454812.jpg</video:thumbnail_loc><video:title>Determining limits at infinity of quotients (Part 1)</video:title><video:description>Discover how to determine the limits at positive and negative infinity for rational functions like (4x⁵-3x²+3)/(6x⁵-100x²-10). By focusing on the dominant terms and their growth rates, you&apos;ll learn to identify horizontal asymptotes and understand the function&apos;s behavior as x approaches infinity.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gv9ogppphso.mp4/gv9ogppphso.mp4</video:content_loc><video:duration>247</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/more-limits-at-infinity</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1313658038.jpg</video:thumbnail_loc><video:title>Determining limits at infinity of quotients (Part 2)</video:title><video:description>In this exploration of limits at infinity for rational functions, we examine three general cases of limit behavior. By identifying dominating terms and simplifying expressions, we can determine horizontal asymptotes and unbounded limits, ultimately deepening our understanding these essential calculus concepts.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/KcqO1fX9b_I.mp4/KcqO1fX9b_I.mp4</video:content_loc><video:duration>273</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/limits-with-two-horizontal-asymptotes</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1315254826.jpg</video:thumbnail_loc><video:title>Determining limits at infinity of quotients with square roots (odd power)</video:title><video:description>Discover how to find the limits at positive and negative infinity for the function x/√(x²+1). Learn how the leading term&apos;s odd power (1) results in different limits at positive and negative infinity, and understand how this impacts horizontal asymptotes and end behavior.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xks4cETlN58.mp4/xks4cETlN58.mp4</video:content_loc><video:duration>314</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/limit-at-infinity-of-rational-expression-with-radical-even</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0d461730.jpg</video:thumbnail_loc><video:title>Determining limits at infinity of quotients with square roots (even power)</video:title><video:description>Discover how to find the limit at infinity of rational expressions with radicals by dividing the numerator and denominator by the highest degree term. Mastering this technique will help us to analyze end behavior and to evaluate other limits involving infinity.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/uPksX_O9ARo.mp4/uPksX_O9ARo.mp4</video:content_loc><video:duration>217</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/intermediate-value-theorem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf5e9f146.jpg</video:thumbnail_loc><video:title>Discovering the intermediate value theorem</video:title><video:description>Discover the Intermediate Value Theorem, a fundamental concept in calculus that states if a function is continuous over a closed interval [a, b], it encompasses every value between f(a) and f(b) within that range. Dive into this foundational theorem and explore its connection to continuous functions and their behavior on intervals.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9xgO-EJ3sr0.mp4/9xgO-EJ3sr0.mp4</video:content_loc><video:duration>485</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/intermediate-value-theorem-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9233a0b3.jpg</video:thumbnail_loc><video:title>Working an example: using the intermediate value theorem</video:title><video:description>Discover how the Intermediate Value Theorem guarantees specific outcomes for continuous functions. With a given function f, where f(-2) = 3 and f(1) = 6, learn to identify the correct statement that aligns with the theorem&apos;s principles and understand its real-life applications.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TrQTK-B4bzM.mp4/TrQTK-B4bzM.mp4</video:content_loc><video:duration>403</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/justification-with-the-intermediate-value-theorem-table</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x04398cbad4cdf87c.jpg</video:thumbnail_loc><video:title>Applying the intermediate value theorem: table</video:title><video:description>Discover how to apply the Intermediate Value Theorem with a table-defined function. Learn to determine if a continuous function has a solution within a specified interval, and justify your reasoning using the theorem&apos;s principles. Explore real-life applications and enhance your understanding of calculus concepts.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/B0A2lDzn3yw.mp4/B0A2lDzn3yw.mp4</video:content_loc><video:duration>329</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/justification-with-the-intermediate-value-theorem-equation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbd6d29e4792ae6b7.jpg</video:thumbnail_loc><video:title>Applying the intermediate value theorem: equation</video:title><video:description>Discover how to apply the Intermediate Value Theorem to determine if a function has a solution within a specific interval. This engaging lesson explores the theorem&apos;s conditions, continuity, and justification using real-world examples and equations. Master the art of working with rational functions and their domains to enhance your calculus skills.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/cSw5R-jdMiI.mp4/cSw5R-jdMiI.mp4</video:content_loc><video:duration>226</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/limit-intuition-review</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1312376615.jpg</video:thumbnail_loc><video:title>Exploring the formal definition of limits Part 1: intuition review</video:title><video:description>Discover the essence of limits in calculus as we prepare to dive into the formal definition. Enhance your understanding of this fundamental concept by reviewing how function values approach a specific limit as the input variable gets closer to a certain point. Get ready to explore the mathematical rigor behind limits!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5i8HLmVTcRQ.mp4/5i8HLmVTcRQ.mp4</video:content_loc><video:duration>216</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/building-the-idea-of-epsilon-delta-definition</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1312579492.jpg</video:thumbnail_loc><video:title>Exploring the formal definition of limits Part 2: building the idea</video:title><video:description>Explore the rigorous mathematical definition of a limit as x approaches c, and understand how to get f(x) as close to L as desired by finding a range around c. Dive into the epsilon-delta definition and its application in proving limits for various functions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ljzn4SADuZc.mp4/ljzn4SADuZc.mp4</video:content_loc><video:duration>366</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/epsilon-delta-definition-of-limits</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1312571391.jpg</video:thumbnail_loc><video:title>Exploring the formal definition of limits Part 3: the definition</video:title><video:description>Explore the epsilon-delta definition of limits, which states that the limit of f(x) at x=c equals L if, for any ε&gt;0, there&apos;s a δ&gt;0 ensuring that when the distance between x and c is less than δ, the distance between f(x) and L is less than ε. This concept captures the idea of getting arbitrarily close to L.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/w70af5Ou70M.mp4/w70af5Ou70M.mp4</video:content_loc><video:duration>419</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/proving-a-limit-using-epsilon-delta-definition</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1312638166.jpg</video:thumbnail_loc><video:title>Exploring the formal definition of limits Part 4: using the definition</video:title><video:description>Explore the epsilon-delta definition of limits in calculus, as we rigorously prove a limit exists for a piecewise function. Dive into the process of defining delta as a function of epsilon, and learn how to apply this concept to validate limits with precision.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0sCttufU-jQ.mp4/0sCttufU-jQ.mp4</video:content_loc><video:duration>510</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/2011-calculus-ab-free-response-6a</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/244051677.jpg</video:thumbnail_loc><video:title>Determining continuity: 2011 Calculus AB free response #6a</video:title><video:description>Continuity of piecewise-defined functions</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/fr-8tjLoeDw.mp4/fr-8tjLoeDw.mp4</video:content_loc><video:duration>263</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/newton-leibniz-and-usain-bolt</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/581541547.jpg</video:thumbnail_loc><video:title>Connecting Newton, Leibniz, and Usain Bolt</video:title><video:description>Why do we study differential calculus? Dive into the core concepts of instantaneous rates of change and their practical applications. Uncover the connection between Newton and Leibniz&apos;s pioneering work and Usain Bolt&apos;s impressive sprinting speeds, while grasping the significance of determining instantaneous velocity in diverse situations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/EKvHQc3QEow.mp4/EKvHQc3QEow.mp4</video:content_loc><video:duration>547</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/derivative-as-a-concept</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfea4e4d112667558.jpg</video:thumbnail_loc><video:title>Exploring derivatives as a concept</video:title><video:description>Learn about derivatives as the instantaneous rate of change and the slope of the tangent line. This video introduces key concepts, including the difference between average and instantaneous rates of change, and how derivatives are central to differential calculus. Master various notations used to represent derivatives, such as Leibniz&apos;s, Lagrange&apos;s, and Newton&apos;s notations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/N2PpRnFqnqY.mp4/N2PpRnFqnqY.mp4</video:content_loc><video:duration>436</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/secant-lines-and-average-rate-of-change</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9c4c1968ea8e3c9f.jpg</video:thumbnail_loc><video:title>Connecting secant lines and average rate of change</video:title><video:description>Learn how to calculate the average rate of change for a function and its connection to the slope of a secant line. Grasp the concept of instantaneous rate of change and its significance in calculus, leading to the idea of the derivative.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0z_MDIWMBwU.mp4/0z_MDIWMBwU.mp4</video:content_loc><video:duration>317</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/derivative-as-slope-of-curve</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa17015bd.jpg</video:thumbnail_loc><video:title>Exploring the derivative as slope of a curve</video:title><video:description>Explore how to interpret the derivative of a function at a specific point as the curve&apos;s slope or the tangent line&apos;s slope at that point. Dive into problem-solving examples that demonstrate this concept and strengthen your understanding of derivatives in calculus.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/S-dcMvJlMJs.mp4/S-dcMvJlMJs.mp4</video:content_loc><video:duration>370</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/derivative-as-slope-of-tangent-line</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xad889a94.jpg</video:thumbnail_loc><video:title>Connecting the derivative and tangent line equations</video:title><video:description>Discover how the derivative of a function reveals the slope of the tangent line at any point on the graph. We&apos;ll explore how to use this powerful tool to determine the equation of the tangent line, enhancing our understanding of instantaneous rates of change.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/fqQ6sslzyhY.mp4/fqQ6sslzyhY.mp4</video:content_loc><video:duration>453</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/calculus-derivatives-1-new-hd-version</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24100.jpg</video:thumbnail_loc><video:title>Exploring the formal definition of the derivative as a limit</video:title><video:description>Discover how to define the derivative of a function at a specific point using the limit of the slope of the secant line. We&apos;ll explore the concept of finding the slope as the difference in function values approaches zero, represented by the limit of [f(c)-f(c+h)]/h as h→0.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ANyVpMS3HL4.mp4/ANyVpMS3HL4.mp4</video:content_loc><video:duration>943</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/alternate-form-of-the-derivative</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2c6e38f4.jpg</video:thumbnail_loc><video:title>Understanding the formal and alternate form of the derivative</video:title><video:description>Discover the two methods for defining the derivative of a function at a specific point using limit expressions. In this video we&apos;ll explore the standard form and alternate form, enhancing our understanding of tangent line slopes and secant line approximations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Df2escG-Vu0.mp4/Df2escG-Vu0.mp4</video:content_loc><video:duration>293</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/formal-and-alternate-form-of-the-derivative-for-ln-x</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x86a51654.jpg</video:thumbnail_loc><video:title>Working an example: Derivative as a limit</video:title><video:description>Discover how to apply the formal and alternate forms of the derivative in real-world scenarios. We&apos;ll explore the process of finding the slope of tangent lines using both methods and compare their effectiveness in solving calculus problems. Let&apos;s dive into the practical side of derivatives to deepen our understanding.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/m8yC7kR5Fuk.mp4/m8yC7kR5Fuk.mp4</video:content_loc><video:duration>346</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/formal-and-alternate-form-of-the-derivative-example-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x04bbe3f0.jpg</video:thumbnail_loc><video:title>Working an example: Derivative from limit expression</video:title><video:description>We explore a limit expression and discover that it represents the derivative of the function f(x) = x³ at the point x = 5. By analyzing the alternate form of the derivative, we gain a deeper understanding of tangent lines and their slopes.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ePh8iCbcXfA.mp4/ePh8iCbcXfA.mp4</video:content_loc><video:duration>317</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/calculus-derivatives-2-new-hd-version</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24102.jpg</video:thumbnail_loc><video:title>Finding the derivative of x² at x=3 using the formal definition</video:title><video:description>Discover how to find the derivative of x² at x=3 using the formal definition of a derivative. Learn to calculate the slope of the tangent line at a specific point on the curve y=x² by applying the limit as the change in x approaches zero. This method helps determine the instantaneous rate of change for the function.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/IePCHjMeFkE.mp4/IePCHjMeFkE.mp4</video:content_loc><video:duration>508</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/calculus-derivatives-2-5-new-hd-version</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24104.jpg</video:thumbnail_loc><video:title>Finding the derivative of x² at any point using the formal definition</video:title><video:description>Let&apos;s find the derivative of x² at any point using the formal definition of a derivative. We will learn to apply the limit as h approaches 0 to determine the slope of the tangent line at a given point on the curve y = x². This powerful concept leads to a general formula for the derivative: f&apos;(x) = 2x.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/HEH_oKNLgUU.mp4/HEH_oKNLgUU.mp4</video:content_loc><video:duration>665</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/estimating-derivative-at-a-point</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd63a671d93acf351.jpg</video:thumbnail_loc><video:title>Estimating derivatives</video:title><video:description>Let&apos;s explore how to estimate the derivative of a function at a specific point using the slope of a secant line connecting nearby points. By finding the average rate of change between these points, we can make our best guess for the instantaneous rate of change at the desired point.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jvYZNp5myXg.mp4/jvYZNp5myXg.mp4</video:content_loc><video:duration>356</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/differentiability</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2eefa38e99f06afd.jpg</video:thumbnail_loc><video:title>Exploring differentiability and continuity</video:title><video:description>We explore the notion of differentiability at a point and its relationship with continuity, using the definition of a derivative. If a function is differentiable at x = c, then it is continuous at x = c. However, a function being continuous does not guarantee that it is differentiable, as demonstrated with an absolute value function.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xuAiQOzIkWY.mp4/xuAiQOzIkWY.mp4</video:content_loc><video:duration>578</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/differentiability-at-a-point-graphical</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xcec6c3f0.jpg</video:thumbnail_loc><video:title>Understanding differentiability at a point: graphical</video:title><video:description>Let&apos;s dive into examples of functions and their graphs, focusing on finding points where the function isn&apos;t differentiable. By examining various cases such as vertical tangents, discontinuities, and sharp turns, we gain a deeper understanding of the conditions that make a function non-differentiable. We then determine the x-values where the derivative doesn&apos;t exist, further solidifying our knowledge of differentiability.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pwh1dK3vTkM.mp4/pwh1dK3vTkM.mp4</video:content_loc><video:duration>339</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/differentiability-at-a-point-algebraic-is-differentiable</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x75490a85.jpg</video:thumbnail_loc><video:title>Examining differentiability at a point: algebraic (function is differentiable)</video:title><video:description>We examine a piecewise function to determine its continuity and differentiability at an edge point. By analyzing left and right hand limits, we establish continuity. Checking the limit of the difference quotient confirms both left and right hand limits are equal, making the function continuous and differentiable at the edge point.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_DkttKctXFY.mp4/_DkttKctXFY.mp4</video:content_loc><video:duration>302</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/differentiability-at-a-point-algebraic-not-differentiable</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xac6f5146.jpg</video:thumbnail_loc><video:title>Examining differentiability at a point: algebraic (function isn&apos;t differentiable)</video:title><video:description>We examine a piecewise function to determine its differentiability and continuity at an edge point. Through analyzing left and right-hand limits, we find that the function is continuous at the point. However, due to differing slopes from the left and right, the function is not differentiable at the edge point.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/BpPHve1cCCs.mp4/BpPHve1cCCs.mp4</video:content_loc><video:duration>382</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/power-rule</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1280002940.jpg</video:thumbnail_loc><video:title>Exploring the power rule</video:title><video:description>Let&apos;s dive into the power rule, a handy tool for finding the derivative of xⁿ. This rule simplifies the process of taking derivatives, especially for polynomials, by bringing the exponent out front and decrementing the power. We explore examples with positive, negative, and fractional exponents.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/bRZmfc1YFsQ.mp4/bRZmfc1YFsQ.mp4</video:content_loc><video:duration>234</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/power-rule-with-rewriting</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x13db1ccef0efc252.jpg</video:thumbnail_loc><video:title>Applying the power rule (with rewriting the expression)</video:title><video:description>Discover how the power rule helps us find derivatives of functions like 1/x, ∛x, or ∛x². By rewriting these functions as xⁿ, where n is a negative or fractional exponent, we can apply the power rule to calculate their derivatives with ease.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/H-v4oraDjuM.mp4/H-v4oraDjuM.mp4</video:content_loc><video:duration>264</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/derivative-properties-and-polynomial-derivatives</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1280224216.jpg</video:thumbnail_loc><video:title>Exploring basic derivative rules</video:title><video:description>Let&apos;s explore how to find the derivative of any polynomial using the power rule and additional properties. The derivative of a constant is always 0, and we can pull out a scalar constant when taking the derivative. Furthermore, the derivative of a sum of two functions is simply the sum of their derivatives.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/mzOBlH32qdk.mp4/mzOBlH32qdk.mp4</video:content_loc><video:duration>593</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/differentiating-linear-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x949b135c.jpg</video:thumbnail_loc><video:title>Applying basic derivative rules: find the error</video:title><video:description>We analyze two students&apos; attempts to differentiate linear functions using basic rules. One student forgets a negative sign, while another incorrectly assumes the derivative of a product equals the product of derivatives. By identifying common mistakes, we help improve our understanding of differentiation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4l_IvxXD9o8.mp4/4l_IvxXD9o8.mp4</video:content_loc><video:duration>286</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/derivative-properties-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6d547a43.jpg</video:thumbnail_loc><video:title>Applying basic derivative rules: table</video:title><video:description>Let&apos;s explore a problem involving two functions, f and g, and their derivatives at specific points. Our goal is to find the derivative of a new function, h(x), which is a combination of these functions: 3f(x)+2g(x). By applying basic derivative rules, we determine the derivative—and thus the slope of the tangent line—of h(x) at x = 9.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/rOftmuhGLjY.mp4/rOftmuhGLjY.mp4</video:content_loc><video:duration>540</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/differentiating-polynomials-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc6fb9f2b.jpg</video:thumbnail_loc><video:title>Differentiating polynomials</video:title><video:description>Let&apos;s explore how to differentiate polynomials using the power rule and derivative properties. We work with the function f(x)=x⁵+2x³-x² and apply the power rule to find its derivative, f&apos;(x)=5x⁴+6x²-2x. Next, we evaluate f&apos;(x) at x=2, determining that f&apos;(2)=100, which represents the rate of change or slope of the tangent line at the specified point.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-CTaxKTzbEI.mp4/-CTaxKTzbEI.mp4</video:content_loc><video:duration>399</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/negative-powers-differentiation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb74318e1.jpg</video:thumbnail_loc><video:title>Differentiating integer powers (mixed positive and negative)</video:title><video:description>Let&apos;s explore how to differentiate the function g(x) = 2/(x³) - 1/(x²) and evaluate the derivative at x = 2. By applying the Power Rule and simplifying, we efficiently find the slope of the tangent line at the given point.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/W233qRK6HPs.mp4/W233qRK6HPs.mp4</video:content_loc><video:duration>289</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/tangents-of-polynomials</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0cea991e.jpg</video:thumbnail_loc><video:title>Finding equations of tangents to polynomials</video:title><video:description>Let&apos;s explore the process of finding the equation of the tangent line to the graph of f(x) = x³ - 6x² + x - 5 at x = 1. By calculating the derivative and evaluating it at x = 1, we determine the slope and use point-slope form to obtain the tangent line equation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/j9FDoYNxZlw.mp4/j9FDoYNxZlw.mp4</video:content_loc><video:duration>282</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/derivatives-of-sinx-and-cosx</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe7075be468fa015c.jpg</video:thumbnail_loc><video:title>Exploring derivatives of sin(x) and cos(x)</video:title><video:description>Now we explore the intuition behind the derivatives of trigonometric functions, discovering that the derivative of sin(x) is cos(x) and the derivative of cos(x) is -sin(x). By analyzing tangent line slopes, we gain a deeper understanding of these fundamental relationships.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/UwFlrPNf5ZE.mp4/UwFlrPNf5ZE.mp4</video:content_loc><video:duration>221</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/sine-and-cosine-differentiation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0015df60.jpg</video:thumbnail_loc><video:title>Working an example: Derivatives of sin(x) and cos(x)</video:title><video:description>Dive into the derivative of the function g(x) = 7sin(x) - 3cos(x) - (π/∛x)². By applying the power rule and the derivatives of sine and cosine functions, we efficiently determine the derivative g&apos;(x) = 7cos(x) + 3sin(x) + 2π²/3 * x^(-5/3). Through algebraic manipulation and careful attention to detail, we tackle the problem&apos;s initially intimidating appearance.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Iur13MNO0Ro.mp4/Iur13MNO0Ro.mp4</video:content_loc><video:duration>314</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/derivative-of-ex</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x707a8c1550464685.jpg</video:thumbnail_loc><video:title>Finding the derivative of 𝑒ˣ</video:title><video:description>Discover the fascinating property of the derivative of 𝑒ˣ, which remains 𝑒ˣ after differentiation. This unique characteristic is central to our understanding and exploration of exponential functions, showcasing the remarkable nature of the number 𝑒.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/W_gNAjWWvBg.mp4/W_gNAjWWvBg.mp4</video:content_loc><video:duration>182</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/derivative-of-lnx</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd9664db59c1550c6.jpg</video:thumbnail_loc><video:title>Finding the derivative of ln(x)</video:title><video:description>Let&apos;s explore the concept that the derivative of ln(x) is 1/x by examining the slopes of tangent lines at various points on the graph of y=ln(x). We&apos;ll observe that the slopes match the values of 1/x, reinforcing the statement. A future video will provide a proof for this concept.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Qm1TDobNrns.mp4/Qm1TDobNrns.mp4</video:content_loc><video:duration>123</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/finding-limits-with-derivatives</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0ec8624760fbf06b.jpg</video:thumbnail_loc><video:title>Finding limits with derivatives</video:title><video:description>Use the definition of the derivative of a function whose derivative is known to determine a limit.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/aJ55LrZ_Vqw.mp4/aJ55LrZ_Vqw.mp4</video:content_loc><video:duration>133</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/applying-the-product-rule-for-derivatives</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1332054864.jpg</video:thumbnail_loc><video:title>Discovering the product rule</video:title><video:description>Discover the product rule, a fundamental technique for finding the derivative of a function expressed as a product of two functions. We&apos;ll learn how to apply this rule to simplify differentiation and enhance our understanding of calculus.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/79ngr0Bur38.mp4/79ngr0Bur38.mp4</video:content_loc><video:duration>160</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/differentiating-products</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc926838b.jpg</video:thumbnail_loc><video:title>Differentiating products</video:title><video:description>We explore the product rule by finding the derivative of eˣcos(x). We identify eˣ as the first function and cos(x) as the second, then apply the product rule to calculate the derivative, simplifying our result for a clearer understanding.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/WxTrxxW0qeM.mp4/WxTrxxW0qeM.mp4</video:content_loc><video:duration>268</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/product-rule-example-implicit</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf0f4ce72.jpg</video:thumbnail_loc><video:title>Working an example: Product rule with table</video:title><video:description>We explore how to evaluate the derivative of the product of two functions, f(x) and h(x), at x=3, using given values for f, h, and their derivatives. Applying the product rule, we calculate the derivative of f(x)⋅h(x) at x=3 with ease.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/SQUSh1LNjIo.mp4/SQUSh1LNjIo.mp4</video:content_loc><video:duration>189</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/product-rule-example-mixed-implicit-explicit</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x80b91d3f.jpg</video:thumbnail_loc><video:title>Working an example: Product rule with mixed implicit and explicit</video:title><video:description>We explore how to calculate the derivative of F(x) = f(x)⋅g(x) at x = -1, given the values of f and f&apos; at x = -1 and g(x) = 1/x. By applying the product rule, we efficiently determine F&apos;(x) and evaluate it at the specified point.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xioPD_ldZNY.mp4/xioPD_ldZNY.mp4</video:content_loc><video:duration>190</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/quotient-rule</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xef64cebda9ec86f4.jpg</video:thumbnail_loc><video:title>Discovering the quotient rule</video:title><video:description>Discover the quotient rule, a powerful technique for finding the derivative of a function expressed as a quotient. We&apos;ll explore how to apply this rule by differentiating the numerator and denominator functions, and then combining them to simplify the result.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/WqzY3xibFL8.mp4/WqzY3xibFL8.mp4</video:content_loc><video:duration>233</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/quotient-rule-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc807f948.jpg</video:thumbnail_loc><video:title>Working an example: Quotient rule with table</video:title><video:description>Let&apos;s explore how to find the derivative of F(x) = f(x)/g(x) at x = -1, given the values of f and f&apos; at x = -1 and g(x) = 2x³. By applying the quotient rule, we efficiently calculate the derivative, F&apos;(x), and evaluate it at the specified point.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ZAElYVh5DXU.mp4/ZAElYVh5DXU.mp4</video:content_loc><video:duration>351</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/rational-functions-differentiation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6df23c44.jpg</video:thumbnail_loc><video:title>Differentiating rational functions</video:title><video:description>Let&apos;s dive into the differentiation of the rational function (5-3x)/(x²+3x) using the Quotient Rule. By identifying the numerator and denominator as separate functions, we apply the Quotient Rule to find the derivative, simplifying the expression for a clear understanding of the process. This approach can be applied to differentiate any other rational function as well.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/wjm5ZYZ4hj8.mp4/wjm5ZYZ4hj8.mp4</video:content_loc><video:duration>404</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/derivatives-of-tanx-and-cotx</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x19c6a074.jpg</video:thumbnail_loc><video:title>Finding derivatives of tan(x) and cot(x)</video:title><video:description>We find the derivatives of tan(x) and cot(x) by rewriting them as quotients of sin(x) and cos(x). Using the quotient rule, we determine that the derivative of tan(x) is sec^2(x) and the derivative of cot(x) is -csc^2(x). This process involves applying the Pythagorean identity to simplify final results.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Rr_1GQyiRYs.mp4/Rr_1GQyiRYs.mp4</video:content_loc><video:duration>278</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/derivatives-of-secx-and-cscx</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x813a440b.jpg</video:thumbnail_loc><video:title>Finding derivatives of sec(x) and csc(x)</video:title><video:description>Let&apos;s explore the derivatives of sec(x) and csc(x) by expressing them as 1/cos(x) and 1/sin(x), respectively, and applying the quotient rule. We discover that the derivative of sec(x) can be written as sin(x)/cos²(x) or tan(x)sec(x), and the derivative of csc(x) can be expressed as -cos(x)/sin²(x) or -cot(x)csc(x).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TDJ5nXWEkWM.mp4/TDJ5nXWEkWM.mp4</video:content_loc><video:duration>268</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/differentiability-implies-continuity</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x428a8acc.jpg</video:thumbnail_loc><video:title>Exploring the proof: Differentiability implies continuity</video:title><video:description>We explore the connection between differentiability and continuity, demonstrating that if a function is differentiable at a point, it must also be continuous at that point. By examining the properties of limits and using algebra, we prove this relationship for a function at a given point.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/eytyVWA5ZQs.mp4/eytyVWA5ZQs.mp4</video:content_loc><video:duration>700</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/is-the-power-rule-reasonable</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1280226135.jpg</video:thumbnail_loc><video:title>Justifying the power rule</video:title><video:description>Let&apos;s explore the power rule&apos;s validity by examining the derivatives of x¹ and x². We&apos;ll analyze the slopes of tangent lines for these functions and then see how the power rule provides reasonable results, building our confidence in its usefulness.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/BYTfCnR9Sl0.mp4/BYTfCnR9Sl0.mp4</video:content_loc><video:duration>402</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/proof-d-dx-x-n</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24124.jpg</video:thumbnail_loc><video:title>Proving the power rule for positive integer powers</video:title><video:description>We dive into proving the formula for the derivative of x^n by skillfully applying the binomial theorem. Together, we expand (x + Δx)^n, simplify the expression, and take the limit as Δx approaches zero to reveal the power rule for derivatives.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/dZnc3PtNaN4.mp4/dZnc3PtNaN4.mp4</video:content_loc><video:duration>423</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/proof-d-dx-sqrt-x</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24126.jpg</video:thumbnail_loc><video:title>Proving the power rule for the square root function</video:title><video:description>We explore a proof of the power rule for the special case when n=½, focusing on the derivative of √x. By applying the definition of a derivative and utilizing the conjugate, we demonstrate that the power rule holds true for this specific case.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/789aMeepbxI.mp4/789aMeepbxI.mp4</video:content_loc><video:duration>307</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/derivative-of-sin-x</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x58015703874630dc.jpg</video:thumbnail_loc><video:title>Proving the derivative of sin(x)</video:title><video:description>Let&apos;s dive into the proof that the derivative of sin(x) equals cos(x). By applying angle addition formulas, the squeeze theorem, and exploring the concept of limits, we unravel this interesting proof. This exploration not only solidifies our understanding, but also equips us to handle more complex derivatives in the future.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/HVvCbnrUxek.mp4/HVvCbnrUxek.mp4</video:content_loc><video:duration>352</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/derivative-of-cos-x</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x15e2d5aca402cdb0.jpg</video:thumbnail_loc><video:title>Proving the derivative of cos(x)</video:title><video:description>Let&apos;s leverage our understanding that the derivative of sin(x) equals cos(x) to visually demonstrate that the derivative of cos(x) equals -sin(x). By strategically shifting graphs and applying trigonometric identities, we&apos;ll establish a strong visual argument, deepening our comprehension of these key calculus concepts.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PszFmdiMUcs.mp4/PszFmdiMUcs.mp4</video:content_loc><video:duration>198</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/product-rule-proof</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd4dbda2d.jpg</video:thumbnail_loc><video:title>Proving the product rule</video:title><video:description>Let&apos;s delve into the proof of the product rule, a key concept in calculus. We apply the definition of a derivative to the product of two functions, making sense of this rule. Through smart algebraic manipulation, we arrive at the classic product rule formula.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/L5ErlC0COxI.mp4/L5ErlC0COxI.mp4</video:content_loc><video:duration>566</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/estimating-rate-of-change-2011-ap-calculus-ab-free-response-2a</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe1fed4290b5bf938.jpg</video:thumbnail_loc><video:title>Estimating rate of change 2011 AP Calculus AB free response 2a</video:title><video:description>Estimating rate of change using a table.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gXVKbTwricA.mp4/gXVKbTwricA.mp4</video:content_loc><video:duration>216</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/writing-equation-of-tangent-line-ap-calculus-ab-free-response-2011-3a</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3e1d1ce7afa6ae82.jpg</video:thumbnail_loc><video:title>Writing equation of tangent line AP Calculus AB free response 2011 3a</video:title><video:description>Writing the equation of a tangent line given a function and an x-value.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-KaohGMliAU.mp4/-KaohGMliAU.mp4</video:content_loc><video:duration>179</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/2015-ap-calculus-abbc-3a</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5356f90d.jpg</video:thumbnail_loc><video:title>Estimating rate of change: 2015 AP Calculus AB/BC 3a</video:title><video:description>Estimating acceleration</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/sdFT_8AJsy0.mp4/sdFT_8AJsy0.mp4</video:content_loc><video:duration>349</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/2015-ap-calculus-ab-6a</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3c9aaf26.jpg</video:thumbnail_loc><video:title>Writing equation of tangent line: 2015 AP Calculus AB 6a</video:title><video:description>Equation for tangent line</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4ThUMRAvUkY.mp4/4ThUMRAvUkY.mp4</video:content_loc><video:duration>148</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/using-the-quotient-rule-2016-calculus-ab-free-response-6b</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf48db77409954f3c.jpg</video:thumbnail_loc><video:title>Using the quotient rule, 2016 Calculus AB free response 6b</video:title><video:description>Demonstrate how to apply the quotient rule to find the first derivative of a function. All the values necessary to find the value of the derivative are found in the table that is given in the stem, 2016 Calculus AB free response 6b.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5RJZhyeUuHk.mp4/5RJZhyeUuHk.mp4</video:content_loc><video:duration>173</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/using-average-rate-of-change-and-first-derivative-2018-calculus-ab-free-response</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xaabc4b1438ae3762.jpg</video:thumbnail_loc><video:title>Using average rate of change and first derivative, 2018 Calculus AB free response 5a,b</video:title><video:description>Calculate the average rate of change on an interval, determine the equation for the first derivative using the product rule, and use the first derivative to determine the slope of a line tangent to a graph at a given point, 2018 Calculus AB free response 5a,b.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/zXfGK-Eh4c0.mp4/zXfGK-Eh4c0.mp4</video:content_loc><video:duration>233</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/relating-derivative-to-tangent-line-2019-calculus-ab-free-response-6ab</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x701e098ed14f048f.jpg</video:thumbnail_loc><video:title>Relating derivative to tangent line, 2019 Calculus AB free response 6a,b</video:title><video:description>The relationship between the value of the first derivative of a function at a point and the slope of the tangent line, and how to use the product rule, 2019 Calculus AB free response 6a,b.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/w_hXTuSwNJ4.mp4/w_hXTuSwNJ4.mp4</video:content_loc><video:duration>252</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/determining-when-first-derivative-equals-average-rate-of-change-2025-calculus-ab</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x255cc3edab9361b3.jpg</video:thumbnail_loc><video:title>Determining when first derivative equals average rate of change, 2025 Calculus AB free response 1b</video:title><video:description>Calculate the average rate of change, and the relationship between the first derivative and instantaneous rate of change, 2025 Calculus AB free response 1b.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/HDwfKnZ5A2U.mp4/HDwfKnZ5A2U.mp4</video:content_loc><video:duration>427</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/chain-rule-introduction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1332165556.jpg</video:thumbnail_loc><video:title>Using the chain rule</video:title><video:description>The chain rule states that the derivative of f(g(x)) is f&apos;(g(x))⋅g&apos;(x). In other words, it helps us differentiate *composite functions*. For example, sin(x²) is a composite function because it can be constructed as f(g(x)) for f(x)=sin(x) and g(x)=x². Using the chain rule and the derivatives of sin(x) and x², we can then find the derivative of sin(x²).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0T0QrHO56qg.mp4/0T0QrHO56qg.mp4</video:content_loc><video:duration>307</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/common-chain-rule-misunderstandings</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd1df901f5054119f.jpg</video:thumbnail_loc><video:title>Examining common chain rule misunderstandings</video:title><video:description>We tackle common misconceptions about the Chain Rule, ensuring we distinguish between product and composition of functions. We also emphasize the importance of fully applying the Chain Rule, and avoid the pitfall of taking the derivative of the outer function with respect to the derivative of the inner function.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/WVdPekbXSfE.mp4/WVdPekbXSfE.mp4</video:content_loc><video:duration>408</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/recognizing-compositions-of-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xec328d89b4ff5a8f.jpg</video:thumbnail_loc><video:title>Identifying composite functions</video:title><video:description>Now let&apos;s explore the world of composite functions, honing our skills at recognizing them in various forms. This understanding is crucial to get the most out of the Chain Rule. We&apos;ll explore how functions can be composed, and even how they can be expressed as products, setting a strong foundation for advanced calculus concepts.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/MT1-bqKpal8.mp4/MT1-bqKpal8.mp4</video:content_loc><video:duration>493</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/differentiating-composite-functions-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1c1ae57d.jpg</video:thumbnail_loc><video:title>Working an example: Derivative of cos³(x) using the chain rule</video:title><video:description>Now let&apos;s tackle a worked example of composite functions, using the example f(x) = cos³(x). By applying the chain rule, we differentiate this function, breaking it down into its components x³ and cos(x). This helps us understand how to handle other complex derivatives with ease.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/yAFphxolU5w.mp4/yAFphxolU5w.mp4</video:content_loc><video:duration>557</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/chain-rule-definition-and-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1331367901.jpg</video:thumbnail_loc><video:title>Working an example: Derivative of √(3x²-x) using the chain rule</video:title><video:description>Let&apos;s dive into the process of differentiating a composite function, specifically f(x)=sqrt(3x^2-x), using the chain rule. By breaking down the function into its components, sqrt(x) and 3x^2-x, we demonstrate how their derivatives work together to make differentiation easier.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/IiBC4ngwH6E.mp4/IiBC4ngwH6E.mp4</video:content_loc><video:duration>331</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/differentiating-composite-functions-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd528cea6.jpg</video:thumbnail_loc><video:title>Working an example: Derivative of ln(√x) using the chain rule</video:title><video:description>In this worked example, we dissect the composite function f(x)=ln(√x) into its parts, ln(x) and √x. By applying the chain rule, we successfully differentiate this function, providing a clear step-by-step process for finding the derivative of similar composite functions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/G2ZXpbMukEQ.mp4/G2ZXpbMukEQ.mp4</video:content_loc><video:duration>405</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/chain-rule-example-implicit</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x17495d13.jpg</video:thumbnail_loc><video:title>Working an example: Chain rule with table</video:title><video:description>Through a worked example, we explore the Chain rule with a table. Using specific x-values for functions f and g, and their derivatives, we collaboratively evaluate the derivative of a composite function F(x) = f(g(x)). By applying the chain rule, we illuminate the process, making it easy to understand.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/bLKTkM-w5ps.mp4/bLKTkM-w5ps.mp4</video:content_loc><video:duration>147</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/exponential-functions-differentiation-intro</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x43b56dc0.jpg</video:thumbnail_loc><video:title>Determining the derivative of aˣ (for any positive base a)</video:title><video:description>Let&apos;s dive deeper into the fascinating world of derivatives, specifically focusing on the derivative of aˣ for any positive base a. Using the derivative of eˣ and the chain rule, we unravel the mystery behind differentiating exponential functions. We then apply our newfound knowledge to differentiate the expression 8⋅3ˣ.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gHzLHknEk1M.mp4/gHzLHknEk1M.mp4</video:content_loc><video:duration>325</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/logarithmic-functions-differentiation-intro</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3d849d5f.jpg</video:thumbnail_loc><video:title>Determining the derivative of logₐx (for any positive base a≠1)</video:title><video:description>Now let&apos;s look into the fascinating world of logarithms, exploring how to find the derivative of logₐx for any positive base a≠1. Leveraging the derivative of ln(x) and the change of base rule, we successfully differentiate log₇x and -3log_π(x). Join us on this mathematical journey!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2XB4K6T-yKo.mp4/2XB4K6T-yKo.mp4</video:content_loc><video:duration>288</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/exponential-functions-differentiation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6bc656f4.jpg</video:thumbnail_loc><video:title>Working an example: Derivative of 7^(x²-x) using the chain rule</video:title><video:description>In this worked example we explore the process of differentiating the exponential function 7^(x²-x). We Leverage our previous understanding of the derivative of aˣ and the chain rule to unravel the complexities of this composite function to find its derivative.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/fqYds-feWcw.mp4/fqYds-feWcw.mp4</video:content_loc><video:duration>220</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/log-functions-differentiation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfad2980a.jpg</video:thumbnail_loc><video:title>Working an example: Derivative of log₄(x²+x) using the chain rule</video:title><video:description>Let&apos;s explore a worked example of differentiating the logarithmic function log₄(x²+x) using the chain rule. Leveraging our understanding of the derivative of logₐ(x), we simplify the complexities of composite functions, making differentiation more approachable and fun!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/WZPpbkVESVk.mp4/WZPpbkVESVk.mp4</video:content_loc><video:duration>250</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/trig-functions-differentiation-sec</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x08b4707d.jpg</video:thumbnail_loc><video:title>Working an example: Derivative of sec(3π/2-x) using the chain rule</video:title><video:description>We explore the fascinating process of differentiating the function sec(3π/2-x) in this worked example. Using the chain rule and trigonometric identities, we calculate the derivative and evaluate it at x=π/4. This problem illuminates the beauty of composite functions and their derivatives.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6QRtLh_THmo.mp4/6QRtLh_THmo.mp4</video:content_loc><video:duration>431</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/radical-functions-differentiation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xec617875.jpg</video:thumbnail_loc><video:title>Working an example: Derivative of ∜(x³+4x²+7) using the chain rule</video:title><video:description>Let&apos;s tackle the challenge of differentiating the fourth root of a polynomial expression in this worked example. Using the chain rule and the power rule, we simplify the complex function and evaluate the derivative at x=-3. Join us on this mathematical journey!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-_7td0mDbQs.mp4/-_7td0mDbQs.mp4</video:content_loc><video:duration>355</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/implicit-differentiation-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1335926801.jpg</video:thumbnail_loc><video:title>Exploring implicit differentiation</video:title><video:description>Some relationships cannot be represented by an explicit function. For example, x²+y²=1. Implicit differentiation helps us find ​dy/dx even for relationships like that. This is done using the chain ​rule, and viewing y as an implicit function of x. For example, according to the chain rule, the derivative of y² would be 2y⋅(dy/dx).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/mSVrqKZDRF4.mp4/mSVrqKZDRF4.mp4</video:content_loc><video:duration>482</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/implicit-derivative-of-x-y-2-x-y-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1309724635.jpg</video:thumbnail_loc><video:title>Working an example: Implicit differentiation</video:title><video:description>Using implicit differentiation, let&apos;s take on the challenge of the equation (x-y)² = x + y - 1 in this worked example. We utilize the chain rule and algebraic techniques to find the derivative of y with respect to x. This adventure deepens our grasp of how variables interact within intricate equations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9uxvm-USEYE.mp4/9uxvm-USEYE.mp4</video:content_loc><video:duration>296</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/finding-slope-of-tangent-line-with-implicit-differentiation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1336152047.jpg</video:thumbnail_loc><video:title>Working an example: Evaluating derivative with implicit differentiation</video:title><video:description>Uncover the process of calculating the slope of a tangent line at a specific point on a curve using implicit differentiation. We navigate through the steps of finding the derivative, substituting values, and simplifying to reveal the slope at x=1 for the curve x²+(y-x)³=28.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/KyYC8XzKsHU.mp4/KyYC8XzKsHU.mp4</video:content_loc><video:duration>325</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/showing-explicit-and-implicit-differentiation-give-same-result</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1336144047.jpg</video:thumbnail_loc><video:title>Showing explicit and implicit differentiation give same result</video:title><video:description>Discover the fascinating connection between implicit and explicit differentiation! In this video we&apos;ll explore a simple equation, unravel it using both methods, and find that they both lead us to the same derivative. This engaging journey demonstrates the versatility and consistency of calculus.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2CsQ_l1S2_Y.mp4/2CsQ_l1S2_Y.mp4</video:content_loc><video:duration>468</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/derivatives-of-inverse-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc6bf99923afd4174.jpg</video:thumbnail_loc><video:title>Exploring the derivatives of inverse functions</video:title><video:description>Explore the intriguing connection between inverse functions and their derivatives. We delve into the unique relationship that exists when f(g(x))=x=g(f(x)), using the functions 𝑒ˣ and ln(x) as examples. Uncover how this principle can help us understand the derivatives of these inverses in a new light.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/XOs9vVmzE70.mp4/XOs9vVmzE70.mp4</video:content_loc><video:duration>286</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/derivatives-of-inverse-functions-implicit</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x60332421.jpg</video:thumbnail_loc><video:title>Exploring the derivatives of inverse functions: from equations</video:title><video:description>Let&apos;s explore the intriguing relationship between a function and its inverse, focusing on the function f(x)=½x³+3x-4. We delve into the derivative of the inverse of f, applying the chain rule and the power rule to evaluate it at x=-14. Join us as we unravel this complex calculus concept.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/UBctoCirje0.mp4/UBctoCirje0.mp4</video:content_loc><video:duration>304</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/derivatives-of-inverse-functions-table</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x21b6e9c4.jpg</video:thumbnail_loc><video:title>Exploring the derivatives of inverse functions: from tables</video:title><video:description>Let&apos;s delve into the fascinating realm of inverse functions, exploring how to evaluate the derivative of an inverse function, h&apos;, at a specific x-value. Using a provided table of values for function g, its inverse h, and its derivative g&apos;, we unravel the mystery of h&apos; using the chain rule and the concept of inverse functions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9Eg97Rtg-pE.mp4/9Eg97Rtg-pE.mp4</video:content_loc><video:duration>312</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/derivative-inverse-sine</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x27ff4cd3.jpg</video:thumbnail_loc><video:title>Determining the derivative of inverse sine</video:title><video:description>Unlock the mystery of the derivative of inverse sine! Let&apos;s dive into the world of calculus, rearranging equations and applying implicit differentiation to find the derivative of y with respect to x. Using trigonometric identities, we transform the derivative into a function of x, revealing a fascinating relationship.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/yIQUhXa-n-M.mp4/yIQUhXa-n-M.mp4</video:content_loc><video:duration>296</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/derivative-inverse-cosine</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb6e07b84.jpg</video:thumbnail_loc><video:title>Determining the derivative of inverse cosine</video:title><video:description>Unraveling the mystery of the inverse cosine function, we find its derivative equals -1/(sqrt(1 - x^2)). This step-by-step proof guides us to a fascinating comparison with the derivative of inverse sine, revealing a captivating connection between these two trigonometric functions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/v_OfFmMRvOc.mp4/v_OfFmMRvOc.mp4</video:content_loc><video:duration>224</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/derivative-inverse-tangent</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x44778b77.jpg</video:thumbnail_loc><video:title>Determining the derivative of inverse tangent</video:title><video:description>Now let&apos;s explore the derivative of the inverse tangent function. Starting with the derivative of tangent, we use the chain rule and trigonometric identities to find the derivative of its inverse. Join us as we investigate this fascinating mathematical process!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/G7WyEp8gHs0.mp4/G7WyEp8gHs0.mp4</video:content_loc><video:duration>362</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/correcting-work-on-derivative-strategies</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x837229133733f991.jpg</video:thumbnail_loc><video:title>Differentiating functions: Find the error</video:title><video:description>Let&apos;s delve into the process of differentiating functions, analyzing student work for potential errors. Our focus is on the correct application of the product, chain, and quotient rules. This exploration underscores the crucial role these rules play in calculus, enhancing our grasp of differentiation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1l4mmTSIbvU.mp4/1l4mmTSIbvU.mp4</video:content_loc><video:duration>639</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/strategies-applying-derivative-rules</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4a3a5f3dfd06dfa8.jpg</video:thumbnail_loc><video:title>Manipulating functions before differentiation</video:title><video:description>Let&apos;s explore how manipulating functions before differentiating can make our calculus journey smoother and quicker. By tweaking our functions a bit, we can make differentiation less complex. We&apos;ll walk through several examples, showing how a touch of algebra can go a long way!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/AntQBDFOjUw.mp4/AntQBDFOjUw.mp4</video:content_loc><video:duration>680</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/disguised-derivatives</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3b58cdbf.jpg</video:thumbnail_loc><video:title>Exploring disguised derivatives</video:title><video:description>We tackle a complex limit expression, viewing it as 5 times the derivative of log(x) when x=2. This perspective enables us to evaluate the limit using differentiation rules, providing a simpler alternative to direct limit analysis. Together, let&apos;s navigate this challenging problem.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/fUWn_SJSLBk.mp4/fUWn_SJSLBk.mp4</video:content_loc><video:duration>273</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/differentiating-using-multiple-rules-strategy</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x34eb537c5c891863.jpg</video:thumbnail_loc><video:title>Differentiating using multiple rules: strategy</video:title><video:description>Let&apos;s explore how to break down complex expressions and determine the right derivative rules to apply. We&apos;ll learn how to identify the structure of these expressions and decide the order of operations, using the chain rule and product rule. This strategy will help us tackle even the most elaborate expressions with confidence.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Qgj2_4r3VBs.mp4/Qgj2_4r3VBs.mp4</video:content_loc><video:duration>347</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/applying-the-chain-rule-and-product-rule</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1f82ad74663177f8.jpg</video:thumbnail_loc><video:title>Applying the chain rule and product rule</video:title><video:description>Let&apos;s explore multiple strategies to tackle derivatives involving both the product and chain rules. We start by applying the chain rule first, then the product rule. Next, we switch it up, using the product rule first, then the chain rule. Discover how these different approaches lead us to the same answer, demonstrating the flexibility and interconnectedness of these mathematical rules.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/QqAPCIIdx-E.mp4/QqAPCIIdx-E.mp4</video:content_loc><video:duration>354</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/applying-chain-rule-twice</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8f0090e095853d20.jpg</video:thumbnail_loc><video:title>Applying the chain rule twice</video:title><video:description>Unravel the intricacies of applying the chain rule twice in a single problem. We&apos;ll dissect the process of finding the derivative of a function like sin(x^2)^3, demonstrating the power and adaptability of the chain rule when used not just once, but twice!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/eY1LuoSfiys.mp4/eY1LuoSfiys.mp4</video:content_loc><video:duration>190</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/using-the-product-rule-and-the-chain-rule</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1334798762.jpg</video:thumbnail_loc><video:title>Determining the derivative of eᶜᵒˢˣ⋅cos(eˣ)</video:title><video:description>By applying both the product and chain rule, we tackle the task of differentiating the function eᶜᵒˢˣ⋅cos(eˣ). This exercise not only provides us with a solution to this complex problem, but also deepens our understanding of these fundamental calculus techniques, reinforcing the importance of these rules in the broader context of calculus.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/UXQGzgPf1LE.mp4/UXQGzgPf1LE.mp4</video:content_loc><video:duration>352</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/chain-rule-with-triple-composition</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1332001812.jpg</video:thumbnail_loc><video:title>Determining the derivative of sin(ln(x²))</video:title><video:description>We apply the chain rule twice to differentiate sin(ln(x²)), breaking down this composite function into simpler elements. This double application allows us to handle the complexity of the function, turning it into manageable parts. Together, we&apos;ll tackle this mathematical task with precision and clarity.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1015d63VKh4.mp4/1015d63VKh4.mp4</video:content_loc><video:duration>292</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/second-derivatives</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf0d302c5.jpg</video:thumbnail_loc><video:title>Exploring second derivatives</video:title><video:description>We dive into the fascinating realm of second derivatives, starting with the function y=6/x². Together, we apply the power rule to find the first derivative, then repeat the process to reveal the second derivative. This journey illuminates how we can use mathematical tools to uncover deeper layers of a function&apos;s behavior.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/WC5VYKI807Q.mp4/WC5VYKI807Q.mp4</video:content_loc><video:duration>147</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/finding-second-derivative-implicit</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbcaed91db72d24e2.jpg</video:thumbnail_loc><video:title>Exploring second derivatives (implicit equations): find expression</video:title><video:description>Let&apos;s explore the process of determining the second derivative of y with respect to x from an implicit equation. Using implicit differentiation, we apply the chain rule and quotient rule. This leads us to a simplified expression for the second derivative in terms of x and y.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/oPijG5Bfemg.mp4/oPijG5Bfemg.mp4</video:content_loc><video:duration>287</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/evaluating-second-derivative-implicit</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6c67e58001ee1c64.jpg</video:thumbnail_loc><video:title>Exploring second derivatives (implicit equations): evaluate derivative</video:title><video:description>We tackle the challenge of implicit differentiation, using an equation in x and y to find the first derivative. Then, we step it up a notch by evaluating the second derivative at a specific point. All this is based on a problem from the 2015 AP Calculus AB exam.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/komjMq5jm9k.mp4/komjMq5jm9k.mp4</video:content_loc><video:duration>290</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/change-in-continuous-function-approaches-0</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdadf5f63.jpg</video:thumbnail_loc><video:title>Exploring if function u is continuous at x, then Δu→0 as Δx→0</video:title><video:description>Let&apos;s explore the fascinating relationship between changes in function values and x-values. When we have a continuous function, we discover that as the change in x-values (Δx) nears zero, the change in the function&apos;s values (Δu) also tends towards zero. This insight offers us a unique way to understand continuity.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/l6T4RhlgkG0.mp4/l6T4RhlgkG0.mp4</video:content_loc><video:duration>385</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/chain-rule-proof</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb6e914af.jpg</video:thumbnail_loc><video:title>Proving the chain rule</video:title><video:description>Let&apos;s explore the proof of the chain rule, using the formal properties of continuity and differentiability. This proof helps us to more deeply understand this fundamental concept. In making sense of the chain rule, we turn it into a powerful tool in our mathematical toolkit.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/FKraGDm2fUY.mp4/FKraGDm2fUY.mp4</video:content_loc><video:duration>340</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/quotient-rule-from-product-rule</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1332076874.jpg</video:thumbnail_loc><video:title>Exploring the quotient rule from product and chain rules</video:title><video:description>We explore the connection between the quotient rule, product rule, and chain rule in calculus. Rather than memorizing another rule, we see how the quotient rule naturally emerges from applying the product and chain rules. This approach simplifies our understanding of these fundamental calculus tools.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ho87DN9wO70.mp4/ho87DN9wO70.mp4</video:content_loc><video:duration>315</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/2015-ap-calculus-ab-6c</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x82672503.jpg</video:thumbnail_loc><video:title>Differentiating implicitly: 2015 AP Calculus AB 6c</video:title><video:description>Finding second derivative through implicit differentiation</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qSb78ptLZU0.mp4/qSb78ptLZU0.mp4</video:content_loc><video:duration>377</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/using-the-chain-rule-2017-calculus-ab-free-response-6abc</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x71a2abdd5772cc84.jpg</video:thumbnail_loc><video:title>Using the chain rule, 2017 Calculus AB free response 6a,b,c</video:title><video:description>Determine the slope of a line tangent to the graph of a function (which involves using the chain rule), and evaluate the first derivative of a function using the chain rule, 2017 Calculus AB free response 6a,b,c.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/IeCRLXKu2Lk.mp4/IeCRLXKu2Lk.mp4</video:content_loc><video:duration>552</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/applying-implicit-differentiation-2023-calculus-ab-free-response-6a</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe260ce5c53b4a4a2.jpg</video:thumbnail_loc><video:title>Applying implicit differentiation, 2023 Calculus AB free response 6a</video:title><video:description>Use implicit differentiation to find the first derivative of an equation, 2023 Calculus AB free response 6a.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/13kB8wPSiuo.mp4/13kB8wPSiuo.mp4</video:content_loc><video:duration>202</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/interpreting-the-meaning-of-the-derivative-in-context</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x926ec566b9e26d0d.jpg</video:thumbnail_loc><video:title>Interpreting the meaning of the derivative in context</video:title><video:description>Let&apos;s get hands-on with the concept of derivatives! We&apos;ll learn how to interpret the meaning of a derivative within a real-world context, turning complex calculus into practical applications. We&apos;ll see how derivatives can effectively express rates of change and motion in our everyday lives.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/IElkjzC9YhQ.mp4/IElkjzC9YhQ.mp4</video:content_loc><video:duration>293</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/one-dimensional-motion-with-calculus</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x36586540e4f670e8.jpg</video:thumbnail_loc><video:title>Introducing one-dimensional motion with calculus</video:title><video:description>Let&apos;s explore one-dimensional motion! We&apos;ll use calculus to connect position, velocity, speed, and acceleration. By understanding how position changes over time, we&apos;ll gain insights into the intricate dynamics of straight-line motion. It&apos;s all about making sense of movement in a one-dimensional world!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/MFrpe4Wm8-g.mp4/MFrpe4Wm8-g.mp4</video:content_loc><video:duration>391</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/interpreting-direction-from-position-time</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4c422f7b71d9d21d.jpg</video:thumbnail_loc><video:title>Interpreting direction of motion from position-time graph</video:title><video:description>Given the position-time graph of a linear motion, we can interpret whether the moving object moves forward or backward (or right or left, depending on how we define the motion!).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PNBJQ2OtS_4.mp4/PNBJQ2OtS_4.mp4</video:content_loc><video:duration>159</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/interpreting-direction-from-velocity-time</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9c2767f4bc513a73.jpg</video:thumbnail_loc><video:title>Interpreting direction of motion from velocity-time graph</video:title><video:description>Let&apos;s explore how a velocity-time graph can reveal the direction of an object&apos;s linear motion. We&apos;ll decipher whether the object is moving forward or backward, or even right or left, based on the graph&apos;s details. Together, we&apos;ll make sense of these intriguing mathematical representations of motion.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lsufpQEVHZ8.mp4/lsufpQEVHZ8.mp4</video:content_loc><video:duration>106</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/interpreting-speed-from-velocity-time</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2b01a75d8d96b72c.jpg</video:thumbnail_loc><video:title>Interpreting change in speed from velocity-time graph</video:title><video:description>Let&apos;s examine a velocity-time graph to understand an object&apos;s motion. By distinguishing between positive and negative slopes, we discern whether the object is speeding up, slowing down, or maintaining its speed. It&apos;s a practical application of calculus concepts to real-world motion scenarios!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pp08hpkTN-o.mp4/pp08hpkTN-o.mp4</video:content_loc><video:duration>237</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/motion-problems-with-derivatives</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf18565f55a7b2a76.jpg</video:thumbnail_loc><video:title>Working an example: Motion problems with derivatives</video:title><video:description>Join us as we explore the relationship between position, velocity, and acceleration for a particle moving along the x-axis. We&apos;ll calculate velocity and acceleration from a given position function, and interpret these values to understand the particle&apos;s direction of motion and changes in speed. It&apos;s another practical application of calculus to real-world motion problems!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/b4w0xmuOiQo.mp4/b4w0xmuOiQo.mp4</video:content_loc><video:duration>298</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/modeling-a-forgetting-curve</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1c23041a.jpg</video:thumbnail_loc><video:title>Exploring applied rate of change: forgetfulness</video:title><video:description>Let&apos;s face it—sometimes we forget things! Ever wonder about the dynamics underpinning this phenomenon? Let&apos;s explore this by tracking the number of vocabulary words remembered over time. Together, we&apos;ll use a mathematical model to calculate the rate of change in our memory, revealing the fascinating dynamics of knowledge retention and loss.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/WbyODj_OiZU.mp4/WbyODj_OiZU.mp4</video:content_loc><video:duration>300</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/derivative-and-marginal-cost</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa93afa81.jpg</video:thumbnail_loc><video:title>Examining marginal cost and differential calculus</video:title><video:description>Through the lens of economics, we examine how the derivative can be used as a tool to understand marginal cost. We&apos;ll use a factory scenario to see how cost changes with quantity, and how this insight informs production decisions. Calculus—in real life!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Wkjz1LlX1CQ.mp4/Wkjz1LlX1CQ.mp4</video:content_loc><video:duration>280</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/rates-of-change-between-radius-and-area-of-circle</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1339382000.jpg</video:thumbnail_loc><video:title>Introducing related rates</video:title><video:description>Join us as we explore the intriguing relationship between the rate at which a circle&apos;s radius expands and the corresponding rate of area growth. Using the tools of calculus, specifically derivatives, we&apos;ll tackle this concept, providing a practical application to real-world problems involving rates of change. This understanding forms a key part of mastering calculus and its applications.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/kQF9pOqmS0U.mp4/kQF9pOqmS0U.mp4</video:content_loc><video:duration>463</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/analyzing-related-rates-problems-expressions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x54c311a6a4dfe567.jpg</video:thumbnail_loc><video:title>Analyzing related rates problems: expressions</video:title><video:description>Grasping related rates problems starts with understanding the quantities involved. In this exploration, we&apos;ll identify these quantities, match each expression with its units and values, and use this information to confidently tackle these problems. It&apos;s all about making sense of the relationships and changes over time.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TX69hjJpBFk.mp4/TX69hjJpBFk.mp4</video:content_loc><video:duration>487</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/analyzing-related-rates-problems-equations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8b79a8b9220004e6.jpg</video:thumbnail_loc><video:title>Analyzing related rates problems: equations (Pythagoras)</video:title><video:description>Mastering related rates problems hinges on the careful selection of an equation that accurately links the quantities. We&apos;ll illustrate this with a diagram, emphasizing the role of the right equation in solving these problems and understanding the interplay of quantities over time.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hFRQBhHdINM.mp4/hFRQBhHdINM.mp4</video:content_loc><video:duration>215</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/related-rates-example-with-trigonometry</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x16eb78b269660673.jpg</video:thumbnail_loc><video:title>Analyzing related rates problems: equations (trig)</video:title><video:description>Let&apos;s tackle a practical problem involving a ladder sliding down a wall. We&apos;ll examine how the changing position of the ladder influences the angle it makes with the ground. We&apos;ll use calculus to calculate the rate of change of this angle. It&apos;s a hands-on way to see calculus in action!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/XwEGKNPLQfQ.mp4/XwEGKNPLQfQ.mp4</video:content_loc><video:duration>481</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/differentiating-related-functions-intro</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6086e3c067b3b3de.jpg</video:thumbnail_loc><video:title>Differentiating related functions intro</video:title><video:description>In this video, we explore how to differentiate related functions. We&apos;ll use the chain rule to find the derivatives of these functions, all linked to the same variable. It&apos;s a cool way to see how changes in one function can affect another.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Mj_2fVKWa0k.mp4/Mj_2fVKWa0k.mp4</video:content_loc><video:duration>204</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/differentiating-related-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x322654ab7f8eebbd.jpg</video:thumbnail_loc><video:title>Working an example: Differentiating related functions</video:title><video:description>In this video, we tackle a fascinating problem involving related functions. We&apos;ll explore how to use implicit differentiation to find the derivatives of these functions with respect to a shared variable. By the end, we&apos;ll have a clear understanding of how these functions interact and change together.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/C3MI_mspN3o.mp4/C3MI_mspN3o.mp4</video:content_loc><video:duration>472</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/rate-of-change-of-distance-between-approaching-cars</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1353379359.jpg</video:thumbnail_loc><video:title>Exploring related rates: Approaching cars</video:title><video:description>In this video, we explore the fascinating world of related rates with two cars approaching an intersection. We&apos;ll figure out how the rate of change of the distance between the two cars changes as they move. It&apos;s a real-world application of math that shows how calculus helps us understand motion and rates of change.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/wV59XWLmv0c.mp4/wV59XWLmv0c.mp4</video:content_loc><video:duration>413</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/falling-ladder-related-rates</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1339617514.jpg</video:thumbnail_loc><video:title>Exploring related rates: Falling ladder</video:title><video:description>Let&apos;s explore a thrilling real-world scenario in this video: a ladder slipping away from a wall! We&apos;ll use related rates to calculate how fast the top of the ladder falls. It&apos;s a fun and practical application of calculus that&apos;ll keep us on our toes.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/kBVDSu7v8os.mp4/kBVDSu7v8os.mp4</video:content_loc><video:duration>349</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/related-rates-of-water-pouring-into-cone</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1339646438.jpg</video:thumbnail_loc><video:title>Exploring related rates: water pouring into a cone</video:title><video:description>In this video, we explore an intriguing scenario where we pour water into a cone-shaped cup at a constant rate. We&apos;ll discover how the rate of change in the water&apos;s depth connects to the rate of change in volume, all with the help of our new related rates tools.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Xe6YlrCgkIo.mp4/Xe6YlrCgkIo.mp4</video:content_loc><video:duration>692</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/speed-of-shadow-of-diving-bird</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1353395672.jpg</video:thumbnail_loc><video:title>Exploring related rates: shadow</video:title><video:description>Let&apos;s take a look at a problem involving an owl hunting a mouse and the shadow it casts. We can use calculus to determine how fast the shadow moves as the owl dives towards its prey. It&apos;s a real-world application of related rates that brings the concept to life!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/cPOjnyjii-4.mp4/cPOjnyjii-4.mp4</video:content_loc><video:duration>639</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/rate-of-change-of-balloon-height</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1341818796.jpg</video:thumbnail_loc><video:title>Exploring related rates: balloon</video:title><video:description>Let&apos;s imagine we&apos;re at a hot air balloon show, and we&apos;re tracking a balloon&apos;s ascent. Using our knowledge of angles, distances, and related rates we can apply trigonometry and calculus to find the rate of change in the balloon&apos;s height.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_kbd6troMgA.mp4/_kbd6troMgA.mp4</video:content_loc><video:duration>497</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/local-linearization-intro</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1822071e.jpg</video:thumbnail_loc><video:title>Introducing local linearity</video:title><video:description>Sal introduces the idea of approximating curves using their tangent line equations. This is also called &quot;local linearization.&quot;</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/u7dhn-hBHzQ.mp4/u7dhn-hBHzQ.mp4</video:content_loc><video:duration>578</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/local-linearity-and-differentiability</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfb771e9ced51a63c.jpg</video:thumbnail_loc><video:title>Relating local linearity and differentiability</video:title><video:description>Intuition for how local linearity relates to differentiability using the Desmos graphing calculator.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/h2lARdo7Xko.mp4/h2lARdo7Xko.mp4</video:content_loc><video:duration>390</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/approximation-with-local-linearity</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x35355b305a3b40be.jpg</video:thumbnail_loc><video:title>Working an example: Approximation with local linearity</video:title><video:description>Finding the equation of a tangent line at a point of a curve by knowing the derivative at that point. Then using that equation to approximate the value of the function at close by x-values.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/wdQRY3Er7PE.mp4/wdQRY3Er7PE.mp4</video:content_loc><video:duration>215</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/linear-approximation-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xac8728bc.jpg</video:thumbnail_loc><video:title>Using linear approximation of a rational function</video:title><video:description>Sal finds a linear expression that approximates y=1/(x-1) around x=-1. This is done by finding the equation of the line tangent to the graph at x=-1, a process called &quot;linear approximation.&quot;</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vRw4ovZK1CQ.mp4/vRw4ovZK1CQ.mp4</video:content_loc><video:duration>431</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/introduction-to-l-hopital-s-rule</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/27376.jpg</video:thumbnail_loc><video:title>Introducing L&apos;Hôpital&apos;s rule</video:title><video:description>When you are solving a limit, and get 0/0 or ∞/∞, L&apos;Hôpital&apos;s rule is the tool you need.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PdSzruR5OeE.mp4/PdSzruR5OeE.mp4</video:content_loc><video:duration>531</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/l-hopital-s-rule-example-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/27377.jpg</video:thumbnail_loc><video:title>Applying L&apos;Hôpital&apos;s rule: limit at 0 example</video:title><video:description>Sal uses L&apos;Hôpital&apos;s rule to find the limit at 0 of (2sin(x)-sin(2x))/(x-sin(x)).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/BiVOC3WocXs.mp4/BiVOC3WocXs.mp4</video:content_loc><video:duration>463</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/l-hopital-s-rule-example-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/27378.jpg</video:thumbnail_loc><video:title>Applying L&apos;Hôpital&apos;s rule: limit at infinity example</video:title><video:description>Sal uses L&apos;Hôpital&apos;s rule to find the limit at infinity of (4x²-5x)/(1-3x²).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/FJo18AwLfuI.mp4/FJo18AwLfuI.mp4</video:content_loc><video:duration>315</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/proof-of-special-case-of-l-hopital-s-rule</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1383606650.jpg</video:thumbnail_loc><video:title>Proving a special case of l&apos;Hôpital&apos;s rule</video:title><video:description>This isn&apos;t a full proof of L&apos;Hopital&apos;s rule, but it should give some intuition for why it works.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/SIB4WDYF5DQ.mp4/SIB4WDYF5DQ.mp4</video:content_loc><video:duration>321</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/2011-calculus-ab-free-response-1a</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/244051678.jpg</video:thumbnail_loc><video:title>Analyzing speed of a particle: 2011 Calculus AB free response #1a</video:title><video:description>Determining whether speed is increasing. Difference between speed and acceleration</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ppBJWf_Wdmc.mp4/ppBJWf_Wdmc.mp4</video:content_loc><video:duration>448</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/2011-calculus-ab-free-response-5a</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/238520370.jpg</video:thumbnail_loc><video:title>Using tangent line for approximation: 2011 Calculus AB free response #5a</video:title><video:description>Using a tangent line to extrapolate a function from a known initial condition</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/n9UvuzI2fq0.mp4/n9UvuzI2fq0.mp4</video:content_loc><video:duration>419</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/estimating-rate-of-change-2015-ap-calculus-ab-bc-1b</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x12330977f2e83320.jpg</video:thumbnail_loc><video:title>Estimating rate of change 2015 AP Calculus AB BC 1b</video:title><video:description>Estimating a rate of change based on given functions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PTWT41LmPl8.mp4/PTWT41LmPl8.mp4</video:content_loc><video:duration>228</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/2015-ap-calculus-2c</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb51b7830.jpg</video:thumbnail_loc><video:title>Finding rate of change: 2015 AP Calculus 2c</video:title><video:description>Rate of change of difference between functions</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Ncv6gt2Luew.mp4/Ncv6gt2Luew.mp4</video:content_loc><video:duration>225</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/calculating-acceleration-ap-calculus-ab-bc-2015-3c</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7d3d1a48e3de2b9c.jpg</video:thumbnail_loc><video:title>Calculating acceleration AP Calculus AB BC 2015 3c</video:title><video:description>Calculating acceleration from a velocity function with context.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/bt1eSGeC3ak.mp4/bt1eSGeC3ak.mp4</video:content_loc><video:duration>106</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/2017-ap-calculus-abbc-4a</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1b6d8fe24f533104.jpg</video:thumbnail_loc><video:title>Writing and using equation of tangent line: 2017 AP Calculus AB/BC 4a</video:title><video:description>Potato problem from 2017 AP exam (Question 4). Finding and using the equation of a tangent line to approximate solution to differential equation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tMA17GzO0TY.mp4/tMA17GzO0TY.mp4</video:content_loc><video:duration>368</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/mean-value-theorem-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x497fcea6.jpg</video:thumbnail_loc><video:title>Introducing the mean value theorem</video:title><video:description>The Mean Value Theorem states that if a function f is continuous on the closed interval [a,b] and differentiable on the open interval (a,b), then there exists a point c in the interval (a,b) such that f&apos;(c) is equal to the function&apos;s average rate of change over [a,b]. In other words, the graph has a tangent somewhere in (a,b) that is parallel to the secant line over [a,b].</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6hri9k_2R8o.mp4/6hri9k_2R8o.mp4</video:content_loc><video:duration>397</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/finding-where-the-derivative-is-equal-to-the-average-change</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb8ad8f0a.jpg</video:thumbnail_loc><video:title>Applying the mean value theorem example: polynomial</video:title><video:description>Sal finds the number that satisfies the Mean value theorem for f(x)=x²-6x+8 over the interval [2,5].</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/S_YIUXy-WFM.mp4/S_YIUXy-WFM.mp4</video:content_loc><video:duration>290</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/mean-value-theorem-example-square-root</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0c6ab8b7.jpg</video:thumbnail_loc><video:title>Applying the mean value theorem example: square root function</video:title><video:description>Sal finds the number that satisfies the Mean value theorem for f(x)=√(4x-3) over the interval [1,3].</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Xg24JhQHVCM.mp4/Xg24JhQHVCM.mp4</video:content_loc><video:duration>384</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/justification-with-the-mean-value-theorem-table</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa788d96f0783b454.jpg</video:thumbnail_loc><video:title>Justifying use of the mean value theorem: table</video:title><video:description>Example justifying use of mean value theorem (where function is defined with a table).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PE8NNZG9IYw.mp4/PE8NNZG9IYw.mp4</video:content_loc><video:duration>221</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/justification-with-the-mean-value-theorem-equation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfa2d1f5961783950.jpg</video:thumbnail_loc><video:title>Justifying use of the mean value theorem: equation</video:title><video:description>Example justifying use of mean value theorem (where function is defined with an equation).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/IJ-obdnR_j8.mp4/IJ-obdnR_j8.mp4</video:content_loc><video:duration>174</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/getting-a-ticket-because-of-the-mean-value-theorem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe252a20d.jpg</video:thumbnail_loc><video:title>Applying the mean value theorem</video:title><video:description>Even if a cop never spots you while you are speeding, he can still infer when you must have been speeding...</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/InrLtU3k3Y8.mp4/InrLtU3k3Y8.mp4</video:content_loc><video:duration>432</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/extreme-value-theorem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbf69f66b.jpg</video:thumbnail_loc><video:title>Introducing the extreme value theorem</video:title><video:description>The Extreme value theorem states that if a function is continuous on a closed interval [a,b], then the function must have a maximum and a minimum on the interval. This makes sense: when a function is continuous you can draw its graph without lifting the pencil, so you must hit a high point and a low point on that interval.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/bZYTDst1MOo.mp4/bZYTDst1MOo.mp4</video:content_loc><video:duration>478</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/minima-maxima-and-critical-points</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1337154539.jpg</video:thumbnail_loc><video:title>Introducing critical points</video:title><video:description>Sal introduces the &quot;critical points&quot; of a function and discusses their relationship with the extremum points of the function.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lDY9JcFaRd4.mp4/lDY9JcFaRd4.mp4</video:content_loc><video:duration>473</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/finding-critical-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x13fa2a4c.jpg</video:thumbnail_loc><video:title>Finding critical points</video:title><video:description>Sal finds the critical points of f(x)=xe^(-2x²).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/MUQfl385Yug.mp4/MUQfl385Yug.mp4</video:content_loc><video:duration>351</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/increasing-decreasing-intervals-given-the-function</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa3538e83.jpg</video:thumbnail_loc><video:title>Finding decreasing interval given the function</video:title><video:description>Sal finds the intervals where the function f(x)=x⁶-3x⁵ is decreasing by analyzing the intervals where f&apos; is positive or negative.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Fk4pn8ZOy1w.mp4/Fk4pn8ZOy1w.mp4</video:content_loc><video:duration>318</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/finding-increasing-interval-given-derivative</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x69b9761a.jpg</video:thumbnail_loc><video:title>Finding increasing interval given the derivative</video:title><video:description>Sal is given that the derivative of function g, is g&apos;(x)=x²/(x-2)³. He uses that to find the intervals where g is increasing, by looking for the intervals where g&apos; is positive.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/sOluh1zX5tE.mp4/sOluh1zX5tE.mp4</video:content_loc><video:duration>360</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/testing-critical-points-for-local-extrema</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1337206217.jpg</video:thumbnail_loc><video:title>Finding relative extrema (first derivative test)</video:title><video:description>Once you find a critical point, how can you tell if it is a minimum, maximum or neither?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lFQ4kMcODzU.mp4/lFQ4kMcODzU.mp4</video:content_loc><video:duration>325</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/finding-relative-maximum-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb5d57cc3.jpg</video:thumbnail_loc><video:title>Working an example: finding relative extrema</video:title><video:description>Sal finds the relative maximum point of g(x)=x⁴-x⁵ by analyzing the intervals where its derivative, g&apos;, is negative or positive.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/x09FpMmGB4A.mp4/x09FpMmGB4A.mp4</video:content_loc><video:duration>469</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/analyzing-mistakes-when-finding-extrema-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xac26df03383cb341.jpg</video:thumbnail_loc><video:title>Analyzing mistakes when finding extrema (example 1)</video:title><video:description>Analyzing the work of someone who tried to find extrema of a function, to see whether they made mistakes.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-ihDprWkcY8.mp4/-ihDprWkcY8.mp4</video:content_loc><video:duration>273</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/analyzing-mistakes-when-finding-extrema-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x82b0ec2f6975a56d.jpg</video:thumbnail_loc><video:title>Analyzing mistakes when finding extrema (example 2)</video:title><video:description>Analyzing the work of someone who tried to find extrema of a function, to see whether they made mistakes.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Qcn8A5Ll7g4.mp4/Qcn8A5Ll7g4.mp4</video:content_loc><video:duration>282</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/using-extreme-value-theorem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1efba280.jpg</video:thumbnail_loc><video:title>Finding absolute extrema on a closed interval</video:title><video:description>Sal finds the absolute maximum value of f(x)=8ln(x)-x² over the interval [1,4].</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/JXVGPEOQCb8.mp4/JXVGPEOQCb8.mp4</video:content_loc><video:duration>416</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/absolute-extrema-on-entire-domain</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0caa19a6.jpg</video:thumbnail_loc><video:title>Analyzing absolute minima and maxima (entire domain)</video:title><video:description>Sal analyzes the absolute minimum and maximum points of g(x)=x²ln(x) over its entire domain.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Xhc7Hens0f8.mp4/Xhc7Hens0f8.mp4</video:content_loc><video:duration>564</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/concavity-concave-upwards-and-concave-downwards-intervals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1337193144.jpg</video:thumbnail_loc><video:title>Introducing concavity</video:title><video:description>Sal introduces the concept of concavity, what it means for a graph to be &quot;concave up&quot; or &quot;concave down,&quot; and how this relates to the second derivative of a function.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LcEqOzNov4E.mp4/LcEqOzNov4E.mp4</video:content_loc><video:duration>594</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/recognizing-concavity-exercise</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x22647994.jpg</video:thumbnail_loc><video:title>Analyzing concavity (graphical)</video:title><video:description>Sal walks through an exercise where you are asked to recognize the concavity of a function in certain regions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ulyyusmpc9w.mp4/ulyyusmpc9w.mp4</video:content_loc><video:duration>143</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/inflection-points</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1336987809.jpg</video:thumbnail_loc><video:title>Introducing inflection points</video:title><video:description>Inflection points are points where the function changes concavity, i.e. from being &quot;concave up&quot; to being &quot;concave down&quot; or vice versa. They can be found by considering where the second derivative changes signs. In similar to critical points in the first derivative, inflection points will occur when the second derivative is either zero or undefined.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/UK2shgCXALo.mp4/UK2shgCXALo.mp4</video:content_loc><video:duration>154</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/inflection-points-graphically-given-function</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x70e8e6ed.jpg</video:thumbnail_loc><video:title>Analyzing inflection points (graphical)</video:title><video:description>Sal analyzes the graph of a function g to find all the inflection points of g.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/iWgW2nD4wGQ.mp4/iWgW2nD4wGQ.mp4</video:content_loc><video:duration>200</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/analyzing-concavity-algebraically</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8e1390d7.jpg</video:thumbnail_loc><video:title>Analyzing concavity (algebraic)</video:title><video:description>Sal finds the intervals where g(x)=-x⁴+6x²-2x-3 is concave down/up by finding where its second derivative, g&apos;&apos;, is positive/negative.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/72L_N7AtCRE.mp4/72L_N7AtCRE.mp4</video:content_loc><video:duration>556</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/inflection-points-algebraically</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xcc3df6cb.jpg</video:thumbnail_loc><video:title>Analyzing inflection points (algebraic)</video:title><video:description>Sal analyzes the points of inflection of g(x)=¼x⁴-4x³+24x² by looking for values where the second derivative g&apos;&apos; changes signs.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/RoxefQ_Qgm8.mp4/RoxefQ_Qgm8.mp4</video:content_loc><video:duration>335</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/mistakes-when-finding-inflection-points-second-derivative-undefined</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x23301524ce5be9eb.jpg</video:thumbnail_loc><video:title>Exploring mistakes when finding inflection points: second derivative undefined</video:title><video:description>Candidates for inflection points are points where the second derivative is zero *and* points where the second derivative is undefined. It&apos;s important not to overlook any candidate.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TaRPDFqEd-c.mp4/TaRPDFqEd-c.mp4</video:content_loc><video:duration>371</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/mistakes-when-finding-inflection-points-not-checking-candidates</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xda174a6c45f7203f.jpg</video:thumbnail_loc><video:title>Exploring mistakes when finding inflection points: not checking candidates</video:title><video:description>Candidates for inflection points are x-values where the second derivative is equal to zero or undefined. But they are only candidates! Once we&apos;ve found them, we need to test them and see if they really are inflection points.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1lA1hWdw62Q.mp4/1lA1hWdw62Q.mp4</video:content_loc><video:duration>242</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/second-derivative-test</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x404646fd.jpg</video:thumbnail_loc><video:title>Applying the second derivative test</video:title><video:description>Sal justifies the second derivative test, which is a way of determining relative minima &amp; maxima, and gives an example.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-cW5hCsc9Yc.mp4/-cW5hCsc9Yc.mp4</video:content_loc><video:duration>373</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/calculus-graphing-using-derivatives</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/355054.jpg</video:thumbnail_loc><video:title>Sketching a curve with calculus: polynomial</video:title><video:description>Sal sketches a graph of f(x)=3x⁴-4x³+2 including extremum and inflection points.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hIgnece9ins.mp4/hIgnece9ins.mp4</video:content_loc><video:duration>1231</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/calculus-graphing-with-derivatives-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/366056.jpg</video:thumbnail_loc><video:title>Sketching a curve with calculus: logarithm</video:title><video:description>Sal sketches a graph of f(x)=ln(x⁴+27) including extremum and inflection points.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/zC_dTaEY2AY.mp4/zC_dTaEY2AY.mp4</video:content_loc><video:duration>1508</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/analyzing-a-function-with-its-derivative</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1337114573.jpg</video:thumbnail_loc><video:title>Analyzing a function with its derivative</video:title><video:description>Taking the derivative of f(x)=x³-12x+2 and graphing the derivative, so we can tell when f is increasing or decreasing, and where is its relative extremum points.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pInFesXIfg8.mp4/pInFesXIfg8.mp4</video:content_loc><video:duration>582</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/calculus-based-justification-for-function-increasing</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc63dbafee7c67364.jpg</video:thumbnail_loc><video:title>Establishing a calculus-based justification for a function increasing</video:title><video:description>A calculus-based justification is when we explain a property of a function f based on its derivative f&apos;. See a good example (and a few wrong ones) for how to do this when explaining why a function increases.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qLhZdSNDQ0M.mp4/qLhZdSNDQ0M.mp4</video:content_loc><video:duration>192</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/justification-using-first-derivative</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x559e4677ad53fe94.jpg</video:thumbnail_loc><video:title>Justifying a function&apos;s features using the first derivative</video:title><video:description>We can explain why a function is increasing, decreasing, or having a relative maximum using information about its first derivative. This is called calculus-based justification.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/t-RXwwBjxsc.mp4/t-RXwwBjxsc.mp4</video:content_loc><video:duration>353</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/identifying-inflection-points-from-graphs-of-function-and-derivatives</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5875debbcd4d8e9e.jpg</video:thumbnail_loc><video:title>Identifying inflection points from graphs of function and derivatives</video:title><video:description>Identifying inflection points from graphs of function, first derivative and second derivative. Graphs are done using Desmos.com.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/YBQUw0NhqgU.mp4/YBQUw0NhqgU.mp4</video:content_loc><video:duration>306</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/justification-for-inflection-point</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x69ba0a53e7397e88.jpg</video:thumbnail_loc><video:title>Justifying a function&apos;s features using the second derivative: inflection point</video:title><video:description>We can justify whether a function has an inflection point by looking at where the second derivative changes its sign.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/QgpjYgAAW7o.mp4/QgpjYgAAW7o.mp4</video:content_loc><video:duration>227</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/calculus-based-justification-using-second-derivative-max</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xcf9943a1a5d9101e.jpg</video:thumbnail_loc><video:title>Justifying a function&apos;s features using the second derivative: maximum point</video:title><video:description>Given that the derivative of a function is zero, we can justify whether the function has a relative maximum point by looking at the second derivative.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PvZaQZBJzGU.mp4/PvZaQZBJzGU.mp4</video:content_loc><video:duration>254</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/connecting-function-and-derivatives-graphically</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3ef49788b2269af6.jpg</video:thumbnail_loc><video:title>Connecting f, f&apos;, and f&apos;&apos; graphically</video:title><video:description>Analyzing three graphs to see which describes the derivative of which other graph.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/elugjT_Np3M.mp4/elugjT_Np3M.mp4</video:content_loc><video:duration>336</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/connecting-function-and-derivatives-graphically-exp</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc58a981587b5fb54.jpg</video:thumbnail_loc><video:title>Connecting f, f&apos;, and f&apos;&apos; graphically (another example)</video:title><video:description>Analyzing three graphs to see which describes the derivative of which other graph.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/G6ReTLn9vLc.mp4/G6ReTLn9vLc.mp4</video:content_loc><video:duration>261</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/minimizing-sum-of-squares</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1339427794.jpg</video:thumbnail_loc><video:title>Applying optimization: sum of squares</video:title><video:description>What is the minimum possible value of x^2+y^2 given that their product has to be fixed at xy = -16</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1TK8V_qmqrk.mp4/1TK8V_qmqrk.mp4</video:content_loc><video:duration>455</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/optimizing-box-volume-graphically</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1338874025.jpg</video:thumbnail_loc><video:title>Applying optimization: box volume (Part 1)</video:title><video:description>If you are making a box out of a flat piece of cardboard, how do you maximize the volume of that box?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/MC0tq6fNRwU.mp4/MC0tq6fNRwU.mp4</video:content_loc><video:duration>590</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/optimizing-box-volume-analytically</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1339153034.jpg</video:thumbnail_loc><video:title>Applying optimization: box volume (Part 2)</video:title><video:description>Finishing up the last video by working through the formulas.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/cRboY08YG8g.mp4/cRboY08YG8g.mp4</video:content_loc><video:duration>540</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/optimizing-profit-at-a-shoe-factory</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1339412561.jpg</video:thumbnail_loc><video:title>Applying optimization: profit</video:title><video:description>Who knows, you may end up running a shoe factory one day. So it might not be a bad idea to know how to maximize profits.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/dam16G6cZ8k.mp4/dam16G6cZ8k.mp4</video:content_loc><video:duration>687</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/minimizing-the-cost-of-a-storage-container</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1339500281.jpg</video:thumbnail_loc><video:title>Applying optimization: cost of materials</video:title><video:description>With all the storage you might have to handle for your shoe factory, I bet you&apos;d also like to be able to minize the cost of storage.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tSMuKcN-RKM.mp4/tSMuKcN-RKM.mp4</video:content_loc><video:duration>760</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/expression-for-combined-area-of-triangle-and-square</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1393028914.jpg</video:thumbnail_loc><video:title>Applying optimization: area of triangle &amp; square (Part 1)</video:title><video:description>Sal constructs an equilateral triangle &amp; a square whose bases are 100m together, such that their area is the smallest possible.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/IFU7Go6Qg6E.mp4/IFU7Go6Qg6E.mp4</video:content_loc><video:duration>379</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/minimizing-combined-area</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1392948670.jpg</video:thumbnail_loc><video:title>Applying optimization: area of triangle &amp; square (Part 2)</video:title><video:description>Sal constructs an equilateral triangle &amp; a square whose bases are 100m together, such that their area is the smallest possible.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/eS-_ZFzHjYA.mp4/eS-_ZFzHjYA.mp4</video:content_loc><video:duration>331</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/rectilinear-motion-example-maximum-acceleration</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4a5d6352.jpg</video:thumbnail_loc><video:title>Analyzing motion problems: finding the maximum acceleration</video:title><video:description>The speed of a particle moving along the x-axis is given by v(t)=-t³+6t²+2t. Sal analyzes it to find the time when the particle&apos;s acceleration attains its maximum value.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5P1O6tBiTlQ.mp4/5P1O6tBiTlQ.mp4</video:content_loc><video:duration>265</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
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<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/2015-ap-calculus-ab-5b</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x29c15a44.jpg</video:thumbnail_loc><video:title>Analyzing function features: 2015 AP Calculus AB 5b</video:title><video:description>Intervals where f is concave downwards and decreasing.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/bba11I93w8o.mp4/bba11I93w8o.mp4</video:content_loc><video:duration>181</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/2015-ap-calculus-ab-5c</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x05f1c7c9.jpg</video:thumbnail_loc><video:title>Finding inflection points: 2015 AP Calculus AB 5c</video:title><video:description>Inflection points for a function</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ol4bW-3qs_s.mp4/ol4bW-3qs_s.mp4</video:content_loc><video:duration>196</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/2015-ap-calculus-ab-6b</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdf20cb71.jpg</video:thumbnail_loc><video:title>Finding vertical tangent lines: 2015 AP Calculus AB 6b</video:title><video:description>Point on curve where tangent is vertical</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/s3jvXHQlO-c.mp4/s3jvXHQlO-c.mp4</video:content_loc><video:duration>282</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/2017-ap-calculus-abbc-4b</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8c6b96ca66873089.jpg</video:thumbnail_loc><video:title>Using concavity for reasoning: 2017 AP Calculus AB/BC 4b</video:title><video:description>Potato problem from 2017 AP exam (Question 4, part b). Taking the second derivative using the chain rule to think about concavity.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OzhjlMnQ114.mp4/OzhjlMnQ114.mp4</video:content_loc><video:duration>312</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/introduction-to-integral-calculus</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x26ac85dafbab3184.jpg</video:thumbnail_loc><video:title>Introducing integral calculus</video:title><video:description>The basic idea of Integral calculus is finding the area under a curve. To find it exactly, we can divide the area into infinite rectangles of infinitely small width and sum their areas—calculus is great for working with infinite things! This idea is actually quite rich, and it&apos;s also tightly related to Differential calculus, as you will see in the upcoming videos.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/__Uw1SXPW7s.mp4/__Uw1SXPW7s.mp4</video:content_loc><video:duration>292</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/definite-integrals-intro</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5d1b85e9cd11f651.jpg</video:thumbnail_loc><video:title>Introducing definite integrals</video:title><video:description>Definite integrals represent the area under the curve of a function and above the 𝘹-axis. Learn about the notation we use to write them and see some introductory examples.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0dDIPzqKgYk.mp4/0dDIPzqKgYk.mp4</video:content_loc><video:duration>148</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/area-under-rate-function-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4d22ba5a.jpg</video:thumbnail_loc><video:title>Working an example: accumulation of change</video:title><video:description>An example relating rates of change with a leaky bathtub.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/okjt-OZY1JU.mp4/okjt-OZY1JU.mp4</video:content_loc><video:duration>415</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/simple-riemann-approximation-using-rectangles</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1319674060.jpg</video:thumbnail_loc><video:title>Introducing Riemann approximations</video:title><video:description>Approximating the area under a curve using some rectangles. This is called a Riemann sum.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/dEAk0BHBYCM.mp4/dEAk0BHBYCM.mp4</video:content_loc><video:duration>405</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/riemann-sums-over-and-under-estimation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2dd8112342f80589.jpg</video:thumbnail_loc><video:title>Over- and under-estimating of Riemann sums</video:title><video:description>Riemann sums are approximations of area, so usually they aren&apos;t equal to the exact area. Sometimes they are larger than the exact area (this is called overestimation) and sometimes they are smaller (this is called underestimation).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ER5eoDkjsrc.mp4/ER5eoDkjsrc.mp4</video:content_loc><video:duration>241</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/riemann-sum-from-table</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdeb8581d02120d29.jpg</video:thumbnail_loc><video:title>Working an example: finding a Riemann sum using a table</video:title><video:description>When we have a table of values of a function, we can use it to find a Riemann sum approximation of that function.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/dki2K3Z-1kI.mp4/dki2K3Z-1kI.mp4</video:content_loc><video:duration>399</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/riemann-sums-over-under-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2449dade551c2767.jpg</video:thumbnail_loc><video:title>Working an example: over- and under-estimation of Riemann sums</video:title><video:description>Ordering different areas from least to greatest.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/XmI80eJZAWM.mp4/XmI80eJZAWM.mp4</video:content_loc><video:duration>282</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/midpoint-sums</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3c51cdc21a21f6f6.jpg</video:thumbnail_loc><video:title>Approximating area using midpoint sums</video:title><video:description>Approximating area under a curve using rectangle where the heights are the value of the function at the midpoint of each interval.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/kJ57S0Z4Vp8.mp4/kJ57S0Z4Vp8.mp4</video:content_loc><video:duration>329</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/trapezoidal-approximation-of-area-under-curve</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1319516835.jpg</video:thumbnail_loc><video:title>Approximating area using trapezoidal sums</video:title><video:description>The area under a curve is commonly approximated using rectangles (e.g. left, right, and midpoint Riemann sums), but it can also be approximated by trapezoids. Trapezoidal sums actually give a better approximation, in general, than rectangular sums that use the same number of subdivisions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1p0NHR5w0Lc.mp4/1p0NHR5w0Lc.mp4</video:content_loc><video:duration>507</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/summation-notation-worked-examples</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6cf630144647fe01.jpg</video:thumbnail_loc><video:title>Working examples: Summation notation</video:title><video:description>Summation notation uses the sigma Σ symbol to represent sums with multiple terms. See some more involved examples of how we read expressions in summation notation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/luSh3hz_b18.mp4/luSh3hz_b18.mp4</video:content_loc><video:duration>321</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/generalizing-a-left-riemann-sum-with-equally-spaced-rectangles</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1319350944.jpg</video:thumbnail_loc><video:title>Using Riemann sums in summation notation</video:title><video:description>Generalizing the technique of approximating area under a curve with rectangles.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ViqrHGae7FA.mp4/ViqrHGae7FA.mp4</video:content_loc><video:duration>511</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/practice-approximating-area-under-curve</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf873a305.jpg</video:thumbnail_loc><video:title>Working an example: Riemann sums in summation notation</video:title><video:description>Here we express the approximation of the area under a curve in sigma notation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3ZhUdleD1lQ.mp4/3ZhUdleD1lQ.mp4</video:content_loc><video:duration>427</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/riemann-sums-and-integrals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1319594360.jpg</video:thumbnail_loc><video:title>Representing a definite integral as the limit of a Riemann sum</video:title><video:description>Definite integrals represent the exact area under a given curve, and Riemann sums are used to approximate those areas. However, if we take Riemann sums with infinite rectangles of infinitely small width (using limits), we get the exact area, i.e. the definite integral!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/CXCtqBlEZ7g.mp4/CXCtqBlEZ7g.mp4</video:content_loc><video:duration>266</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/rewriting-definite-integral-as-limit-of-riemann-sum</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc09fd81209309140.jpg</video:thumbnail_loc><video:title>Working an example: Rewriting definite integral as limit of Riemann sum</video:title><video:description>Given a definite integral expression, we can write the corresponding limit of a Riemann sum with infinite rectangles.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/eidemLqiPyQ.mp4/eidemLqiPyQ.mp4</video:content_loc><video:duration>334</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/writing-riemann-sum-limit-as-definite-integral</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6ba31798dda20c91.jpg</video:thumbnail_loc><video:title>Working an example: Rewriting limit of Riemann sum as definite integral</video:title><video:description>When given a limit of Riemann sum with infinite rectangles, we can analyze the expression to find the corresponding definite integral.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Himr2l8Rd18.mp4/Himr2l8Rd18.mp4</video:content_loc><video:duration>395</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/fundamental-theorem-of-calculus</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1353533334.jpg</video:thumbnail_loc><video:title>Introducing the fundamental theorem of calculus and accumulation functions</video:title><video:description>The fundamental theorem of calculus shows how, in some sense, integration is the opposite of differentiation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/C7ducZoLKgw.mp4/C7ducZoLKgw.mp4</video:content_loc><video:duration>483</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/functions-defined-by-definite-integrals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5d0078e4e21024fd.jpg</video:thumbnail_loc><video:title>Understanding functions defined by definite integrals (accumulation functions)</video:title><video:description>Understanding that a function can be defined using a definite integral. Thinking about how to evaluate functions defined this way.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qJMbAfbb_Ek.mp4/qJMbAfbb_Ek.mp4</video:content_loc><video:duration>257</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/applying-the-fundamental-theorem-of-calculus</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1362669934.jpg</video:thumbnail_loc><video:title>Finding derivative with fundamental theorem of calculus</video:title><video:description>The Fundamental Theorem of Calculus tells us that the derivative of the definite integral from 𝘢 to 𝘹 of ƒ(𝑡)𝘥𝑡 is ƒ(𝘹), provided that ƒ is continuous. See how this can be used to evaluate the derivative of accumulation functions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/WapSrovs7yM.mp4/WapSrovs7yM.mp4</video:content_loc><video:duration>204</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/derivative-with-ftc-and-chain-rule</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x56ccc0203d1640e5.jpg</video:thumbnail_loc><video:title>Finding derivative with fundamental theorem of calculus: chain rule</video:title><video:description>The Fundamental Theorem of Calculus tells us how to find the derivative of the integral from 𝘢 to 𝘹 of a certain function. But what if instead of 𝘹 we have a function of 𝘹, for example sin(𝘹)? Then we need to also use the chain rule.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/dptES2sb1oc.mp4/dptES2sb1oc.mp4</video:content_loc><video:duration>187</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/interpreting-behavior-of-antiderivative</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe75754b91c3ca2f4.jpg</video:thumbnail_loc><video:title>Interpreting the behavior of accumulation functions</video:title><video:description>When given the graph of function ƒ, we can reason about the graph of its antiderivative 𝑔 (so 𝑔&apos;=ƒ).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/51JgTZKnytA.mp4/51JgTZKnytA.mp4</video:content_loc><video:duration>502</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/negative-definite-integrals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe6d840e1958cb41c.jpg</video:thumbnail_loc><video:title>Understanding definite integrals with a negative value</video:title><video:description>We learned that definite integrals give us the area under the curve and above the x-axis. But what if the curve itself is below the x-axis? In this case, the definite integral is still related to area, but it&apos;s negative. See how this works and get some intuition for why this is so.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TtRAY6Eyp4w.mp4/TtRAY6Eyp4w.mp4</video:content_loc><video:duration>324</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/definite-integrals-with-area-formulas</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xce6edc1757a2754a.jpg</video:thumbnail_loc><video:title>Finding definite integrals using area formulas</video:title><video:description>Since definite integrals are the net area between a curve and the x-axis, we can sometimes use geometric area formulas to find definite integrals. See how it&apos;s done.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7R_DTzVHw5Y.mp4/7R_DTzVHw5Y.mp4</video:content_loc><video:duration>257</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/calculating-net-area-using-geometry</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5c0aa1089f1709ae.jpg</video:thumbnail_loc><video:title>Calculating net area using geometry</video:title><video:description>There are definite integrals that can be evaluated using geometry.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/077LCl3IX7M.mp4/077LCl3IX7M.mp4</video:content_loc><video:duration>242</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/same-integration-bounds</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x931cc126.jpg</video:thumbnail_loc><video:title>Evaluating a definite integral over a single point</video:title><video:description>What happens when the bounds of your integral are the same?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/q3qvkZxhchE.mp4/q3qvkZxhchE.mp4</video:content_loc><video:duration>151</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/integrating-scaled-function</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdfa7ddb8.jpg</video:thumbnail_loc><video:title>Integrating scaled version of function</video:title><video:description>Sal uses a graph to explain why we can take a constant out of a definite integral.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/JyArK4jw3XU.mp4/JyArK4jw3XU.mp4</video:content_loc><video:duration>321</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/switching-integral-bounds</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x87d0c9ae.jpg</video:thumbnail_loc><video:title>Switching bounds of definite integral</video:title><video:description>What happens when you swap the bounds on an integral?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/L5eBJjx2FP8.mp4/L5eBJjx2FP8.mp4</video:content_loc><video:duration>277</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/integrating-function-sums</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x78778540.jpg</video:thumbnail_loc><video:title>Integrating sums of functions</video:title><video:description>If you know the integrals of two functions, what is the integral of their sum?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/JUouea9XoF8.mp4/JUouea9XoF8.mp4</video:content_loc><video:duration>406</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/properties-of-definite-integrals-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb67ea312.jpg</video:thumbnail_loc><video:title>Working examples: Finding definite integrals using algebraic properties</video:title><video:description>Sal evaluates definite integrals of functions given their graphs. He does so using various properties of integrals.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pRZzfoM-9lc.mp4/pRZzfoM-9lc.mp4</video:content_loc><video:duration>139</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/breaking-integral-interval</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x99ada59b.jpg</video:thumbnail_loc><video:title>Evaluating definite integrals on adjacent intervals</video:title><video:description>By subdividing the interval of numbers where you are integrating, you can break up an integral into parts.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/BE1FK7vDVq0.mp4/BE1FK7vDVq0.mp4</video:content_loc><video:duration>186</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/evaluating-function-defined-by-integral</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1decd87a.jpg</video:thumbnail_loc><video:title>Working an example: Breaking up the integral&apos;s interval</video:title><video:description>Finding a definite integral by breaking it down to smaller intervals that are adjacent to each other.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/h6mZLTpTHcU.mp4/h6mZLTpTHcU.mp4</video:content_loc><video:duration>445</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/merging-definite-integrals-over-adjacent-intervals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa3d0a3c8c0bf97f6.jpg</video:thumbnail_loc><video:title>Working an example: Merging definite integrals over adjacent intervals</video:title><video:description>Thinking about how to evaluate the sum of definite integrals over adjacent intervals.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/w00eCt3i9KM.mp4/w00eCt3i9KM.mp4</video:content_loc><video:duration>242</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/evaluating-function-defined-by-integral-switch</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x44acaab0.jpg</video:thumbnail_loc><video:title>Evaluating functions defined by integrals: switched interval</video:title><video:description>Sal evaluates a function defined by the integral of a graphed function. In order to evaluate he must switch the sides of the interval.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Kq5hqFg17bg.mp4/Kq5hqFg17bg.mp4</video:content_loc><video:duration>174</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/swapping-the-bounds-for-definite-integral</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1363004264.jpg</video:thumbnail_loc><video:title>Finding derivative with fundamental theorem of calculus: x is on lower bound</video:title><video:description>Sometimes you need to swap the bounds of integration before applying the fundamental theorem of calculus.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TqGCNNlx6pU.mp4/TqGCNNlx6pU.mp4</video:content_loc><video:duration>180</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/both-bounds-being-a-function-of-x</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1362611642.jpg</video:thumbnail_loc><video:title>Finding derivative with fundamental theorem of calculus: x is on both bounds</video:title><video:description>How do you apply the fundamental theorem of calculus when both integral bounds are a function of x.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0z52CLjC2C0.mp4/0z52CLjC2C0.mp4</video:content_loc><video:duration>304</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/connecting-the-first-and-second-fundamental-theorems-of-calculus</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1362356573.jpg</video:thumbnail_loc><video:title>Exploring the fundamental theorem of calculus and definite integrals</video:title><video:description>There are really two versions of the fundamental theorem of calculus, and we go through the connection here.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/JbfVrwxuPxM.mp4/JbfVrwxuPxM.mp4</video:content_loc><video:duration>285</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/antiderivatives-and-indefinite-integrals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1328880986.jpg</video:thumbnail_loc><video:title>Exploring antiderivatives and indefinite integrals</video:title><video:description>What&apos;s the opposite of a derivative? It&apos;s something called the indefinite integral.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/MMv-027KEqU.mp4/MMv-027KEqU.mp4</video:content_loc><video:duration>223</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/indefinite-integrals-of-x-raised-to-a-power</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1328847625.jpg</video:thumbnail_loc><video:title>Determining the reverse power rule</video:title><video:description>Can you find a function whose derivative is x^n?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/QxbJsg-Vdms.mp4/QxbJsg-Vdms.mp4</video:content_loc><video:duration>348</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/indefinite-integral-properties</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x178e6d86e8b0bec8.jpg</video:thumbnail_loc><video:title>Exploring indefinite integrals: sums and multiples</video:title><video:description>An indefinite integral of a sum is the same as the sum of the integrals of the component parts. Constants can be taken out of integrals.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/YwR_82jgJ_Q.mp4/YwR_82jgJ_Q.mp4</video:content_loc><video:duration>278</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/rewriting-integrand-before-integrating</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc8d3f667a3156637.jpg</video:thumbnail_loc><video:title>Rewriting before integrating</video:title><video:description>Some indefinite integrals are much simpler to integrate by algebraically rewriting the integrand first.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hzSef_HVqz4.mp4/hzSef_HVqz4.mp4</video:content_loc><video:duration>317</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/antiderivative-of-x-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1328998382.jpg</video:thumbnail_loc><video:title>Determining the indefinite integral of 1/x</video:title><video:description>In differential ​calculus we learned that the derivative of ln(x) is 1/x. Integration goes the other way: the integral (or antiderivative) of 1/x should be a function whose derivative is 1/x. As we just saw, this is ln(x). However, if x is negative then ln(x) is undefined! The solution is quite simple: the antiderivative of 1/x is ln(|x|).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/sPPjk4aXzmQ.mp4/sPPjk4aXzmQ.mp4</video:content_loc><video:duration>455</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/basic-trig-and-exponential-antiderivatives</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1329132099.jpg</video:thumbnail_loc><video:title>Determining the indefinite integrals of sin(x), cos(x), and eˣ</video:title><video:description>Integral of sin(x)dx is -cos(x)+C, integral of cos(x)dx is sin(x)+C, and integral of eˣdx is eˣ+C. Learn why and see worked examples.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hXg-6YgAARk.mp4/hXg-6YgAARk.mp4</video:content_loc><video:duration>244</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/reverse-power-rule-for-definite-integrals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x057a358cb0b0afa3.jpg</video:thumbnail_loc><video:title>Evaluating definite integrals: reverse power rule</video:title><video:description>Examples of calculating definite integrals of polynomials using the fundamental theorem of calculus and the reverse power rule.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/auOcNZFKfo0.mp4/auOcNZFKfo0.mp4</video:content_loc><video:duration>254</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/evaluating-definite-integral-with-power-rule</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa03481ca.jpg</video:thumbnail_loc><video:title>Evaluating definite integral of a rational function</video:title><video:description>Sal finds the definite integral of (16-x^3)/x^3; between -1 and -2 using the reverse power rule.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4WJUEXIksH0.mp4/4WJUEXIksH0.mp4</video:content_loc><video:duration>305</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/definite-integral-of-cube-root</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x89fe4f56.jpg</video:thumbnail_loc><video:title>Evaluating definite integral of a radical function</video:title><video:description>Sal finds the definite integral of 12∛x between -1 and 8 using the reverse power rule.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5UWdzPq8_Qs.mp4/5UWdzPq8_Qs.mp4</video:content_loc><video:duration>231</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/definite-integral-of-sine-based-function</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x41874f6b.jpg</video:thumbnail_loc><video:title>Evaluating definite integral of a trig function</video:title><video:description>Sal finds the definite integral of 9sin(x) between 11π/2 and 6π.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ldLdWj6DLTw.mp4/ldLdWj6DLTw.mp4</video:content_loc><video:duration>300</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/definite-integral-involving-natural-log</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x651ef59b.jpg</video:thumbnail_loc><video:title>Evaluating definite integral involving a natural log function</video:title><video:description>Sal finds the definite integral of (6+x^2;)/x^3; between 2 and 4. To do that, he has to use the integral of 1/x, which is ln(x).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/JMqKtEC2bbY.mp4/JMqKtEC2bbY.mp4</video:content_loc><video:duration>447</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/definite-integrals-of-piecewise-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3953c53a.jpg</video:thumbnail_loc><video:title>Evaluating definite integral of a piecewise function</video:title><video:description>Sal evaluates definite integral of a piecewise function over an interval that goes through the two cases of the function.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/f5qr1lH6ViU.mp4/f5qr1lH6ViU.mp4</video:content_loc><video:duration>374</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/definite-integral-of-absolute-value</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3b98bdf7.jpg</video:thumbnail_loc><video:title>Evaluating definite integral of an absolute value function</video:title><video:description>Sal evaluates the definite integral of f(x)=|x+2| between -4 and 0.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PWcwhA2BwVk.mp4/PWcwhA2BwVk.mp4</video:content_loc><video:duration>413</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/evaluating-definite-integral-of-function-with-removable-and-jump-discontinuities</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe89d09dff1fe417d.jpg</video:thumbnail_loc><video:title>Evaluating definite integral of function with removable and jump discontinuities</video:title><video:description>Evaluate definite integrals of functions with removable or jump discontinuities.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/cnw9lhxQGn4.mp4/cnw9lhxQGn4.mp4</video:content_loc><video:duration>430</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/u-substitution</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1254417751.jpg</video:thumbnail_loc><video:title>Introducing 𝘶-substitution</video:title><video:description>Using u-substitution to find the anti-derivative of a function. Seeing that u-substitution is the inverse of the chain rule.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/b76wePnIBdU.mp4/b76wePnIBdU.mp4</video:content_loc><video:duration>311</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/u-substitution-example-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1254165861.jpg</video:thumbnail_loc><video:title>Using 𝘶-substitution: multiplying by a constant</video:title><video:description>Manipulating the expression to make u-substitution a little more obvious.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/oqCfqIcbE10.mp4/oqCfqIcbE10.mp4</video:content_loc><video:duration>333</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/u-substitution-defining-u</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xcef304a893f93d7a.jpg</video:thumbnail_loc><video:title>Using 𝘶-substitution: defining 𝘶</video:title><video:description>A common challenge when performing 𝘶-substitution is to realize which part should be our 𝘶.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/r5XXDSOh5Nk.mp4/r5XXDSOh5Nk.mp4</video:content_loc><video:duration>215</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/u-substitution-defining-u-exp</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf4e4b2d05feeefa8.jpg</video:thumbnail_loc><video:title>Using 𝘶-substitution: defining 𝘶 (more examples)</video:title><video:description>A common challenge when performing 𝘶-substitution is to realize which part should be our 𝘶.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/rsBALP8QNns.mp4/rsBALP8QNns.mp4</video:content_loc><video:duration>274</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/u-substitution-example-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1254490089.jpg</video:thumbnail_loc><video:title>Using 𝘶-substitution: rational function</video:title><video:description>Another example of using u-substitution with a rational function.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Zp5z0wa0kgo.mp4/Zp5z0wa0kgo.mp4</video:content_loc><video:duration>244</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/u-substitution-with-ln-x</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1254468209.jpg</video:thumbnail_loc><video:title>Using 𝘶-substitution: logarithmic function</video:title><video:description>Doing u-substitution with ln(x)</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OLO64d4Y1qI.mp4/OLO64d4Y1qI.mp4</video:content_loc><video:duration>219</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/u-substitution-definite-integrals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf96099c4eaa7e1db.jpg</video:thumbnail_loc><video:title>Using 𝘶-substitution: definite integrals</video:title><video:description>When using 𝘶-substitution in definite integrals, we must make sure we take care of the boundaries of integration.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/paNqHnR3-aM.mp4/paNqHnR3-aM.mp4</video:content_loc><video:duration>353</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/u-substitution-exponential</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xadef2972.jpg</video:thumbnail_loc><video:title>Using 𝘶-substitution: definite integral of exponential function</video:title><video:description>Finding the definite integral from 0 to 1 of x^2(2^(x^3)).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1ct7LUx23io.mp4/1ct7LUx23io.mp4</video:content_loc><video:duration>473</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/integral-partial-fraction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa5f8f98b.jpg</video:thumbnail_loc><video:title>Integrating using long division</video:title><video:description>Here we do polynomial long division to make an integral easier to evaluate.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5j81gyHn9i0.mp4/5j81gyHn9i0.mp4</video:content_loc><video:duration>318</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/integration-using-completing-the-square-arctan</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1ff0a76ebf38d991.jpg</video:thumbnail_loc><video:title>Integrating using completing the square and the derivative of arctan(x)</video:title><video:description>Sometimes we can integrate rational functions by using the method of completing the square in the denominator and then integrating using u-substitution and our knowledge about the derivative of arctan(x).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1nXSO3POyZ8.mp4/1nXSO3POyZ8.mp4</video:content_loc><video:duration>328</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/proof-of-fundamental-theorem-of-calculus</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1363005217.jpg</video:thumbnail_loc><video:title>Proving the fundamental theorem of calculus</video:title><video:description>The first part of the fundamental theorem of calculus tells us that if we define 𝘍(𝘹) to be the definite integral of function ƒ from some constant 𝘢 to 𝘹, then 𝘍 is an antiderivative of ƒ. In other words, 𝘍&apos;(𝘹)=ƒ(𝘹). See why this is so.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pWtt0AvU0KA.mp4/pWtt0AvU0KA.mp4</video:content_loc><video:duration>840</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/intuition-for-second-fundamental-theorem-of-calculus</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1319534849.jpg</video:thumbnail_loc><video:title>Proving the second part of fundamental theorem of calculus</video:title><video:description>The second part of the fundamental theorem of calculus tells us that to find the definite integral of a function f; from 𝘢 to 𝘣, we need to take an antiderivative of f, call it 𝘍, and calculate 𝘍(𝘣)-𝘍(𝘢). Get some intuition into why this is true.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Cz_GWNdf_68.mp4/Cz_GWNdf_68.mp4</video:content_loc><video:duration>744</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/2011-calculus-ab-free-response-4a</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/237109444.jpg</video:thumbnail_loc><video:title>Using equations involving integrals: 2011 Calculus AB free response #4a</video:title><video:description>Taking derivatives and integrals of strangely defined functions</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tnoPnyvVjyc.mp4/tnoPnyvVjyc.mp4</video:content_loc><video:duration>288</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/differential-equation-introduction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x64571eb4.jpg</video:thumbnail_loc><video:title>Introducing differential equations</video:title><video:description>Differential equations are equations that relate a function with one or more of its derivatives. This means their solution is a function! Learn more in this video.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6o7b9yyhH7k.mp4/6o7b9yyhH7k.mp4</video:content_loc><video:duration>470</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/writing-a-differential-equation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc721bc33777fe0a5.jpg</video:thumbnail_loc><video:title>Writing a differential equation</video:title><video:description>Differential equations describe relationships that involve quantities and their rates of change. See how we write the equation for such a relationship.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/H9h-Xg7zjPU.mp4/H9h-Xg7zjPU.mp4</video:content_loc><video:duration>139</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/verifying-solutions-to-differential-equations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x38bbf6ba25cf4539.jpg</video:thumbnail_loc><video:title>Verifying solutions to differential equations</video:title><video:description>We can check whether a potential solution to a differential equation is indeed a solution. What we need to do is differentiate and substitute both the solution and the derivative into the equation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/KZqg4L--YC0.mp4/KZqg4L--YC0.mp4</video:content_loc><video:duration>352</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/creating-a-slope-field</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc8a02f3a.jpg</video:thumbnail_loc><video:title>Introducing slope fields</video:title><video:description>Slope fields allow us to analyze differential equations graphically. Learn how to draw them and use them to find particular solutions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8Amgakx5aII.mp4/8Amgakx5aII.mp4</video:content_loc><video:duration>352</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/differential-equation-from-slope-field</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb57e783b.jpg</video:thumbnail_loc><video:title>Working an example: equation from slope field</video:title><video:description>Given a slope field and a few differential equations, we can determine which equation corresponds to the slope field by considering specific slopes.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/sU5MCM3npXU.mp4/sU5MCM3npXU.mp4</video:content_loc><video:duration>371</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/identifying-slope-field-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe8ae4b4059518a88.jpg</video:thumbnail_loc><video:title>Working an example: slope field from equation</video:title><video:description>Given a differential equation in x and y, we can draw a segment with dy/dx as slope at any point (x,y). That&apos;s the slope field of the equation. See how we match an equation to its slope field by considering the various slopes in the diagram.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/sPe6qoQFFD8.mp4/sPe6qoQFFD8.mp4</video:content_loc><video:duration>183</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/example-of-steps-for-constructing-slope-field</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5d6cbc82222694cb.jpg</video:thumbnail_loc><video:title>Working an example: forming a slope field</video:title><video:description>Given a differential equation in x and y, we can draw a segment with dy/dx as slope at any point (x,y). That&apos;s the slope field of the equation. See how we determine the slopes of a few segments in the slope field of an equation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tgS5kgkZNGw.mp4/tgS5kgkZNGw.mp4</video:content_loc><video:duration>211</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/slope-field-to-visualize-solutions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8ea5d072.jpg</video:thumbnail_loc><video:title>Approximating solution curves in slope fields</video:title><video:description>Given the slope field of a differential equation, we can sketch various solutions to the equation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LoaagZPWvpM.mp4/LoaagZPWvpM.mp4</video:content_loc><video:duration>416</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/range-of-solution-curve-from-slope-field</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfcaa1cd3c0b4ece0.jpg</video:thumbnail_loc><video:title>Working an example: range of solution curve from slope field</video:title><video:description>Given the slope field of a differential equation, we can sketch various solutions to the equation. In this example, we analyze the range of a specific solution.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8EA5wv-kQPw.mp4/8EA5wv-kQPw.mp4</video:content_loc><video:duration>129</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/separable-differential-equations-introduction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4bbc820f.jpg</video:thumbnail_loc><video:title>Introducing separable equations</video:title><video:description>Separation of variables allows us to rewrite differential equations so we obtain an equality between two integrals we can evaluate. Separable equations are the class of differential equations that can be solved using this method.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DL-ozRGDlkY.mp4/DL-ozRGDlkY.mp4</video:content_loc><video:duration>546</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/addressing-treating-differentials-algebraically</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x31a949b063c9d896.jpg</video:thumbnail_loc><video:title>Addressing treating differentials algebraically</video:title><video:description>Addressing treating differentials algebraically</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/KQ7Y31QgX_w.mp4/KQ7Y31QgX_w.mp4</video:content_loc><video:duration>284</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/separable-differential-equations-examples</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xcd8d49b4a7193569.jpg</video:thumbnail_loc><video:title>Working examples: separable differential equations</video:title><video:description>Two worked examples of finding general solutions to separable differential equations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/UAcRCt9pEDI.mp4/UAcRCt9pEDI.mp4</video:content_loc><video:duration>264</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/identifying-separable-equations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4d1f7dd1f9ad4a51.jpg</video:thumbnail_loc><video:title>Working an example: identifying separable equations</video:title><video:description>Separable equations can be written in the form dy/dx=f(x)g(y). See how we analyze various differential equations to see if they are separable.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6vUjGgI8Dso.mp4/6vUjGgI8Dso.mp4</video:content_loc><video:duration>297</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/finding-constant-of-integration-rational</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5e2c88b0.jpg</video:thumbnail_loc><video:title>Finding particular solutions to differential equations: rational function</video:title><video:description>Sal finds f(-1) given that f(x)=24/x^3; and f(2)=12.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/bjdOWH43-9s.mp4/bjdOWH43-9s.mp4</video:content_loc><video:duration>264</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/finding-constant-of-integration-exponential</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5b20ed82.jpg</video:thumbnail_loc><video:title>Finding particular solutions to differential equations: exponential function</video:title><video:description>Sal finds f(0) given that f(x)=5eˣ and f(7)=40+5e⁷.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/T8rbpI4OZCc.mp4/T8rbpI4OZCc.mp4</video:content_loc><video:duration>188</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/particular-solution-to-differential-equation-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc7b88d99.jpg</video:thumbnail_loc><video:title>Working an example: finding a specific solution to a separable equation</video:title><video:description>Solving a separable differential equation given initial conditions. In this video, the equation is dy/dx=2y^2; with y(1)=1.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/E444KhRcWSk.mp4/E444KhRcWSk.mp4</video:content_loc><video:duration>338</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/using-particular-solution-to-separable-differential-equation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2db6052e61b90ad0.jpg</video:thumbnail_loc><video:title>Working an example: separable equation with an implicit solution</video:title><video:description>Sometimes the solution of a separable differential equation can&apos;t be written as an explicit function. This doesn&apos;t mean we can&apos;t use it!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/72xChzYjJdM.mp4/72xChzYjJdM.mp4</video:content_loc><video:duration>198</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/determining-the-domain-of-particular-solution-to-differential-equation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1719599353ddb91e.jpg</video:thumbnail_loc><video:title>Determining the domain of particular solution to differential equation</video:title><video:description>Determine any restrictions on the domain of a particular solution to a differential equation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/R_tIbSCqioU.mp4/R_tIbSCqioU.mp4</video:content_loc><video:duration>228</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/modeling-population-with-simple-differential-equation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x71b1c9d7.jpg</video:thumbnail_loc><video:title>Exploring exponential models and differential equations (Part 1)</video:title><video:description>Assuming a quantity grows proportionally to its size results in the general equation dy/dx=ky. Solving it with separation of variables results in the general exponential function y=Ceᵏˣ.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/IYFkXWlgC_w.mp4/IYFkXWlgC_w.mp4</video:content_loc><video:duration>461</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/particular-solution-given-initial-conditions-for-population</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb0ac5177.jpg</video:thumbnail_loc><video:title>Exploring exponential models and differential equations (Part 2)</video:title><video:description>Given the general solution P=Ceᵏᵗ and the conditions P(0)=100 and P(50)=200, we find the solution to an exponential modeling problem.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6jqx5uEBs5U.mp4/6jqx5uEBs5U.mp4</video:content_loc><video:duration>293</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/exponential-solution-to-differential-equation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xeaa1614aea9948f2.jpg</video:thumbnail_loc><video:title>Working an example: exponential solution to differential equation</video:title><video:description>The solution of the general differential equation dy/dx=ky (for some k) is Ceᵏˣ (for some C). See how this is derived and used for finding a particular solution to a differential equation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pRuwcphjJeg.mp4/pRuwcphjJeg.mp4</video:content_loc><video:duration>267</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/2011-calculus-ab-free-response-5c</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/238520371.jpg</video:thumbnail_loc><video:title>Finding particular solution to differential equation: 2011 Calculus AB free response #5c</video:title><video:description>Solving a differential equation using separation of variables</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/R-2Uw10QgIo.mp4/R-2Uw10QgIo.mp4</video:content_loc><video:duration>555</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/sketching-a-slope-field-ap-calculus-ab-bc-2015-4a</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe106de13958d1a93.jpg</video:thumbnail_loc><video:title>Sketching a slope field AP Calculus AB BC 2015 4a</video:title><video:description>Sketching a slope field given a differential equation</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/cbkrtV5Qajs.mp4/cbkrtV5Qajs.mp4</video:content_loc><video:duration>494</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/2017-ap-calculus-abbc-4c</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8a58bdc13f086d4e.jpg</video:thumbnail_loc><video:title>Finding particular solution to differential equation: 2017 AP Calculus AB/BC 4c</video:title><video:description>Potato problem from 2017 AP exam (Question 4, part c). Finding a particular solution for a separable differential equation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0DGrdJA5Mx4.mp4/0DGrdJA5Mx4.mp4</video:content_loc><video:duration>424</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/average-function-value-closed-interval</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x32f2123f.jpg</video:thumbnail_loc><video:title>Calculating average value over a closed interval</video:title><video:description>Average value of a function over a closed interval</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/NCF4m8BDs7w.mp4/NCF4m8BDs7w.mp4</video:content_loc><video:duration>283</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/calculating-function-average-over-interval</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x24937653.jpg</video:thumbnail_loc><video:title>Calculating average value of function over interval</video:title><video:description>Here we find the average value of x^2+1 on the interval between 0 and 3.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0rzL08BHr5c.mp4/0rzL08BHr5c.mp4</video:content_loc><video:duration>308</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/mean-value-theorem-integrals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5ca5c5c1.jpg</video:thumbnail_loc><video:title>Exploring the mean value theorem for integrals</video:title><video:description>Here Sal goes through the connection between the mean value theorem and integration.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/59UeshgSuEE.mp4/59UeshgSuEE.mp4</video:content_loc><video:duration>547</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/motion-problems-with-integrals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3722df7eacb6e00b.jpg</video:thumbnail_loc><video:title>Solving motion problems with integrals: displacement vs. distance</video:title><video:description>The definite integral of a velocity function gives us the displacement. To find the actual distance traveled, we need to use the speed function, which is the absolute value of the velocity.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Sy_7PkoTCtA.mp4/Sy_7PkoTCtA.mp4</video:content_loc><video:duration>484</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/analyzing-motion-problems-position</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x08f18c2e8eb0e883.jpg</video:thumbnail_loc><video:title>Analyzing motion problems: position</video:title><video:description>Finding the appropriate expression to use when looking for the position at a certain time.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/M7IZClYqdEo.mp4/M7IZClYqdEo.mp4</video:content_loc><video:duration>176</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/analyzing-motion-problems-total-dist-traveled</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6334a37724249bbe.jpg</video:thumbnail_loc><video:title>Analyzing motion problems: total distance traveled</video:title><video:description>Finding the appropriate expression to use when looking for the total distance traveled over a certain time interval.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Ih-NVgXuTnQ.mp4/Ih-NVgXuTnQ.mp4</video:content_loc><video:duration>173</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/antiderivative-acceleration</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xecee68b6.jpg</video:thumbnail_loc><video:title>Working an example: motion problems (with definite integrals)</video:title><video:description>What can you say about the velocity and position of a particle given its acceleration.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/sLw902V40L0.mp4/sLw902V40L0.mp4</video:content_loc><video:duration>512</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/average-acceleration-over-interval</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xeac69708.jpg</video:thumbnail_loc><video:title>Finding the average acceleration over interval</video:title><video:description>As an example of finding a mean value, we find an average acceleration.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/wdAgEzdkFZI.mp4/wdAgEzdkFZI.mp4</video:content_loc><video:duration>307</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/area-under-rate-net-change</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x195c42e1.jpg</video:thumbnail_loc><video:title>Determining area under rate function gives the net change</video:title><video:description>If you have a function representing rate, what does the area under its curve represent?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6FTiHeius1c.mp4/6FTiHeius1c.mp4</video:content_loc><video:duration>447</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/interpreting-definite-integral-as-net-change</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb67abbc5a7b138fa.jpg</video:thumbnail_loc><video:title>Interpreting definite integral as net change</video:title><video:description>The definite integral of a rate function gives us the net change in the quantity described by the rate. See how we interpret definite integrals in a real-world context.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5-qpfFTaY8c.mp4/5-qpfFTaY8c.mp4</video:content_loc><video:duration>316</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/interpreting-definite-integrals-in-context</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5ad32ab30fabf1f0.jpg</video:thumbnail_loc><video:title>Working examples: interpreting definite integrals in context</video:title><video:description>Interpreting expressions involving definite integrals in a real-world context.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/FWcXFU8Zj8U.mp4/FWcXFU8Zj8U.mp4</video:content_loc><video:duration>261</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/analyzing-problems-involving-definite-integrals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf42789b7e0119925.jpg</video:thumbnail_loc><video:title>Analyzing problems involving definite integrals</video:title><video:description>See worked example of how to find the appropriate expression to use in order to solve word problems using definite integrals.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/U4dtruMdQ7Y.mp4/U4dtruMdQ7Y.mp4</video:content_loc><video:duration>352</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/definite-integral-word-problem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x98122687f9058cd3.jpg</video:thumbnail_loc><video:title>Working an example: problem involving definite integral (algebraic)</video:title><video:description>Using definite integral to solve a word problem about the growth in the population of a town.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vYix-RPhT64.mp4/vYix-RPhT64.mp4</video:content_loc><video:duration>470</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/evaluating-simple-definite-integral</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1319502914.jpg</video:thumbnail_loc><video:title>Calculating area between a curve and the x-axis</video:title><video:description>Based on the fundamental theorem of calculus, we can use antiderivatives to compute integrals.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xR4AnXDBnsw.mp4/xR4AnXDBnsw.mp4</video:content_loc><video:duration>354</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/definite-integrals-and-negative-area</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1329076337.jpg</video:thumbnail_loc><video:title>Calculating area between a curve and the x-axis: negative area</video:title><video:description>With integrals, it can be helpful to introduce the notion of negative area. See why!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/MM0FTzvedH4.mp4/MM0FTzvedH4.mp4</video:content_loc><video:duration>448</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/area-between-curves</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1337260457.jpg</video:thumbnail_loc><video:title>Calculating the area between curves</video:title><video:description>By integrating the difference of two functions, you can find the area between them.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/wQXYtsyfbqg.mp4/wQXYtsyfbqg.mp4</video:content_loc><video:duration>410</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/area-between-curves-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x731d2664722c6dbc.jpg</video:thumbnail_loc><video:title>Working an example: area between curves</video:title><video:description>The area between the graphs of functions ƒ and 𝑔 can be found by taking the definite integral of ƒ-𝑔 (suppose ƒ is above 𝑔).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/aaCRnT8o-Ng.mp4/aaCRnT8o-Ng.mp4</video:content_loc><video:duration>325</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/area-between-curves-with-multiple-boundaries</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1337371091.jpg</video:thumbnail_loc><video:title>Calculating the composite area between curves</video:title><video:description>Sometimes we need to break the area into multiple different areas, because the enclosing functions change.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LbTH7MGMNjk.mp4/LbTH7MGMNjk.mp4</video:content_loc><video:duration>414</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/area-between-curve-and-y-axis</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0ed00c813377b4ac.jpg</video:thumbnail_loc><video:title>Calculating area between a curve and the 𝘺-axis</video:title><video:description>We can use a definite integral in terms of 𝘺 to find the area between a curve and the 𝘺-axis.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6XqsLv0QDUE.mp4/6XqsLv0QDUE.mp4</video:content_loc><video:duration>230</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/area-between-two-functions-of-y</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8dcff5d39bb68119.jpg</video:thumbnail_loc><video:title>Calculating horizontal area between curves</video:title><video:description>We can use a definite integral in terms of 𝘺 to find the horizontal area between curves of two functions of 𝘺.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/B5441_DREY0.mp4/B5441_DREY0.mp4</video:content_loc><video:duration>483</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/calculating-areas-between-curves-with-calculator</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfe150f653277effb.jpg</video:thumbnail_loc><video:title>Calculating areas between curves with calculator</video:title><video:description>Calculate the area between curves that intersect in 3 points using a sum of two or more definite integrals.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OzTI5d5VKkM.mp4/OzTI5d5VKkM.mp4</video:content_loc><video:duration>251</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/volume-with-cross-sections-intro</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa76e90a6f6f16638.jpg</video:thumbnail_loc><video:title>Introducing volume with cross sections</video:title><video:description>Using definite integration to find volume of a solid whose base is given as a region between function and whose cross sections are squares.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4vLy5VoUcQE.mp4/4vLy5VoUcQE.mp4</video:content_loc><video:duration>330</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/determining-integral-for-volume-with-rectangular-cross-sections</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3f3ce37d6316a884.jpg</video:thumbnail_loc><video:title>Determining integral for volume with rectangular cross sections</video:title><video:description>Determine the integral used to calculate the volume of a solid with a known base and a cross section that is a rectangle.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Cm-sRrHY-HM.mp4/Cm-sRrHY-HM.mp4</video:content_loc><video:duration>348</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/volume-from-cross-sections-without-graph-shown</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x94793087a3fe91f9.jpg</video:thumbnail_loc><video:title>Exploring volume with cross sections: squares and rectangles (no graph)</video:title><video:description>Expressing the volume of a 3-D figure as a definite integral (where the area of cross sections are functions of x). The problem doesn&apos;t come with a graph but that doesn&apos;t mean we shouldn&apos;t sketch one!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_y6zKNoWiKI.mp4/_y6zKNoWiKI.mp4</video:content_loc><video:duration>357</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/volume-with-cross-sections-perpendicular-to-y-axis</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9f023c02bceb6cae.jpg</video:thumbnail_loc><video:title>Exploring volume with cross sections perpendicular to y-axis</video:title><video:description>Worked example expressing the volume of a figure based on cross sections perpendicular to the y-axis as a definite integral (integrating with respect to y).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/aYT0Gm-v5T8.mp4/aYT0Gm-v5T8.mp4</video:content_loc><video:duration>265</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/volume-solid-semicircle-cross-section</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x50d51a99.jpg</video:thumbnail_loc><video:title>Exploring volume with cross sections: semicircle</video:title><video:description>The volume of a solid with semi-circular cross sections and a triangular base.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tf4C8x8e7HQ.mp4/tf4C8x8e7HQ.mp4</video:content_loc><video:duration>497</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/volume-triangular-cross-section</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2605e92e.jpg</video:thumbnail_loc><video:title>Exploring volume with cross sections: triangle</video:title><video:description>This time, the cross section of our solid is given as the area between two curves.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/S-agS4YaxxU.mp4/S-agS4YaxxU.mp4</video:content_loc><video:duration>514</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/disk-method-around-x-axis</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1276987869.jpg</video:thumbnail_loc><video:title>Using the disc method around x-axis</video:title><video:description>Finding the solid of revolution (constructed by revolving around the x-axis) using the disc method.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/btGaOTXxXs8.mp4/btGaOTXxXs8.mp4</video:content_loc><video:duration>541</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/generalizing-disc-method-around-x-axis</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1276878010.jpg</video:thumbnail_loc><video:title>Generalizing the disc method around x-axis</video:title><video:description>Generalizing what we did in the last video for f(x) to get the &quot;formula&quot; for using the disc method around the x-axis</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vmS3cTaxKdA.mp4/vmS3cTaxKdA.mp4</video:content_loc><video:duration>155</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/disc-method-around-y-axis</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1277026678.jpg</video:thumbnail_loc><video:title>Using the disc method around y-axis</video:title><video:description>Finding the volume of a figure that is rotated around the y-axis using the disc method</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/43AS7bPUORc.mp4/43AS7bPUORc.mp4</video:content_loc><video:duration>453</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/disc-method-rotation-around-horizontal-line</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1276975478.jpg</video:thumbnail_loc><video:title>Using the disc method: rotation around horizontal line</video:title><video:description>Solid of revolution constructing by rotating around line that is not an axis</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/XdzcU5JbVcA.mp4/XdzcU5JbVcA.mp4</video:content_loc><video:duration>594</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/disc-method-rotating-around-vertical-line</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1276946626.jpg</video:thumbnail_loc><video:title>Using the disc method: rotation around vertical line</video:title><video:description>Volume of solid created by rotating around vertical line that is not the y-axis using the disc method.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jxf7XqvZWWg.mp4/jxf7XqvZWWg.mp4</video:content_loc><video:duration>291</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/calculating-integral-disc-method-around-vertical-line</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1277077144.jpg</video:thumbnail_loc><video:title>Calculating integral: disc around vertical line</video:title><video:description>Calculate the integral from the last video.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/eLdhifUUMmk.mp4/eLdhifUUMmk.mp4</video:content_loc><video:duration>339</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/disc-method-washer-method-for-rotation-around-x-axis</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1277082263.jpg</video:thumbnail_loc><video:title>Finding the solid of revolution between two functions (leading up to the washer method)</video:title><video:description>Finding the volume of a solid of revolution that is defined between two functions</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vhMl755vR5Q.mp4/vhMl755vR5Q.mp4</video:content_loc><video:duration>547</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/generalizing-the-washer-method</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1276911918.jpg</video:thumbnail_loc><video:title>Generalizing the washer method</video:title><video:description>Looking at the example from the last video in a more generalized way</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Thvc2s9aUP4.mp4/Thvc2s9aUP4.mp4</video:content_loc><video:duration>511</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/washer-method-rotating-around-non-axis</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1277007629.jpg</video:thumbnail_loc><video:title>Using the washer method: rotating around horizontal line (not x-axis), part 1</video:title><video:description>Washer method when rotating around a horizontal line that is not the x-axis</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OFNGpKGg9IQ.mp4/OFNGpKGg9IQ.mp4</video:content_loc><video:duration>398</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/part-2-of-washer-for-not-axis-rotation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1276843891.jpg</video:thumbnail_loc><video:title>Using the washer method: rotating around horizontal line (not x-axis), part 2</video:title><video:description>Doing some hairy algebra and arithmetic to evaluate the definite integral from the last video</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LKzpw_HUKNQ.mp4/LKzpw_HUKNQ.mp4</video:content_loc><video:duration>494</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/washer-or-ring-method-for-vertical-line-rotation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1278890062.jpg</video:thumbnail_loc><video:title>Using the washer method: rotating around vertical line (not y-axis), part 1</video:title><video:description>Setting up the definite integral for the volume of a solid of revolution around a vertical line using the washer or ring method.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/WAPZihVUmzE.mp4/WAPZihVUmzE.mp4</video:content_loc><video:duration>470</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/evaluating-integral-for-washer-method-around-vertical-line</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1278699793.jpg</video:thumbnail_loc><video:title>Using the washer method: rotating around vertical line (not y-axis), part 2</video:title><video:description>Evaluating the integral set up in the last video using the washer method.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/i-Rb4_n929k.mp4/i-Rb4_n929k.mp4</video:content_loc><video:duration>335</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/2011-calculus-ab-free-response-1-parts-b-c-d</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/237109442.jpg</video:thumbnail_loc><video:title>Using integrals to analyze particle motion: 2011 Calculus AB Free Response #1 (b, c, &amp; d)</video:title><video:description>Integration to find average value of a function. Using a graphing calculator to calculate definite integrals.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OSipkz8vDjE.mp4/OSipkz8vDjE.mp4</video:content_loc><video:duration>484</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/2011-calculus-ab-free-response-2-c-d</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/235193472.jpg</video:thumbnail_loc><video:title>Applying second fundamental theorem of calculus: 2011 Calculus AB free response #2 (c &amp; d)</video:title><video:description>Second fundamental theorem of calculus application</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2axaRJQkfVk.mp4/2axaRJQkfVk.mp4</video:content_loc><video:duration>447</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/calculating-area-between-curves-ap-calculus-ab-free-response-2011-3b</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1f2813e75d8391c4.jpg</video:thumbnail_loc><video:title>Calculating area between curves AP Calculus AB free response 2011 3b</video:title><video:description>Calculating the area between curves.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0QsFXGAqx9c.mp4/0QsFXGAqx9c.mp4</video:content_loc><video:duration>315</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/2011-calculus-ab-free-response-3-c</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/235193473.jpg</video:thumbnail_loc><video:title>Writing integral for solid of revolution: 2011 Calculus AB free response #3 (c)</video:title><video:description>Disk method to find the volume of a solid generated by rotation of a function</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/v-H_7o7EMoU.mp4/v-H_7o7EMoU.mp4</video:content_loc><video:duration>399</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/2011-calculus-ab-free-response-6c</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/244051676.jpg</video:thumbnail_loc><video:title>Finding average value: 2011 Calculus AB free response #6c</video:title><video:description>Average value of a piecewise-defined function on an interval</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ucghWyc2_qs.mp4/ucghWyc2_qs.mp4</video:content_loc><video:duration>449</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/2015-ap-calculus-ab-bc-1a</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb6e61bac6ad2b410.jpg</video:thumbnail_loc><video:title>Using accumulation functions 2015 AP Calculus AB BC 1a</video:title><video:description>Using accumulation functions to estimate the amount of water in a pipe.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DQsYrGDDs5I.mp4/DQsYrGDDs5I.mp4</video:content_loc><video:duration>285</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/2015-ap-calculus-abbc-1d</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x44d517e4.jpg</video:thumbnail_loc><video:title>Writing integral to solve problem in context: 2015 AP Calculus AB/BC 1d</video:title><video:description>When the pipe overflows</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9Fqy_stBdFk.mp4/9Fqy_stBdFk.mp4</video:content_loc><video:duration>199</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/2015-ap-calculus-ap-2a</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe129d8d1.jpg</video:thumbnail_loc><video:title>Finding area between curves: 2015 AP Calculus AB 2a</video:title><video:description>Areas between curves</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5QY8yvZViO0.mp4/5QY8yvZViO0.mp4</video:content_loc><video:duration>295</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/2015-ap-calculus-ap-2b</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x59861801.jpg</video:thumbnail_loc><video:title>Finding volume of solid with known cross section: 2015 AP Calculus AB 2b</video:title><video:description>Volume of solid with known cross section</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xmVBv7vk3Gg.mp4/xmVBv7vk3Gg.mp4</video:content_loc><video:duration>387</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/finding-average-velocity-2015-ap-calculus-ab-bc-3d</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6cb1a7b4c4bcfbf9.jpg</video:thumbnail_loc><video:title>Finding average velocity 2015 AP Calculus AB BC 3d</video:title><video:description>Finding the average velocity over a given time interval in context.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/31pieUEqLWw.mp4/31pieUEqLWw.mp4</video:content_loc><video:duration>200</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/2015-ap-calculus-ab-5d</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5c1c07cc.jpg</video:thumbnail_loc><video:title>Using function that involves an integral: 2015 AP Calculus AB 5d</video:title><video:description>Constructing expression for f with integral.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/a601bUPEYUs.mp4/a601bUPEYUs.mp4</video:content_loc><video:duration>329</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/estimating-average-value-with-trapezoidal-sum-ap-calculus-ab-free-response-2011-</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x54712dc49943244a.jpg</video:thumbnail_loc><video:title>Estimating average value with trapezoidal sum AP Calculus AB free response 2011 2b</video:title><video:description>Estimating the average value of a function using a trapezoidal sum.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qS7P8pOgYTI.mp4/qS7P8pOgYTI.mp4</video:content_loc><video:duration>338</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-ab/v/differentiating-implicitly-and-determining-concavity-ap-calculus-ab-bc-2015-4b</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf2606ff017f925c1.jpg</video:thumbnail_loc><video:title>Differentiating implicitly and determining concavity AP Calculus AB BC 2015 4b</video:title><video:description>Differentiating implicitly and determining concavity of a given differential equation</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gPEgwN4ZHCA.mp4/gPEgwN4ZHCA.mp4</video:content_loc><video:duration>494</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/deriving-integration-by-parts-formula</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1329232699.jpg</video:thumbnail_loc><video:title>Integration by parts intro</video:title><video:description>This video explains integration by parts, a technique for finding antiderivatives. It starts with the product rule for derivatives, then takes the antiderivative of both sides. By rearranging the equation, we get the formula for integration by parts. It helps simplify complex antiderivatives.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/dh__n9FVKA0.mp4/dh__n9FVKA0.mp4</video:content_loc><video:duration>232</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/antiderivative-of-xcosx-using-integration-by-parts</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1329293927.jpg</video:thumbnail_loc><video:title>Integration by parts: ∫x⋅cos(x)dx</video:title><video:description>This video shows how to find the antiderivative of x*cos(x) using integration by parts. It assigns f(x)=x and g&apos;(x)=cos(x), making f&apos;(x)=1 and g(x)=sin(x). The formula becomes x*sin(x) - ∫sin(x)dx, which simplifies to x*sin(x) + cos(x) + C.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/bZ8YAHDTFJ8.mp4/bZ8YAHDTFJ8.mp4</video:content_loc><video:duration>232</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/integral-of-ln-x</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1377705570.jpg</video:thumbnail_loc><video:title>Integration by parts: ∫ln(x)dx</video:title><video:description>This video shows how to find the antiderivative of the natural log of x using integration by parts. We rewrite the integral as ln(x) times 1dx, then choose f(x) = ln(x) and g&apos;(x) = 1. The antiderivative is xln(x) - x + C.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/iw5eLJV0Sj4.mp4/iw5eLJV0Sj4.mp4</video:content_loc><video:duration>230</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/integration-by-parts-twice-for-antiderivative-of-x-2-e-x</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1329248194.jpg</video:thumbnail_loc><video:title>Integration by parts: ∫x²⋅𝑒ˣdx</video:title><video:description>Integration by parts helps find antiderivatives of products of functions. We assign f(x) and g&apos;(x) to parts of the product. Then, we find f&apos;(x) and g(x). The formula is ∫f(x)g&apos;(x)dx = f(x)g(x) - ∫f&apos;(x)g(x)dx. Sometimes, we use integration by parts twice!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/n-iEqLhGfd4.mp4/n-iEqLhGfd4.mp4</video:content_loc><video:duration>406</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/integration-by-parts-of-e-x-cos-x-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1369495388.jpg</video:thumbnail_loc><video:title>Integration by parts: ∫𝑒ˣ⋅cos(x)dx</video:title><video:description>In the video, we learn about integration by parts to find the antiderivative of e^x * cos(x). We assign f(x) = e^x and g&apos;(x) = cos(x), then apply integration by parts twice. The result is the antiderivative e^x * sin(x) + e^x * cos(x) / 2 + C.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LJqNdG6Y2cM.mp4/LJqNdG6Y2cM.mp4</video:content_loc><video:duration>437</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/integration-by-parts-of-definite-integral</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x72ccc1ab3a4944c6.jpg</video:thumbnail_loc><video:title>Integration by parts: definite integrals</video:title><video:description>When finding a definite integral using integration by parts, we should first find the antiderivative (as we do with indefinite integrals), but then we should also evaluate the antiderivative at the boundaries and subtract.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vS3bpx5ubBI.mp4/vS3bpx5ubBI.mp4</video:content_loc><video:duration>343</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/integration-with-partial-fractions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xcf3c678b37108e75.jpg</video:thumbnail_loc><video:title>Integration with partial fractions</video:title><video:description>Finding the integral of a rational function using linear partial fraction decomposition.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Mt92Ozs7aJg.mp4/Mt92Ozs7aJg.mp4</video:content_loc><video:duration>439</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/introduction-to-improper-integrals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1377828561.jpg</video:thumbnail_loc><video:title>Introduction to improper integrals</video:title><video:description>Improper integrals are definite integrals where one or both of the ​boundaries is at infinity, or where the integrand has a vertical asymptote in the interval of integration. As crazy as it may sound, we can actually calculate some improper integrals using some clever methods that involve limits.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qv7DM5Ph0vU.mp4/qv7DM5Ph0vU.mp4</video:content_loc><video:duration>232</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/divergent-improper-integral</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1378156106.jpg</video:thumbnail_loc><video:title>Divergent improper integral</video:title><video:description>Sometimes the value of an infinite integral is, well, infinite.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9VqL6POWIoc.mp4/9VqL6POWIoc.mp4</video:content_loc><video:duration>162</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/eulers-method</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5c5705d2.jpg</video:thumbnail_loc><video:title>Euler&apos;s method</video:title><video:description>This video introduces Euler&apos;s Method, a numerical way to approximate solutions to differential equations when analytical methods don&apos;t work. Using a table with x, y, and dy/dx values, we start with an initial condition and increment x by a chosen delta x to estimate y values: smaller delta x gives better approximations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/q87L9R9v274.mp4/q87L9R9v274.mp4</video:content_loc><video:duration>608</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/example-eulers-method-exercise</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7ac26ce4.jpg</video:thumbnail_loc><video:title>Worked example: Euler&apos;s method</video:title><video:description>Finding the initial condition based on the result of approximating with Euler&apos;s method.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_-a-yNubpk8.mp4/_-a-yNubpk8.mp4</video:content_loc><video:duration>275</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/modeling-population-with-differential-equations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xff25b528.jpg</video:thumbnail_loc><video:title>Growth models: introduction</video:title><video:description>Population should grow proportionally to its size, but it can&apos;t keep growing forever! Learn more about this problem, posed by Malthus, and embark on a journey towards its mathematical solution.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_JpS8k1a9yE.mp4/_JpS8k1a9yE.mp4</video:content_loc><video:duration>577</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/logistic-differential-equation-intuition</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb9599623.jpg</video:thumbnail_loc><video:title>The logistic growth model</video:title><video:description>The logistic differential equation dN/dt=rN(1-N/K) describes the situation where a population grows proportionally to its size, but stops growing when it reaches the size of K.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/oiDvNs15tkE.mp4/oiDvNs15tkE.mp4</video:content_loc><video:duration>649</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/analyzing-logistic-differential-equations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe60ace5dccb9437f.jpg</video:thumbnail_loc><video:title>Worked example: Logistic model word problem</video:title><video:description>Finding the carrying capacity of a population that grows logistically. Also finding the population&apos;s size when it&apos;s growing the fastest.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/kDZlMFkKhWA.mp4/kDZlMFkKhWA.mp4</video:content_loc><video:duration>527</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/solving-logistic-differential-equation-part-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x152ee0ed.jpg</video:thumbnail_loc><video:title>Logistic equations (Part 1)</video:title><video:description>Finding the general solution of the general logistic equation dN/dt=rN(1-N/K). The solution is kind of hairy, but it&apos;s worth bearing with us!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/j_Taf2Tgggo.mp4/j_Taf2Tgggo.mp4</video:content_loc><video:duration>818</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/solving-logistic-differential-equation-part2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd9cb2b32.jpg</video:thumbnail_loc><video:title>Logistic equations (Part 2)</video:title><video:description>Finding the general solution of the general logistic equation dN/dt=rN(1-N/K). The solution is kind of hairy, but it&apos;s worth bearing with us!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/NU1v-8VRirU.mp4/NU1v-8VRirU.mp4</video:content_loc><video:duration>598</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/arc-length-formula</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x28571cbc.jpg</video:thumbnail_loc><video:title>Arc length intro</video:title><video:description>In this video, learn how to find the arc length of a curve using definite integrals. To find arc length, take the derivative of the function, square it, add 1, find the square root, and integrate from a to b.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8Y-snjheI9M.mp4/8Y-snjheI9M.mp4</video:content_loc><video:duration>381</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/arc-length-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x35f6ea19.jpg</video:thumbnail_loc><video:title>Worked example: arc length</video:title><video:description>This video shows how to find the arc length of a curve using the arc length formula. It uses the function y = x^(3/2) and finds the arc length from x = 0 to x = 32/9. The main steps are: find the derivative, square it, add 1, take the square root, and integrate.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OhISsmqv4_8.mp4/OhISsmqv4_8.mp4</video:content_loc><video:duration>423</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/parametric-function-differentiation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x037d4a44.jpg</video:thumbnail_loc><video:title>Parametric equations differentiation</video:title><video:description>Sal finds the derivative of the function defined by the parametric equations x=sin(1+3t) and y=2t³, and evaluates it at t=-⅓.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/AXasQLqazWU.mp4/AXasQLqazWU.mp4</video:content_loc><video:duration>335</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/second-derivative-of-parametric-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x32dbbbf7.jpg</video:thumbnail_loc><video:title>Second derivatives (parametric functions)</video:title><video:description>Sal finds the second derivative of the function defined by the parametric equations x=3e²ᵗ and y=3³ᵗ-1.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/iHNa1fhV7IA.mp4/iHNa1fhV7IA.mp4</video:content_loc><video:duration>390</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/parametric-curve-arc-length</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf846ca3307ce3b26.jpg</video:thumbnail_loc><video:title>Parametric curve arc length</video:title><video:description>Conceptual introduction to the formula for arc length of a parametric curve.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DXHM7LYGcbI.mp4/DXHM7LYGcbI.mp4</video:content_loc><video:duration>365</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/parametric-arc-length-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1cd2aab57f889617.jpg</video:thumbnail_loc><video:title>Worked example: Parametric arc length</video:title><video:description>Finding the length of the parametric curve 𝘹=cos(𝑡), 𝘺=sin(𝑡) from 𝑡=0 to 𝑡=π/2, using the formula for arc length of a parametric curve.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/F3KyoI26fKI.mp4/F3KyoI26fKI.mp4</video:content_loc><video:duration>288</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/position-vector-valued-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24316.jpg</video:thumbnail_loc><video:title>Vector-valued functions intro</video:title><video:description>Using a position vector valued function to describe a curve or path</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7fYDCUIvZnM.mp4/7fYDCUIvZnM.mp4</video:content_loc><video:duration>425</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/derivative-of-a-position-vector-valued-function</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24318.jpg</video:thumbnail_loc><video:title>Vector-valued functions differentiation</video:title><video:description>Visualizing the derivative of a position vector valued function</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/E9Q_Lc0g1xE.mp4/E9Q_Lc0g1xE.mp4</video:content_loc><video:duration>885</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/second-derivatives-of-vector-valued-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc0b3f860.jpg</video:thumbnail_loc><video:title>Second derivatives (vector-valued functions)</video:title><video:description>Sal finds the first and the second derivatives of the vector-valued function h(t)=(-t⁵-6,4t⁴+2t+1).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-vv63FS__bY.mp4/-vv63FS__bY.mp4</video:content_loc><video:duration>222</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/planar-motion-example-acceleration-vector</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9cae018f.jpg</video:thumbnail_loc><video:title>Planar motion example: acceleration vector</video:title><video:description>The position of a particle moving in the xy-plane is given by the position vector (-3t³+4t²,t³+2). Sal analyzes it to find the acceleration vector of the particle at time t=3.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/HFdeHX_wA4k.mp4/HFdeHX_wA4k.mp4</video:content_loc><video:duration>275</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/motion-along-a-curve-example-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc751f553.jpg</video:thumbnail_loc><video:title>Motion along a curve: finding rate of change</video:title><video:description>Given that a particle moves along the implicit curve x²y²=16 and given the rate of change of x with respect to t at some point, Sal finds the particle&apos;s rate of change with respect to y using implicit differentiation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Sv3Y0F0ASZ0.mp4/Sv3Y0F0ASZ0.mp4</video:content_loc><video:duration>352</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/motion-along-a-curve-example-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x123d8b65.jpg</video:thumbnail_loc><video:title>Motion along a curve: finding velocity magnitude</video:title><video:description>Given that a particle moves along the implicit curve xy=16 and given its rate of change with respect to y at some point, Sal finds the magnitude of the particle&apos;s velocity vector using implicit differentiation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/nC5UgHDjbcg.mp4/nC5UgHDjbcg.mp4</video:content_loc><video:duration>382</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/planar-motion-with-integrals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2729df269f69de0e.jpg</video:thumbnail_loc><video:title>Planar motion (with integrals)</video:title><video:description>To analyze planar motion where the rate vector is given, we need to find the displacement in each direction separately. Then we will either use that to find the new position, or to find the magnitude of the displacement using the Pythagorean theorem.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/EZbgMfuh9C8.mp4/EZbgMfuh9C8.mp4</video:content_loc><video:duration>428</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/derivatives-in-polar-coordinates</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6005fd8e4a8e9fcd.jpg</video:thumbnail_loc><video:title>Polar functions derivatives</video:title><video:description>Finding derivatives of 𝑟, 𝘹, and 𝘺 of a function given in polar coordinates.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8mS9eDHf0fQ.mp4/8mS9eDHf0fQ.mp4</video:content_loc><video:duration>565</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/differentiating-polar-functions-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x58a369d140415dc6.jpg</video:thumbnail_loc><video:title>Worked example: differentiating polar functions</video:title><video:description>An AP Calculus sample item where we find the rate of change of 𝘹 with respect to θ.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ConsnUZGfmw.mp4/ConsnUZGfmw.mp4</video:content_loc><video:duration>357</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/formula-area-polar-graph</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb44c8c08.jpg</video:thumbnail_loc><video:title>Area bounded by polar curves</video:title><video:description>Develop intuition for the area enclosed by polar graph formula</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qVn_Lfec-Ac.mp4/qVn_Lfec-Ac.mp4</video:content_loc><video:duration>391</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/cardioid-area</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8a47b52d.jpg</video:thumbnail_loc><video:title>Worked example: Area enclosed by cardioid</video:title><video:description>Area enclosed by cardioid</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-cR6FzM1zNE.mp4/-cR6FzM1zNE.mp4</video:content_loc><video:duration>386</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/area-defined-by-two-polar-graphs</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd198d3cc.jpg</video:thumbnail_loc><video:title>Worked example: Area between two polar graphs</video:title><video:description>More practice with the area encloised by polar functions, this time with two graphs.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/KwR_ysrv3sg.mp4/KwR_ysrv3sg.mp4</video:content_loc><video:duration>369</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/calculator-integral</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb21bd894.jpg</video:thumbnail_loc><video:title>Evaluating definite integral with calculator</video:title><video:description>This video shows how to find the overlapping area between two circles using definite integrals and a graphing calculator. It demonstrates entering the integral function, specifying the variable, and setting the bounds of integration. The result matches the hand-calculated answer.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4tWFdI7DkJ4.mp4/4tWFdI7DkJ4.mp4</video:content_loc><video:duration>179</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/convergent-and-divergent-sequences</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1383707269.jpg</video:thumbnail_loc><video:title>Convergent and divergent sequences</video:title><video:description>This video talks about a sequence that alternates between positive and negative values. It shows how to find the limit of the sequence as n approaches infinity. If the limit exists, the sequence converges; if not, it diverges.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lfZGtjSWcQs.mp4/lfZGtjSWcQs.mp4</video:content_loc><video:duration>299</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/identifying-sequence-convergence-divergence</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1a7b5891.jpg</video:thumbnail_loc><video:title>Worked example: sequence convergence/divergence</video:title><video:description>How can we tell if a sequence converges or diverges? See Sal in action, determining the convergence/divergence of several sequences.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/muqyereWEh4.mp4/muqyereWEh4.mp4</video:content_loc><video:duration>233</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/infinite-series-as-limit-of-partial-sums</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb8d9548c.jpg</video:thumbnail_loc><video:title>Infinite series as limit of partial sums</video:title><video:description>Infinite series are defined as the limit of the infinite sequence of partial sums. Since we already know how to work with limits of sequences, this definition is really useful.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/bh1UrCGWz1k.mp4/bh1UrCGWz1k.mp4</video:content_loc><video:duration>288</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/divergence-test</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1404a71d.jpg</video:thumbnail_loc><video:title>nth term divergence test</video:title><video:description>The video introduces the divergence test, a tool to check if a series diverges. If the limit of a sequence aₙ as n approaches infinity isn&apos;t zero, the series will diverge. The test can&apos;t prove convergence, but it helps identify divergence.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1yInzfzDDKY.mp4/1yInzfzDDKY.mp4</video:content_loc><video:duration>476</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/integral-test-intuition</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x05f544f8.jpg</video:thumbnail_loc><video:title>Integral test</video:title><video:description>The integral test helps us determine a series convergence by comparing it to an improper integral, which is something we already know how to find. Learn how it works in this video.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/u1UKIljUWuc.mp4/u1UKIljUWuc.mp4</video:content_loc><video:duration>526</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/integral-test-divergence</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe42fe616.jpg</video:thumbnail_loc><video:title>Worked example: Integral test</video:title><video:description>See how the integral test is put to use in determining whether a sequence converges or diverges.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xRyXz_UZ14Q.mp4/xRyXz_UZ14Q.mp4</video:content_loc><video:duration>545</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/harmonic-and-p-series</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa3a79760191bd066.jpg</video:thumbnail_loc><video:title>Harmonic series and 𝑝-series</video:title><video:description>𝑝-series is a family of series where the terms are of the form 1/(nᵖ) for some value of 𝑝. The Harmonic series is the special case where 𝑝=1. These series are very interesting and useful.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/m6ByHObCs6Y.mp4/m6ByHObCs6Y.mp4</video:content_loc><video:duration>310</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/p-series-convergence</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x71d725aa03d31325.jpg</video:thumbnail_loc><video:title>Worked example: p-series</video:title><video:description>In this video, we&apos;ll explore p-series, which are infinite sums written as Σ(1/xᵖ) with a positive p value. Through engaging examples, we&apos;ll learn how to identify if a p-series converges (has a finite sum) or diverges (doesn&apos;t have a finite sum) by examining the value of p. Get ready for a fun and informative journey into the world of p-series!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vspcKkcLuuA.mp4/vspcKkcLuuA.mp4</video:content_loc><video:duration>175</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/comparison-test</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xaf5004b1.jpg</video:thumbnail_loc><video:title>Direct comparison test</video:title><video:description>The comparison test helps us decide if a series converges (sums to a finite value) or diverges (goes to infinity). If a smaller series converges, the larger one does too. If a smaller series diverges, the larger one also diverges. This test works for series with non-negative terms.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0tXxFPHzFFI.mp4/0tXxFPHzFFI.mp4</video:content_loc><video:duration>270</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/comparison-test-convergence</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8d385a4e.jpg</video:thumbnail_loc><video:title>Worked example: direct comparison test</video:title><video:description>Using the direct comparison test to determine that the infinite sum of 1/(2ⁿ+n) converges by comparing it to the infinite sum 1/2ⁿ.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/XoBlfbrdBpQ.mp4/XoBlfbrdBpQ.mp4</video:content_loc><video:duration>295</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/limit-comparison-test-cor</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5b63d7f9.jpg</video:thumbnail_loc><video:title>Limit comparison test</video:title><video:description>The video explains the Comparison Test and Limit Comparison Test for infinite series. The Comparison Test checks if a series converges by comparing it to another series with known convergence. The Limit Comparison Test compares the behavior of two series as n approaches infinity. If their limit is positive and finite, both series either converge or diverge together.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/AtbZZiSLemQ.mp4/AtbZZiSLemQ.mp4</video:content_loc><video:duration>413</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/limit-comparison-test-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa4936ff42719938e.jpg</video:thumbnail_loc><video:title>Worked example: limit comparison test</video:title><video:description>To use the limit comparison test for a series S₁, we need to find another series S₂ that is similar in structure (so the infinite limit of S₁/S₂ is finite) and whose convergence is already determined. See a worked example of using the test in this video.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0dWF35WPKfM.mp4/0dWF35WPKfM.mp4</video:content_loc><video:duration>290</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/harmonic-series-divergent</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0039c7d4.jpg</video:thumbnail_loc><video:title>Proof: harmonic series diverges</video:title><video:description>Showing that the harmonic series 1 + ½ + ⅓ + ¼ + ... actually diverges, using the direct comparison test. This proof is famous for its clever use of algebraic manipulation!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4yyLfrsSXQQ.mp4/4yyLfrsSXQQ.mp4</video:content_loc><video:duration>393</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/alternating-series-test</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x30ab4c93.jpg</video:thumbnail_loc><video:title>Alternating series test</video:title><video:description>When a series alternates (plus, minus, plus, minus,...) there&apos;s a fairly simple way to determine whether it converges or diverges: see if the terms of the series approach 0.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/UsMom3yNsX8.mp4/UsMom3yNsX8.mp4</video:content_loc><video:duration>348</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/worked-example-alternating-series</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfd653f28e36ff338.jpg</video:thumbnail_loc><video:title>Worked example: alternating series</video:title><video:description>Example using the alternating series test to determine which values of a variable will make the series converge.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DPxf4-ta4PM.mp4/DPxf4-ta4PM.mp4</video:content_loc><video:duration>177</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/ratio-test-convergence</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x18608b0a.jpg</video:thumbnail_loc><video:title>Ratio test</video:title><video:description>The ratio test is a most useful test for series convergence. It caries over intuition from geometric series to more general series. Learn more about it here.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/av947KCWf2U.mp4/av947KCWf2U.mp4</video:content_loc><video:duration>539</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/conditional-and-absolute-convergence</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf35d880b.jpg</video:thumbnail_loc><video:title>Conditional &amp; absolute convergence</video:title><video:description>This video talks about two types of convergence: conditional and absolute. A series converges conditionally if it converges, but taking the absolute value of its terms makes it diverge. A series converges absolutely if it converges even when taking the absolute value of its terms.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ORTI4kk1okM.mp4/ORTI4kk1okM.mp4</video:content_loc><video:duration>301</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/alternating-series-error-estimation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x37b67eba.jpg</video:thumbnail_loc><video:title>Alternating series remainder</video:title><video:description>This video shows how to estimate the sum of an alternating series using partial sums. It demonstrates that the error (remainder) is between 0 and the first term not included. This helps find a range for the actual sum.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gs9O255gdEY.mp4/gs9O255gdEY.mp4</video:content_loc><video:duration>558</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/alternating-series-remainder</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xef940f21.jpg</video:thumbnail_loc><video:title>Worked example: alternating series remainder</video:title><video:description>Using the alternating series remainder to approximating the sum of an alternating series to a given error bound.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vTYxY4IpmF8.mp4/vTYxY4IpmF8.mp4</video:content_loc><video:duration>621</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/maclaurin-and-taylor-series-intuition</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/89857202.jpg</video:thumbnail_loc><video:title>Taylor &amp; Maclaurin polynomials intro (part 1)</video:title><video:description>This video introduces the Maclaurin series, a way to approximate functions using polynomials. It shows how to create better approximations by adding more terms, making the function and its derivatives match at x=0. The general formula for the n-th term is the n-th derivative of the function at 0 times x^n divided by n factorial.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/epgwuzzDHsQ.mp4/epgwuzzDHsQ.mp4</video:content_loc><video:duration>779</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/generalized-taylor-series-approximation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/90906157.jpg</video:thumbnail_loc><video:title>Taylor &amp; Maclaurin polynomials intro (part 2)</video:title><video:description>This video explains Taylor series, a way to approximate functions around any point x=c. It starts with a constant approximation (f(c)), then adds terms for matching the slope (f&apos;(c)(x-c)) and higher derivatives. More terms give better approximations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1LxhXqD3_CE.mp4/1LxhXqD3_CE.mp4</video:content_loc><video:duration>447</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/maclaurin-polynomial-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf501bdc865844281.jpg</video:thumbnail_loc><video:title>Worked example: Maclaurin polynomial</video:title><video:description>Finding the second degree Maclaurin polynomial of 1/√(x+1).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tWNxdsWoAd4.mp4/tWNxdsWoAd4.mp4</video:content_loc><video:duration>283</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/finding-coefficient-of-maclaurin-polynomial</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4edb6df3557032e7.jpg</video:thumbnail_loc><video:title>Worked example: coefficient in Maclaurin polynomial</video:title><video:description>Finding the coefficient of the x² term in a Maclaurin polynomial, given the formula for the value of any derivative at x=0.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/RRYh4cqv6ZQ.mp4/RRYh4cqv6ZQ.mp4</video:content_loc><video:duration>185</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/fourth-degree-coefficient-for-taylor-polynomial</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3c942abd69be14fd.jpg</video:thumbnail_loc><video:title>Worked example: coefficient in Taylor polynomial</video:title><video:description>Finding the coefficient of the term containing (x+2)⁴ in the Taylor polynomial centered at x=-2 of x⁶-x³.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/eo9dra_yIbc.mp4/eo9dra_yIbc.mp4</video:content_loc><video:duration>233</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/visualizing-taylor-series-for-e-x</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/90906158.jpg</video:thumbnail_loc><video:title>Visualizing Taylor polynomial approximations</video:title><video:description>Approximating eˣ with a Taylor polynomial centered at x=3. In the video we find the first few terms of such a polynomial and graph it to see how close it gets to eˣ.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/AFMXixBVP-0.mp4/AFMXixBVP-0.mp4</video:content_loc><video:duration>398</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/error-or-remainder-of-a-taylor-polynomial-approximation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/250668427.jpg</video:thumbnail_loc><video:title>Taylor polynomial remainder (part 1)</video:title><video:description>The more terms we have in a Taylor polynomial approximation of a function, the closer we get to the function. But HOW close? Let&apos;s embark on a journey to find a bound for the error of a Taylor polynomial approximation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/wgkRH5Uoavk.mp4/wgkRH5Uoavk.mp4</video:content_loc><video:duration>687</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/proof-bounding-the-error-or-remainder-of-a-taylor-polynomial-approximation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/250668428.jpg</video:thumbnail_loc><video:title>Taylor polynomial remainder (part 2)</video:title><video:description>The more terms we have in a Taylor polynomial approximation of a function, the closer we get to the function. But HOW close? In this video, we prove the Lagrange error bound for Taylor polynomials.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/yUUPP70Fhpo.mp4/yUUPP70Fhpo.mp4</video:content_loc><video:duration>908</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/lagrange-error-bound-for-sine-function</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7a80166ea896e1ec.jpg</video:thumbnail_loc><video:title>Worked example: estimating sin(0.4) using Lagrange error bound</video:title><video:description>Lagrange error bound (also called Taylor remainder theorem) can help us determine the degree of Taylor/Maclaurin polynomial to use to approximate a function to a given error bound. See how it&apos;s done when approximating the sine function.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2KWifFPOy5s.mp4/2KWifFPOy5s.mp4</video:content_loc><video:duration>527</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/lagrange-error-bound-exponential-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd240c30ca59e3c2d.jpg</video:thumbnail_loc><video:title>Worked example: estimating eˣ using Lagrange error bound</video:title><video:description>This video explains how to find the least degree of a Taylor polynomial to estimate e^x with an error smaller than 0.001. It uses the LaGrange error bound and Taylor&apos;s remainder theorem to find the smallest n (degree) that satisfies the error condition.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/IeHlXGpfaeA.mp4/IeHlXGpfaeA.mp4</video:content_loc><video:duration>560</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/power-series-radius-interval-convergence</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf2f4de02.jpg</video:thumbnail_loc><video:title>Power series intro</video:title><video:description>Power series define functions using infinite sums. A geometric series is a special case of a power series with a constant coefficient. Convergence happens when the common ratio&apos;s absolute value is less than 1. The interval of convergence is the range of x values where the series converges. The radius of convergence is half the interval.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DlBQcj_zQk0.mp4/DlBQcj_zQk0.mp4</video:content_loc><video:duration>409</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/radius-convergence-ratio-test</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1f1a1ec842581890.jpg</video:thumbnail_loc><video:title>Worked example: interval of convergence</video:title><video:description>This video focuses on finding the interval of convergence for an infinite series using the ratio test. It shows how to calculate the limit of the ratio of consecutive terms, then determine when the series converges, diverges, or is inconclusive. Finally, it tests the inconclusive cases.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/oXUJXsoCtDs.mp4/oXUJXsoCtDs.mp4</video:content_loc><video:duration>506</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/function-as-a-geometric-series</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x43a07b696ac7d30f.jpg</video:thumbnail_loc><video:title>Function as a geometric series</video:title><video:description>Expressions of the form a/(1-r) represent the infinite sum of a geometric series whose initial term is a and constant ratio is r, which is written as Σa(r)ⁿ. Since geometric series are a class of power series, we obtained the power series representation of a/(1-r) very quickly.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/EXIUYib9d8M.mp4/EXIUYib9d8M.mp4</video:content_loc><video:duration>241</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/function-as-geometric-series</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4776b79b.jpg</video:thumbnail_loc><video:title>Geometric series as a function</video:title><video:description>Power series of the form Σk(x-a)ⁿ (where k is constant) are a geometric series with initial term k and common ratio (x-a). Since we have an expression for the sum of a geometric series, we can rewrite such power series as a finite expression.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OzH735zyTWs.mp4/OzH735zyTWs.mp4</video:content_loc><video:duration>298</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/finding-power-series-through-integration</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc5188ec7.jpg</video:thumbnail_loc><video:title>Power series of arctan(2x)</video:title><video:description>We can represent arctan(2x) with a power series by representing its derivative as a power series and then integrating that series. You have to admit this is pretty neat.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/NgYrsqoKXpM.mp4/NgYrsqoKXpM.mp4</video:content_loc><video:duration>666</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/power-series-using-integration</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x420cdc1d.jpg</video:thumbnail_loc><video:title>Power series of ln(1+x³)</video:title><video:description>We can represent ln(1+x³) with a power series by representing its derivative as a power series and then integrating that series. You have to admit this is pretty neat.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/znT4W6n3WkI.mp4/znT4W6n3WkI.mp4</video:content_loc><video:duration>800</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/cosine-taylor-series-at-0-maclaurin</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/89857203.jpg</video:thumbnail_loc><video:title>Maclaurin series of cos(x)</video:title><video:description>This video explains the Maclaurin series, a special case of the Taylor series. It shows how to find the Maclaurin series for cosine of x by taking derivatives and evaluating them at 0. The resulting pattern creates a polynomial representation of cos(x).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/WWe7pZjc4s8.mp4/WWe7pZjc4s8.mp4</video:content_loc><video:duration>337</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/sine-taylor-series-at-0-maclaurin</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/89860962.jpg</video:thumbnail_loc><video:title>Maclaurin series of sin(x)</video:title><video:description>We can approximate sin(x) using a Maclaurin series, which is like a Taylor polynomial centered at x=0 with infinite terms. Surprisingly, this series is the same as the sin(x) function itself! The series includes odd powers of x divided by their factorials, with alternating signs. This pattern helps us understand the relationship between sin(x) and cos(x).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LlKvubIqHc8.mp4/LlKvubIqHc8.mp4</video:content_loc><video:duration>393</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/taylor-series-at-0-maclaurin-for-e-to-the-x</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/89858536.jpg</video:thumbnail_loc><video:title>Maclaurin series of eˣ</video:title><video:description>We can estimate eˣ using a Maclaurin series, which is an infinite Taylor polynomial centered at x=0. Surprisingly, this series is identical to the original function, eˣ! This means the approximation gets closer to eˣ as we add more terms.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/JYQqml4-4q4.mp4/JYQqml4-4q4.mp4</video:content_loc><video:duration>370</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/maclaurin-series-based-on-cos-x</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1aeaa19d.jpg</video:thumbnail_loc><video:title>Worked example: power series from cos(x)</video:title><video:description>Finding a power series to represent x³cos(x²) using the Maclaurin series of cos(x).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/kXULrUxGzmU.mp4/kXULrUxGzmU.mp4</video:content_loc><video:duration>481</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/evaluating-power-series-for-mystery-function</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x13b06289.jpg</video:thumbnail_loc><video:title>Worked example: cosine function from power series</video:title><video:description>Given a power series, we recognize it as the Maclaurin series of cos(x³) and evaluate it at a given x-value.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/BAFOOQxiwkU.mp4/BAFOOQxiwkU.mp4</video:content_loc><video:duration>369</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/recognizing-function-from-taylor-series</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xcf549f34c730725c.jpg</video:thumbnail_loc><video:title>Worked example: recognizing function from Taylor series</video:title><video:description>Sample AP Calculus question asking to recognize a function from its Taylor series.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0BdZZCwDE-I.mp4/0BdZZCwDE-I.mp4</video:content_loc><video:duration>266</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/visualizing-taylor-series-approximations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/90906156.jpg</video:thumbnail_loc><video:title>Visualizing Taylor series approximations</video:title><video:description>The larger the degree of a Taylor polynomial, the better it approximates the function. See that in action with sin(x) and its Taylor polynomials.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8dMLK2Wueaw.mp4/8dMLK2Wueaw.mp4</video:content_loc><video:duration>361</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/euler-s-formula-and-euler-s-identity</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/90906155.jpg</video:thumbnail_loc><video:title>Euler&apos;s formula &amp; Euler&apos;s identity</video:title><video:description>Euler&apos;s Formula, e^(ix) = cos(x) + i*sin(x), and Euler&apos;s Identity, e^(iπ) + 1 = 0, are incredible math discoveries. They connect e, i, and pi through Maclaurin series of cos(x), sin(x), and e^x. These formulas reveal a deep, mysterious connection between important numbers in math.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/mgNtPOgFje0.mp4/mgNtPOgFje0.mp4</video:content_loc><video:duration>687</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/rep-function-with-geometric-series</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x38e71a1b.jpg</video:thumbnail_loc><video:title>Geometric series interval of convergence</video:title><video:description>When a power series is a geometric series, we can find its interval of convergence without using the ratio test!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/aiwy2fNF_ZQ.mp4/aiwy2fNF_ZQ.mp4</video:content_loc><video:duration>332</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/integrating-power-series</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbf473cee828d6007.jpg</video:thumbnail_loc><video:title>Integrating power series</video:title><video:description>Within its interval of convergence, the integral of a power series is the sum of integrals of individual terms: ∫Σf(x)dx=Σ∫f(x)dx. See how this is used to find the integral of a power series.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/dEHZV7q5VV0.mp4/dEHZV7q5VV0.mp4</video:content_loc><video:duration>365</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/differentiating-power-series</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe25757f0bfe90db1.jpg</video:thumbnail_loc><video:title>Differentiating power series</video:title><video:description>Within its interval of convergence, the derivative of a power series is the sum of derivatives of individual terms: [Σf(x)]&apos;=Σf&apos;(x). See how this is used to find the derivative of a power series.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/904esvqoJns.mp4/904esvqoJns.mp4</video:content_loc><video:duration>482</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/finding-function-from-series-by-integrating</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x263746f1c1fe3e3e.jpg</video:thumbnail_loc><video:title>Finding function from power series by integrating</video:title><video:description>When a power series S₁ is an antiderivative of a geometric series S₂, we can find the function represented by S₁ by integrating the expression for S₂.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ixFgd1lFe9g.mp4/ixFgd1lFe9g.mp4</video:content_loc><video:duration>347</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/interval-of-convergence-for-derivative-and-integral</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1449caf36ce2ba6a.jpg</video:thumbnail_loc><video:title>Interval of convergence for derivative and integral</video:title><video:description>Integrating or differentiating a power series term-by-term can only work within the interval of convergence. The interval of convergence of the integral/derivative will be the same, except maybe for the endpoints. See an example here.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TeIgljoLIxA.mp4/TeIgljoLIxA.mp4</video:content_loc><video:duration>515</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/definition-of-limit-of-a-sequence-and-sequence-convergence</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1392656058.jpg</video:thumbnail_loc><video:title>Formal definition for limit of a sequence</video:title><video:description>A sequence is &quot;converging&quot; if its terms approach a specific value at infinity. This video is a more formal definition of what it means for a sequence to converge.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/wzw9ll80Zbc.mp4/wzw9ll80Zbc.mp4</video:content_loc><video:duration>289</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/proving-a-sequence-converges</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1392561319.jpg</video:thumbnail_loc><video:title>Proving a sequence converges using the formal definition</video:title><video:description>Applying the formal definition of the limit of a sequence to prove that a sequence converges.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-XRQovTI04Q.mp4/-XRQovTI04Q.mp4</video:content_loc><video:duration>331</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/proving-p-series-convergence-criteria</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x530a4495c588ee72.jpg</video:thumbnail_loc><video:title>Proof of p-series convergence criteria</video:title><video:description>A p-series converges for p&gt;1 and diverges for 0</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4WChwIGKdaA.mp4/4WChwIGKdaA.mp4</video:content_loc><video:duration>577</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/2015-ap-calculus-bc-2a</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x48730aff.jpg</video:thumbnail_loc><video:title>2015 AP Calculus BC 2a</video:title><video:description>x coordinate of particle at a certain time</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/UmU0L6j-48s.mp4/UmU0L6j-48s.mp4</video:content_loc><video:duration>251</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/2015-ap-calculus-bc-2b</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x67e9485a.jpg</video:thumbnail_loc><video:title>2015 AP Calculus BC 2b</video:title><video:description>Point on curve where tangent line has a certain slope</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ZFBwkvVa6NE.mp4/ZFBwkvVa6NE.mp4</video:content_loc><video:duration>303</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/2015-ap-calculus-bc-2c</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x592677be.jpg</video:thumbnail_loc><video:title>2015 AP Calculus BC 2c</video:title><video:description>Time when particle reaches a certain speed</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/eU7MCBQTvoY.mp4/eU7MCBQTvoY.mp4</video:content_loc><video:duration>280</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/2015-ap-calculus-bc-2d</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfaa31c60.jpg</video:thumbnail_loc><video:title>2015 AP Calculus BC 2d</video:title><video:description>Finding distance travelled</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/zhNP1LM479g.mp4/zhNP1LM479g.mp4</video:content_loc><video:duration>285</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/2015-ap-calculus-bc-5a</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x831577c3.jpg</video:thumbnail_loc><video:title>2015 AP Calculus BC 5a</video:title><video:description>Equation of tangent line</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1RGnb-QvQzU.mp4/1RGnb-QvQzU.mp4</video:content_loc><video:duration>276</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/2015-ap-calculus-bc-5b</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5cb99082.jpg</video:thumbnail_loc><video:title>2015 AP Calculus BC 5b</video:title><video:description>Relative minima and maxima</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/kWQzA37MqAk.mp4/kWQzA37MqAk.mp4</video:content_loc><video:duration>293</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/2015-ap-calculus-bc-5c</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x294f1da5.jpg</video:thumbnail_loc><video:title>2015 AP Calculus BC 5c</video:title><video:description>Engineering expression for critical point</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DYCwLAtNsjQ.mp4/DYCwLAtNsjQ.mp4</video:content_loc><video:duration>267</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-calculus-bc/v/2015-ap-calculus-bc-5d</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x60b91981.jpg</video:thumbnail_loc><video:title>2015 AP Calculus BC 5d</video:title><video:description>Partial fraction expansion</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/wwc5yi3c4gY.mp4/wwc5yi3c4gY.mp4</video:content_loc><video:duration>302</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
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<url><loc>https://puzzicle.org/math/ap-precalculus/v/exploring-the-characteristics-of-periodic-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x21a0e90230791bbe.jpg</video:thumbnail_loc><video:title>Exploring the characteristics of periodic functions</video:title><video:description>Explore characteristics of periodic functions and identify patterns to fill in a table of values.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/GIhvaBecuO8.mp4/GIhvaBecuO8.mp4</video:content_loc><video:duration>101</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-precalculus/v/identifying-reference-angles-of-positive-angles-in-standard-position</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2d92b89cf1d866a7.jpg</video:thumbnail_loc><video:title>Identifying reference angles of positive angles in standard position</video:title><video:description>Find the reference angle of a positive angle drawn in standard position in either radians or degrees.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DUNQsJAJZOU.mp4/DUNQsJAJZOU.mp4</video:content_loc><video:duration>276</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-precalculus/v/identifying-reference-angles-for-negative-angles-in-standard-position</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xddc4ac5183c57437.jpg</video:thumbnail_loc><video:title>Identifying reference angles for negative angles in standard position</video:title><video:description>Identifying the reference angle of a negative angle drawn in standard position in either radians or degrees.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ZJk9y3sdZYE.mp4/ZJk9y3sdZYE.mp4</video:content_loc><video:duration>206</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-precalculus/v/evaluating-trigonometric-angles-in-standard-position</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9673ffc4a1049883.jpg</video:thumbnail_loc><video:title>Evaluating trigonometric angles in standard position</video:title><video:description>Use your knowledge of the unit circle and right triangle trigonometry to evaluate angles in standard position.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ROG5LyuP-yo.mp4/ROG5LyuP-yo.mp4</video:content_loc><video:duration>216</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-precalculus/v/graphing-sinusoidal-functions-with-phase-shifts-ap-precalculus-khan-academy</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf9279539f0fc8bcc.jpg</video:thumbnail_loc><video:title>Graphing sinusoidal functions with transformations</video:title><video:description>Graph a sine function that has multiple transformations, including a phase shift.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/QnuCfZD2Xyw.mp4/QnuCfZD2Xyw.mp4</video:content_loc><video:duration>290</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-precalculus/v/understanding-the-tangent-function</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7bb00dd00a9038a3.jpg</video:thumbnail_loc><video:title>Understanding the tangent function</video:title><video:description>Understand how the tangent function performs on a graph and how different transformations change it.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/XwyawGBo3Lw.mp4/XwyawGBo3Lw.mp4</video:content_loc><video:duration>554</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-precalculus/v/graphs-of-arccos-and-arcsin</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xae03ba5dd585fc45.jpg</video:thumbnail_loc><video:title>Graphs of arccosine and arcsine</video:title><video:description>Graph the parent functions of the inverse of cosine and the inverse of sine.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/UinjqPjVrWU.mp4/UinjqPjVrWU.mp4</video:content_loc><video:duration>217</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/interpreting-solutions-of-trigonometric-equations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfe047acd4c891e24.jpg</video:thumbnail_loc><video:title>Interpreting solutions of trigonometric equations</video:title><video:description>Starting from a context represented by a trigonometric function, interpret equations based on the function.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/c-VkOXIGTqU.mp4/c-VkOXIGTqU.mp4</video:content_loc><video:duration>249</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-precalculus/v/identifying-the-asymptote-equations-of-transformed-reciprocal-trigonometric-func</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x35b7d540d79b555c.jpg</video:thumbnail_loc><video:title>Identifying the asymptote equations of transformed reciprocal trigonometric functions</video:title><video:description>Learn how to identify the asymptote equations of transformed reciprocal trigonometric functions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/fiH1jEPP3I0.mp4/fiH1jEPP3I0.mp4</video:content_loc><video:duration>371</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-precalculus/v/graphing-polar-coordinates</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x815c23cc43edd979.jpg</video:thumbnail_loc><video:title>Graphing polar coordinates</video:title><video:description>Graph polar coordinates with radii that may be positive or negative, using angles measured in either degrees or radians.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/MiIC7zvBbOI.mp4/MiIC7zvBbOI.mp4</video:content_loc><video:duration>246</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-precalculus/v/converting-polar-and-rectangular-coordinates-precalculus-khan-academy</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xaab37e5499c392b7.jpg</video:thumbnail_loc><video:title>Converting polar and rectangular coordinates</video:title><video:description>Convert polar coordinates to rectangular, and vice versa, using conversion formulas.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LWje358QRkU.mp4/LWje358QRkU.mp4</video:content_loc><video:duration>363</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/convert-complex-polar-to-rectangular</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3528768eebf3981a.jpg</video:thumbnail_loc><video:title>Converting a complex number from polar to rectangular form</video:title><video:description>Given a complex number in polar form, we can convert that number to rectangular form and plot it on the complex plane.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/auywa7dydAk.mp4/auywa7dydAk.mp4</video:content_loc><video:duration>159</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-precalculus/v/graphing-polar-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0586475f6f8ca1fc.jpg</video:thumbnail_loc><video:title>Graphing polar functions</video:title><video:description>Graph polar functions by using a table of values.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/KbPj4xXrBrk.mp4/KbPj4xXrBrk.mp4</video:content_loc><video:duration>508</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-precalculus/v/describing-characteristics-of-polar-function-graphs</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9a971e698ab3ec6d.jpg</video:thumbnail_loc><video:title>Describing characteristics of polar function graphs</video:title><video:description>Use your understanding of increasing and decreasing functions to identify how the distance a polar graph is from the origin changes.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/oDKomV5oLrI.mp4/oDKomV5oLrI.mp4</video:content_loc><video:duration>307</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-precalculus/v/estimating-the-value-of-a-polar-function-with-linear-approximation-ap-precalculu</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7b6dac6d5d69d1d9.jpg</video:thumbnail_loc><video:title>Estimating the value of a polar function with linear approximation</video:title><video:description>Use linear approximation to estimate the value of a point on a polar function graph.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Z7492K-qa_c.mp4/Z7492K-qa_c.mp4</video:content_loc><video:duration>397</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-precalculus/v/identifying-vertical-extremum-of-parametric-planar-motion-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf73f86224186f66f.jpg</video:thumbnail_loc><video:title>Identifying vertical extremum of parametric planar motion functions</video:title><video:description>Learn how to identify extremum of parametric planar motion functions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/rEuOOY7PO-Q.mp4/rEuOOY7PO-Q.mp4</video:content_loc><video:duration>266</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-precalculus/v/identifying-intercepts-of-parametric-planar-motion-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x78510ff84da6372f.jpg</video:thumbnail_loc><video:title>Identifying intercepts of parametric planar motion functions</video:title><video:description>When given a parametric planar motion function, Sal shows how to identify a specified intercept.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tcbD-QLtB3o.mp4/tcbD-QLtB3o.mp4</video:content_loc><video:duration>188</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-precalculus/v/determining-the-average-rate-of-change-of-parametric-planar-motion-functions-ove</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7ebab024bd36c5e9.jpg</video:thumbnail_loc><video:title>Determining the average rate of change of parametric planar motion functions over a given interval</video:title><video:description>Learn how to determine the average rate of change of parametric planar motion functions over a given interval.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/s0C08510fHs.mp4/s0C08510fHs.mp4</video:content_loc><video:duration>311</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-precalculus/v/parametric-equations-for-projectile-motion</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x61ba17ed7ef6518e.jpg</video:thumbnail_loc><video:title>Parametric equations for projectile motion</video:title><video:description>Use parametric equations to solve applications of projectile motion.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pNiydPVY6Z8.mp4/pNiydPVY6Z8.mp4</video:content_loc><video:duration>552</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-precalculus/v/writing-the-equation-of-an-ellipse-from-graph</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd4725704bcee78db.jpg</video:thumbnail_loc><video:title>Writing the equation of an ellipse from graph</video:title><video:description>Write the equation of an ellipse when provided a graph by finding the radii of the major and minor axes.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pae1hExrc5o.mp4/pae1hExrc5o.mp4</video:content_loc><video:duration>205</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-precalculus/v/parameterizing-implicitly-defined-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4c2f2aef5c412b1f.jpg</video:thumbnail_loc><video:title>Parameterizing implicitly defined functions</video:title><video:description>Learn how to identify a parameterization that satisfies a given equation for all real values.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/eKygWXbAZRI.mp4/eKygWXbAZRI.mp4</video:content_loc><video:duration>256</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/representing-quantities-with-vectors</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2b6cd2a4f67ecbb0.jpg</video:thumbnail_loc><video:title>Representing quantities with vectors</video:title><video:description>Vectors can represent real-world quantities where it&apos;s important to have both a magnitude and a direction. One example for that is force: you want to represent a force&apos;s magnitude (or strength), but it&apos;s also important to indicate in what direction the force is applied.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TCOQzIONaz8.mp4/TCOQzIONaz8.mp4</video:content_loc><video:duration>166</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/interpreting-statements-about-vectors</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5ce6dc5dc16cfb72.jpg</video:thumbnail_loc><video:title>Interpreting statements about vectors</video:title><video:description>Vector quantities have both a magnitude and a direction. In this example, we interpret a mathematical statement about two vector quantities in terms of the real-world quantities they represent.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/eA2AW5F4N_M.mp4/eA2AW5F4N_M.mp4</video:content_loc><video:duration>158</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/introduction-to-vector-components</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4a572c4edae38f8e.jpg</video:thumbnail_loc><video:title>Introduction to vector components</video:title><video:description>Vectors are quantities that have a magnitude and a direction. In the two-dimensional plane, we can describe them in an equivalent way, by thinking about the changes in x and y from the vector&apos;s tail to its head.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hJkKADcQWj0.mp4/hJkKADcQWj0.mp4</video:content_loc><video:duration>316</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/adding-vectors-in-magnitude-and-direction-form</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x429b31be7da5c379.jpg</video:thumbnail_loc><video:title>Adding vectors in magnitude and direction form</video:title><video:description>In this example, Sal takes two vectors given by magnitude and direction, and finds the magnitude and direction of their sum.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/yFPfO_eHJdY.mp4/yFPfO_eHJdY.mp4</video:content_loc><video:duration>501</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/matrix-vector-products-as-linear-transformations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25291.jpg</video:thumbnail_loc><video:title>Matrix vector products as linear transformations</video:title><video:description>Matrix Vector Products as Linear Transformations</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ondmopWLiEg.mp4/ondmopWLiEg.mp4</video:content_loc><video:duration>1024</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/using-matrices-to-manipulate-data-game-show</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x56b27d8d6e4815b6.jpg</video:thumbnail_loc><video:title>Using matrices to manipulate data: Game show</video:title><video:description>In other videos, we saw how we can use matrices to represent real-world situations. Once we do that, we can also manipulate the matrices (using common matrix operations like addition, subtraction, and scalar multiplication) to reveal more information about the context. Here, we manipulate matrices that represent the possible prizes in a game show.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/NKG6DifB3OA.mp4/NKG6DifB3OA.mp4</video:content_loc><video:duration>216</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/using-matrices-to-manipulate-data-pet-store</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8fb8a59d203b117c.jpg</video:thumbnail_loc><video:title>Using matrices to manipulate data: Pet store</video:title><video:description>In other videos, we saw how we can use matrices to represent real-world situations. Once we do that, we can also manipulate the matrices (using common matrix operations like addition, subtraction, and scalar multiplication) to reveal more information about the context. Here, we manipulate matrices that represent the inventory of dog food in a pet store chain.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/g-ljbR62EAQ.mp4/g-ljbR62EAQ.mp4</video:content_loc><video:duration>246</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/identifying-a-sample-and-population</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8f6cbec077980a24.jpg</video:thumbnail_loc><video:title>Identifying a sample and population</video:title><video:description>Identifying a sample and population</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/VPM84_yfx5Q.mp4/VPM84_yfx5Q.mp4</video:content_loc><video:duration>132</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/statistical-questions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x875b9f8c.jpg</video:thumbnail_loc><video:title>Statistical and non statistical questions</video:title><video:description>A statistical question is one that can be answered by collecting data and where there will be variability in that data. For example, there will likely be variability in the data collected to answer the question, &quot;How much do the animals at Fancy Farm weigh?&quot; but not to answer, &quot;What color hat is Sara wearing?&quot;.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qyYSQDcSNlY.mp4/qyYSQDcSNlY.mp4</video:content_loc><video:duration>471</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/classifying-discrete-and-continuous-variables</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa50293e781216840.jpg</video:thumbnail_loc><video:title>Classifying discrete and continuous variables</video:title><video:description>Sal shows how to classify a quantitative variable as discrete or continuous, and give the reason for the classification.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OnnWywg0q3Y.mp4/OnnWywg0q3Y.mp4</video:content_loc><video:duration>269</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/creating-a-relative-frequency-table-for-one-categorical-variable</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x988d2d17a6a0e115.jpg</video:thumbnail_loc><video:title>Creating a relative frequency table for one categorical variable</video:title><video:description>Sal shows how to turn counts for a single categorical variable into proportions in a relative frequency table.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xQSTwehQdCc.mp4/xQSTwehQdCc.mp4</video:content_loc><video:duration>113</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/reading-bar-charts-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4f968262.jpg</video:thumbnail_loc><video:title>Reading bar charts: comparing two sets of data</video:title><video:description>A bar chart is especially useful with comparing two sets of data. The difference in the bars give us a quick snapshot that allows us to draw some conclusions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gnyHsgTFXIY.mp4/gnyHsgTFXIY.mp4</video:content_loc><video:duration>90</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/u08-l1-t2-we3-stem-and-leaf-plots</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/380855565.jpg</video:thumbnail_loc><video:title>Stem-and-leaf plots</video:title><video:description>We learn how to interpret a stem-and-leaf plot using basketball scores as an example. The video demonstrates how to read the plot, translate it into individual scores, and then use those scores to calculate the team&apos;s total points. This method provides a clear view of data distribution and makes it easier to understand the range of scores.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LEFE1km5ROY.mp4/LEFE1km5ROY.mp4</video:content_loc><video:duration>358</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/reading-stem-and-leaf-plots</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb424e537.jpg</video:thumbnail_loc><video:title>Reading stem and leaf plots</video:title><video:description>A stem and leaf plot displays data by breaking each data point into two parts: the &quot;stem&quot; and the &quot;leaf.&quot; Each stem represents a range of values (e.g. if the stem is 2, the corresponding leaves might be data points in the 20s). Each leaf typically represents the last digit of a data point (e.g. if the leaf is 6 next to a stem of 2, it could represent a data point whose value is 26).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PXKHyT__B2k.mp4/PXKHyT__B2k.mp4</video:content_loc><video:duration>188</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/comparing-distributions-using-summary-statistics</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x29d4a4cd6116d063.jpg</video:thumbnail_loc><video:title>Comparing distributions using summary statistics</video:title><video:description>In this video, Sal shows how to compare the center, shape, and variability of two distributions, and determine whether summary statistics support claims about the corresponding populations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7zK6OejZhjk.mp4/7zK6OejZhjk.mp4</video:content_loc><video:duration>219</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/z-score-introduction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdc0f07c2c91917f7.jpg</video:thumbnail_loc><video:title>Z-score introduction</video:title><video:description>A z-score is an example of a standardized score. A z-score measures how many standard deviations a data point is from the mean in a distribution.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5S-Zfa-vOXs.mp4/5S-Zfa-vOXs.mp4</video:content_loc><video:duration>305</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/comparing-with-z-scores</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x250dec1c92a744df.jpg</video:thumbnail_loc><video:title>Comparing with z-scores</video:title><video:description>Use standardized scores—also called z-scores— to compare data points from different distributions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_rtQGAX5wsQ.mp4/_rtQGAX5wsQ.mp4</video:content_loc><video:duration>210</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/identifying-a-census</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x30b62db229d3940f.jpg</video:thumbnail_loc><video:title>Identifying a census</video:title><video:description>Sal shows how to decide whether a described data collection method is a census, by naming the population and checking that every individual in it was recorded.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/apc8jmzOqzE.mp4/apc8jmzOqzE.mp4</video:content_loc><video:duration>151</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/worked-example-identifying-experiment</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfb74d7129be01707.jpg</video:thumbnail_loc><video:title>Worked example identifying experiment</video:title><video:description>Worked example identifying experiment</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/28lzQ_OhBHY.mp4/28lzQ_OhBHY.mp4</video:content_loc><video:duration>276</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/generalizabilty-of-survey-results-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x166bd2fcd09e99a0.jpg</video:thumbnail_loc><video:title>Generalizability of survey results example</video:title><video:description>Practice identifying to which population the results of a survey can be generalized.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2FXwGI_debU.mp4/2FXwGI_debU.mp4</video:content_loc><video:duration>150</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/sampling-with-and-without-replacement</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x98ba54da73335b8d.jpg</video:thumbnail_loc><video:title>Sampling with and without replacement</video:title><video:description>Sal shows how to classify a described sampling procedure as with or without replacement.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ZU7lZAaNgVA.mp4/ZU7lZAaNgVA.mp4</video:content_loc><video:duration>195</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/techniques-for-generating-a-simple-random-sample</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe7433b050109a6da.jpg</video:thumbnail_loc><video:title>Techniques for generating a simple random sample</video:title><video:description>Techniques for generating a simple random sample</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/acfjqWTwee0.mp4/acfjqWTwee0.mp4</video:content_loc><video:duration>386</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/techniques-for-random-sampling-and-avoiding-bias</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9db3cdd29f45dfba.jpg</video:thumbnail_loc><video:title>Techniques for random sampling and avoiding bias</video:title><video:description>Techniques for random sampling and avoiding bias</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PdXDLNNXPik.mp4/PdXDLNNXPik.mp4</video:content_loc><video:duration>553</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/systematic-random-sampling</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0a7759e472f9c753.jpg</video:thumbnail_loc><video:title>Systematic random sampling</video:title><video:description>In a systematic random sample, we arrange members of a population in some order, pick a random starting point, and select every member in a set interval.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TrOS8OnM1u4.mp4/TrOS8OnM1u4.mp4</video:content_loc><video:duration>288</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/examples-of-bias-in-surveys</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x69eb52cf5567f908.jpg</video:thumbnail_loc><video:title>Examples of bias in surveys</video:title><video:description>Examples of bias in surveys</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/r1R00l8Z5lg.mp4/r1R00l8Z5lg.mp4</video:content_loc><video:duration>342</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/example-of-under-coverage-introducing-bias</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9e8eb23cad527582.jpg</video:thumbnail_loc><video:title>Example of undercoverage introducing bias</video:title><video:description>Nonresponse, undercoverage, and voluntary responses can all introduce bias when we sample a population for a study. Given the description of a study, we can think about potential sources of bias, and how they may have impacted the results of the study.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/D9f7dCMxu2Y.mp4/D9f7dCMxu2Y.mp4</video:content_loc><video:duration>261</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/introduction-to-experiment-design</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xaf6650305a49db77.jpg</video:thumbnail_loc><video:title>Introduction to experiment design</video:title><video:description>Introduction to experiment design. Explanatory and response variables. Control and treatment groups.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DaBq0naj0YY.mp4/DaBq0naj0YY.mp4</video:content_loc><video:duration>628</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/matched-pairs-experiment-design</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x20a1993463318741.jpg</video:thumbnail_loc><video:title>Matched pairs experiment design</video:title><video:description>The video presents an in-depth exploration of experimental design in statistics, focusing on the use of control and treatment groups, block design, and matched pairs design. It emphasizes the importance of random assignment to mitigate lurking variables and bias, and the value of double-blind experiments. The video also discusses the potential for imbalance in experimental groups and how matched pairs design can help address this issue.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/UEFBGewP2ik.mp4/UEFBGewP2ik.mp4</video:content_loc><video:duration>337</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/mosaic-plots-intro</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb767da60dfdca857.jpg</video:thumbnail_loc><video:title>Mosaic plots and segmented bar charts</video:title><video:description>We can display categorical data from a two-way table with a segmented bar chart or a mosaic plot.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/b9G5pWuxb1Y.mp4/b9G5pWuxb1Y.mp4</video:content_loc><video:duration>346</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/analyzing-mosaic-plots</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9d2347a8565b6267.jpg</video:thumbnail_loc><video:title>Analyzing mosaic plots</video:title><video:description>We can use mosaic plots to draw conclusions about relationships between two categorical variables.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2sHkluggZp8.mp4/2sHkluggZp8.mp4</video:content_loc><video:duration>160</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/experimental-versus-theoretical-probability-simulation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdd932b06d7d9ffac.jpg</video:thumbnail_loc><video:title>Experimental versus theoretical probability simulation</video:title><video:description>Experimental versus theoretical probability simulation</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Nos-xOCpQqg.mp4/Nos-xOCpQqg.mp4</video:content_loc><video:duration>297</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/coin-flipping-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/380860449.jpg</video:thumbnail_loc><video:title>Example: All the ways you can flip a coin</video:title><video:description>Manually going through the combinatorics to determine the probability of an event occuring</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3UlE8gyKbkU.mp4/3UlE8gyKbkU.mp4</video:content_loc><video:duration>134</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/testing-independence-from-experimental-data</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x484ec0da2dc9ed37.jpg</video:thumbnail_loc><video:title>Conditional probability and independence</video:title><video:description>Use conditional probability to see if events are independent or not.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pIfpHdGVwLU.mp4/pIfpHdGVwLU.mp4</video:content_loc><video:duration>247</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/conditional-probability-tree-diagram-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf4d467541e2b366a.jpg</video:thumbnail_loc><video:title>Conditional probability tree diagram example</video:title><video:description>Using a tree diagram to work out a conditional probability question. If someone fails a drug test, what is the probability that they actually are taking drugs?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hxEdXUB_IdQ.mp4/hxEdXUB_IdQ.mp4</video:content_loc><video:duration>644</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/general-multiplication-example-independent</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9b4022f8d54d2ee0.jpg</video:thumbnail_loc><video:title>General multiplication rule example: independent events</video:title><video:description>We can use the general multiplication rule to find the probability that two events both occur when the events are independent.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OqbkCYy37hI.mp4/OqbkCYy37hI.mp4</video:content_loc><video:duration>149</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/introduction-to-dependent-probability</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1200026245.jpg</video:thumbnail_loc><video:title>Dependent probability introduction</video:title><video:description>Let&apos;s get you started with a great explanation of dependent probability using a scenario involving a casino game.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/VjLEoo3hIoM.mp4/VjLEoo3hIoM.mp4</video:content_loc><video:duration>398</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/general-multiplication-rule-example-dependent</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd746275804f8a727.jpg</video:thumbnail_loc><video:title>General multiplication rule example: dependent events</video:title><video:description>We can use the general multiplication rule to find the probability that two events both occur when the events are not independent.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/iyQNk090FGM.mp4/iyQNk090FGM.mp4</video:content_loc><video:duration>159</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/discrete-probability-distribution</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x970b9601.jpg</video:thumbnail_loc><video:title>Constructing a probability distribution for random variable</video:title><video:description>Sal breaks down how to create the probability distribution of the number of &quot;heads&quot; after 3 flips of a fair coin.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/cqK3uRoPtk0.mp4/cqK3uRoPtk0.mp4</video:content_loc><video:duration>408</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/valid-discrete-probability-distribution-examples</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x32040e0dffffea40.jpg</video:thumbnail_loc><video:title>Valid discrete probability distribution examples</video:title><video:description>Worked examples on identifying valid discrete probability distributions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/uXtxKxYl1Iw.mp4/uXtxKxYl1Iw.mp4</video:content_loc><video:duration>240</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/example-analyzing-discrete-probability-distribution</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x344d97846e9fa2e4.jpg</video:thumbnail_loc><video:title>Probability with discrete random variable example</video:title><video:description>Example analyzing discrete probability distribution</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/d2STHFVHGAg.mp4/d2STHFVHGAg.mp4</video:content_loc><video:duration>230</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/theoretical-probability-distribution-example-tables</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6eea606716b37dba.jpg</video:thumbnail_loc><video:title>Theoretical probability distribution example: tables</video:title><video:description>We can create the probability distribution for rolling two dice by creating a table to represent the events that make up the sample space.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hA8VmhkKEJo.mp4/hA8VmhkKEJo.mp4</video:content_loc><video:duration>195</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/theoretical-probability-distribution-example-multiplication</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa325f9755680187e.jpg</video:thumbnail_loc><video:title>Theoretical probability distribution example: multiplication</video:title><video:description>We can create a probability distribution for the number of times someone wins a prize using the multiplication rule.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2jExPaoTrQE.mp4/2jExPaoTrQE.mp4</video:content_loc><video:duration>205</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/expected-value-of-a-discrete-random-variable</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9996bd6c7bed2406.jpg</video:thumbnail_loc><video:title>Mean (expected value) of a discrete random variable</video:title><video:description>We can calculate the mean (or expected value) of a discrete random variable as the weighted average of all the outcomes of that random variable based on their probabilities. We interpret expected value as the predicted average outcome if we looked at that random variable over an infinite number of trials.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qafPcWNUiM8.mp4/qafPcWNUiM8.mp4</video:content_loc><video:duration>272</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/interpreting-expected-value</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6bac398edf6f3339.jpg</video:thumbnail_loc><video:title>Interpreting expected value</video:title><video:description>We can interpret expected value as a long term average outcome. This example looks at expected value in the context of a lottery ticket.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/SNIW7MmCdhA.mp4/SNIW7MmCdhA.mp4</video:content_loc><video:duration>174</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/variance-and-standard-deviation-of-a-discrete-random-variable</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x74e7ad7c9d4508ca.jpg</video:thumbnail_loc><video:title>Variance and standard deviation of a discrete random variable</video:title><video:description>We learn how to calculate the mean and standard deviation of a discrete random variable. The concept of a random variable is explained, along with methods to calculate its expected value (mean) and measure its spread (variance and standard deviation). A practical example makes the concept easier to understand.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2egl_5c8i-g.mp4/2egl_5c8i-g.mp4</video:content_loc><video:duration>386</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/binomial-variables</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x04c2ddde6bb2c5b3.jpg</video:thumbnail_loc><video:title>Binomial variables</video:title><video:description>An introduction to a special class of random variables called binomial random variables</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/yUDFir8oYl8.mp4/yUDFir8oYl8.mp4</video:content_loc><video:duration>451</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/recognizing-binomial-variables</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5a9f0870c146fc09.jpg</video:thumbnail_loc><video:title>Recognizing binomial variables</video:title><video:description>Some examples and counterexamples of binomial variables</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ITtFw5PH-hs.mp4/ITtFw5PH-hs.mp4</video:content_loc><video:duration>402</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/expected-value-of-binomial-variable</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6349c94e04e93b4b.jpg</video:thumbnail_loc><video:title>Expected value of a binomial variable</video:title><video:description>Deriving and using the expected value (mean) formula for binomial random variables</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/fjjhAm5trSM.mp4/fjjhAm5trSM.mp4</video:content_loc><video:duration>393</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/variance-of-binomial-variable</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1062c356a16065ba.jpg</video:thumbnail_loc><video:title>Variance of a binomial variable</video:title><video:description>We can derive the variance of a binomial variable to be p(1-p), and the standard deviation is the square root of the variance.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/uudB5XiAYOw.mp4/uudB5XiAYOw.mp4</video:content_loc><video:duration>411</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/finding-the-mean-and-standard-deviation-of-a-binomial-random-variable</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x15bc0464cc477e7a.jpg</video:thumbnail_loc><video:title>Finding the mean and standard deviation of a binomial random variable</video:title><video:description>For a binomal random variable, the mean is n times p (np), where n is the sample size and p is the probability of success. The standard deviation is the square root of np(1-p). We can use them to make predictions in a binomial setting. In this example, we look at how many defective chips we expect, on average, in a sample.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gro5b3PZ-Bw.mp4/gro5b3PZ-Bw.mp4</video:content_loc><video:duration>302</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/probability-of-making-2-shots-in-6-attempts</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x88ef095e.jpg</video:thumbnail_loc><video:title>Binomial probability example</video:title><video:description>We can use the binomial distribution to find the probability of getting a certain number of successes, like successful basketball shots, out of a fixed number of trials. We use the binomial distribution to find discrete probabilities.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Ctytn4a6zjw.mp4/Ctytn4a6zjw.mp4</video:content_loc><video:duration>624</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/ck12-org-normal-distribution-problems-qualitative-sense-of-normal-distributions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26198.jpg</video:thumbnail_loc><video:title>Qualitative sense of normal distributions</video:title><video:description>Discussion of how &quot;normal&quot; a distribution might be.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/79duxPXpyKQ.mp4/79duxPXpyKQ.mp4</video:content_loc><video:duration>653</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/ck12-org-normal-distribution-problems-empirical-rule</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26202.jpg</video:thumbnail_loc><video:title>Normal distribution problems: Empirical rule</video:title><video:description>The empirical rule (also called the &quot;68-95-99.7 rule&quot;) is a guideline for how data is distributed in a normal distribution. The rule states that (approximately): - 68% of the data points will fall within one standard deviation of the mean. - 95% of the data points will fall within two standard deviations of the mean. - 99.7% of the data points will fall within three standard deviations of the mean.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OhRr26AfFBU.mp4/OhRr26AfFBU.mp4</video:content_loc><video:duration>625</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/z-table-for-proportion-below</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd7aeb1e8fab6fb00.jpg</video:thumbnail_loc><video:title>Standard normal table for proportion below</video:title><video:description>Finding the proportion of a normal distribution that is below a value by calculating a z-score and using a z-table.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Fo4kitkFB3I.mp4/Fo4kitkFB3I.mp4</video:content_loc><video:duration>260</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/z-table-for-proportion-above</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xaff92a3b77dfe7d7.jpg</video:thumbnail_loc><video:title>Standard normal table for proportion above</video:title><video:description>Finding the proportion of a normal distribution that is above a value by calculating a z-score and using a z-table.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/i9FzFfv1rQg.mp4/i9FzFfv1rQg.mp4</video:content_loc><video:duration>307</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/z-table-for-proportion-between-values</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd01bbf159422bc87.jpg</video:thumbnail_loc><video:title>Standard normal table for proportion between values</video:title><video:description>Finding the proportion of a normal distribution that is between two values by calculating z-scores and using a z-table.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/uwhV0TAPmWc.mp4/uwhV0TAPmWc.mp4</video:content_loc><video:duration>430</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/threshold-for-low-percentile</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe17171ee612b4210.jpg</video:thumbnail_loc><video:title>Threshold for low percentile</video:title><video:description>Find the cutoff for a given lower percentile in a normal distribution</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/umYWWMfxUCI.mp4/umYWWMfxUCI.mp4</video:content_loc><video:duration>360</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/introduction-to-sampling-distributions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x52e03bfc13da458b.jpg</video:thumbnail_loc><video:title>Introduction to sampling distributions</video:title><video:description>Introduction to sampling distributions</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/z0Ry_3_qhDw.mp4/z0Ry_3_qhDw.mp4</video:content_loc><video:duration>438</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/central-limit-theorem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/371055.jpg</video:thumbnail_loc><video:title>Central limit theorem</video:title><video:description>Introduction to the central limit theorem and the sampling distribution of the mean</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/JNm3M9cqWyc.mp4/JNm3M9cqWyc.mp4</video:content_loc><video:duration>589</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/sampling-distribution-of-the-sample-mean</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/411022.jpg</video:thumbnail_loc><video:title>Sampling distribution of the sample mean</video:title><video:description>Take a sample from a population, calculate the mean of that sample, put everything back, and do it over and over. No matter what the population looks like, those sample means will be roughly normally distributed given a reasonably large sample size (at least 30). This is the main idea of the Central Limit Theorem — the sampling distribution of the sample mean is approximately normal for &quot;large&quot; samples.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/FXZ2O1Lv-KE.mp4/FXZ2O1Lv-KE.mp4</video:content_loc><video:duration>652</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/sampling-distribution-of-the-sample-mean-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/378042.jpg</video:thumbnail_loc><video:title>Sampling distribution of the sample mean (part 2)</video:title><video:description>More on the Central Limit Theorem and the Sampling Distribution of the Sample Mean</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/NYd6wzYkQIM.mp4/NYd6wzYkQIM.mp4</video:content_loc><video:duration>800</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/identifying-statistics-and-parameters</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd0d35ef2986c09dc.jpg</video:thumbnail_loc><video:title>Identifying statistics and parameters</video:title><video:description>In this video, Sal explains how to identify sample statistics and population parameters in context, and recognize the appropriate reasoning for using each term.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_WGYJrZlUPk.mp4/_WGYJrZlUPk.mp4</video:content_loc><video:duration>223</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/sample-statistic-bias-worked-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x41b8a947b56549fd.jpg</video:thumbnail_loc><video:title>Sample statistic bias worked example</video:title><video:description>Determining bias of sample statistics based on approximate sampling distributions example</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/SRwMfEmKx3A.mp4/SRwMfEmKx3A.mp4</video:content_loc><video:duration>171</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/sampling-distribution-of-sample-proportion-part-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf3a96d17db7a0a33.jpg</video:thumbnail_loc><video:title>Sampling distribution of sample proportion part 1</video:title><video:description>Formulas for the mean and standard deviation of a sampling distribution of sample proportions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Br067hrasc8.mp4/Br067hrasc8.mp4</video:content_loc><video:duration>597</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/sampling-distribution-of-sample-proportion-part-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe64811e724d79e4e.jpg</video:thumbnail_loc><video:title>Sampling distribution of sample proportion part 2</video:title><video:description>Building intuition for the sampling distribution of sample proportions using a simulation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ftYKMNfFcI8.mp4/ftYKMNfFcI8.mp4</video:content_loc><video:duration>274</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/normal-conditions-for-sampling-distributions-of-sample-proportions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x04a6f94b827f8df4.jpg</video:thumbnail_loc><video:title>Normal conditions for sampling distributions of sample proportions</video:title><video:description>Conditions for roughly normal sampling distribution of sample proportions</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/L7AX2RcbqCg.mp4/L7AX2RcbqCg.mp4</video:content_loc><video:duration>377</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/probability-of-sample-proportions-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x70dec620eba28cbd.jpg</video:thumbnail_loc><video:title>Probability of sample proportions example</video:title><video:description>Probability of sample proportions example</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/BkRJJsHoRdw.mp4/BkRJJsHoRdw.mp4</video:content_loc><video:duration>455</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/conditions-for-valid-confidence-intervals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xafe586eaa18b21b5.jpg</video:thumbnail_loc><video:title>Conditions for valid confidence intervals for a proportion</video:title><video:description>There are three conditions we need to satisfy before we make a one-sample z-interval to estimate a population proportion. We need to satisfy the random, normal, and independence conditions for these confidence intervals to be valid.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8E8YQY5qE3s.mp4/8E8YQY5qE3s.mp4</video:content_loc><video:duration>404</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/conditions-for-confidence-intervals-worked-examples</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x59be24b1707f5dff.jpg</video:thumbnail_loc><video:title>Conditions for confidence interval for a proportion worked examples</video:title><video:description>Conditions for confidence intervals for a population proportion worked examples--random condition, independence condition and normal condition.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PwMqupyG4D0.mp4/PwMqupyG4D0.mp4</video:content_loc><video:duration>294</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/critical-value-for-a-given-confidence-level</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x07560ab28415eebe.jpg</video:thumbnail_loc><video:title>Critical value (z*) for a given confidence level</video:title><video:description>If we want to be 95% confident, we need to build a confidence interval that extends about 2 standard errors above and below our estimate. More precisely, it&apos;s actually 1.96 standard errors. This is called a critical value (z*). We can calculate a critical value z* for any given confidence level using normal distribution calculations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/VILsYH84HJE.mp4/VILsYH84HJE.mp4</video:content_loc><video:duration>382</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/example-calculating-confidence-interval</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfa0cc7216c02b4bd.jpg</video:thumbnail_loc><video:title>Example constructing and interpreting a confidence interval for p</video:title><video:description>Check conditions, calculate, and interpret a confidence interval to estimate a population proportion</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/sjG9Ns_8x6c.mp4/sjG9Ns_8x6c.mp4</video:content_loc><video:duration>395</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/determining-sample-size-based-on-confidence-and-margin-of-error</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xeeac6e2fe9157c97.jpg</video:thumbnail_loc><video:title>Determining sample size based on confidence and margin of error</video:title><video:description>Determining sample size based on confidence level and margin of error</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/VyFs7fsWE6w.mp4/VyFs7fsWE6w.mp4</video:content_loc><video:duration>481</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/idea-behind-hypothesis-testing</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe84952a8.jpg</video:thumbnail_loc><video:title>Idea behind hypothesis testing</video:title><video:description>The lesson explores hypothesis testing in statistics, demonstrating how varied outcomes from a test with a known accuracy rate can influence the acceptance or rejection of a hypothesis. This understanding is key to evaluating the reliability of statistical tests.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/dpGmVV0-4jc.mp4/dpGmVV0-4jc.mp4</video:content_loc><video:duration>469</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/examples-of-null-and-alternative-hypotheses</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1e4199a69e22e6db.jpg</video:thumbnail_loc><video:title>Examples of null and alternative hypotheses</video:title><video:description>The null and alternative hypotheses are both statements about the population that you are studying. The null hypothesis is often stated as the assumption that there is no change, no difference between two groups, or no relationship between two variables. The alternative hypothesis, on the other hand, is the statement that there is a change, difference, or relationship.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_3_6wjycJdk.mp4/_3_6wjycJdk.mp4</video:content_loc><video:duration>342</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/constructing-hypotheses-for-a-significance-test</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4d18b4c2c1fb3da4.jpg</video:thumbnail_loc><video:title>Constructing hypotheses for a significance test about a proportion</video:title><video:description>Constructing hypotheses for a significance test about a proportion</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8MJvK26PwSo.mp4/8MJvK26PwSo.mp4</video:content_loc><video:duration>256</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/conditions-for-a-z-test-about-a-proportion</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb2824472b0e22385.jpg</video:thumbnail_loc><video:title>Conditions for a z test about a proportion</video:title><video:description>Examples showing how to check whether or not the conditions have been met for doing a z test about a proportion.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5JlJ4Qfk8g4.mp4/5JlJ4Qfk8g4.mp4</video:content_loc><video:duration>333</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/p-values-and-significance-tests</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x05c8d25c91aab4bb.jpg</video:thumbnail_loc><video:title>P-values and significance tests</video:title><video:description>We compare a P-value to a significance level to make a conclusion in a significance test. Given the null hypothesis is true, a p-value is the probability of getting a result as or more extreme than the sample result by random chance alone. If a p-value is lower than our significance level, we reject the null hypothesis. If not, we fail to reject the null hypothesis.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/KS6KEWaoOOE.mp4/KS6KEWaoOOE.mp4</video:content_loc><video:duration>478</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/comparing-p-value-diff-significance-levels</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9672ca0f07f2f79d.jpg</video:thumbnail_loc><video:title>Comparing P-values to different significance levels</video:title><video:description>Example comparing P-values to different significance levels, and why it&apos;s important to set the significance level before a test.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DQCF4kTXf9Q.mp4/DQCF4kTXf9Q.mp4</video:content_loc><video:duration>281</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/estimating-p-value-from-simulation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x830e99a9880651fa.jpg</video:thumbnail_loc><video:title>Estimating a P-value from a simulation</video:title><video:description>Example of estimating a P-value based on a simulation to approximate a sampling distribution assuming the null hypothesis is true.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hNDlqAYRDyg.mp4/hNDlqAYRDyg.mp4</video:content_loc><video:duration>285</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/calculating-a-z-statistic-in-a-significance-test</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x083d0a99edd2451d.jpg</video:thumbnail_loc><video:title>Calculating a z statistic in a test about a proportion</video:title><video:description>Calculating a z statistic in a one-sample z test about a proportion</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DfpFfIdwcIo.mp4/DfpFfIdwcIo.mp4</video:content_loc><video:duration>291</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/calculating-p-value-from-z-table</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb627473a87be1a83.jpg</video:thumbnail_loc><video:title>Calculating a P-value given a z statistic</video:title><video:description>In a significance test about a population proportion, we first calculate a test statistic based on our sample results. We then calculate a p-value based on that test statistic using a normal distribution.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/NNpv-n_Hbvc.mp4/NNpv-n_Hbvc.mp4</video:content_loc><video:duration>327</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/introduction-to-type-i-and-type-ii-errors</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf25154435cc3c778.jpg</video:thumbnail_loc><video:title>Introduction to Type I and Type II errors</video:title><video:description>Both type 1 and type 2 errors are mistakes made when testing a hypothesis. A type 1 error occurs when you wrongly reject the null hypothesis (i.e. you think you found a significant effect when there really isn&apos;t one). A type 2 error occurs when you wrongly fail to reject the null hypothesis (i.e. you miss a significant effect that is really there).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Hdbbx7DIweQ.mp4/Hdbbx7DIweQ.mp4</video:content_loc><video:duration>303</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/examples-identifying-type-i-and-type-ii-errors</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x458609e30135e0d0.jpg</video:thumbnail_loc><video:title>Examples identifying Type I and Type II errors</video:title><video:description>Examples identifying Type I and Type II errors</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/JNOWWJeZBTc.mp4/JNOWWJeZBTc.mp4</video:content_loc><video:duration>344</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/introduction-to-power-in-significance-tests</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x69796141f98e1fbb.jpg</video:thumbnail_loc><video:title>Introduction to power in significance tests</video:title><video:description>Introduction to power in significance tests</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6_Cuz0QqRWc.mp4/6_Cuz0QqRWc.mp4</video:content_loc><video:duration>585</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/examples-thinking-about-power-in-significance-tests</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5ddacb57b3192721.jpg</video:thumbnail_loc><video:title>Examples thinking about power in significance tests</video:title><video:description>Examples thinking about power in significance tests</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/XnYUFgfbvm4.mp4/XnYUFgfbvm4.mp4</video:content_loc><video:duration>262</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/sampling-dist-diff-proportions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x779db425586e4212.jpg</video:thumbnail_loc><video:title>Sampling distribution of the difference in sample proportions</video:title><video:description>We can calculate the mean and standard deviation for the sampling distribution of the difference in sample proportions. Also, we can tell if the shape of that sampling distribution is approximately normal.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/oThlns-qBaI.mp4/oThlns-qBaI.mp4</video:content_loc><video:duration>538</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/sampling-dist-diff-proportion-probability</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0192a06875173c7b.jpg</video:thumbnail_loc><video:title>Sampling distribution of the difference in sample proportions: Probability example</video:title><video:description>We can use the mean and standard deviation and normal shape to calculate probability in a sampling distribution of the difference in sample proportions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-Sg3F-vK_cY.mp4/-Sg3F-vK_cY.mp4</video:content_loc><video:duration>232</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/confidence-intervals-for-the-difference-between-two-proportions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x18d0aa6bccac869c.jpg</video:thumbnail_loc><video:title>Confidence intervals for the difference between two proportions</video:title><video:description>Introducing two-sample z intervals to estimate the difference between two population proportions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hcUxFwUjCxM.mp4/hcUxFwUjCxM.mp4</video:content_loc><video:duration>523</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/examples-identifying-conditions-for-two-sample-z-tests-and-z-intervals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x442bd7f649a8f16c.jpg</video:thumbnail_loc><video:title>Examples identifying conditions for inference on two proportions</video:title><video:description>Examples identifying conditions for confidence intervals and tests about two proportions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DR5ZytN7Pj0.mp4/DR5ZytN7Pj0.mp4</video:content_loc><video:duration>276</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/calculating-two-sample-z-interval-confidence-interval-for-difference-of-proporti</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb316c2bc7a3ece27.jpg</video:thumbnail_loc><video:title>Calculating a confidence interval for the difference of proportions</video:title><video:description>Calculating two-sample z interval to estimate the difference between two population proportions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/h_ZIMHgKTP0.mp4/h_ZIMHgKTP0.mp4</video:content_loc><video:duration>341</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/hypothesis-test-for-difference-in-proportions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x906625cbaa9c085c.jpg</video:thumbnail_loc><video:title>Hypothesis test for difference in proportions</video:title><video:description>Hypothesis test for difference in proportions</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7iTWX8bfBv0.mp4/7iTWX8bfBv0.mp4</video:content_loc><video:duration>559</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/constructing-hypotheses-for-two-proportions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9c00eba8ee3befe5.jpg</video:thumbnail_loc><video:title>Constructing hypotheses for two proportions</video:title><video:description>Constructing hypotheses for two proportions</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/NCENjXTMp9I.mp4/NCENjXTMp9I.mp4</video:content_loc><video:duration>291</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/hypothesis-test-for-difference-in-proportions-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf576d78506270a34.jpg</video:thumbnail_loc><video:title>Hypothesis test for difference in proportions example</video:title><video:description>Hypothesis test for difference in proportions example</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/HOyNEU94xJQ.mp4/HOyNEU94xJQ.mp4</video:content_loc><video:duration>628</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/p-value-conclusions-difference-proportions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x83803c85b979bb7d.jpg</video:thumbnail_loc><video:title>Comparing P value to significance level for test involving difference of proportions</video:title><video:description>Comparing P value to significance level for test involving difference of proportions</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Y650kaYNlJU.mp4/Y650kaYNlJU.mp4</video:content_loc><video:duration>150</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/chi-square-test-homogeneity</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa927b364259449d6.jpg</video:thumbnail_loc><video:title>Introduction to the chi-square test for homogeneity</video:title><video:description>We investigate a scenario that includes applying the chi-squared statistic for a test of homogeneity, setting up null and alternative hypotheses, calculating expected values, verifying conditions for conducting a chi-squared test, and determining degrees of freedom based on the structure of a contingency table.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/t_jfTOE44YQ.mp4/t_jfTOE44YQ.mp4</video:content_loc><video:duration>476</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/chi-square-test-association-independence</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3fa714d0d3bae06f.jpg</video:thumbnail_loc><video:title>Chi-square test for association (independence)</video:title><video:description>Chi-square test for association/independence.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/zOvUQWOzTlc.mp4/zOvUQWOzTlc.mp4</video:content_loc><video:duration>628</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/standard-error-of-the-mean</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/397052.jpg</video:thumbnail_loc><video:title>Standard error of the mean</video:title><video:description>Take a sample from a population, calculate the mean of that sample, put everything back, and do it over and over. How much do those sample means tend to vary from the &quot;average&quot; sample mean? This is what the standard error of the mean measures. Its longer name is the standard deviation of the sampling distribution of the sample mean.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/J1twbrHel3o.mp4/J1twbrHel3o.mp4</video:content_loc><video:duration>915</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/sampling-distribution-example-problem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/6022796.jpg</video:thumbnail_loc><video:title>Example: Probability of sample mean exceeding a value</video:title><video:description>Estimating the probability that the sample mean exceeds a given value in the sampling distribution of the sample mean.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0ZstEh_8bYc.mp4/0ZstEh_8bYc.mp4</video:content_loc><video:duration>868</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/introduction-to-t-statistics</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8c7a88d2d7e2e655.jpg</video:thumbnail_loc><video:title>Introduction to t statistics</video:title><video:description>An introduction to why we use t statistics.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/a2rd4Qy8yNI.mp4/a2rd4Qy8yNI.mp4</video:content_loc><video:duration>266</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/simulation-showing-value-of-t-statistic</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd476a6729ce90085.jpg</video:thumbnail_loc><video:title>Simulation showing value of t statistic</video:title><video:description>See why we use t statistics when building confidence intervals for a mean using the sample standard deviation in place of the population standard deviation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gLE6y_NwmhQ.mp4/gLE6y_NwmhQ.mp4</video:content_loc><video:duration>194</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/conditions-for-valid-t-intervals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x76eae7745fbf1dc1.jpg</video:thumbnail_loc><video:title>Conditions for valid t intervals</video:title><video:description>Examples showing how to determine if the conditions have been met for making a t interval to estimate a mean.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/WPxnNjD_yoU.mp4/WPxnNjD_yoU.mp4</video:content_loc><video:duration>294</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/example-finding-critical-t-value</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4d48d6d578ca9c06.jpg</video:thumbnail_loc><video:title>Example finding critical t value</video:title><video:description>Given a confidence level, we can calculate a critical value (t*) in a t-distribution with n-1 degrees of freedom.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/mLh_FPwMdcY.mp4/mLh_FPwMdcY.mp4</video:content_loc><video:duration>239</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/calculating-a-one-sample-t-interval-for-a-mean</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7d96e465ca35a4b0.jpg</video:thumbnail_loc><video:title>Example constructing a t interval for a mean</video:title><video:description>Example showing how to calculate a one-sample t interval for a mean.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6G3jMjAqNqM.mp4/6G3jMjAqNqM.mp4</video:content_loc><video:duration>358</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/confidence-interval-for-a-mean-difference</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x06d4814f0bdba692.jpg</video:thumbnail_loc><video:title>Confidence interval for a mean with paired data</video:title><video:description>Confidence interval for a mean difference with paired data</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gWaA8mVBZQk.mp4/gWaA8mVBZQk.mp4</video:content_loc><video:duration>586</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/writing-hypotheses-for-significance-test-about-means</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd988b0853e5e8e20.jpg</video:thumbnail_loc><video:title>Writing hypotheses for a significance test about a mean</video:title><video:description>Example of constructing hypotheses for a test about a mean</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/89Dp9Xq4eaA.mp4/89Dp9Xq4eaA.mp4</video:content_loc><video:duration>154</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/conditions-t-test-mean</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x946974efaad1ff8e.jpg</video:thumbnail_loc><video:title>Conditions for a t test about a mean</video:title><video:description>Example showing how to check which conditions have been met for a t test about a mean</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/GtokpL4f32s.mp4/GtokpL4f32s.mp4</video:content_loc><video:duration>348</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/when-to-use-z-or-t-statistics-in-significance-tests</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x587b2b5cf9c4884a.jpg</video:thumbnail_loc><video:title>When to use z or t statistics in significance tests</video:title><video:description>When to use z or t statistics in significance tests</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-bhfcBvyWoc.mp4/-bhfcBvyWoc.mp4</video:content_loc><video:duration>291</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/example-calculating-t-statistic-for-signficance-test</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xed967efdbf796cc7.jpg</video:thumbnail_loc><video:title>Example calculating t statistic for a test about a mean</video:title><video:description>The lesson demonstrates conducting a t-test for a population mean with a teacher experience sample. It explains the t-statistic calculation and the p-value interpretation to test a null hypothesis. This process helps ascertain if the true mean is less than the hypothesized mean.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/BJl9WA787-Q.mp4/BJl9WA787-Q.mp4</video:content_loc><video:duration>302</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/using-ti-calculator-for-p-value-from-t-statistic</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7905126b8d0a8152.jpg</video:thumbnail_loc><video:title>Using TI calculator for P-value from t statistic</video:title><video:description>In a significance test about a population mean, we first calculate a test statistic based on our sample results. We can then use technology to calculate the p-value based on that test statistic using a t distribution with n-1 degrees of freedom.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/M2P96TJMEaM.mp4/M2P96TJMEaM.mp4</video:content_loc><video:duration>199</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/calculating-p-value-from-t-statistic</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x23ff937dfc559767.jpg</video:thumbnail_loc><video:title>Using a table to estimate P-value from t statistic</video:title><video:description>In a significance test about a population mean, we first calculate a test statistic based on our sample results. We can then use a table to estimate the p-value based on that test statistic using a t distribution with n-1 degrees of freedom.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/z-HSsVARNnk.mp4/z-HSsVARNnk.mp4</video:content_loc><video:duration>293</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/comparing-p-value-from-t-statistic-to-significance-level</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1bbbd6bc7ce03c14.jpg</video:thumbnail_loc><video:title>Comparing P-value from t statistic to significance level</video:title><video:description>Example showing how to compare the P-value to a significance level to make a conclusion in a t test.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/I5WSC_iRtwE.mp4/I5WSC_iRtwE.mp4</video:content_loc><video:duration>219</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/ap-statistics-free-response-on-significance-test-for-mean</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd576802c969703a3.jpg</video:thumbnail_loc><video:title>Free response example: Significance test for a mean</video:title><video:description>AP Statistics free response on significance test for a mean</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8nCsnsD8Fnw.mp4/8nCsnsD8Fnw.mp4</video:content_loc><video:duration>713</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/sampling-distribution-diff-means</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2fac87e4484b6025.jpg</video:thumbnail_loc><video:title>Sampling distribution of the difference in sample means</video:title><video:description>We can calculate the mean and standard deviation for the sampling distribution of the difference in sample means. And we can tell if the shape of that sampling distribution is approximately normal.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/p24UTvbKZog.mp4/p24UTvbKZog.mp4</video:content_loc><video:duration>487</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/sampling-dist-diff-means-probability</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8e08ca1374efe3a6.jpg</video:thumbnail_loc><video:title>Sampling distribution of the difference in sample means: Probability example</video:title><video:description>We can use the mean and standard deviation and normal shape to calculate probability in a sampling distribution of the difference in sample means.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5OYtncxCR50.mp4/5OYtncxCR50.mp4</video:content_loc><video:duration>223</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/conditions-for-inference-for-difference-of-means</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x332a11a1b1aa7c98.jpg</video:thumbnail_loc><video:title>Conditions for inference for difference of means</video:title><video:description>Conditions for inference for difference of means</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Yadshgsx6FQ.mp4/Yadshgsx6FQ.mp4</video:content_loc><video:duration>203</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/constructing-t-interval-for-difference-of-means</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x55b4bb1b6469ce0b.jpg</video:thumbnail_loc><video:title>Constructing t interval for difference of means</video:title><video:description>Constructing t interval for difference of means</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Lh1TPIFH7iI.mp4/Lh1TPIFH7iI.mp4</video:content_loc><video:duration>393</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/calculating-confidence-interval-for-difference-of-means</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf4da59b85aaf41fc.jpg</video:thumbnail_loc><video:title>Calculating confidence interval for difference of means</video:title><video:description>Calculating confidence interval for difference of means</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pVPPDbZGd04.mp4/pVPPDbZGd04.mp4</video:content_loc><video:duration>290</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/alternative-hypothesis-for-2-sample-t-test</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x28325b281c9a31f9.jpg</video:thumbnail_loc><video:title>Hypotheses for a two-sample t test</video:title><video:description>Example of how to write hypotheses for a two-sample t test, and how to distinguish between paired and two-sample comparisons between means.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8CJ-RsoYbg0.mp4/8CJ-RsoYbg0.mp4</video:content_loc><video:duration>240</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/example-of-hypotheses-for-paired-and-2-sample-t-tests</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfea83edcce1cd42b.jpg</video:thumbnail_loc><video:title>Example of hypotheses for paired and two-sample t tests</video:title><video:description>Example of hypotheses for paired and two-sample t tests</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/X0gIJUXz6jc.mp4/X0gIJUXz6jc.mp4</video:content_loc><video:duration>229</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/two-sample-t-test-for-difference-of-means</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5108846a61b527e8.jpg</video:thumbnail_loc><video:title>Two-sample t test for difference of means</video:title><video:description>Given data from two samples, we can do a signficance test to compare the sample means with a test statistic and p-value, and determine if there is enough evidence to suggest a difference between the two population means.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/NkGvw18zlGQ.mp4/NkGvw18zlGQ.mp4</video:content_loc><video:duration>416</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/conclusion-for-2-sample-t-test-from-p-value</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd4c85a8cd12c1924.jpg</video:thumbnail_loc><video:title>Conclusion for a two-sample t test using a P-value</video:title><video:description>Given results of a two-sample t test, compare the P-value to the significance level to make a conclusion in context about the difference between two means.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ogFLbvKru8A.mp4/ogFLbvKru8A.mp4</video:content_loc><video:duration>149</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/calculating-the-equation-of-a-regression-line</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3acdc86c38b8c2f6.jpg</video:thumbnail_loc><video:title>Calculating the equation of a regression line</video:title><video:description>We determine the correlation coefficient for bivariate data, which helps understand the relationship between variables. We then build the equation for the least squares line, using standard deviations and the correlation coefficient. The regression line equation y hat = mx + b is calculated.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/FGesqq22TCM.mp4/FGesqq22TCM.mp4</video:content_loc><video:duration>491</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/using-least-squares-regression-output</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x143f9602822e8462.jpg</video:thumbnail_loc><video:title>Using least squares regression output</video:title><video:description>Worked example using least squares regression output</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vEon1weoA3o.mp4/vEon1weoA3o.mp4</video:content_loc><video:duration>214</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/review-and-intuition-why-we-divide-by-n-1-for-the-unbiased-sample-variance</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1164004886.jpg</video:thumbnail_loc><video:title>Review and intuition why we divide by n-1 for the unbiased sample variance</video:title><video:description>Reviewing the population mean, sample mean, population variance, sample variance and building an intuition for why we divide by n-1 for the unbiased sample variance</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/KkaU2ur3Ymw.mp4/KkaU2ur3Ymw.mp4</video:content_loc><video:duration>584</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/another-simulation-giving-evidence-that-n-1-gives-us-an-unbiased-estimate-of-var</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1174713420.jpg</video:thumbnail_loc><video:title>Why we divide by n - 1 in variance</video:title><video:description>Another visualization providing evidence that dividing by n-1 truly gives an unbiased estimate of population variance. Simulation at: http://www.khanacademy.org/cs/unbiased-variance-visualization/1167453164</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/F2mfEldxsPI.mp4/F2mfEldxsPI.mp4</video:content_loc><video:duration>286</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/simulation-showing-bias-in-sample-variance</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1174647817.jpg</video:thumbnail_loc><video:title>Simulation showing bias in sample variance</video:title><video:description>Simulation by Peter Collingridge giving us a better understanding of why we divide by (n-1) when calculating the unbiased sample variance. Simulation available at: http://www.khanacademy.org/cs/challenge-unbiased-estimate-of-population-variance/1169428428</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Cn0skMJ2F3c.mp4/Cn0skMJ2F3c.mp4</video:content_loc><video:duration>384</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/simulation-providing-evidence-that-n-1-gives-us-unbiased-estimate</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1174782081.jpg</video:thumbnail_loc><video:title>Simulation providing evidence that (n-1) gives us unbiased estimate</video:title><video:description>Simulation by KA user tetef showing that dividing by (n-1) gives us an unbiased estimate of population variance. Simulation at: http://www.khanacademy.org/cs/will-it-converge-towards-1/1167579097</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0QS4VHPV4JA.mp4/0QS4VHPV4JA.mp4</video:content_loc><video:duration>270</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/probability/v/calculating-percentile</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x14d5c1380b3b7971.jpg</video:thumbnail_loc><video:title>Calculating percentile</video:title><video:description>Learn how to calculate the percentile rank for a given data point.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Ngyt8Q5tWkU.mp4/Ngyt8Q5tWkU.mp4</video:content_loc><video:duration>218</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/analyzing-a-cumulative-relative-frequency-graph</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6970bb2f4549cd5e.jpg</video:thumbnail_loc><video:title>Analyzing a cumulative relative frequency graph</video:title><video:description>We investigate a scenario that includes interpreting cumulative relative frequency graphs, using percentiles and quartiles to estimate central tendency and spread within a distribution, and calculating the interquartile range based on the interpretation of the graph.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TwGYLQ-DNdc.mp4/TwGYLQ-DNdc.mp4</video:content_loc><video:duration>355</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/density-curves</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x38d7e38a58c80236.jpg</video:thumbnail_loc><video:title>Density Curves</video:title><video:description>An introduction to density curves for visualizing distributions. A brief review of frequency histograms and relative frequency histograms as well.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PUvUQMQ7xQk.mp4/PUvUQMQ7xQk.mp4</video:content_loc><video:duration>574</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/median-mean-and-skew-from-density-curves</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb4e2aa7a83b8779f.jpg</video:thumbnail_loc><video:title>Median, mean and skew from density curves</video:title><video:description>High level analysis of density curves. A focus on median, mean, left-skew and right-skew.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/JFesFhraX2M.mp4/JFesFhraX2M.mp4</video:content_loc><video:duration>365</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/probability/v/finding-z-score-for-a-percentile</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2f6934241a8b25ce.jpg</video:thumbnail_loc><video:title>Finding z-score for a percentile</video:title><video:description>In any normal distribution, we can find the z-score that corresponds to some percentile rank. If we&apos;re given a particular normal distribution with some mean and standard deviation, we can use that z-score to find the actual cutoff for that percentile. In this example, we find what pulse rate represents the top 30% of all pulse rates in a population.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/S5_5KyCVjrU.mp4/S5_5KyCVjrU.mp4</video:content_loc><video:duration>254</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/r-squared-or-coefficient-of-determination</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187298.jpg</video:thumbnail_loc><video:title>R-squared or coefficient of determination</video:title><video:description>In linear regression, r-squared (also called the coefficient of determination) is the proportion of variation in the response variable that is explained by the explanatory variable in the model.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lng4ZgConCM.mp4/lng4ZgConCM.mp4</video:content_loc><video:duration>761</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/standard-dev-residuals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xaecf749b9a5db4fb.jpg</video:thumbnail_loc><video:title>Standard deviation of residuals or root mean square deviation (RMSD)</video:title><video:description>Standard deviation of the residuals are a measure of how well a regression line fits the data. It is also known as root mean square deviation or root mean square error.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hSP_rmNHU_U.mp4/hSP_rmNHU_U.mp4</video:content_loc><video:duration>426</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/interpreting-computer-regression-data</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xde97338b3dce169e.jpg</video:thumbnail_loc><video:title>Interpreting computer regression data</video:title><video:description>Interpreting computer generated regression data to find the equation of a least-squares regression line. Predictors and coefficients. S and R-squared.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/sIJj7Q77SVI.mp4/sIJj7Q77SVI.mp4</video:content_loc><video:duration>313</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/impact-of-removing-outliers-on-regression-lines</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc6423bf0474428d0.jpg</video:thumbnail_loc><video:title>Impact of removing outliers on regression lines</video:title><video:description>Impact of removing outliers on slope, y-intercept and r of least-squares regression lines.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TbS7S7lb9Es.mp4/TbS7S7lb9Es.mp4</video:content_loc><video:duration>344</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/influential-points-regression</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x69913ce3b3f4e63e.jpg</video:thumbnail_loc><video:title>Influential points in regression</video:title><video:description>Outliers and high-leverage points can be influential to different measurements in least-squares regression like the slope, y-intercept, and correlation coefficient (r).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jHHPGhrcMOY.mp4/jHHPGhrcMOY.mp4</video:content_loc><video:duration>255</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/transforming-nonlinear-data</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x62fff31072ed0c1c.jpg</video:thumbnail_loc><video:title>Transforming nonlinear data</video:title><video:description>Use logarithms to transform nonlinear data into a linear relationship so we can use least-squares regression methods.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/A1H4j97paI4.mp4/A1H4j97paI4.mp4</video:content_loc><video:duration>175</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/transformed-linear-regression-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x27e206519815626b.jpg</video:thumbnail_loc><video:title>Worked example of linear regression using transformed data</video:title><video:description>Worked example of linear regression using transformed data. Adapted from 2007 AP Statistics free response, form b, question 6, part d.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/dEVGfxHF1yo.mp4/dEVGfxHF1yo.mp4</video:content_loc><video:duration>460</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/probability/v/intro-experiment-design</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2d7343379f74c4c7.jpg</video:thumbnail_loc><video:title>Introduction to experiment design</video:title><video:description>Explanatory and response variables. Random sampling and random assignment (including block design). Placebos and blind/double-blind experiments.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Fw8qsuZNzH4.mp4/Fw8qsuZNzH4.mp4</video:content_loc><video:duration>400</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/probability/v/bayes-theorem-visualized</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1317894497.jpg</video:thumbnail_loc><video:title>Conditional probability with Bayes&apos; Theorem</video:title><video:description>Conditional probability visualized using trees.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Zxm4Xxvzohk.mp4/Zxm4Xxvzohk.mp4</video:content_loc><video:duration>306</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/getting-at-least-one-heads</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/191769946.jpg</video:thumbnail_loc><video:title>&quot;At least one&quot; probability with coin flipping</video:title><video:description>In this video, we &apos;ll explore the probability of getting at least one heads in multiple flips of a fair coin.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/mkyZ45KQYi4.mp4/mkyZ45KQYi4.mp4</video:content_loc><video:duration>560</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/impact-of-scaling-and-shifting-random-variables</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x39496cee07d4d44f.jpg</video:thumbnail_loc><video:title>Impact of transforming (scaling and shifting) random variables</video:title><video:description>Linear transformations (addition and multiplication of a constant) and their impacts on center (mean) and spread (standard deviation) of a distribution.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/fx3TtExi9e8.mp4/fx3TtExi9e8.mp4</video:content_loc><video:duration>386</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/example-transforming-a-discrete-random-variable</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x09997886d004552f.jpg</video:thumbnail_loc><video:title>Example: Transforming a discrete random variable</video:title><video:description>Example of transforming a discrete random variable</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/nb3m_Q7rfT4.mp4/nb3m_Q7rfT4.mp4</video:content_loc><video:duration>250</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/mean-of-sum-and-difference-of-random-variables</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0961ac866dd6c24a.jpg</video:thumbnail_loc><video:title>Mean of sum and difference of random variables</video:title><video:description>Mean of sum and difference of random variables</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/RYSN1CARHtE.mp4/RYSN1CARHtE.mp4</video:content_loc><video:duration>202</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/variance-of-sum-and-difference-of-random-variables</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbed7d77d46342fbc.jpg</video:thumbnail_loc><video:title>Variance of sum and difference of random variables</video:title><video:description>Intuition for why the variance of both the sum and difference of two independent random variables is equal to the sum of their variances.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3VXhi_0Mclg.mp4/3VXhi_0Mclg.mp4</video:content_loc><video:duration>487</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/intuition-for-why-independence-matters-for-variance-of-sum</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xcd147b9df75754e0.jpg</video:thumbnail_loc><video:title>Intuition for why independence matters for variance of sum</video:title><video:description>Intuition for why independence matters for variance of sum</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/UAOJgqdsK9w.mp4/UAOJgqdsK9w.mp4</video:content_loc><video:duration>263</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/variance-of-differences-of-random-variables</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/6022811.jpg</video:thumbnail_loc><video:title>Deriving the variance of the difference of random variables</video:title><video:description>Sal derives the variance of the difference of random variables</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/rLdoKZ7w0xI.mp4/rLdoKZ7w0xI.mp4</video:content_loc><video:duration>647</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/analyzing-distribution-of-sum-of-two-normally-distributed-random-variables</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x874938306036423b.jpg</video:thumbnail_loc><video:title>Example: Analyzing distribution of sum of two normally distributed random variables</video:title><video:description>Finding the probability that the total of some random variables exceeds an amount by understanding the distribution of the sum of normally distributed variables.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Z6vANdo1L68.mp4/Z6vANdo1L68.mp4</video:content_loc><video:duration>351</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/analyzing-the-difference-in-distributions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x45f991a6e84e9da8.jpg</video:thumbnail_loc><video:title>Example: Analyzing the difference in distributions</video:title><video:description>Finding the probability that a randomly selected woman is taller than a randomly selected man by understanding the distribution of the difference of normally distributed variables.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_Pq547nYFaE.mp4/_Pq547nYFaE.mp4</video:content_loc><video:duration>585</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/10-percent-rule-independence</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xee11001de8e951c9.jpg</video:thumbnail_loc><video:title>10% Rule of assuming &quot;independence&quot; between trials</video:title><video:description>10% Rule of assuming &quot;independence&quot; between trials</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/elcLysy7exM.mp4/elcLysy7exM.mp4</video:content_loc><video:duration>403</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/generalizing-k-scores-in-n-attempts</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0a129ac6.jpg</video:thumbnail_loc><video:title>Generalizing k scores in n attempts</video:title><video:description>Sal generalizes 2 scores in 6 attempts to k scores in n attempts.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/efE8xuvUjAo.mp4/efE8xuvUjAo.mp4</video:content_loc><video:duration>253</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/free-throw-binomial-probability-distribution</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xead3220b.jpg</video:thumbnail_loc><video:title>Free throw binomial probability distribution</video:title><video:description>Sal uses the binomial distribution to calculate the probability of making different number of free throws.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/eL965_Lscb8.mp4/eL965_Lscb8.mp4</video:content_loc><video:duration>519</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/graphing-basketball-binomial-distribution</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xba5fcceb.jpg</video:thumbnail_loc><video:title>Graphing basketball binomial distribution</video:title><video:description>Sal graphs the results of using the binomial distribution to find the probabilities of making different numbers of free throws.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/y2G03Lumhe0.mp4/y2G03Lumhe0.mp4</video:content_loc><video:duration>262</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/ti-84-binompdf-and-binomcdf-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1138367bae9683e9.jpg</video:thumbnail_loc><video:title>Binompdf and binomcdf functions</video:title><video:description>This tutorial demonstrates how to use a graphing calculator to calculate probabilities for a binomial distribution. It covers key concepts like binomial random variables, binomial probability distribution function, and binomial cumulative distribution function, using the example of making free throws in basketball.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/IngLJs6T1Qw.mp4/IngLJs6T1Qw.mp4</video:content_loc><video:duration>327</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/geometric-random-variables-introduction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x19fae2466b67f624.jpg</video:thumbnail_loc><video:title>Geometric random variables introduction</video:title><video:description>Distinguishing between geometric and binomial random variables</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/IVlzp8g1McE.mp4/IVlzp8g1McE.mp4</video:content_loc><video:duration>375</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/geometric-mean-std-deviation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xee486f6ef9da8309.jpg</video:thumbnail_loc><video:title>Geometric distribution mean and standard deviation</video:title><video:description>We can calculate and interpret the mean and standard deviation for the distribution of a geometric random variable, and describe its shape.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/XKCeLA4UsXw.mp4/XKCeLA4UsXw.mp4</video:content_loc><video:duration>386</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/probability-for-a-geometric-random-variable</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x372e97d6330a7fe3.jpg</video:thumbnail_loc><video:title>Probability for a geometric random variable</video:title><video:description>Finding the probability for a single outcome of a geometric random variable</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jKlgEvRFItE.mp4/jKlgEvRFItE.mp4</video:content_loc><video:duration>171</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/cumulative-geometric-probability-greater-than-a-value</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfdbbc68b8f5b3a7f.jpg</video:thumbnail_loc><video:title>Cumulative geometric probability (greater than a value)</video:title><video:description>Probability for a geometric random variable being greater than a certain value.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7TYMKKQK8s8.mp4/7TYMKKQK8s8.mp4</video:content_loc><video:duration>303</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/cumulative-geometric-probability-less-than-a-value</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xaacc5e5c87f80355.jpg</video:thumbnail_loc><video:title>Cumulative geometric probability (less than a value)</video:title><video:description>Probability for a geometric random variable being less than a certain value.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/nxUP4lJ_hbU.mp4/nxUP4lJ_hbU.mp4</video:content_loc><video:duration>247</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/ti-84-geometpdf-and-geometcdf-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x120d1a2744a614d3.jpg</video:thumbnail_loc><video:title>TI-84 geometpdf and geometcdf functions</video:title><video:description>Using a TI-84 (very similar for TI-85 or TI-89) calculator for making calculations regarding geometric random variables.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/RMf0F72I7dY.mp4/RMf0F72I7dY.mp4</video:content_loc><video:duration>348</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/proof-of-expected-value-of-geometric-random-variable</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x609952a24493dc6d.jpg</video:thumbnail_loc><video:title>Proof of expected value of geometric random variable</video:title><video:description>Proof of expected value of geometric random variable</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7br_-emGNec.mp4/7br_-emGNec.mp4</video:content_loc><video:duration>439</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/probabilities-from-density-curves</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xcf52ad8fc5bff8ac.jpg</video:thumbnail_loc><video:title>Probabilities from density curves</video:title><video:description>Examples finding probabilities from probability distributions for continuous random variables.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3E8BO7VRMEA.mp4/3E8BO7VRMEA.mp4</video:content_loc><video:duration>293</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/confidence-intervals-and-margin-of-error</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6f4d752a0bd525e7.jpg</video:thumbnail_loc><video:title>Confidence intervals and margin of error</video:title><video:description>If we poll 100 people, and 56% of them support a candidate, we can use what we know about sampling distributions and margin of error to build a confidence interval to estimate the true value of the percentage in the population.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hlM7zdf7zwU.mp4/hlM7zdf7zwU.mp4</video:content_loc><video:duration>705</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/confidence-interval-simulation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3514d7ca10c2a248.jpg</video:thumbnail_loc><video:title>Confidence interval simulation</video:title><video:description>Confidence interval simulation</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/bGALoCckICI.mp4/bGALoCckICI.mp4</video:content_loc><video:duration>265</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/interpreting-confidence-intervals-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2136930aa89bfa56.jpg</video:thumbnail_loc><video:title>Interpreting confidence level example</video:title><video:description>Interpreting confidence level example</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/XZAGtQt-lQo.mp4/XZAGtQt-lQo.mp4</video:content_loc><video:duration>300</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/comparing-p-value-to-significance-level-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xff94fdc886b2120a.jpg</video:thumbnail_loc><video:title>Making conclusions in a test about a proportion</video:title><video:description>Example of how to make a conclusion in a test about a proportion</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/RcjZwZJO5qo.mp4/RcjZwZJO5qo.mp4</video:content_loc><video:duration>314</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/full-significance-test-example-from-ap-test</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9b9b2ac10698f2ee.jpg</video:thumbnail_loc><video:title>Significance test for a proportion free response example</video:title><video:description>Carrying out every step of a significance test on a proportion.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/sqRQSPwNE-4.mp4/sqRQSPwNE-4.mp4</video:content_loc><video:duration>782</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/ap-statistics/v/full-significance-test-example-from-ap-test-part-2-with-correction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3cd99e7c7d0dd3f2.jpg</video:thumbnail_loc><video:title>Significance test for a proportion free response (part 2 with correction)</video:title><video:description>Full significance test example from AP test part 2 with correction for maximum points on AP exam.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/l5uCPu2t7W4.mp4/l5uCPu2t7W4.mp4</video:content_loc><video:duration>170</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-tx/v/confidence-interval-for-hypothesis-test-for-difference-in-proportions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x35d1563873c98288.jpg</video:thumbnail_loc><video:title>Confidence interval for hypothesis test for difference in proportions</video:title><video:description>Confidence interval for hypothesis test for difference in proportions</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-VZUijm02h0.mp4/-VZUijm02h0.mp4</video:content_loc><video:duration>330</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-tx/v/conclusion-for-2-sample-t-test-from-confidence-interval</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x23ef855ee4d013f8.jpg</video:thumbnail_loc><video:title>Conclusion for a two-sample t test using a confidence interval</video:title><video:description>Given a confidence interval estimating the difference between two means, make a conclusion in a significance test about the difference between those means.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/iJr9PpY3PjM.mp4/iJr9PpY3PjM.mp4</video:content_loc><video:duration>226</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/chi-square-statistic</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x842fa2bbaaeadaef.jpg</video:thumbnail_loc><video:title>Chi-square statistic for hypothesis testing</video:title><video:description>Chi-square statistic for hypothesis testing (chi-square goodness-of-fit test)</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jABsbNBPXIk.mp4/jABsbNBPXIk.mp4</video:content_loc><video:duration>506</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/goodness-of-fit-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x202e0eed5e346fd9.jpg</video:thumbnail_loc><video:title>Chi-square goodness-of-fit example</video:title><video:description>Chi-square goodness-of-fit example</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/VjO9hWVlOBo.mp4/VjO9hWVlOBo.mp4</video:content_loc><video:duration>409</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/intro-inference-slope</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa84bb36461ffc2b3.jpg</video:thumbnail_loc><video:title>Introduction to inference about slope in linear regression</video:title><video:description>Introduction to sample slopes and using them to make confidence intervals or do a test about the population slope in least-squares regression</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Pzglbt9_xCI.mp4/Pzglbt9_xCI.mp4</video:content_loc><video:duration>432</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/conditions-inference-slope</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x997bc64c21b63d1f.jpg</video:thumbnail_loc><video:title>Conditions for inference on slope</video:title><video:description>Introducing the conditions for making a confidence interval or doing a test about slope in least-squares regression.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/kOQx3LtWHEQ.mp4/kOQx3LtWHEQ.mp4</video:content_loc><video:duration>291</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/confidence-interval-slope</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd40810aa6b9f90e4.jpg</video:thumbnail_loc><video:title>Confidence interval for the slope of a regression line</video:title><video:description>Confidence interval for the slope of a regression line</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8w6EPyEqE9M.mp4/8w6EPyEqE9M.mp4</video:content_loc><video:duration>415</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/t-statistic-slope</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8e50c43032661b0c.jpg</video:thumbnail_loc><video:title>Calculating t statistic for slope of regression line</video:title><video:description>Calculate the test statistic in a test about the slope of a regression line</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7MAuojBTF-g.mp4/7MAuojBTF-g.mp4</video:content_loc><video:duration>436</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/making-conclusions-for-regression-slope-hypothesis-test</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe4ba7721c7cc54d9.jpg</video:thumbnail_loc><video:title>Using a P-value to make conclusions in a test about slope</video:title><video:description>Making conclusions in a hypothesis test about the slope of a least-squares regression line.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Mpd83AuDTrU.mp4/Mpd83AuDTrU.mp4</video:content_loc><video:duration>385</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/interval-test-slope</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x40f4765e2292a3e6.jpg</video:thumbnail_loc><video:title>Using a confidence interval to test slope</video:title><video:description>Using confidence interval for hypothesis test on regression slope</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/rL9MPL3wqsk.mp4/rL9MPL3wqsk.mp4</video:content_loc><video:duration>234</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-2nd-grade-math/v/expanded-form-of-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1e06e0d4e43f89e1.jpg</video:thumbnail_loc><video:title>Expanded form of numbers</video:title><video:description>Sal shows how to turn numbers from expanded form to number form.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/drZjIlmHdME.mp4/drZjIlmHdME.mp4</video:content_loc><video:duration>177</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-1st-grade-math/v/number-grid</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb19b2406.jpg</video:thumbnail_loc><video:title>Number grid</video:title><video:description>Sal goes through all the numbers from 0 to 100 and shows some interesting patterns.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9XZypM2Z3Ro.mp4/9XZypM2Z3Ro.mp4</video:content_loc><video:duration>298</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-1st-grade-math/v/numbers-to-120</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf78091c1.jpg</video:thumbnail_loc><video:title>Missing numbers between 0 and 120</video:title><video:description>Sal finds missing numbers between 0 and 120.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1AqkBdCBm9o.mp4/1AqkBdCBm9o.mp4</video:content_loc><video:duration>114</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-1st-grade-math/v/place-value-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x426bd66b.jpg</video:thumbnail_loc><video:title>Place value example: 25</video:title><video:description>Sal shows 25 as 2 tens and 5 ones.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/X_PnRFAKbkg.mp4/X_PnRFAKbkg.mp4</video:content_loc><video:duration>175</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-1st-grade-math/v/rep-quantity-with-digits</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8a682fbc.jpg</video:thumbnail_loc><video:title>Place value example: 42</video:title><video:description>Sal shows 42 as 4 tens and 2 ones.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-Zlq5tNl94M.mp4/-Zlq5tNl94M.mp4</video:content_loc><video:duration>259</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-2nd-grade-math/v/greater-than-and-less-than-symbols</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x48102d13.jpg</video:thumbnail_loc><video:title>Greater than and less than symbols</video:title><video:description>This video teaches comparing numbers using equal, greater than, and less than symbols. It clarifies the equal sign&apos;s meaning and demonstrates using comparison symbols with numbers and expressions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/nFsQA2Zvy1o.mp4/nFsQA2Zvy1o.mp4</video:content_loc><video:duration>304</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-2nd-grade-math/v/number-and-word-form-of-a-number</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2ca722b3f06e68c6.jpg</video:thumbnail_loc><video:title>Number and word form of a number</video:title><video:description>Sal shows how to turn a number from number form into word form.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hBCz0VDt2cI.mp4/hBCz0VDt2cI.mp4</video:content_loc><video:duration>137</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-2nd-grade-math/v/word-form-and-expanded-form</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x10d92a563c3a621a.jpg</video:thumbnail_loc><video:title>Word form and expanded form</video:title><video:description>Sal shows how to write numbers from word form to expanded form.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/83Tji22tYGY.mp4/83Tji22tYGY.mp4</video:content_loc><video:duration>86</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/place-value-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/2600658.jpg</video:thumbnail_loc><video:title>Writing a number in standard form</video:title><video:description>This video demonstrates converting large numbers from expanded and written form to standard form. Using the example &quot;six hundred forty-five million five hundred eighty-four thousand four hundred sixty-two,&quot; it explains the process and arrives at 645,584,462, emphasizing place value understanding.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/wd4cRAoBOiE.mp4/wd4cRAoBOiE.mp4</video:content_loc><video:duration>249</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/intro-to-roman-numerals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x496ef053298635d7.jpg</video:thumbnail_loc><video:title>Intro to Roman numerals</video:title><video:description>Let&apos;s get a quick introduction to what Roman numerals are why we learn about them.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Q3X6Coa2FWo.mp4/Q3X6Coa2FWo.mp4</video:content_loc><video:duration>267</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/how-to-read-and-write-roman-numerals-class-6-india-khan-academy</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xba705027c2eec9e8.jpg</video:thumbnail_loc><video:title>Reading and writing Roman numerals</video:title><video:description>Let&apos;s learn how to read and write Roman numerals.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/W_NymI3Aamo.mp4/W_NymI3Aamo.mp4</video:content_loc><video:duration>454</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/roman-numerals-worked-example-class-6-india-khan-academy</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5d30f29cd339dbbb.jpg</video:thumbnail_loc><video:title>Roman numerals worked example</video:title><video:description>Let&apos;s look at an example of how to convert a number from the usual Hindu-Arabic numerals to Roman numerals.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/dGZTQxyfwPI.mp4/dGZTQxyfwPI.mp4</video:content_loc><video:duration>205</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/basic-addition</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23798.jpg</video:thumbnail_loc><video:title>Basic addition</video:title><video:description>Let&apos;s learn about basic addition by starting with simple examples and moving on to more difficult problems. Two methods for solving these problems are demonstrated: drawing circles to represent each quantity, or using a number line. Practice is emphasized as the key to mastering this skill.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/AuX7nPBqDts.mp4/AuX7nPBqDts.mp4</video:content_loc><video:duration>462</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/basic-subtraction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23808.jpg</video:thumbnail_loc><video:title>Basic subtraction</video:title><video:description>Introduction to subtraction.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/aNqG4ChKShI.mp4/aNqG4ChKShI.mp4</video:content_loc><video:duration>512</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-kindergarten-math/v/adding-fruit</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x041e77f7.jpg</video:thumbnail_loc><video:title>Add and subtract: pieces of fruit</video:title><video:description>Sal adds fruit and subtracts fruit. The examples he uses are 5+3 and 5-3.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ie0waMJxnTs.mp4/ie0waMJxnTs.mp4</video:content_loc><video:duration>137</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-1st-grade-math/v/relating-addition-and-subtraction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa7a18531.jpg</video:thumbnail_loc><video:title>Relating addition and subtraction</video:title><video:description>Sal shows the relationship between 2+3=5, 5-2=3, and 5-3=2.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/zVLjWIftX_o.mp4/zVLjWIftX_o.mp4</video:content_loc><video:duration>125</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-kindergarten-math/v/getting-to-10-by-filling-boxes</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5d9fb90d.jpg</video:thumbnail_loc><video:title>Getting to 10 by filling boxes</video:title><video:description>Sal shows how to add two numbers to make 10. He uses 3 + ___ = 10 and 6 + ___ = 10 as examples.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/An46SYAxhtc.mp4/An46SYAxhtc.mp4</video:content_loc><video:duration>114</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-kindergarten-math/v/adding-to-10-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xeebd76e8.jpg</video:thumbnail_loc><video:title>Adding to 10</video:title><video:description>Sal finds out how many bananas we need to add to 3 bananas to make 10 bananas.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9FC0WT186aY.mp4/9FC0WT186aY.mp4</video:content_loc><video:duration>120</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-kindergarten-math/v/addition-word-problems-within-10</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd3451833.jpg</video:thumbnail_loc><video:title>Addition word problems within 10</video:title><video:description>Sal solves word problems by adding small numbers (numbers 10 or less).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-3DFzxbP9Fk.mp4/-3DFzxbP9Fk.mp4</video:content_loc><video:duration>102</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-kindergarten-math/v/subtraction-word-problems-within-10</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9854c66d.jpg</video:thumbnail_loc><video:title>Subtraction word problems within 10</video:title><video:description>Sal solves word problems by subtracting small numbers (numbers 10 or less).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qSkpZswoZTc.mp4/qSkpZswoZTc.mp4</video:content_loc><video:duration>63</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-2nd-grade-math/v/adding-within-20-using-place-value-blocks</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8cc10311ecdb3895.jpg</video:thumbnail_loc><video:title>Adding within 20 using place value blocks</video:title><video:description>Sal adds 8 + 6 using place value blocks.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/dDv4FTqKBmY.mp4/dDv4FTqKBmY.mp4</video:content_loc><video:duration>84</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-2nd-grade-math/v/adding-within-20-using-ten-frames</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfa530001a926b085.jpg</video:thumbnail_loc><video:title>Adding within 20 using ten frames</video:title><video:description>Sal adds 8 + 7 using ten frames.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/UzQnoXrJg1o.mp4/UzQnoXrJg1o.mp4</video:content_loc><video:duration>158</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-2nd-grade-math/v/adding-within-20</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x22d1c9bd.jpg</video:thumbnail_loc><video:title>Adding 7 + 6</video:title><video:description>Sal adds 7 + 6 using the number line.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ZgzpTx-s9Zo.mp4/ZgzpTx-s9Zo.mp4</video:content_loc><video:duration>233</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-2nd-grade-math/v/adding-within-20-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x515583ed.jpg</video:thumbnail_loc><video:title>Adding 8 + 7</video:title><video:description>In the video it demonstrates adding 8 + 7 using a visual approach. Adding emphasizes the concept of place value, showing that 15 is made up of 1 group of 10 and 5 ones. This method helps students understand addition within 20 in a more concrete way.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/AK0NZITv5Ns.mp4/AK0NZITv5Ns.mp4</video:content_loc><video:duration>199</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-2nd-grade-math/v/adding-with-arrays</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5f1f4fa5b655b190.jpg</video:thumbnail_loc><video:title>Adding with arrays</video:title><video:description>Sal shows how to relate repeated addition to an array.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/IRjLEJWVtLQ.mp4/IRjLEJWVtLQ.mp4</video:content_loc><video:duration>114</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/subtraction-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23810.jpg</video:thumbnail_loc><video:title>Subtracting different ways</video:title><video:description>Sal subtracts numbers using models and number lines.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/incKJchBCLo.mp4/incKJchBCLo.mp4</video:content_loc><video:duration>752</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-2nd-grade-math/v/subtract-within-20-using-a-number-line</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1ed4febfd0a96ed1.jpg</video:thumbnail_loc><video:title>Subtract within 20 using a number line</video:title><video:description>Sal subtracts 17 - 9 using a number line.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/HjRcLJMHuVA.mp4/HjRcLJMHuVA.mp4</video:content_loc><video:duration>80</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-2nd-grade-math/v/subtract-within-20-using-place-value-blocks</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4412c816995f85ee.jpg</video:thumbnail_loc><video:title>Subtract within 20 using place value blocks</video:title><video:description>Sal subtracts 13-4 using place value blocks.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jhkYFCMUYwA.mp4/jhkYFCMUYwA.mp4</video:content_loc><video:duration>79</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-2nd-grade-math/v/subtract-within-20-using-ten-frames</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x02a60b8a9b838251.jpg</video:thumbnail_loc><video:title>Subtract within 20 using ten frames</video:title><video:description>Sal subtracts 13-6 using ten frames.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/r8HsSXMn-4E.mp4/r8HsSXMn-4E.mp4</video:content_loc><video:duration>56</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-2nd-grade-math/v/subtracting-within-20</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x616fafa9.jpg</video:thumbnail_loc><video:title>Subtracting 14 - 6</video:title><video:description>Sal subtracts 14 - 6 by first thinking about subtracting 2 and 4.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9McJ3GobPaY.mp4/9McJ3GobPaY.mp4</video:content_loc><video:duration>243</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-2nd-grade-math/v/sea-monsters-and-superheroes</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2e0bef65.jpg</video:thumbnail_loc><video:title>Addition and subtraction word problems: superheroes</video:title><video:description>Sal solves 1 addition and 1 subtraction word problem.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/fGok2nHOjnI.mp4/fGok2nHOjnI.mp4</video:content_loc><video:duration>218</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-2nd-grade-math/v/exercising-gorillas</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb8abeb4c.jpg</video:thumbnail_loc><video:title>Addition and subtraction word problems: gorillas</video:title><video:description>Sal solves addition and subtraction word problems.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/SfgD7Sm08ns.mp4/SfgD7Sm08ns.mp4</video:content_loc><video:duration>332</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-1st-grade-math/v/comparison-word-problems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa765b7ce.jpg</video:thumbnail_loc><video:title>Comparison word problems: marbles</video:title><video:description>Sal solves word problems comparing 2 numbers. Numbers in the problems are less than 10.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/osIFa9zcI-w.mp4/osIFa9zcI-w.mp4</video:content_loc><video:duration>203</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-1st-grade-math/v/more-comparison-word-problems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2a46299a.jpg</video:thumbnail_loc><video:title>Comparison word problems: roly-polies</video:title><video:description>Sal solves word problems comparing 2 numbers. Numbers in the problems are less than 10.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3rs7sFPoiZ4.mp4/3rs7sFPoiZ4.mp4</video:content_loc><video:duration>194</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-1st-grade-math/v/adding-two-digit-numbers-no-regrouping</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6c1f38f1.jpg</video:thumbnail_loc><video:title>Adding 2-digit numbers without regrouping 1</video:title><video:description>Sal adds 71 + 24.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/EV38zfiY6Vs.mp4/EV38zfiY6Vs.mp4</video:content_loc><video:duration>113</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/adding-whole-numbers-and-applications-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/2600666.jpg</video:thumbnail_loc><video:title>Example: Adding 2-digit numbers (no carrying)</video:title><video:description>Adding Whole Numbers and Applications 1</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/b22tMEc6Kko.mp4/b22tMEc6Kko.mp4</video:content_loc><video:duration>92</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-2nd-grade-math/v/breaking-apart-two-digit-addition-problems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbbe54e50.jpg</video:thumbnail_loc><video:title>Breaking apart 2-digit addition problems</video:title><video:description>Sal thinks about different ways to break up addition problems.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/UjfmOmPARyk.mp4/UjfmOmPARyk.mp4</video:content_loc><video:duration>288</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-1st-grade-math/v/regrouping-when-adding-two-digit-and-one-digit-number</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe227d7c8.jpg</video:thumbnail_loc><video:title>Regrouping to add 1-digit number</video:title><video:description>Sal adds 35 + 6.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/G1cNKc3PD74.mp4/G1cNKc3PD74.mp4</video:content_loc><video:duration>253</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-2nd-grade-math/v/adding-by-getting-to-group-of-10-first</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x03b57659.jpg</video:thumbnail_loc><video:title>Adding by making a group of 10</video:title><video:description>Sal adds 5+68 by breaking the 5 into a 2 and a 3.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DzJvR56Suss.mp4/DzJvR56Suss.mp4</video:content_loc><video:duration>170</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-2nd-grade-math/v/example-exercises-on-ways-to-add-two-digit-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9d9dccf4.jpg</video:thumbnail_loc><video:title>Strategies for adding 2-digit numbers</video:title><video:description>Sal goes through multiple strategies for adding 2-digit numbers.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/kMHFY6ZrKbU.mp4/kMHFY6ZrKbU.mp4</video:content_loc><video:duration>196</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-2nd-grade-math/v/correct-number-lines-for-addition-and-subtraction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x39288e47.jpg</video:thumbnail_loc><video:title>Addition and subtraction with number lines</video:title><video:description>Sal figures out which number line matches up with a 2-digit addition or subtraction problem.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/I5xcZgyY4ag.mp4/I5xcZgyY4ag.mp4</video:content_loc><video:duration>117</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-2nd-grade-math/v/understanding-place-value-when-adding-ones</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x971fdd55.jpg</video:thumbnail_loc><video:title>Understanding place value when adding ones</video:title><video:description>Sal adds 37 + 2 by thinking about place value.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7_QPAdHILzw.mp4/7_QPAdHILzw.mp4</video:content_loc><video:duration>156</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-2nd-grade-math/v/understanding-place-value-while-adding-tens</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb228ca07.jpg</video:thumbnail_loc><video:title>Understanding place value when adding tens</video:title><video:description>Sal adds 23 + 30 by thinking about place value.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Dy5uDkOoMNc.mp4/Dy5uDkOoMNc.mp4</video:content_loc><video:duration>196</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/early-math/v/introduction-to-regrouping-borrowing</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x340aa2ea.jpg</video:thumbnail_loc><video:title>Subtracting with regrouping (borrowing)</video:title><video:description>Sal subtracts 25 from 83 by thinking about tens and ones.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/egjDLFX9VHg.mp4/egjDLFX9VHg.mp4</video:content_loc><video:duration>327</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-2nd-grade-math/v/adding-two-digit-numbers-on-a-number-line</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5d5dfc84de48cb7a.jpg</video:thumbnail_loc><video:title>Adding two digit numbers on a number line</video:title><video:description>Sal uses a number line to add two digit numbers.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qHbw1_9HstU.mp4/qHbw1_9HstU.mp4</video:content_loc><video:duration>216</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/early-math/v/snow-on-friday</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfce06433.jpg</video:thumbnail_loc><video:title>Subtraction word problem: snow</video:title><video:description>Sal solves a subtraction word problem with numbers less than 100.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/wyWy4PouQxQ.mp4/wyWy4PouQxQ.mp4</video:content_loc><video:duration>259</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-2nd-grade-math/v/multi-step-addition-word-problem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xeb55304ed2298655.jpg</video:thumbnail_loc><video:title>Multi step addition word problem</video:title><video:description>Sal solves a multi-step addition word problems using a tape diagram.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/dbCub716oSg.mp4/dbCub716oSg.mp4</video:content_loc><video:duration>251</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-2nd-grade-math/v/multi-step-subtraction-word-problem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x94e9c6f7067f562a.jpg</video:thumbnail_loc><video:title>Multi-step subtraction word problem</video:title><video:description>Sal solves a multi-step subtraction word problem using a tape diagram.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qAUnDB0LZL4.mp4/qAUnDB0LZL4.mp4</video:content_loc><video:duration>257</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/early-math/v/rethinking-three-digit-addition-for-mental-calculation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc14c8a26.jpg</video:thumbnail_loc><video:title>Solving 3-digit addition in your head</video:title><video:description>Sal shows some techniques for doing mental addition, such as making groups of 10 and 100.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jAfJcgPGqgI.mp4/jAfJcgPGqgI.mp4</video:content_loc><video:duration>448</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/mental-technique-for-subtraction-without-regrouping</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc1b529a7.jpg</video:thumbnail_loc><video:title>Subtracting in your head (no regrouping)</video:title><video:description>Sal uses an understanding of place value to subtract.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/iivtjjdSu9I.mp4/iivtjjdSu9I.mp4</video:content_loc><video:duration>157</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-2nd-grade-math/v/missing-numbers-in-addition-and-subtraction-within-100</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3266cde9.jpg</video:thumbnail_loc><video:title>Missing numbers in addition and subtraction</video:title><video:description>Sal solves missing number in problems like 73 = ___ + 57.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/zTK6XUF0HAs.mp4/zTK6XUF0HAs.mp4</video:content_loc><video:duration>344</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/addition-4</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23806.jpg</video:thumbnail_loc><video:title>Multi-digit addition with regrouping</video:title><video:description>Sal adds multi-digit numbers like 9367 and 2459 using an understanding of place value.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/fOXo4p4WDKM.mp4/fOXo4p4WDKM.mp4</video:content_loc><video:duration>529</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/alternate-mental-subtraction-method</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23814.jpg</video:thumbnail_loc><video:title>Alternate mental subtraction method</video:title><video:description>Sal explains how he subtracts numbers like 9456 and 7589 in his head.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/GBtcGO44e-A.mp4/GBtcGO44e-A.mp4</video:content_loc><video:duration>310</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/basic-multiplication</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23824.jpg</video:thumbnail_loc><video:title>Basic multiplication</video:title><video:description>Introduction to multiplication.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/mvOkMYCygps.mp4/mvOkMYCygps.mp4</video:content_loc><video:duration>800</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/number-line-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5c700875.jpg</video:thumbnail_loc><video:title>Worked example: Whole numbers on the number line</video:title><video:description>Worked example: Whole numbers on the number line from Arithmetic (all content)</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ez1MIB8_2O0.mp4/ez1MIB8_2O0.mp4</video:content_loc><video:duration>80</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/multiplying-whole-numbers-and-applications-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/2600673.jpg</video:thumbnail_loc><video:title>Ways to represent multiplication</video:title><video:description>Sal explains different ways to represent 7 times 5.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Yw3EoxC_GXU.mp4/Yw3EoxC_GXU.mp4</video:content_loc><video:duration>183</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/multiplication-3-10-11-12-times-tables</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23828.jpg</video:thumbnail_loc><video:title>Multiplication tables for 10, 11, 12</video:title><video:description>Learn to multiply 10, 11, and 12 using &apos;times tables.&apos;</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qihoczo1Ujk.mp4/qihoczo1Ujk.mp4</video:content_loc><video:duration>731</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/lattice-multiplication</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23840.jpg</video:thumbnail_loc><video:title>Lattice multiplication</video:title><video:description>Sal introduces lattice multiplication.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gS6TfWUv97I.mp4/gS6TfWUv97I.mp4</video:content_loc><video:duration>435</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/why-lattice-multiplication-works</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23842.jpg</video:thumbnail_loc><video:title>Why lattice multiplication works</video:title><video:description>Sal explains why lattice multiplication works.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/S3z4XqC_YSc.mp4/S3z4XqC_YSc.mp4</video:content_loc><video:duration>501</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/2-digit-times-1-digit-example-no-carrying</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x82d7bb46.jpg</video:thumbnail_loc><video:title>Multiplying 2-digit by 1-digit</video:title><video:description>Learn to multiply a 2-digit number by a 1-digit number without regrouping. In this video, we will multiply 32x3.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/k68CPfcehTE.mp4/k68CPfcehTE.mp4</video:content_loc><video:duration>111</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/multiplication-5-2-digit-times-a-2-digit-number</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23832.jpg</video:thumbnail_loc><video:title>Multiplying 2-digit by 2-digit: 36x23</video:title><video:description>Learn to multiply two-digit numbers. In this video, we will multiply 36 times 23.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/t8m0NalQtEk.mp4/t8m0NalQtEk.mp4</video:content_loc><video:duration>675</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/multiplying-whole-numbers-and-applications-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/2600674.jpg</video:thumbnail_loc><video:title>Multiplying 2-digit by 2-digit: 23x44</video:title><video:description>Learn to multiply two-digit numbers. In this video, we will multiply 23 times 44.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0WUXQNjdRvM.mp4/0WUXQNjdRvM.mp4</video:content_loc><video:duration>198</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/division-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23844.jpg</video:thumbnail_loc><video:title>Intro to division</video:title><video:description>Introduction to division.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/MTzTqvzWzm8.mp4/MTzTqvzWzm8.mp4</video:content_loc><video:duration>1022</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/dividing-whole-numbers-and-applications-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/2600678.jpg</video:thumbnail_loc><video:title>Ways to represent division</video:title><video:description>Sal explains different ways to represent 18 divided by 2.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4I9iibPLdBw.mp4/4I9iibPLdBw.mp4</video:content_loc><video:duration>148</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/canceling-zeros-when-dividing</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3ad9bd47.jpg</video:thumbnail_loc><video:title>Canceling zeros when dividing</video:title><video:description>Lindsay breaks down division problems involving multiples of 10.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ccS5Fy5yLjk.mp4/ccS5Fy5yLjk.mp4</video:content_loc><video:duration>459</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/division-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23846.jpg</video:thumbnail_loc><video:title>Intro to long division (remainders)</video:title><video:description>Introduction to long division with remainders</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8Ft5iHhauJ0.mp4/8Ft5iHhauJ0.mp4</video:content_loc><video:duration>699</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/level-4-division</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23850.jpg</video:thumbnail_loc><video:title>Dividing by 2-digits: 6250÷25</video:title><video:description>Learn to divide a 2-digit number into a larger number.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gHTH6PKfpMc.mp4/gHTH6PKfpMc.mp4</video:content_loc><video:duration>575</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/multi-step-word-problems-with-whole-numbers-exercise-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x17e8cc3e.jpg</video:thumbnail_loc><video:title>Multiplication, division word problem: pedaling</video:title><video:description>Using multiplication and division to make estimates. Easy? Maybe, but what&apos;s more important is that you try.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/l7h8A6SX5kY.mp4/l7h8A6SX5kY.mp4</video:content_loc><video:duration>130</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/absolute-value-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26784.jpg</video:thumbnail_loc><video:title>Identify and order absolute values</video:title><video:description>Use a number line to find absolute value and then order absolute values from least to greatest.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/NvGTCzAfvr0.mp4/NvGTCzAfvr0.mp4</video:content_loc><video:duration>202</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/absolute-value-word-problems-exercise</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7fd5c099.jpg</video:thumbnail_loc><video:title>Absolute value word problems</video:title><video:description>Learn to solve word problems that ask us to apply our new absolute value knowledge.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Ig7RSc-93Bs.mp4/Ig7RSc-93Bs.mp4</video:content_loc><video:duration>232</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/multiplying-negative-real-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179320.jpg</video:thumbnail_loc><video:title>Multiplying numbers with different signs</video:title><video:description>Find the product of numbers with different signs.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4ve7OaCnDLs.mp4/4ve7OaCnDLs.mp4</video:content_loc><video:duration>146</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/multiplying-and-dividing-negative-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25749.jpg</video:thumbnail_loc><video:title>Multiplying and dividing negative numbers</video:title><video:description>Sal explains multiplying and dividing positive and negative numbers.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/d8lP5tR2R3Q.mp4/d8lP5tR2R3Q.mp4</video:content_loc><video:duration>510</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/introduction-to-fractions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4b75a153.jpg</video:thumbnail_loc><video:title>More about fractions</video:title><video:description>Sal shows fractions as parts of a whole and parts of a group.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/kZzoVCmUyKg.mp4/kZzoVCmUyKg.mp4</video:content_loc><video:duration>341</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/recognizing-fractions-exercise</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0b18ce2b.jpg</video:thumbnail_loc><video:title>Worked example: Recognizing fractions</video:title><video:description>Worked example: Recognizing fractions from Arithmetic (all content)</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/dXHqO955HxE.mp4/dXHqO955HxE.mp4</video:content_loc><video:duration>117</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/fractions-with-like-denominators-numerators</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8fe87fd9.jpg</video:thumbnail_loc><video:title>Comparing fractions with like numerators and denominators</video:title><video:description>Comparing fractions with like numerators and denominators from Arithmetic (all content)</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/wbAxarp_Ug4.mp4/wbAxarp_Ug4.mp4</video:content_loc><video:duration>288</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/comparing-fractions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/2600757.jpg</video:thumbnail_loc><video:title>Comparing fractions</video:title><video:description>Comparing Fractions</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Io9i1JkKgN4.mp4/Io9i1JkKgN4.mp4</video:content_loc><video:duration>150</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/ordering-fractions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/211177354.jpg</video:thumbnail_loc><video:title>Comparing and ordering fractions</video:title><video:description>Finding common denominators of multiple fractions to order them</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/N8dIOmk_lHs.mp4/N8dIOmk_lHs.mp4</video:content_loc><video:duration>468</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/equivalent-fractions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/4802211.jpg</video:thumbnail_loc><video:title>Equivalent fractions</video:title><video:description>Learn how to write equivalent fractions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/U2ovEuEUxXQ.mp4/U2ovEuEUxXQ.mp4</video:content_loc><video:duration>351</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/comparing-improper-fractions-and-mixed-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/915154307.jpg</video:thumbnail_loc><video:title>Comparing improper fractions and mixed numbers</video:title><video:description>Worked examples comparing improper fractions and mixed numbers</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/R8YKuGJ0plI.mp4/R8YKuGJ0plI.mp4</video:content_loc><video:duration>294</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/postive-improper-fractions-on-the-number-line</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf78b285e.jpg</video:thumbnail_loc><video:title>Mixed number or improper fraction on a number line</video:title><video:description>Fraction or mixed number...either way you should end up on the same spot on the number line. Give it a try with us.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/g-SfwjbpA4U.mp4/g-SfwjbpA4U.mp4</video:content_loc><video:duration>132</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/multiplying-a-fraction-by-a-fraction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x369b9278.jpg</video:thumbnail_loc><video:title>Intro to multiplying 2 fractions</video:title><video:description>Sal introduces multiplying 2 fractions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/x6xtezhuCZ4.mp4/x6xtezhuCZ4.mp4</video:content_loc><video:duration>306</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/multiplying-fractions-word-problem-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x683d1719.jpg</video:thumbnail_loc><video:title>Multiplying fractions word problem: pumpkin pie</video:title><video:description>Oops! Someone tried to solve this problem and made a mistake. See if you can spot the error.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/XDjbNykJ28E.mp4/XDjbNykJ28E.mp4</video:content_loc><video:duration>276</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/decimal-place-value</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1804.jpg</video:thumbnail_loc><video:title>Decimal place value</video:title><video:description>Introduction to decimal place values and the value of decimal digits</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/x-Dqe5U1TXA.mp4/x-Dqe5U1TXA.mp4</video:content_loc><video:duration>240</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/converting-fractions-to-decimals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23852.jpg</video:thumbnail_loc><video:title>Rewriting tricky fractions to decimals</video:title><video:description>Learn to convert the fraction, 17/93 to a decimal.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Gn2pdkvdbGQ.mp4/Gn2pdkvdbGQ.mp4</video:content_loc><video:duration>562</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/significant-figures</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/67068552.jpg</video:thumbnail_loc><video:title>Intro to significant figures</video:title><video:description>Significant figures are the number of digits in a value, often a measurement, that contribute to the degree of accuracy of the value. We start counting significant figures at the first non-zero digit. Calculate the number of significant figures for an assortment of numbers.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/eCJ76hz7jPM.mp4/eCJ76hz7jPM.mp4</video:content_loc><video:duration>303</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/more-on-significant-figures</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/67068553.jpg</video:thumbnail_loc><video:title>Rules of significant figures</video:title><video:description>This video teaches significant figures rules, crucial for measurements and calculations. It covers identifying significant digits, including non-zero digits, zeros in between, leading zeros, and trailing zeros. Additionally, it introduces scientific notation for clearer representation of significant figures.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/eMl2z3ezlrQ.mp4/eMl2z3ezlrQ.mp4</video:content_loc><video:duration>340</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/multiplying-and-dividing-with-significant-figures</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/67068554.jpg</video:thumbnail_loc><video:title>Multiplying and dividing with significant figures</video:title><video:description>Learn to multiply and divide with significant figures.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/iorZdz4dsBU.mp4/iorZdz4dsBU.mp4</video:content_loc><video:duration>571</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/arithmetic-home/v/addition-and-subtraction-with-significant-figures</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/67861020.jpg</video:thumbnail_loc><video:title>Addition and subtraction with significant figures</video:title><video:description>This video teaches addition and subtraction with significant figures, emphasizing that the result should match the least precise measurement. It offers examples and explains the real-world importance of maintaining precision in calculations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xHgPtFUbAeU.mp4/xHgPtFUbAeU.mp4</video:content_loc><video:duration>539</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-calculus/v/determining-which-limit-statements-are-true</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1313140631.jpg</video:thumbnail_loc><video:title>Connecting limits and graphical behavior (more examples)</video:title><video:description>Sal analyzes various 1- and 2-sided limits of a function given graphically.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_WOr9-_HbAM.mp4/_WOr9-_HbAM.mp4</video:content_loc><video:duration>316</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-calculus/v/unbounded-limits-graphical</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x39979770.jpg</video:thumbnail_loc><video:title>Connecting limits at infinity notation and graph</video:title><video:description>Sal analyzes a function with an asymptote and finds the correct description of the two one-sided limits of the function at that asymptote.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TlWvQvMB9eI.mp4/TlWvQvMB9eI.mp4</video:content_loc><video:duration>118</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-calculus/v/limit-at-infinity-involving-trig-defined</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x60640c11.jpg</video:thumbnail_loc><video:title>Limits at infinity of quotients with trig</video:title><video:description>Sal finds the limit of cosx/(x²-1) at infinity, by putting it between two limits of rational functions, 1/(x²-1) and -1/(x²-1).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/oAQnDsmu41E.mp4/oAQnDsmu41E.mp4</video:content_loc><video:duration>184</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-calculus/v/limit-at-infinity-involving-trig-undefined</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x531d1f13.jpg</video:thumbnail_loc><video:title>Limits at infinity of quotients with trig (limit undefined)</video:title><video:description>Sal analyzes the limit of (x²+1)/sin(x) at infinity. It turns out this limit doesn&apos;t exist, as the function keeps oscillating between positive and negative infinity.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/waWYIKAfkWw.mp4/waWYIKAfkWw.mp4</video:content_loc><video:duration>141</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-calculus/v/limits-infinity-algebra</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb85faf80.jpg</video:thumbnail_loc><video:title>Limit at infinity of a difference of functions</video:title><video:description>Sal finds the limit at infinity of √(100+x)-√(x).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/nDXFgexOM5c.mp4/nDXFgexOM5c.mp4</video:content_loc><video:duration>326</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-calculus/v/slope-of-a-line-secant-to-a-curve</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xed57a1a5.jpg</video:thumbnail_loc><video:title>Slope of a line secant to a curve</video:title><video:description>What is the slope of a line between two points on a curve? This is called a &quot;secant&quot; line.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8r8Vp_1iB4k.mp4/8r8Vp_1iB4k.mp4</video:content_loc><video:duration>437</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-calculus/v/slope-of-a-secant-line-arbitrary-difference</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7f146c13.jpg</video:thumbnail_loc><video:title>Secant line with arbitrary difference</video:title><video:description>Sal finds the slope of the secant line on the graph of ln(x) between the points (2,ln2) and (2+h,ln(2+h)).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/RaNeCD8t01I.mp4/RaNeCD8t01I.mp4</video:content_loc><video:duration>259</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-calculus/v/slope-of-a-secant-line</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdb7e3de5.jpg</video:thumbnail_loc><video:title>Secant line with arbitrary point</video:title><video:description>Sal finds the slope of the secant line on the graph of ln(x) between the points (e,1) and (x,lnx).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0zExhHh7_Ic.mp4/0zExhHh7_Ic.mp4</video:content_loc><video:duration>259</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-calculus/v/simplified-secant-line-arbitrary-difference</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x48d3cd9a.jpg</video:thumbnail_loc><video:title>Secant line with arbitrary difference (with simplification)</video:title><video:description>Sal finds and simplifies the expression for the slope of the secant line between x=4 and x=4+h on the graph of y=2x²+1.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/l1xdKkIGxOc.mp4/l1xdKkIGxOc.mp4</video:content_loc><video:duration>234</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-calculus/v/simplified-secant-line-arbitrary-point</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4d713576.jpg</video:thumbnail_loc><video:title>Secant line with arbitrary point (with simplification)</video:title><video:description>Sal finds and simplifies the expression for the slope of the secant line between x=3 and x=t on the graph of y=2x²+5x.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/T3nVKbxEQdo.mp4/T3nVKbxEQdo.mp4</video:content_loc><video:duration>232</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-calculus/v/slope-of-a-secant-line-example-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xec2af377.jpg</video:thumbnail_loc><video:title>Secant lines: challenging problem 1</video:title><video:description>Sal solves a challenging problem involving slopes of secant lines to a curve.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/H6ZNLD1AeM8.mp4/H6ZNLD1AeM8.mp4</video:content_loc><video:duration>378</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-calculus/v/graphs-of-functions-and-their-derivatives-example-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x31dde586.jpg</video:thumbnail_loc><video:title>Secant lines: challenging problem 2</video:title><video:description>Sal interprets an expression as the slope of a secant line between a specific point on a graph and any other point on that graph.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/P3IlneCNm8A.mp4/P3IlneCNm8A.mp4</video:content_loc><video:duration>357</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-calculus/v/tangent-slope-as-limiting-value-of-secant-slope-example-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x22e79f7d.jpg</video:thumbnail_loc><video:title>Limit expression for the derivative of function (graphical)</video:title><video:description>Sal interprets limit expressions as the derivatives of a function given graphically, and evaluates them.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hoRISaqp1Po.mp4/hoRISaqp1Po.mp4</video:content_loc><video:duration>226</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-calculus/v/tangent-line-equation-example-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x29623156.jpg</video:thumbnail_loc><video:title>Tangent to y=𝑒ˣ/(2+x³)</video:title><video:description>Sal finds the equation of the line tangent to the curve y=eˣ/(2+x³) at the point (1,e/3).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/GH8-URjRQpQ.mp4/GH8-URjRQpQ.mp4</video:content_loc><video:duration>437</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-calculus/v/normal-line-equation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8626cdc3.jpg</video:thumbnail_loc><video:title>Normal to y=𝑒ˣ/x²</video:title><video:description>Sal finds the equation of the line normal to the curve y=eˣ/x² at the point (1,e).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/C5G2Js2_Ep4.mp4/C5G2Js2_Ep4.mp4</video:content_loc><video:duration>327</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-calculus/v/implicit-derivative-of-y-cos-5x-3y</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1336092146.jpg</video:thumbnail_loc><video:title>Implicit differentiation (advanced example)</video:title><video:description>Implicit differentiation of y = cos(5x - 3y)</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-EG10aI0rt0.mp4/-EG10aI0rt0.mp4</video:content_loc><video:duration>248</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-calculus/v/implicit-derivative-of-x-2-y-2-3-5x-2y-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1335955875.jpg</video:thumbnail_loc><video:title>Implicit differentiation (advanced example)</video:title><video:description>Implicit derivative of (x²+y²)³=5x²y².</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1DcsREjyoiM.mp4/1DcsREjyoiM.mp4</video:content_loc><video:duration>430</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-calculus/v/implicit-derivative-of-e-xy-2-x-y</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1335852020.jpg</video:thumbnail_loc><video:title>Implicit differentiation (advanced example)</video:title><video:description>Sal finds dy/dx for e^(xy²)=x-y using implicit differentiation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ZtI94pI4Uzc.mp4/ZtI94pI4Uzc.mp4</video:content_loc><video:duration>358</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-calculus/v/derivative-natural-logarithm</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x03a2d28c.jpg</video:thumbnail_loc><video:title>Derivative of ln(x) from derivative of 𝑒ˣ and implicit differentiation</video:title><video:description>How can you find the derivative of ln(x) by viewing it as the inverse of e^x?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/765X_PAxhAw.mp4/765X_PAxhAw.mp4</video:content_loc><video:duration>188</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-calculus/v/product-rule-for-more-than-two-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1335339467.jpg</video:thumbnail_loc><video:title>Product rule to find derivative of product of three functions</video:title><video:description>Sal differentiates the product of three different functions, and generalizes for the derivative of the product of any number of functions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Bkkk0RLSEy8.mp4/Bkkk0RLSEy8.mp4</video:content_loc><video:duration>214</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-calculus/v/calculus-derivative-of-x-x-x</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24134.jpg</video:thumbnail_loc><video:title>Composite exponential function differentiation</video:title><video:description>Sal finds the derivatives of xˣ and x^(xˣ). They are surprisingly fun to do!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/N5kkwVoAtkc.mp4/N5kkwVoAtkc.mp4</video:content_loc><video:duration>542</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-calculus/v/composite-exponential-function-differentiation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf03668ef.jpg</video:thumbnail_loc><video:title>Worked example: Composite exponential function differentiation</video:title><video:description>Sal differentiates the composite exponential function [ln(x)]ˣ and evaluates the derivative at x=e. Composite exponential functions are functions where the variable is in both the base and the exponent.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/BSrJi9uEJp0.mp4/BSrJi9uEJp0.mp4</video:content_loc><video:duration>524</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/calculus-1/v/analyzing-particle-movement-based-on-graphs</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc4d31415.jpg</video:thumbnail_loc><video:title>Analyzing straight-line motion graphically</video:title><video:description>Learn how to analyze a particles motion given the graph of its position over time.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/wKPyzrEVqaQ.mp4/wKPyzrEVqaQ.mp4</video:content_loc><video:duration>320</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-calculus/v/total-distance-traveled-by-a-particle</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6ae031ba.jpg</video:thumbnail_loc><video:title>Total distance traveled with derivatives</video:title><video:description>Given a function representing the position of a particle over time, how can you find the total distance traveled?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/HDntI7zfBNs.mp4/HDntI7zfBNs.mp4</video:content_loc><video:duration>609</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-calculus/v/l-hopital-s-rule-example-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/27379.jpg</video:thumbnail_loc><video:title>L&apos;Hôpital&apos;s rule: challenging problem</video:title><video:description>Sal uses L&apos;Hôpital&apos;s rule to find the limit at 1 of x/(x-1)-1/lnx.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/MeVFZjT-ABM.mp4/MeVFZjT-ABM.mp4</video:content_loc><video:duration>470</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-calculus/v/lhopitals-rule-to-solve-for-variable</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x831dfb4a.jpg</video:thumbnail_loc><video:title>L&apos;Hôpital&apos;s rule: solve for a variable</video:title><video:description>Sal uses L&apos;Hôpital&apos;s rule to find the value of a in (√(4+a)-√(4-ax))/x so the expression&apos;s limit at 0 is ¾.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Ot0FxL8Vl7I.mp4/Ot0FxL8Vl7I.mp4</video:content_loc><video:duration>250</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-calculus/v/tricky-lhopitals-rule-problem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdb5ee8fb.jpg</video:thumbnail_loc><video:title>L’Hôpital’s rule (composite exponential functions)</video:title><video:description>Sal uses L&apos;Hôpital&apos;s rule to find the limit at 0 of (sinx)^(1/lnx).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/CDf_aE5yg3A.mp4/CDf_aE5yg3A.mp4</video:content_loc><video:duration>791</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-calculus/v/extreme-derivative-word-problem-advanced</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24136.jpg</video:thumbnail_loc><video:title>Optimization problem: extreme normaline to y=x²</video:title><video:description>A difficult but interesting derivative word problem</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/viaPc8zDcRI.mp4/viaPc8zDcRI.mp4</video:content_loc><video:duration>1393</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/integral-calculus/v/approximating-distance-with-rectangles</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xde408b5b.jpg</video:thumbnail_loc><video:title>Motion problem with Riemann sum approximation</video:title><video:description>Here we see how estimating the area under a curve representing velocity estimates distance traveled.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/v13fraCiLEg.mp4/v13fraCiLEg.mp4</video:content_loc><video:duration>600</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/integral-calculus/v/rectangular-and-trapezoidal-riemann-approximations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1319439886.jpg</video:thumbnail_loc><video:title>Midpoint and trapezoidal sums in summation notation</video:title><video:description>Estimating the area under a curve with trapazoids instead of rectangles can give a closer approximation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/naRUWPvsQbQ.mp4/naRUWPvsQbQ.mp4</video:content_loc><video:duration>493</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/integral-calculus/v/riemann-sum-negative-function</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9cd535ed.jpg</video:thumbnail_loc><video:title>Riemann sums in summation notation: challenge problem</video:title><video:description>When a function is negative, Riemann sums seem to treat it as having &quot;negative area&quot;.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/WeVWv_OEJsY.mp4/WeVWv_OEJsY.mp4</video:content_loc><video:duration>396</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/integral-calculus/v/integral-defined-function-0</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x346b5c30.jpg</video:thumbnail_loc><video:title>Functions defined by integrals: challenge problem</video:title><video:description>Solving for where a function defined by an integral equals 0.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/W20SoZiJOHU.mp4/W20SoZiJOHU.mp4</video:content_loc><video:duration>585</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/integral-calculus/v/antiderivative-of-hairier-expression</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1328896635.jpg</video:thumbnail_loc><video:title>Rewriting before integrating: challenge problem</video:title><video:description>In this example, we find the antiderivative an expression which is not so simple.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/cBi4a1iSaPk.mp4/cBi4a1iSaPk.mp4</video:content_loc><video:duration>376</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/integral-calculus/v/u-substitution-and-back-substitution</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1254533049.jpg</video:thumbnail_loc><video:title>𝘶-substitution: special application</video:title><video:description>Using 𝘶-substitution in a situation that is a bit different than &quot;classic&quot; 𝘶-substitution. In this case, the substitution helps us take a hairy expression and make it easier to expand and integrate.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/J-NC1M6obKo.mp4/J-NC1M6obKo.mp4</video:content_loc><video:duration>301</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/integral-calculus/v/doing-u-substitution-twice-second-time-with-w</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1254240553.jpg</video:thumbnail_loc><video:title>𝘶-substitution: double substitution</video:title><video:description>Finding the indefinite integral of cos(5x)/e^[sin(5x)]. To do that, we need to perform 𝘶-substitution twice.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ShpI3gPgLBA.mp4/ShpI3gPgLBA.mp4</video:content_loc><video:duration>537</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/integral-calculus/v/2-ln-x-x-antiderivative-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24306.jpg</video:thumbnail_loc><video:title>𝘶-substitution: challenging application</video:title><video:description>Finding ∫(2^ln x)/x dx</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/C5Lbjbyr1t4.mp4/C5Lbjbyr1t4.mp4</video:content_loc><video:duration>520</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/integral-calculus/v/using-trig-identity-to-use-u-substitution</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc397250c.jpg</video:thumbnail_loc><video:title>Integral of cos^3(x)</video:title><video:description>A specialized form of u-substitution involves taking advantage of trigonometric identities.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/rElAJA9GyL4.mp4/rElAJA9GyL4.mp4</video:content_loc><video:duration>366</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/integral-calculus/v/integral-of-odd-powered-trig-function-with-u-substitution</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6b973043.jpg</video:thumbnail_loc><video:title>Integral of sin^2(x) cos^3(x)</video:title><video:description>Another example where u substitution combined with certain trigonometric identities can be used.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xSeYS3V5di8.mp4/xSeYS3V5di8.mp4</video:content_loc><video:duration>273</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/integral-calculus/v/trig-identies-for-trig-integral</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc716abcc.jpg</video:thumbnail_loc><video:title>Integral of sin^4(x)</video:title><video:description>It is a bit involved, but we can use u-substitution to find the integral of sin^4(x)</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/n34jx1FIN8M.mp4/n34jx1FIN8M.mp4</video:content_loc><video:duration>333</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/integral-calculus/v/introduction-to-trigonometric-substitution</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7161c395.jpg</video:thumbnail_loc><video:title>Introduction to trigonometric substitution</video:title><video:description>Introduction to trigonometric substitution</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/EV5dhv0A2wU.mp4/EV5dhv0A2wU.mp4</video:content_loc><video:duration>532</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/integral-calculus/v/another-substitution-with-x-sin-theta</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1373246393.jpg</video:thumbnail_loc><video:title>Substitution with x=sin(theta)</video:title><video:description>When you are integrating something that has the expression (1-x^2), try substituting sin(theta) for x.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8Yl_u_Otcjg.mp4/8Yl_u_Otcjg.mp4</video:content_loc><video:duration>308</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/integral-calculus/v/integrals-trig-substitution-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24208.jpg</video:thumbnail_loc><video:title>More trig sub practice</video:title><video:description>Example of using trig substitution to solve an indefinite integral</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/n4EK92CSuBE.mp4/n4EK92CSuBE.mp4</video:content_loc><video:duration>458</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/integral-calculus/v/trig-and-u-substitution-together-part-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1373141693.jpg</video:thumbnail_loc><video:title>Trig and u substitution together (part 1)</video:title><video:description>All of the substitution!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/nMrJ6nbOQhQ.mp4/nMrJ6nbOQhQ.mp4</video:content_loc><video:duration>535</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/integral-calculus/v/trig-and-u-substitution-together-part-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1373336307.jpg</video:thumbnail_loc><video:title>Trig and u substitution together (part 2)</video:title><video:description>More of all of the substitution!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/WAoaBTWKLoI.mp4/WAoaBTWKLoI.mp4</video:content_loc><video:duration>345</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/integral-calculus/v/trig-substitution-with-tangent</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1373225524.jpg</video:thumbnail_loc><video:title>Trig substitution with tangent</video:title><video:description>When you are integrating something which looks like 1+(x^2), try replacing x with tan(theta)</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/CYjAgOTVfZk.mp4/CYjAgOTVfZk.mp4</video:content_loc><video:duration>286</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/integral-calculus/v/integrals-trig-substitution-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24210.jpg</video:thumbnail_loc><video:title>More trig substitution with tangent</video:title><video:description>Another practice problem replacing x with tan(theta) in an integral.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/fD7MbnXbTls.mp4/fD7MbnXbTls.mp4</video:content_loc><video:duration>491</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/integral-calculus/v/integrals-trig-substitution-3-long-problem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24212.jpg</video:thumbnail_loc><video:title>Long trig sub problem</video:title><video:description>More practice with a hairy trig sub problem.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/sw2p2tUIFpc.mp4/sw2p2tUIFpc.mp4</video:content_loc><video:duration>1072</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/integral-calculus/v/improper-integral-with-two-infinite-bounds</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1378097320.jpg</video:thumbnail_loc><video:title>Improper integral with two infinite bounds</video:title><video:description>A worked example of a challenging improper integral that involves two infinite bounds and an inverse trig substitution.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9JX2s90_RNQ.mp4/9JX2s90_RNQ.mp4</video:content_loc><video:duration>687</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/integral-calculus/v/logistic-function-application</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0c018898.jpg</video:thumbnail_loc><video:title>Worked example: logistic model equations</video:title><video:description>The general logistic function is N(t)=(N₀K)/(N₀+(K-N₀)e⁻ʳᵗ). In this video, we solve a real-world word problem about logistic growth.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-fIsaqN-aaQ.mp4/-fIsaqN-aaQ.mp4</video:content_loc><video:duration>574</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/integral-calculus/v/arc-length-example-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x985d984a.jpg</video:thumbnail_loc><video:title>Worked example: arc length (advanced)</video:title><video:description>A worked example of finding arc length using definite integrals. This example involves some challenging algebra.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/MtRXjXdXDow.mp4/MtRXjXdXDow.mp4</video:content_loc><video:duration>558</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/integral-calculus/v/polar-arc-length-formula</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x307ed42c.jpg</video:thumbnail_loc><video:title>Arc length of polar curves</video:title><video:description>Sal shows the polar arc length formula, and explains why it is true.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/CEPuNmVKnZM.mp4/CEPuNmVKnZM.mp4</video:content_loc><video:duration>706</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/integral-calculus/v/polar-arc-length-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x749aa43b.jpg</video:thumbnail_loc><video:title>Worked example: Arc length of polar curves</video:title><video:description>What is the arc length of the polar curve r = 4sin(theta)?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/sFlH7V7QDbQ.mp4/sFlH7V7QDbQ.mp4</video:content_loc><video:duration>383</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/integral-calculus/v/geometric-series-convergence-divergence</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9a18b2d7.jpg</video:thumbnail_loc><video:title>Convergent &amp; divergent geometric series (with manipulation)</video:title><video:description>Sal looks at examples of three infinite geometric series and determines if each of them converges or diverges. To do that, he needs to manipulate the expressions to find the common ratio.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/HP8ZTo2iDtw.mp4/HP8ZTo2iDtw.mp4</video:content_loc><video:duration>428</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/integral-calculus/v/writing-series-sigma-notation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc5145c94.jpg</video:thumbnail_loc><video:title>Converting explicit series terms to summation notation</video:title><video:description>Some sums are really long, but we can use sigma notation to write them in a shorthand way. See such an example here.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0DBDuNYsciY.mp4/0DBDuNYsciY.mp4</video:content_loc><video:duration>196</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/integral-calculus/v/explicitly-defining-series</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1985e33e.jpg</video:thumbnail_loc><video:title>Converting explicit series terms to summation notation (n ≥ 2)</video:title><video:description>Usually, when writing a series in sigma notation, we start summing at n=1 or n=0. Sometimes though, we would like to start at n=2 or larger values. See an example here.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/yvddTWa9ptU.mp4/yvddTWa9ptU.mp4</video:content_loc><video:duration>265</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/integral-calculus/v/telescoping-series</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf1ee6394.jpg</video:thumbnail_loc><video:title>Telescoping series</video:title><video:description>Telescoping series is a series where all terms cancel out except for the first and last one. This makes such series easy to analyze. In this video, we use partial fraction decomposition to find sum of telescoping series.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qUNGPqCPzMg.mp4/qUNGPqCPzMg.mp4</video:content_loc><video:duration>751</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/integral-calculus/v/divergence-telescoping-series</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6f205945.jpg</video:thumbnail_loc><video:title>Divergent telescoping series</video:title><video:description>Telescoping series is a series where all terms cancel out except for the first and last one. This makes such series easy to analyze. In this video we take a close look at the series 1-1+1-1+1-...</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5LMzbgfZ8cA.mp4/5LMzbgfZ8cA.mp4</video:content_loc><video:duration>293</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-1st-grade-math/v/adding-3-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5ef91da0.jpg</video:thumbnail_loc><video:title>Adding 5 + 3 + 6</video:title><video:description>Sal adds 5 + 3 + 6 two ways.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Utm875JRi-o.mp4/Utm875JRi-o.mp4</video:content_loc><video:duration>158</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-1st-grade-math/v/equal-sign</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfa19f713.jpg</video:thumbnail_loc><video:title>Equal sign</video:title><video:description>Learn what the equals sign means.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gEGKvx1wlFg.mp4/gEGKvx1wlFg.mp4</video:content_loc><video:duration>296</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-1st-grade-math/v/comparing-adding-1-and-10</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfb4db072.jpg</video:thumbnail_loc><video:title>Adding 1 vs. adding 10</video:title><video:description>Sal talks about the difference between adding 1 and adding 10.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/mKsKU0BAiRM.mp4/mKsKU0BAiRM.mp4</video:content_loc><video:duration>137</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-1st-grade-math/v/order-by-length</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfc9c120b.jpg</video:thumbnail_loc><video:title>Ordering by length</video:title><video:description>Sal orders 3 objects by length and compares the lengths of 2 objects indirectly by using a third object.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/SQmyTmO8OKw.mp4/SQmyTmO8OKw.mp4</video:content_loc><video:duration>157</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-1st-grade-math/v/reading-bar-graph-examples</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc2bbf559.jpg</video:thumbnail_loc><video:title>Reading bar graphs: dog bones</video:title><video:description>Sal reads and interprets bar graphs.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OmLl6pkvV-I.mp4/OmLl6pkvV-I.mp4</video:content_loc><video:duration>177</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-1st-grade-math/v/halves-and-fourths</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x54bcdbc6.jpg</video:thumbnail_loc><video:title>Halves and fourths</video:title><video:description>When a whole is divided into equal size pieces, the pieces are fractions of the whole. If the whole is divided into 2 equal sized pieces, each piece is ​one half of the whole. If the whole is divided into 4 equal sized pieces, each piece is one fourth of the whole.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0lSTXtwPuOU.mp4/0lSTXtwPuOU.mp4</video:content_loc><video:duration>145</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-2nd-grade-math/v/using-arrays-in-word-problems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf64adba19592ff9f.jpg</video:thumbnail_loc><video:title>Using arrays in word problems</video:title><video:description>Sal uses addition to solve array word problems.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2ey3UYi8VOY.mp4/2ey3UYi8VOY.mp4</video:content_loc><video:duration>101</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-2nd-grade-math/v/creating-the-largest-number</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x76acec6d3e49525a.jpg</video:thumbnail_loc><video:title>Creating the largest number</video:title><video:description>Sal uses 3 numbers to show how to create the largest 3 digit number possible.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1guztZj-RSU.mp4/1guztZj-RSU.mp4</video:content_loc><video:duration>188</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-2nd-grade-math/v/understanding-place-value-while-subtracting-ones</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x535bc6da.jpg</video:thumbnail_loc><video:title>Subtracting 1s using place value</video:title><video:description>Sal subtracts 4 from 46 by thinking about place value.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/FWEqB0J6mgA.mp4/FWEqB0J6mgA.mp4</video:content_loc><video:duration>165</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-2nd-grade-math/v/understanding-place-value-when-subtracting-tens</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x93cf889d.jpg</video:thumbnail_loc><video:title>Subtracting 10s using place value</video:title><video:description>Sal subtracts 40 from 65 by thinking about place value.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/bNNrlzel4Gw.mp4/bNNrlzel4Gw.mp4</video:content_loc><video:duration>157</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-2nd-grade-math/v/fewer-word-problems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x469b5449.jpg</video:thumbnail_loc><video:title>Subtraction word problem: basketball</video:title><video:description>Sal solves a word problem with the term &quot;fewer&quot;.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qyvwN-2PoXA.mp4/qyvwN-2PoXA.mp4</video:content_loc><video:duration>132</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-2nd-grade-math/v/adding-four-two-digit-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xde376408da2d1e66.jpg</video:thumbnail_loc><video:title>Adding four two digit numbers</video:title><video:description>Sal uses place value to add four two digit numbers.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7Y_wVnAHajg.mp4/7Y_wVnAHajg.mp4</video:content_loc><video:duration>195</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-2nd-grade-math/v/adding-multiple-2-digit-numbers-word-problems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4f69fd4e4442fd11.jpg</video:thumbnail_loc><video:title>Adding multiple 2-digit numbers word problems</video:title><video:description>Sal solve word problems that involve adding multiple two digit numbers by using place value.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/WJNOtHFN-mM.mp4/WJNOtHFN-mM.mp4</video:content_loc><video:duration>210</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-2nd-grade-math/v/time-on-a-number-line</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3389df4fee7131c5.jpg</video:thumbnail_loc><video:title>Time on a number line</video:title><video:description>Sal tells time on a number line.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Rc2v8JdebwQ.mp4/Rc2v8JdebwQ.mp4</video:content_loc><video:duration>117</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-2nd-grade-math/v/getting-a-sense-of-meters-and-centimeters</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x429912e303017554.jpg</video:thumbnail_loc><video:title>Getting a sense of meters and centimeters</video:title><video:description>Sal explains how to get a sense of the size of meters and centimeters and applies it to measuring objects.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pyx-6vfCuW0.mp4/pyx-6vfCuW0.mp4</video:content_loc><video:duration>388</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-2nd-grade-math/v/getting-a-sense-of-inches-and-feet</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa86f39f2288d7ef7.jpg</video:thumbnail_loc><video:title>Getting a sense of inches and feet</video:title><video:description>Explore inches and feet as units of length. Learn to visualize an inch with a quarter or thumb and understand a foot equals 12 inches. The video includes examples of when to use inches or feet for measuring various objects.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/o31t2ta-EtQ.mp4/o31t2ta-EtQ.mp4</video:content_loc><video:duration>350</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-2nd-grade-math/v/measuring-lengths-in-different-units</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4e8d34b713688739.jpg</video:thumbnail_loc><video:title>Measuring lengths in different units</video:title><video:description>Sal measures the same rectangle in different units and then compares the size of the different units.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9dur4s-4lhk.mp4/9dur4s-4lhk.mp4</video:content_loc><video:duration>168</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-2nd-grade-math/v/length-word-problem-example-us-customary</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf9a16e0a1728e9fe.jpg</video:thumbnail_loc><video:title>Length word problem example (US Customary)</video:title><video:description>Sal shows how to solve a length word problem example.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/h43MrQ5G_2k.mp4/h43MrQ5G_2k.mp4</video:content_loc><video:duration>223</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-2nd-grade-math/v/partition-rectangles</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7e440e59031fe1cc.jpg</video:thumbnail_loc><video:title>Partitioning rectangles</video:title><video:description>Sal explains how to partition a rectangle into 2 rows and 5 columns.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8AdcPD50aTQ.mp4/8AdcPD50aTQ.mp4</video:content_loc><video:duration>193</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-kindergarten-math/v/counting-with-small-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9b4a5e7a.jpg</video:thumbnail_loc><video:title>Counting with small numbers</video:title><video:description>Sal counts squirrels and horses.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/y2-uaPiyoxc.mp4/y2-uaPiyoxc.mp4</video:content_loc><video:duration>56</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-kindergarten-math/v/counting-in-order</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1a52b63e.jpg</video:thumbnail_loc><video:title>Counting in order</video:title><video:description>Learn how to count without making mistakes.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PEeUTQ0Gri8.mp4/PEeUTQ0Gri8.mp4</video:content_loc><video:duration>118</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-kindergarten-math/v/counting-by-tens-example-problems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x591925fe29fb20c1.jpg</video:thumbnail_loc><video:title>Counting by tens</video:title><video:description>Practice counting by tens using numbers and ten frames.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/UnPpFw3natI.mp4/UnPpFw3natI.mp4</video:content_loc><video:duration>95</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-kindergarten-math/v/counting-in-scenes</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x37933822.jpg</video:thumbnail_loc><video:title>Counting in pictures</video:title><video:description>Sal counts the number of objects in pictures.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/leDYnoNSvD4.mp4/leDYnoNSvD4.mp4</video:content_loc><video:duration>73</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-kindergarten-math/v/how-many-objects-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xaa31d6e5.jpg</video:thumbnail_loc><video:title>Counting objects 1</video:title><video:description>Learn to count groups of whales, sheep, and flowers.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/I9S5CvSqb5A.mp4/I9S5CvSqb5A.mp4</video:content_loc><video:duration>63</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-kindergarten-math/v/counting-objects-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4a6f7890.jpg</video:thumbnail_loc><video:title>Counting objects 2</video:title><video:description>Learn to count dogs, mice, and cookies in random patterns.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/EUqhLxFccbM.mp4/EUqhLxFccbM.mp4</video:content_loc><video:duration>104</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-kindergarten-math/v/comparing-groups-through-10-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1fef85b3.jpg</video:thumbnail_loc><video:title>Comparing numbers of objects</video:title><video:description>Sal talks about what &quot;more than&quot; and &quot;less than&quot; mean.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/__nkbr6DeTg.mp4/__nkbr6DeTg.mp4</video:content_loc><video:duration>123</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-kindergarten-math/v/comparing-numbers-through-10-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x546ea510.jpg</video:thumbnail_loc><video:title>Comparing numbers on the number line</video:title><video:description>Sal uses number line to compare numbers less than or equal to 10.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tJrSILRXOUc.mp4/tJrSILRXOUc.mp4</video:content_loc><video:duration>91</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-kindergarten-math/v/count-by-category</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x21faccb5.jpg</video:thumbnail_loc><video:title>Counting by category</video:title><video:description>Sal categorizes objects then count the number of things in each category.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/UA975j_qsTQ.mp4/UA975j_qsTQ.mp4</video:content_loc><video:duration>44</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-kindergarten-math/v/teens-and-ten</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x79debcfe.jpg</video:thumbnail_loc><video:title>Teens as sums with 10</video:title><video:description>Sal looks at the 1 in each teen number and thinks about what it really means.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ourH3ueWNmA.mp4/ourH3ueWNmA.mp4</video:content_loc><video:duration>180</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-kindergarten-math/v/monkeys-for-party</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x04d6c646.jpg</video:thumbnail_loc><video:title>Teen numbers: monkeys</video:title><video:description>Sal breaks the number 18 into 10 and 8.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/zqwVKhQV_2w.mp4/zqwVKhQV_2w.mp4</video:content_loc><video:duration>178</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-kindergarten-math/v/addition-introduction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7d5effb1.jpg</video:thumbnail_loc><video:title>Intro to addition</video:title><video:description>Learn what it means to add. The examples used are 1+1 and 2+3.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/fsTD_jqseBA.mp4/fsTD_jqseBA.mp4</video:content_loc><video:duration>191</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-kindergarten-math/v/subtraction-introduction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2fefc435.jpg</video:thumbnail_loc><video:title>Intro to subtraction</video:title><video:description>Sal talks about what it means to subtract. The examples he uses are 4-3 and 5-2.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/AO9bHbUdg-M.mp4/AO9bHbUdg-M.mp4</video:content_loc><video:duration>219</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-kindergarten-math/v/making-5</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x65eda1aa.jpg</video:thumbnail_loc><video:title>Making 5</video:title><video:description>Learn how to add numbers to make the number five.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/A-ykhY_IoaU.mp4/A-ykhY_IoaU.mp4</video:content_loc><video:duration>246</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-kindergarten-math/v/addition-and-subtraction-within-10</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xacce5bfc.jpg</video:thumbnail_loc><video:title>Addition and subtraction within 10</video:title><video:description>Sal solves addition and subtraction problems with number 10 or less.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/kpEJwpemL2Q.mp4/kpEJwpemL2Q.mp4</video:content_loc><video:duration>135</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-kindergarten-math/v/relative-position</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x99affdbee2d6c2d8.jpg</video:thumbnail_loc><video:title>Relative position</video:title><video:description>Sal decides if objects are above, below, beside, in front of, or behind other objects.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/uikYPJw0tnE.mp4/uikYPJw0tnE.mp4</video:content_loc><video:duration>65</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/cc-kindergarten-math/v/compose-shapes</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8b5b5806.jpg</video:thumbnail_loc><video:title>Composing shapes</video:title><video:description>Sal combines shapes to make other shapes.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/K3GV13uokbk.mp4/K3GV13uokbk.mp4</video:content_loc><video:duration>124</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-equations/v/finding-particular-linear-solution-to-differential-equation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6f28d28d.jpg</video:thumbnail_loc><video:title>Worked example: linear solution to differential equation</video:title><video:description>If a particular solution to a differential equation is linear, y=mx+b, we can set up a system of equations to find m and b. See how it works in this video.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/zid7J4EhZN8.mp4/zid7J4EhZN8.mp4</video:content_loc><video:duration>391</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-equations/v/separable-differential-equations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24710.jpg</video:thumbnail_loc><video:title>Separable equations (old)</video:title><video:description>An old introduction video to separable differential equations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/C5-lz0hcqsE.mp4/C5-lz0hcqsE.mp4</video:content_loc><video:duration>720</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-equations/v/separable-differential-equations-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24712.jpg</video:thumbnail_loc><video:title>Separable equations example (old)</video:title><video:description>An old worked example video of solving separable equations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xVWCfMe97ws.mp4/xVWCfMe97ws.mp4</video:content_loc><video:duration>337</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-equations/v/newtons-law-of-cooling</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb63a9856.jpg</video:thumbnail_loc><video:title>Newton&apos;s Law of Cooling</video:title><video:description>Newton&apos;s law of cooling can be modeled with the general equation dT/dt=-k(T-Tₐ), whose solutions are T=Ce⁻ᵏᵗ+Tₐ (for cooling) and T=Tₐ-Ce⁻ᵏᵗ (for heating).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/IICR-w1jYcA.mp4/IICR-w1jYcA.mp4</video:content_loc><video:duration>602</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-equations/v/applying-newtons-law-of-cooling-to-warm-oatmeal</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x97e7847e.jpg</video:thumbnail_loc><video:title>Worked example: Newton&apos;s law of cooling</video:title><video:description>The general function for Newton&apos;s law of cooling is T=Ce⁻ᵏᵗ+Tₐ. In this video, we solve a word problem that involves the cooling of a freshly baked cookie!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jH5qflAe3C8.mp4/jH5qflAe3C8.mp4</video:content_loc><video:duration>743</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-equations/v/exact-equations-intuition-1-proofy</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24714.jpg</video:thumbnail_loc><video:title>Exact equations intuition 1 (proofy)</video:title><video:description>Chain rule using partial derivatives (not a proof; more intuition).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/iEpqcdaJNTQ.mp4/iEpqcdaJNTQ.mp4</video:content_loc><video:duration>594</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-equations/v/exact-equations-intuition-2-proofy</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24716.jpg</video:thumbnail_loc><video:title>Exact equations intuition 2 (proofy)</video:title><video:description>More intuitive building blocks for exact equations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/a7wYAtMjORQ.mp4/a7wYAtMjORQ.mp4</video:content_loc><video:duration>651</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-equations/v/exact-equations-example-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24718.jpg</video:thumbnail_loc><video:title>Exact equations example 1</video:title><video:description>First example of solving an exact differential equation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Pb04ntcDJcQ.mp4/Pb04ntcDJcQ.mp4</video:content_loc><video:duration>729</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-equations/v/exact-equations-example-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24720.jpg</video:thumbnail_loc><video:title>Exact equations example 2</video:title><video:description>Some more exact equation examples</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/utQi1ZhF__Q.mp4/utQi1ZhF__Q.mp4</video:content_loc><video:duration>481</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-equations/v/exact-equations-example-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24722.jpg</video:thumbnail_loc><video:title>Exact equations example 3</video:title><video:description>One more exact equation example</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/eu_GFuU7tLI.mp4/eu_GFuU7tLI.mp4</video:content_loc><video:duration>599</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-equations/v/integrating-factors-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24724.jpg</video:thumbnail_loc><video:title>Integrating factors 1</video:title><video:description>Using an integrating factor to make a differential equation exact</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/j511hg7Hlbg.mp4/j511hg7Hlbg.mp4</video:content_loc><video:duration>616</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-equations/v/integrating-factors-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24726.jpg</video:thumbnail_loc><video:title>Integrating factors 2</video:title><video:description>Now that we&apos;ve made the equation exact, let&apos;s solve it!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0NyeDUhKwBE.mp4/0NyeDUhKwBE.mp4</video:content_loc><video:duration>506</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-equations/v/first-order-homegenous-equations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24728.jpg</video:thumbnail_loc><video:title>First order homogenous equations</video:title><video:description>Introduction to first order homogenous equations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9Wfn-WWV1aY.mp4/9Wfn-WWV1aY.mp4</video:content_loc><video:duration>441</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-equations/v/first-order-homogenous-equations-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24730.jpg</video:thumbnail_loc><video:title>First order homogeneous equations 2</video:title><video:description>Another example of using substitution to solve a first order homogeneous differential equations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6YRGEsQWZzY.mp4/6YRGEsQWZzY.mp4</video:content_loc><video:duration>502</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-equations/v/2nd-order-linear-homogeneous-differential-equations-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24732.jpg</video:thumbnail_loc><video:title>2nd order linear homogeneous differential equations 1</video:title><video:description>Introduction to 2nd order, linear, homogeneous differential equations with constant coefficients.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/UFWAu8Ptth0.mp4/UFWAu8Ptth0.mp4</video:content_loc><video:duration>584</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-equations/v/2nd-order-linear-homogeneous-differential-equations-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24734.jpg</video:thumbnail_loc><video:title>2nd order linear homogeneous differential equations 2</video:title><video:description>Let&apos;s find the general solution!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/SPVqgkOZMAc.mp4/SPVqgkOZMAc.mp4</video:content_loc><video:duration>508</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-equations/v/2nd-order-linear-homogeneous-differential-equations-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24736.jpg</video:thumbnail_loc><video:title>2nd order linear homogeneous differential equations 3</video:title><video:description>Let&apos;s use some initial conditions to solve for the particular solution</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/UyCwAFQt4v0.mp4/UyCwAFQt4v0.mp4</video:content_loc><video:duration>359</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-equations/v/2nd-order-linear-homogeneous-differential-equations-4</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24738.jpg</video:thumbnail_loc><video:title>2nd order linear homogeneous differential equations 4</video:title><video:description>Another example with initial conditions!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3uO_uPb9H8w.mp4/3uO_uPb9H8w.mp4</video:content_loc><video:duration>550</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-equations/v/complex-roots-of-the-characteristic-equations-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24740.jpg</video:thumbnail_loc><video:title>Complex roots of the characteristic equations 1</video:title><video:description>What happens when the characteristic equations has complex roots?!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6xEO4BeawzA.mp4/6xEO4BeawzA.mp4</video:content_loc><video:duration>627</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-equations/v/complex-roots-of-the-characteristic-equations-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24742.jpg</video:thumbnail_loc><video:title>Complex roots of the characteristic equations 2</video:title><video:description>What happens when the characteristic equation has complex roots?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jJyRrIZ595c.mp4/jJyRrIZ595c.mp4</video:content_loc><video:duration>623</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-equations/v/complex-roots-of-the-characteristic-equations-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24744.jpg</video:thumbnail_loc><video:title>Complex roots of the characteristic equations 3</video:title><video:description>Lets do an example with initial conditions!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/rGaM6pwqhB0.mp4/rGaM6pwqhB0.mp4</video:content_loc><video:duration>612</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-equations/v/repeated-roots-of-the-characteristic-equation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24746.jpg</video:thumbnail_loc><video:title>Repeated roots of the characteristic equation</video:title><video:description>What happens when the characteristic equation only has 1 repeated root?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/NW9JfMvIsxw.mp4/NW9JfMvIsxw.mp4</video:content_loc><video:duration>718</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-equations/v/repeated-roots-of-the-characterisitic-equations-part-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24748.jpg</video:thumbnail_loc><video:title>Repeated roots of the characteristic equations part 2</video:title><video:description>An example where we use initial conditions to solve a repeated-roots differential equation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/YezsgIlcb68.mp4/YezsgIlcb68.mp4</video:content_loc><video:duration>532</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-equations/v/undetermined-coefficients-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24750.jpg</video:thumbnail_loc><video:title>Undetermined coefficients 1</video:title><video:description>Using the method of undetermined coefficients to solve nonhomogeneous linear differential equations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/znE4Nq9NJCQ.mp4/znE4Nq9NJCQ.mp4</video:content_loc><video:duration>611</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-equations/v/undetermined-coefficients-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24752.jpg</video:thumbnail_loc><video:title>Undetermined coefficients 2</video:title><video:description>Another example using undetermined coefficients.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hbJ2o9EUmJ0.mp4/hbJ2o9EUmJ0.mp4</video:content_loc><video:duration>660</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-equations/v/undetermined-coefficients-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24754.jpg</video:thumbnail_loc><video:title>Undetermined coefficients 3</video:title><video:description>Another example where the nonhomogeneous part is a polynomial</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/I3vIAzMcm4Y.mp4/I3vIAzMcm4Y.mp4</video:content_loc><video:duration>489</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-equations/v/undetermined-coefficients-4</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24756.jpg</video:thumbnail_loc><video:title>Undetermined coefficients 4</video:title><video:description>Putting it all together!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vAepSNDLZRM.mp4/vAepSNDLZRM.mp4</video:content_loc><video:duration>354</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-equations/v/laplace-transform-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24758.jpg</video:thumbnail_loc><video:title>Laplace transform 1</video:title><video:description>Introduction to the Laplace Transform</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OiNh2DswFt4.mp4/OiNh2DswFt4.mp4</video:content_loc><video:duration>481</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-equations/v/laplace-transform-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24760.jpg</video:thumbnail_loc><video:title>Laplace transform 2</video:title><video:description>Laplace transform of e^at</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/33TYoybjqPg.mp4/33TYoybjqPg.mp4</video:content_loc><video:duration>454</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-equations/v/laplace-transform-3-l-sin-at</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24762.jpg</video:thumbnail_loc><video:title>L{sin(at)} - transform of sin(at)</video:title><video:description>Laplace Transform of sin(at) (part 1)</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gMcs6RF_LrQ.mp4/gMcs6RF_LrQ.mp4</video:content_loc><video:duration>644</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-equations/v/laplace-transform-4</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24764.jpg</video:thumbnail_loc><video:title>Part 2 of the transform of the sin(at)</video:title><video:description>Part 2 of getting the Laplace transform of sin(at)</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-cApVwKR1Ps.mp4/-cApVwKR1Ps.mp4</video:content_loc><video:duration>553</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-equations/v/laplace-transform-5</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24766.jpg</video:thumbnail_loc><video:title>Laplace as linear operator and Laplace of derivatives</video:title><video:description>Useful properties of the Laplace Transform</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/E2VxbufzuWQ.mp4/E2VxbufzuWQ.mp4</video:content_loc><video:duration>696</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-equations/v/laplace-transform-6</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24768.jpg</video:thumbnail_loc><video:title>Laplace transform of cos t and polynomials</video:title><video:description>Laplace transform of cosine and polynomials!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/fyJkXBvcA2Q.mp4/fyJkXBvcA2Q.mp4</video:content_loc><video:duration>585</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-equations/v/more-laplace-transform-tools</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24774.jpg</video:thumbnail_loc><video:title>&quot;Shifting&quot; transform by multiplying function by exponential</video:title><video:description>A grab bag of things to know about the Laplace Transform.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_X_QwpXsdOs.mp4/_X_QwpXsdOs.mp4</video:content_loc><video:duration>677</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-equations/v/laplace-transform-of-l-t</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24778.jpg</video:thumbnail_loc><video:title>Laplace transform of t: L{t}</video:title><video:description>Determining the Laplace Transform of t</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qhKJ1DG9kYY.mp4/qhKJ1DG9kYY.mp4</video:content_loc><video:duration>546</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-equations/v/laplace-transform-of-t-n-l-t-n</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24780.jpg</video:thumbnail_loc><video:title>Laplace transform of t^n: L{t^n}</video:title><video:description>Laplace Transform of t^n: L{t^n}</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pZIaUx3UQoA.mp4/pZIaUx3UQoA.mp4</video:content_loc><video:duration>616</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-equations/v/laplace-transform-of-the-unit-step-function</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24782.jpg</video:thumbnail_loc><video:title>Laplace transform of the unit step function</video:title><video:description>Introduction to the unit step function and its Laplace Transform</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4Mr7aEHQr8E.mp4/4Mr7aEHQr8E.mp4</video:content_loc><video:duration>1455</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-equations/v/inverse-laplace-examples</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24784.jpg</video:thumbnail_loc><video:title>Inverse Laplace examples</video:title><video:description>Using our toolkit to take some inverse Laplace Transforms</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/BbqbvSig6Mc.mp4/BbqbvSig6Mc.mp4</video:content_loc><video:duration>1155</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-equations/v/dirac-delta-function</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24788.jpg</video:thumbnail_loc><video:title>Dirac delta function</video:title><video:description>Introduction to the Dirac Delta Function</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4qfdCwys2ew.mp4/4qfdCwys2ew.mp4</video:content_loc><video:duration>1068</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-equations/v/laplace-transform-of-the-dirac-delta-function</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24790.jpg</video:thumbnail_loc><video:title>Laplace transform of the dirac delta function</video:title><video:description>Figuring out the Laplace Transform of the Dirac Delta Function</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vhfjEpQWWeE.mp4/vhfjEpQWWeE.mp4</video:content_loc><video:duration>733</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-equations/v/laplace-transform-to-solve-an-equation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24770.jpg</video:thumbnail_loc><video:title>Laplace transform to solve an equation</video:title><video:description>Using the Laplace Transform to solve an equation we already knew how to solve.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3uYb-RhM7lU.mp4/3uYb-RhM7lU.mp4</video:content_loc><video:duration>651</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-equations/v/laplace-transform-solves-an-equation-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24772.jpg</video:thumbnail_loc><video:title>Laplace transform solves an equation 2</video:title><video:description>Second part of using the Laplace Transform to solve a differential equation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/EdQ7Q9VoF44.mp4/EdQ7Q9VoF44.mp4</video:content_loc><video:duration>646</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-equations/v/using-the-laplace-transform-to-solve-a-nonhomogenous-eq</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24776.jpg</video:thumbnail_loc><video:title>Using the Laplace transform to solve a nonhomogeneous eq</video:title><video:description>Solving a non-homogeneous differential equation using the Laplace Transform</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/nlUG4OKN1IY.mp4/nlUG4OKN1IY.mp4</video:content_loc><video:duration>1128</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-equations/v/laplace-step-function-differential-equation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24786.jpg</video:thumbnail_loc><video:title>Laplace/step function differential equation</video:title><video:description>Hairy differential equation involving a step function that we use the Laplace Transform to solve.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/R0JY8oWsuOY.mp4/R0JY8oWsuOY.mp4</video:content_loc><video:duration>1152</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-equations/v/introduction-to-the-convolution</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24792.jpg</video:thumbnail_loc><video:title>Introduction to the convolution</video:title><video:description>Introduction to the Convolution</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/IW4Reburjpc.mp4/IW4Reburjpc.mp4</video:content_loc><video:duration>1139</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-equations/v/the-convolution-and-the-laplace-transform</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24794.jpg</video:thumbnail_loc><video:title>The convolution and the Laplace transform</video:title><video:description>Understanding how the product of the Transforms of two functions relates to their convolution.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TJgBEI3drUc.mp4/TJgBEI3drUc.mp4</video:content_loc><video:duration>826</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/differential-equations/v/using-the-convolution-theorem-to-solve-an-initial-value-prob</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24796.jpg</video:thumbnail_loc><video:title>Using the convolution theorem to solve an initial value prob</video:title><video:description>Using the Convolution Theorem to solve an initial value problem</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/rfyq32mHcYs.mp4/rfyq32mHcYs.mp4</video:content_loc><video:duration>734</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/early-math/v/comparing-subtracting-1-and-10</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa493150b.jpg</video:thumbnail_loc><video:title>Subtracting 1 vs. subtracting 10</video:title><video:description>Sal talks about the difference between subtracting 1 and subtracting 10.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8YR1E7XWPz8.mp4/8YR1E7XWPz8.mp4</video:content_loc><video:duration>152</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/early-math/v/starfish-rulers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0ca5caaa.jpg</video:thumbnail_loc><video:title>Addition word problem: starfish</video:title><video:description>Sal solves a word problem with the term &quot;fewer&quot;.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/QYOieJuzDr4.mp4/QYOieJuzDr4.mp4</video:content_loc><video:duration>217</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/early-math/v/spots-on-a-die</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc13e6bcb.jpg</video:thumbnail_loc><video:title>Addition word problem: spots</video:title><video:description>Sal solves a word problem with the term &quot;more&quot;.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pvyqucC-0NU.mp4/pvyqucC-0NU.mp4</video:content_loc><video:duration>203</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/comparing-distribution-means</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7c6716a3.jpg</video:thumbnail_loc><video:title>Comparing means of distributions</video:title><video:description>Sal compares the means of two different distributions given as dot plots.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pPnxPrhf6Ww.mp4/pPnxPrhf6Ww.mp4</video:content_loc><video:duration>469</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/comparing-means-and-medians</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3cb6dff6.jpg</video:thumbnail_loc><video:title>Means and medians of different distributions</video:title><video:description>Sal compares the mean and median based on a few different distributions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/eLyLbaXfJXo.mp4/eLyLbaXfJXo.mp4</video:content_loc><video:duration>389</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/trigonometry/v/example-the-six-trig-ratios</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1153576581.jpg</video:thumbnail_loc><video:title>Finding reciprocal trig ratios</video:title><video:description>Sal finds all six trigonometric ratios (sine, cosine, tangent, secant, cosecant, and cotangent) of an angle in a given right triangle.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Q7htxHDN8LE.mp4/Q7htxHDN8LE.mp4</video:content_loc><video:duration>285</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/trigonometry/v/example-using-trig-to-solve-for-missing-information</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1153530471.jpg</video:thumbnail_loc><video:title>Using reciprocal trig ratios</video:title><video:description>Sal is given two sides in a right triangle and the cotangent of one of the angles, and he uses this information to find the missing side.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/rufFQZDDXCE.mp4/rufFQZDDXCE.mp4</video:content_loc><video:duration>372</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/formula-for-arithmetic-series</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1392989924.jpg</video:thumbnail_loc><video:title>Arithmetic series formula</video:title><video:description>Learn how to write an arithmetic sequence in general terms, using a common difference d and a first term a. Next, we&apos;ll see that this formula is equivalent to multiplying the average of the first and last terms by the number of terms.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Uy_L8tnihDM.mp4/Uy_L8tnihDM.mp4</video:content_loc><video:duration>467</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/calculating-conditional-probability</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xcbc59718.jpg</video:thumbnail_loc><video:title>Calculating conditional probability</video:title><video:description>Conditional probabilities are written like P(A|B), which can be read to mean, &quot;the probability that A happens GIVEN B has happened.&quot; If we know probabilities like P(A), P(B), and P(A|B), we can solve for other probabilties like P(B|A).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6xPkG2pA-TU.mp4/6xPkG2pA-TU.mp4</video:content_loc><video:duration>403</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/independent-dependent-probability</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfd725922.jpg</video:thumbnail_loc><video:title>Analyzing event probability for independence</video:title><video:description>Sal uses an example about shirts, scarves, hats, and pants to explain how to use probabilities to figure out if two events are independent.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/R-NeYKSEqns.mp4/R-NeYKSEqns.mp4</video:content_loc><video:duration>408</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/intersection-and-union-of-sets</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x99efa12b.jpg</video:thumbnail_loc><video:title>Intersection and union of sets</video:title><video:description>To find the intersection of two or more sets, you look for elements that are contained in all of the sets. To find the union of two or more sets, you combine all the elements from each set together, making sure to remove any duplicates.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jAfNg3ylZAI.mp4/jAfNg3ylZAI.mp4</video:content_loc><video:duration>464</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/density-curve-worked-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9e13b7bc0c3ce4b4.jpg</video:thumbnail_loc><video:title>Density curve worked example</video:title><video:description>Analyzing skew, median, mean and height of a density curve.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/P5y83-ZnQeo.mp4/P5y83-ZnQeo.mp4</video:content_loc><video:duration>232</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/worked-example-finding-area-under-density-curves</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x947652f549308b0a.jpg</video:thumbnail_loc><video:title>Worked example finding area under density curves</video:title><video:description>Worked example finding area under density curves</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Tu3O9tC3Eh8.mp4/Tu3O9tC3Eh8.mp4</video:content_loc><video:duration>280</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/ck12-org-normal-distribution-problems-z-score</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26200.jpg</video:thumbnail_loc><video:title>Normal distribution problem: z-scores (from ck12.org)</video:title><video:description>Z-score practice</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Wp2nVIzBsE8.mp4/Wp2nVIzBsE8.mp4</video:content_loc><video:duration>468</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/types-of-statistical-studies</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf6f54d0cbcdb49b8.jpg</video:thumbnail_loc><video:title>Types of statistical studies</video:title><video:description>Types of statistical studies</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/SaP1O0i1bdc.mp4/SaP1O0i1bdc.mp4</video:content_loc><video:duration>632</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/worked-example-identifying-sample-study</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x80ec3f947438bdda.jpg</video:thumbnail_loc><video:title>Worked example identifying sample study</video:title><video:description>Worked example identifying sample study</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/QSHMOWQUZ54.mp4/QSHMOWQUZ54.mp4</video:content_loc><video:duration>181</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/statistics-sample-vs-population-mean</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26173.jpg</video:thumbnail_loc><video:title>Inferring population mean from sample mean</video:title><video:description>Much of statistics is based upon using data from a random sample that is representative of the population at large. From that sample mean, we can infer things about the greater population mean. We&apos;ll explain.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/k5EbijWu-Ss.mp4/k5EbijWu-Ss.mp4</video:content_loc><video:duration>603</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/constructing-regular-hexagon-inscribed-in-circle</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3e59c6d1.jpg</video:thumbnail_loc><video:title>Geometric constructions: circle-inscribed regular hexagon</video:title><video:description>Sal constructs a regular hexagon that is inscribed inside a given circle using compass and straightedge.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Yu4eqwGFJK8.mp4/Yu4eqwGFJK8.mp4</video:content_loc><video:duration>221</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/constructing-an-angle-bisector-using-a-compass-and-straightedge</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x999a7ffd.jpg</video:thumbnail_loc><video:title>Geometric constructions: angle bisector</video:title><video:description>Sal constructs a line that bisects a given angle using compass and straightedge.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/KNr52iFk7n4.mp4/KNr52iFk7n4.mp4</video:content_loc><video:duration>137</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/constructing-a-perpendicular-line-using-a-compass-and-straightedge</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb27e19ab.jpg</video:thumbnail_loc><video:title>Geometric constructions: perpendicular line through a point on the line</video:title><video:description>Sal constructs a line perpendicular to a given line through a point on the line using compass and straightedge.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/nM-O8llUdwg.mp4/nM-O8llUdwg.mp4</video:content_loc><video:duration>72</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/constructing-a-perpendicular-bisector-using-a-compass-and-straightedge</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x14f9639b.jpg</video:thumbnail_loc><video:title>Geometric constructions: perpendicular bisector</video:title><video:description>Sal constructs a perpendicular bisector to a given line segment using compass and straightedge.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/WR2R_wrdEVY.mp4/WR2R_wrdEVY.mp4</video:content_loc><video:duration>86</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/incenter-and-incircles-of-a-triangle</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/309318058.jpg</video:thumbnail_loc><video:title>Incenter and incircles of a triangle</video:title><video:description>The incenter of a triangle is the point at which the three angle bisectors intersect. To locate the incenter, one can draw each of the three angle bisectors, and then determine the point at which they all intersect. The incenter is also notable for being the center of the largest possible inscribed circle within the triangle.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/21vbBiCVijE.mp4/21vbBiCVijE.mp4</video:content_loc><video:duration>478</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/constructing-circle-inscribing-triangle</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x22e61e65.jpg</video:thumbnail_loc><video:title>Geometric constructions: triangle-inscribing circle</video:title><video:description>Sal constructs a circle that inscribes a given triangle using compass and straightedge.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lmm767eIsGU.mp4/lmm767eIsGU.mp4</video:content_loc><video:duration>153</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/constructing-circumscribing-circle</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xba7a49ce.jpg</video:thumbnail_loc><video:title>Geometric constructions: triangle-circumscribing circle</video:title><video:description>Sal constructs a circle that circumscribes a given triangle using compass and straightedge.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/eSjbEWb4Qp4.mp4/eSjbEWb4Qp4.mp4</video:content_loc><video:duration>142</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/proof-triangle-altitudes-are-concurrent-orthocenter</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/319066154.jpg</video:thumbnail_loc><video:title>Proof: Triangle altitudes are concurrent (orthocenter)</video:title><video:description>Showing that any triangle can be the medial triangle for some larger triangle. Using this to show that the altitudes of a triangle are concurrent (at the orthocenter).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/aGwT2-RERXY.mp4/aGwT2-RERXY.mp4</video:content_loc><video:duration>601</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/showing-angles-have-same-measure</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x07781167.jpg</video:thumbnail_loc><video:title>Proving angles are congruent</video:title><video:description>Sal proves that two angles are congruent in a really interesting triangle like figure.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2SOK_IrpHeQ.mp4/2SOK_IrpHeQ.mp4</video:content_loc><video:duration>293</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/points-after-rotation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd0c722ed.jpg</video:thumbnail_loc><video:title>Rotating shapes</video:title><video:description>Sal is given a triangle on the coordinate plane and the definition of a rotation about the origin, and he manually draws the image of that rotation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6nUMiJfHLSA.mp4/6nUMiJfHLSA.mp4</video:content_loc><video:duration>492</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/reflecting-segments-over-line</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x135a8040.jpg</video:thumbnail_loc><video:title>Reflecting shapes: diagonal line of reflection</video:title><video:description>Sal is given two line segments on the coordinate plane and the definition of a reflection, and he draws the image of the segments under that reflection.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/kj3ZfOQGKdE.mp4/kj3ZfOQGKdE.mp4</video:content_loc><video:duration>439</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/points-on-line-of-reflection</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2d79cf1a.jpg</video:thumbnail_loc><video:title>Determining reflections (advanced)</video:title><video:description>Sal is given two line segments on the coordinate plane, and determines the reflection that maps one of them into the other.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/63mWxNXQQAk.mp4/63mWxNXQQAk.mp4</video:content_loc><video:duration>341</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/example-rotating-polygons</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6918834b.jpg</video:thumbnail_loc><video:title>Intro to rotational symmetry</video:title><video:description>Sal checks whether various figure are symmetrical under a 180 degrees rotation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/P35LyN9g0oI.mp4/P35LyN9g0oI.mp4</video:content_loc><video:duration>248</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/constructing-quad-based-on-symmetry</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2bf83c62.jpg</video:thumbnail_loc><video:title>Finding a quadrilateral from its symmetries</video:title><video:description>Two of the points that define a certain quadrilateral are (0,9) and (3,4). The quadrilateral has reflective symmetry over the line y=3-x. Draw and classify the quadrilateral.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-nufZ41Kg5c.mp4/-nufZ41Kg5c.mp4</video:content_loc><video:duration>187</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/reflecting-across-two-lines</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x16ace6c3.jpg</video:thumbnail_loc><video:title>Finding a quadrilateral from its symmetries (example 2)</video:title><video:description>Two of the points that define a certain quadrilateral are (-4,-2) and (0,5). The quadrilateral has a reflective symmetry over the lines y=x/2 and y=-2x+5. Draw and classify the quadrilateral.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ANnuQZyEKVo.mp4/ANnuQZyEKVo.mp4</video:content_loc><video:duration>440</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/line-and-angle-proofs-exercise</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xab39abd2.jpg</video:thumbnail_loc><video:title>Proofs with transformations</video:title><video:description>Proofs with transformations from High school geometry</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/uYXhga17q1g.mp4/uYXhga17q1g.mp4</video:content_loc><video:duration>525</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/congruent-triangles-and-sss</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/267245528.jpg</video:thumbnail_loc><video:title>Corresponding parts of congruent triangles are congruent</video:title><video:description>When two triangles are congruent, we can know that all of their corresponding sides and angles are congruent too!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/yp49bc4TT-s.mp4/yp49bc4TT-s.mp4</video:content_loc><video:duration>363</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/other-triangle-congruence-postulates</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/267245529.jpg</video:thumbnail_loc><video:title>Triangle congruence postulates/criteria</video:title><video:description>Sal introduces and justifies the SSS, SAS, ASA and AAS postulates for congruent triangles. He also shows that AAA is only good for similarity. For SSA, better to watch next video.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8Ld8Csu4sEs.mp4/8Ld8Csu4sEs.mp4</video:content_loc><video:duration>808</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/more-on-why-ssa-is-not-a-postulate</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/274218421.jpg</video:thumbnail_loc><video:title>Why SSA isn&apos;t a congruence postulate/criterion</video:title><video:description>There are some cases when SSA can imply triangle congruence, but not always. This is why it&apos;s not like the other triangle congruence postulates/criteria.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/f8svAm237xM.mp4/f8svAm237xM.mp4</video:content_loc><video:duration>444</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/finding-congruent-triangles</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/274218420.jpg</video:thumbnail_loc><video:title>Determining congruent triangles</video:title><video:description>Sal uses the SSS, ASA, SAS, and AAS postulates to find congruent triangles.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/d5UCZ9hO8X4.mp4/d5UCZ9hO8X4.mp4</video:content_loc><video:duration>448</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/congruent-legs-and-base-angles-of-isosceles-triangles</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/281570417.jpg</video:thumbnail_loc><video:title>Proofs concerning isosceles triangles</video:title><video:description>Sal proves that the base angles in isosceles triangles are congruent, and conversely, that triangles with congruent base angles are isosceles. He also proves that the perpendicular to the base of an isosceles triangle bisects it.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7UISwx2Mr4c.mp4/7UISwx2Mr4c.mp4</video:content_loc><video:duration>543</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/equilateral-triangle-sides-and-angles-congruent</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/281570421.jpg</video:thumbnail_loc><video:title>Proofs concerning equilateral triangles</video:title><video:description>Sal proves that the angles of an equilateral triangle are all congruent (and therefore they all measure 60°), and conversely, that triangles with all congruent angles are equilateral.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/CYNUwiUzlPk.mp4/CYNUwiUzlPk.mp4</video:content_loc><video:duration>389</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/figuring-out-all-the-angles-for-congruent-triangles-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/281570422.jpg</video:thumbnail_loc><video:title>Corresponding angles in congruent triangles</video:title><video:description>We write the letters of congruent triangles so their order tells us which parts are corresponding. In this video, Sal uses this notation to solve some angles.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/aDCXPdzyS0s.mp4/aDCXPdzyS0s.mp4</video:content_loc><video:duration>275</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/congruent-triangle-proof-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/274218423.jpg</video:thumbnail_loc><video:title>Geometry proof problem: midpoint</video:title><video:description>Sal proves that a point is the midpoint of a segment using triangle congruence.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/RFesGHsuFZw.mp4/RFesGHsuFZw.mp4</video:content_loc><video:duration>346</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/congruent-triangle-example-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/274218422.jpg</video:thumbnail_loc><video:title>Geometry proof problem: congruent segments</video:title><video:description>Sal proves that two pairs of segments are congruent using the ASA and AAS congruence criteria.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Xc3oHzKXVh8.mp4/Xc3oHzKXVh8.mp4</video:content_loc><video:duration>734</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/problem-involving-angle-derived-from-square-and-circle</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/353965912.jpg</video:thumbnail_loc><video:title>Geometry proof problem: squared circle</video:title><video:description>Sal finds a missing angle using triangle congruence in a diagram that contains sector of a circle inscribed within a square.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3n0LvI99-KM.mp4/3n0LvI99-KM.mp4</video:content_loc><video:duration>495</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/proof-opposite-sides-of-parallelogram-congruent</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/348974659.jpg</video:thumbnail_loc><video:title>Proof: Opposite sides of a parallelogram</video:title><video:description>Sal proves that a figure is a parallelogram if and only if opposite sides are congruent.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LhrGS4-Dd9I.mp4/LhrGS4-Dd9I.mp4</video:content_loc><video:duration>510</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/proof-diagonals-of-a-parallelogram-bisect-each-other</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/348974660.jpg</video:thumbnail_loc><video:title>Proof: Diagonals of a parallelogram</video:title><video:description>Sal proves that a quadrilateral is a parallelogram if and only if its diagonals bisect each other.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TErJ-Yr67BI.mp4/TErJ-Yr67BI.mp4</video:content_loc><video:duration>546</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/proof-opposite-angles-of-parallelogram-congruent</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/348974657.jpg</video:thumbnail_loc><video:title>Proof: Opposite angles of a parallelogram</video:title><video:description>Sal proves that opposite angles of a parallelogram are congruent.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/oIV1zM8qlpk.mp4/oIV1zM8qlpk.mp4</video:content_loc><video:duration>248</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/two-column-proof-showing-segments-are-perpendicular</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/267245527.jpg</video:thumbnail_loc><video:title>Proof: The diagonals of a kite are perpendicular</video:title><video:description>Sal proves that the diagonals of a kite are perpendicular, by using the SSS and SAS triangle congruence criteria.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/fSu1LKnhM5Q.mp4/fSu1LKnhM5Q.mp4</video:content_loc><video:duration>666</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/proof-rhombus-diagonals-are-perpendicular-bisectors</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/348974658.jpg</video:thumbnail_loc><video:title>Proof: Rhombus diagonals are perpendicular bisectors</video:title><video:description>Sal proves that the diagonals of a rhombus are perpendicular, and that they intersect at the midpoints of both.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/GDcVdBAnBdU.mp4/GDcVdBAnBdU.mp4</video:content_loc><video:duration>244</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/proof-rhombus-area-half-product-of-diagonal-length</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/351468822.jpg</video:thumbnail_loc><video:title>Proof: Rhombus area</video:title><video:description>Sal proves that we can find the area of a rhombus by taking half the product of the lengths of the diagonals.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3FManXv4mZM.mp4/3FManXv4mZM.mp4</video:content_loc><video:duration>307</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/triangle-medians-and-centroids</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179266.jpg</video:thumbnail_loc><video:title>Triangle medians &amp; centroids</video:title><video:description>The centroid of a triangle is the point at which the three medians intersect. To locate the centroid, draw each of the three medians (which connect the vertices of the triangle to the midpoints of the opposite sides). It is referred to as the &quot;center of mass&quot; or &quot;balance point&quot; of the triangle. Centroid divides medians in a ratio 2:3.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/GiGLhXFBtRg.mp4/GiGLhXFBtRg.mp4</video:content_loc><video:duration>539</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/triangle-medians-and-centroids-2d-proof</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179267.jpg</video:thumbnail_loc><video:title>Triangle medians and centroids (2D proof)</video:title><video:description>Showing that the centroid is 2/3 of the way along a median</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Vc09LURoMQ8.mp4/Vc09LURoMQ8.mp4</video:content_loc><video:duration>915</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/medians-divide-into-smaller-triangles-of-equal-area</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/311468473.jpg</video:thumbnail_loc><video:title>Dividing triangles with medians</video:title><video:description>Showing that the three medians of a triangle divide it into six smaller triangles of equal area. Brief discussion of the centroid as well</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Xt4sT0fV9Pw.mp4/Xt4sT0fV9Pw.mp4</video:content_loc><video:duration>466</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/exploring-medial-triangles</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/311469473.jpg</video:thumbnail_loc><video:title>Exploring medial triangles</video:title><video:description>The three midsegments (segments joining the midpoints of the sides) of a triangle form a medial triangle. Find out the properties of the midsegments, the medial triangle and the other 3 triangles formed in this way.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Rsi5mzEaCPw.mp4/Rsi5mzEaCPw.mp4</video:content_loc><video:duration>693</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/proving-that-the-centroid-is-2-3rds-along-the-median</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/319053662.jpg</video:thumbnail_loc><video:title>Centroid &amp; median proof</video:title><video:description>Showing that the centroid divides each median into segments with a 2:1 ratio (or that the centroid is 2/3 along the median)</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/i0VS3eEGjiQ.mp4/i0VS3eEGjiQ.mp4</video:content_loc><video:duration>416</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/median-centroid-right-triangle-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/319066153.jpg</video:thumbnail_loc><video:title>Median, centroid example</video:title><video:description>Example involving properties of medians</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/k45QTFCHSVs.mp4/k45QTFCHSVs.mp4</video:content_loc><video:duration>540</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/dilating-from-an-arbitrary-point-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd85b2957.jpg</video:thumbnail_loc><video:title>Performing dilations</video:title><video:description>To dilate a point on a coordinate plane, you multiply its coordinates by a scale factor. The scale factor is a positive number that tells you how much to enlarge or shrink the point. If the scale factor is greater than 1, the point moves away from the origin. If the scale factor is less than 1, the point moves closer to the origin.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/j5xis6Hlnds.mp4/j5xis6Hlnds.mp4</video:content_loc><video:duration>166</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/seeing-circle-similarity-through-translation-and-dilation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc9e9791e.jpg</video:thumbnail_loc><video:title>Proof: all circles are similar</video:title><video:description>Watch Sal informally prove that all circles are similar by showing how we can translate then dilate any circle onto another.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tcQjJssEMgo.mp4/tcQjJssEMgo.mp4</video:content_loc><video:duration>95</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/angle-bisector-theorem-proof</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/309317056.jpg</video:thumbnail_loc><video:title>Intro to angle bisector theorem</video:title><video:description>The Angle Bisector Theorem states that when an angle in a triangle is split into two equal angles, it divides the opposite side into two parts. The ratio of these parts will be the same as the ratio of the sides next to the angle.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TpIBLnRAslI.mp4/TpIBLnRAslI.mp4</video:content_loc><video:duration>515</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/angle-bisector-theorem-examples</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/311469472.jpg</video:thumbnail_loc><video:title>Using the angle bisector theorem</video:title><video:description>Sal uses the angle bisector theorem to solve for sides of a triangle.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PlY3e_-9JUA.mp4/PlY3e_-9JUA.mp4</video:content_loc><video:duration>184</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/finding-area-using-similarity-and-congruence</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/290279019.jpg</video:thumbnail_loc><video:title>Using similar &amp; congruent triangles</video:title><video:description>Sal uses the similarity of triangles and the congruence of others in this multi-step problem to find the area of a polygon.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/EqNzr56h1Ic.mp4/EqNzr56h1Ic.mp4</video:content_loc><video:duration>607</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/challenging-similarity-problem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/289578996.jpg</video:thumbnail_loc><video:title>Challenging similarity problem</video:title><video:description>Interesting similarity problem where we don&apos;t have a lot of information to work with</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7aGEvpHaNJ8.mp4/7aGEvpHaNJ8.mp4</video:content_loc><video:duration>593</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/goldren-ratio-and-rembrandt-s-self-portrait</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xeed4a573.jpg</video:thumbnail_loc><video:title>Geometry word problem: the golden ratio</video:title><video:description>Triangle similarity, the Golden ratio, and art, all converge in this inspiring video!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/v5SAMuRanGM.mp4/v5SAMuRanGM.mp4</video:content_loc><video:duration>503</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/golden-ratio-to-find-radius-of-moon</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbb6e0621.jpg</video:thumbnail_loc><video:title>Geometry word problem: Earth &amp; Moon radii</video:title><video:description>Similarity and the Golden ratio join forces again, this time to save the Earth! (Or maybe just finding its radius)</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/cnCQGKx6LhE.mp4/cnCQGKx6LhE.mp4</video:content_loc><video:duration>383</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/triangle-similarity-in-pool</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd0f9f2e0.jpg</video:thumbnail_loc><video:title>Geometry word problem: a perfect pool shot</video:title><video:description>Sal uses triangle similarity to plan the perfect shot in a pool game.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/MiyFReTAdCA.mp4/MiyFReTAdCA.mp4</video:content_loc><video:duration>409</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/basic-trigonometry</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/19647490.jpg</video:thumbnail_loc><video:title>Intro to the trigonometric ratios</video:title><video:description>Sin, cos, and tan are trigonometric ratios that relate the angles and sides of right triangles. Sin is the ratio of the opposite side to the hypotenuse, cos is the ratio of the adjacent side to the hypotenuse, and tan is the ratio of the opposite side to the adjacent side. They are often written as sin(x), cos(x), and tan(x), where x is an angle in radians or degrees.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Jsiy4TxgIME.mp4/Jsiy4TxgIME.mp4</video:content_loc><video:duration>557</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/basic-trigonometry-ii</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/19647491.jpg</video:thumbnail_loc><video:title>Trigonometric ratios in right triangles</video:title><video:description>Sal shows a few examples where he starts with the two legs of a right triangle and he finds the trig ratios of one of the acute angles.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/G-T_6hCdMQc.mp4/G-T_6hCdMQc.mp4</video:content_loc><video:duration>731</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/similarity-to-define-sine-cosine-and-tangent</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc0627a6a.jpg</video:thumbnail_loc><video:title>Triangle similarity &amp; the trigonometric ratios</video:title><video:description>Sal explains how the trigonometric ratios are derived from triangle similarity considerations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/QuZMXVJNLCo.mp4/QuZMXVJNLCo.mp4</video:content_loc><video:duration>536</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/example-trig-to-solve-the-sides-and-angles-of-a-right-triangle</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1153614407.jpg</video:thumbnail_loc><video:title>Solving for a side in right triangles with trigonometry</video:title><video:description>Sal is given a right triangle with an acute angle of 65° and a leg of 5 units, and he uses trigonometry to find the two missing sides.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/l5VbdqRjTXc.mp4/l5VbdqRjTXc.mp4</video:content_loc><video:duration>424</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/showing-relationship-between-cosine-and-sine-of-complements</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x71f71130.jpg</video:thumbnail_loc><video:title>Sine &amp; cosine of complementary angles</video:title><video:description>Sal shows that the sine of any angle is equal to the cosine of its complementary angle.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/BLQNL_UGONg.mp4/BLQNL_UGONg.mp4</video:content_loc><video:duration>255</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/sine-and-cosine-of-complements-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xee258334.jpg</video:thumbnail_loc><video:title>Using complementary angles</video:title><video:description>Sal solved the following problem: Given that cos(58°)=0.53, find sin(32°).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/yiH6GoscimY.mp4/yiH6GoscimY.mp4</video:content_loc><video:duration>245</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/how-much-of-a-pyramid-is-submerged</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf177c90b.jpg</video:thumbnail_loc><video:title>Trig word problem: complementary angles</video:title><video:description>Sal solves a problem about a submerged pyramid by finding congruent angles in the diagram and using the fact that the cosine of a given angle is always the same, no matter how large the triangle it appears in.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Z5EnuVJawmY.mp4/Z5EnuVJawmY.mp4</video:content_loc><video:duration>344</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/45-45-90-triangles</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24965.jpg</video:thumbnail_loc><video:title>Special right triangles intro (part 1)</video:title><video:description>A 45-45-90 triangle is a special type of right triangle, where the ratio of the lengths of the sides of a 45-45-90 triangle is always 1:1:√2, meaning that if one leg is x units long, then the other leg is also x units long, and the hypotenuse is x√2 units long.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tSHitjFIjd8.mp4/tSHitjFIjd8.mp4</video:content_loc><video:duration>570</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/intro-to-30-60-90-triangles</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24967.jpg</video:thumbnail_loc><video:title>Special right triangles intro (part 2)</video:title><video:description>A 30-60-90 triangle is a special right triangle with angles of 30, 60, and 90 degrees. It has properties similar to the 45-45-90 triangle. The side opposite the 30-degree angle is half the length of the hypotenuse, and the side opposite the 60-degree angle is the length of the short leg times the square root of three. Alternatively, the ratio of the sides is 1 : √3 : 2.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Qwet4cIpnCM.mp4/Qwet4cIpnCM.mp4</video:content_loc><video:duration>579</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/30-60-90-triangle-example-problem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/294677485.jpg</video:thumbnail_loc><video:title>30-60-90 triangle example problem</video:title><video:description>Using what we know about 30-60-90 triangles to solve what at first seems to be a challenging problem</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/dgHksfBFbjk.mp4/dgHksfBFbjk.mp4</video:content_loc><video:duration>400</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/30-60-90-triangle-side-ratios-proof</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/292160871.jpg</video:thumbnail_loc><video:title>Special right triangles proof (part 1)</video:title><video:description>Learn how to prove the ratios between the sides of a 30-60-90 triangle.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/SFL4stapeUs.mp4/SFL4stapeUs.mp4</video:content_loc><video:duration>419</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/45-45-90-triangle-side-ratios</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/292160870.jpg</video:thumbnail_loc><video:title>Special right triangles proof (part 2)</video:title><video:description>Showing the ratios of the sides of a 45-45-90 triangle are 1:1:sqrt(2)</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/McINBOFCGH8.mp4/McINBOFCGH8.mp4</video:content_loc><video:duration>342</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/angle-to-aim-to-get-alien</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9a39e2a2.jpg</video:thumbnail_loc><video:title>Right triangle word problem</video:title><video:description>Sal solves a modeling problem where he finds the necessary angle to shoot at a vicious alien.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/aHzd-u35LuA.mp4/aHzd-u35LuA.mp4</video:content_loc><video:duration>275</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/law-of-sines</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x29e70bc4.jpg</video:thumbnail_loc><video:title>Solving for a side with the law of sines</video:title><video:description>Sal is given a triangle with two angle measures and one side length, and he finds all the missing side lengths and angle measures using the law of sines.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/VjmFKle7xIw.mp4/VjmFKle7xIw.mp4</video:content_loc><video:duration>358</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/law-of-sines-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x955c68f1.jpg</video:thumbnail_loc><video:title>Solving for an angle with the law of sines</video:title><video:description>Sal is given a triangle with two side lengths and one angle measure, and he finds all the missing angle measures using the law of sines.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/IJySBMtFlnQ.mp4/IJySBMtFlnQ.mp4</video:content_loc><video:duration>334</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/proof-law-of-sines</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26258.jpg</video:thumbnail_loc><video:title>Proof of the law of sines</video:title><video:description>Sal gives a simple proof of the Law of sines.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/APNkWrD-U1k.mp4/APNkWrD-U1k.mp4</video:content_loc><video:duration>394</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/law-of-cosines-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x17ddf742.jpg</video:thumbnail_loc><video:title>Solving for a side with the law of cosines</video:title><video:description>Learn how to use the law of cosines to find the missing side length of a triangle when given two side lengths and the contained angle measure.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ZElOxG7_m3c.mp4/ZElOxG7_m3c.mp4</video:content_loc><video:duration>278</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/law-of-cosines-missing-angle</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb7d3bb05.jpg</video:thumbnail_loc><video:title>Solving for an angle with the law of cosines</video:title><video:description>Sal is given a triangle with all side lengths but no angle measure, and he finds one of the angle measures using the law of cosines.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Ei54NnQ0FKs.mp4/Ei54NnQ0FKs.mp4</video:content_loc><video:duration>401</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/law-of-cosines</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26254.jpg</video:thumbnail_loc><video:title>Proof of the law of cosines</video:title><video:description>Sal gives a simple proof of the Law of cosines.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pGaDcOMdw48.mp4/pGaDcOMdw48.mp4</video:content_loc><video:duration>566</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/law-of-cosines-word-problem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x461dc00c.jpg</video:thumbnail_loc><video:title>Trig word problem: stars</video:title><video:description>Sal solves a word problem about the distance between stars using the law of cosines.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6kGi1dvGZNY.mp4/6kGi1dvGZNY.mp4</video:content_loc><video:duration>360</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/specifying-planes-in-three-dimensions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9922e4bf.jpg</video:thumbnail_loc><video:title>Specifying planes in three dimensions</video:title><video:description>In a three-dimensional space, a plane can be defined by three points it contains, as long as those points are not on the same line. Learn more about it in this video.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/J2Qz-7ZWDAE.mp4/J2Qz-7ZWDAE.mp4</video:content_loc><video:duration>252</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/cavalieris-principle-in-3d</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8f8fedc99264b1ee.jpg</video:thumbnail_loc><video:title>Cavalieri&apos;s principle in 3D</video:title><video:description>Cavalieri&apos;s principle tells us that if 2 figures have the same height and the same cross-sectional area at every point along that height, they have the same volume.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2TDFtCKMoKk.mp4/2TDFtCKMoKk.mp4</video:content_loc><video:duration>296</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/using-related-volumes</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x676e3e2d4c24bfe0.jpg</video:thumbnail_loc><video:title>Using related volumes</video:title><video:description>Use related volumes (using the volume of one figure to determine the volume of another).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/knNLHsjIcl8.mp4/knNLHsjIcl8.mp4</video:content_loc><video:duration>376</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/classify-lines</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x36e2a7ae.jpg</video:thumbnail_loc><video:title>Parallel &amp; perpendicular lines from graph</video:title><video:description>The slopes of parallel lines are equal, and the slopes of perpendicular lines are opposite reciprocals. This is a worked example of determining whether given lines are parallel or perpendicular.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6riBTnlI4fw.mp4/6riBTnlI4fw.mp4</video:content_loc><video:duration>446</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/area-of-trapezoid-on-coordinate-plane</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x07456d4c.jpg</video:thumbnail_loc><video:title>Area of trapezoid on the coordinate plane</video:title><video:description>Sal finds the area of a trapezoid using the distance formula and the trapezoid area formula.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3AxyrK2jYc8.mp4/3AxyrK2jYc8.mp4</video:content_loc><video:duration>414</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/minions-within-reach-of-wizard</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x63e2adb6.jpg</video:thumbnail_loc><video:title>Coordinate plane word problem</video:title><video:description>Watch Sal solve an example where has to determine which of the Minions a wizard can reach using the coordinate plane.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gS6s3MGZlRc.mp4/gS6s3MGZlRc.mp4</video:content_loc><video:duration>352</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/finding-a-point-part-way-between-two-points</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x967aacb2.jpg</video:thumbnail_loc><video:title>Dividing line segments: graphical</video:title><video:description>Watch Sal figure out the coordinates of a point between two other points that give a certain ratio. A graph is given to make it easier to visualize the problem.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0rlNHYHhrWs.mp4/0rlNHYHhrWs.mp4</video:content_loc><video:duration>280</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/ratios-of-distances-between-colinear-points</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbc774557.jpg</video:thumbnail_loc><video:title>Dividing line segments</video:title><video:description>Watch Sal figure out the coordinates of a point between two other points that give a certain ratio.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Cx-_PxD4DJM.mp4/Cx-_PxD4DJM.mp4</video:content_loc><video:duration>237</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/proving-triangle-medians-intersect-at-a-point</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0f74f8a208da028f.jpg</video:thumbnail_loc><video:title>Proving triangle medians intersect at a point</video:title><video:description>Prove that for any triangle, the medians intersect at a point 2/3 of the way from each vertex to the midpoint of the opposite side.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/yfcEgqPZBSk.mp4/yfcEgqPZBSk.mp4</video:content_loc><video:duration>442</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/distance-between-a-point-and-a-line</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb8d341b5.jpg</video:thumbnail_loc><video:title>Distance between point &amp; line</video:title><video:description>The distance from a point to a line is the shortest distance between the point and any point on the line. This can be done with a variety of tools like slope-intercept form and the Pythagorean Theorem.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/iATjsfAX8yc.mp4/iATjsfAX8yc.mp4</video:content_loc><video:duration>332</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/inscribed-angles-exercise-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x481d7c00.jpg</video:thumbnail_loc><video:title>Inscribed angles</video:title><video:description>Sal finds a missing inscribed angle using the inscribed angle theorem.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/aNi1-zeEps8.mp4/aNi1-zeEps8.mp4</video:content_loc><video:duration>80</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/inscribed-and-central-angles</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24977.jpg</video:thumbnail_loc><video:title>Inscribed angle theorem proof</video:title><video:description>Proving that an inscribed angle is half of a central angle that subtends the same arc.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/MyzGVbCHh5M.mp4/MyzGVbCHh5M.mp4</video:content_loc><video:duration>856</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/right-triangles-inscribed-in-circles-proof</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24981.jpg</video:thumbnail_loc><video:title>Proof: Right triangles inscribed in circles</video:title><video:description>Proof showing that a triangle inscribed in a circle having a diameter as one side is a right triangle</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/b0U1NxbRU4w.mp4/b0U1NxbRU4w.mp4</video:content_loc><video:duration>335</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/hypotenuse-of-right-triangle-inscribed-in-circle</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2218bca9.jpg</video:thumbnail_loc><video:title>Inscribed shapes: find diameter</video:title><video:description>Find the diameter of a circle using an inscribed right triangle.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/T971zHhZ3S4.mp4/T971zHhZ3S4.mp4</video:content_loc><video:duration>153</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/solving-for-unknown-angle</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6f35e673.jpg</video:thumbnail_loc><video:title>Inscribed shapes: angle subtended by diameter</video:title><video:description>One method using an inscribed angle intercepting a diameter of a circle.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pCLGpRaJfJ8.mp4/pCLGpRaJfJ8.mp4</video:content_loc><video:duration>349</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/finding-inscribed-angle-measure</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0594ad71.jpg</video:thumbnail_loc><video:title>Inscribed shapes: find inscribed angle</video:title><video:description>Using either the inscribed angle theorem or the fact that two inscribed angles that intercept the same arc must be congruent.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/h-_BDon5oes.mp4/h-_BDon5oes.mp4</video:content_loc><video:duration>130</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/proving-the-opposite-angles-of-inscribed-quadrilateral-are-supplementary</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xaaf3d462.jpg</video:thumbnail_loc><video:title>Inscribed quadrilaterals proof</video:title><video:description>Sal uses the inscribed angle theorem and some algebra to prove that opposite angles of an inscribed quadrilateral are supplementary.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LGnL17ESs3Q.mp4/LGnL17ESs3Q.mp4</video:content_loc><video:duration>236</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/example-showing-supplementary-oppositie-angles-in-inscribed-quadrilateral</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x265f991c.jpg</video:thumbnail_loc><video:title>Solving inscribed quadrilaterals</video:title><video:description>Example showing supplementary opposite angles in inscribed quadrilateral.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Y9cznjBl0Hk.mp4/Y9cznjBl0Hk.mp4</video:content_loc><video:duration>298</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/constructing-square-inscribed-in-circle</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe85c0014.jpg</video:thumbnail_loc><video:title>Geometric constructions: circle-inscribed square</video:title><video:description>Sal constructs a square that is inscribed inside a given circle using compass and straightedge.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-gWtl6mdpeY.mp4/-gWtl6mdpeY.mp4</video:content_loc><video:duration>167</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/constructing-equilateral-triangle-inscribed-in-circle</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb4a12e50.jpg</video:thumbnail_loc><video:title>Geometric constructions: circle-inscribed equilateral triangle</video:title><video:description>Sal constructs an equilateral triangle that is inscribed inside a given circle using compass and straightedge.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gWMTTP58_J0.mp4/gWMTTP58_J0.mp4</video:content_loc><video:duration>208</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/sss-to-show-a-radius-is-perpendicular-to-a-chord-that-it-bisects</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/267245530.jpg</video:thumbnail_loc><video:title>Proof: radius is perpendicular to a chord it bisects</video:title><video:description>Sal proves that if a radius in a circle is drawn so it bisects a chord, then the radius is also perpendicular to that chord. The proof uses SSS congruence.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TgDk06Qayxw.mp4/TgDk06Qayxw.mp4</video:content_loc><video:duration>499</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/perpendicular-radius-bisects-chord</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/298420732.jpg</video:thumbnail_loc><video:title>Proof: perpendicular radius bisects chord</video:title><video:description>Simple proof using right triangle-side-hypotenuse (RSH) congruence criterion to show that a radius perpendicular to a chord bisects it</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2NgzruZ4_5c.mp4/2NgzruZ4_5c.mp4</video:content_loc><video:duration>233</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/intro-arc-measure</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa3a0dfdf.jpg</video:thumbnail_loc><video:title>Intro to arc measure</video:title><video:description>Sal introduces arc measure including that they must sum to 360, conventions of minor and major arcs, and a comparison to arc length.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_H4jllna_ec.mp4/_H4jllna_ec.mp4</video:content_loc><video:duration>327</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/arc-measure-example-problems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xda646acf.jpg</video:thumbnail_loc><video:title>Finding arc measures</video:title><video:description>Watch Sal solve a few problems where he finds a missing arc measure.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/GOA9XWEo7QI.mp4/GOA9XWEo7QI.mp4</video:content_loc><video:duration>396</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/arc-measure-with-equations-examples</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2061f76a.jpg</video:thumbnail_loc><video:title>Finding arc measures with equations</video:title><video:description>Sal solves a few items where arc measures are given in equations, we have to find a variable, then use it to find an arc measure.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/bsDu8VQKwxA.mp4/bsDu8VQKwxA.mp4</video:content_loc><video:duration>418</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/length-of-an-arc-that-subtends-a-central-angle</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb22c18d7.jpg</video:thumbnail_loc><video:title>Arc length from subtended angle</video:title><video:description>Finding the length of an arc using the degree of the angle subtended by the arc and the perimeter of the circle.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tVcasOt55Lc.mp4/tVcasOt55Lc.mp4</video:content_loc><video:duration>298</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/finding-central-angle-measure-given-arc-length</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x99baffff.jpg</video:thumbnail_loc><video:title>Subtended angle from arc length</video:title><video:description>Watch Sal solve an example where he finds the central angle given arc length.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1BH2TNzAAik.mp4/1BH2TNzAAik.mp4</video:content_loc><video:duration>138</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/arc-length-as-fraction-of-circumference</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc3486592.jpg</video:thumbnail_loc><video:title>Arc length as fraction of circumference</video:title><video:description>Sal finds the fraction of an arc length out of the entire circumference using the radian measure of the central angle subtended by the arc.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/XFI7GK4Nv-s.mp4/XFI7GK4Nv-s.mp4</video:content_loc><video:duration>179</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/arc-length-from-angle-measure</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x056f0d59.jpg</video:thumbnail_loc><video:title>Arc length from subtended angle: radians</video:title><video:description>Sal finds the length of an arc using the radius and the radian measure of the angle subtended by the arc.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/dtQyiDMoub4.mp4/dtQyiDMoub4.mp4</video:content_loc><video:duration>159</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/area-of-a-sector-given-a-central-angle</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x44915f06.jpg</video:thumbnail_loc><video:title>Area of a sector</video:title><video:description>A worked example of finding the area of a circle&apos;s sector using the area of the circle and the central angle of the sector.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/u8JFdwmBvvQ.mp4/u8JFdwmBvvQ.mp4</video:content_loc><video:duration>146</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/proving-radius-is-perpendicular-to-tangent-line</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5cef9421.jpg</video:thumbnail_loc><video:title>Proof: Radius is perpendicular to tangent line</video:title><video:description>Sal proves that the radius that connects the intersection point of a tangent line with the circle is perpendicular to the tangent line.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/St3MU5i3chc.mp4/St3MU5i3chc.mp4</video:content_loc><video:duration>521</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/segments-tangent-to-circle-from-outside-point-congruent</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7d734c90.jpg</video:thumbnail_loc><video:title>Proof: Segments tangent to circle from outside point are congruent</video:title><video:description>Sal proves that two tangent segments to a circle that are drawn from the same outside point are congruent.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pJABplruJIU.mp4/pJABplruJIU.mp4</video:content_loc><video:duration>236</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/tangents-of-circles-exercise-examples</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1e3a5b56.jpg</video:thumbnail_loc><video:title>Tangents of circles problem (example 1)</video:title><video:description>Sal finds missing angles using the property that tangents are perpendicular to the radius.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8vFhNhL-zm8.mp4/8vFhNhL-zm8.mp4</video:content_loc><video:duration>277</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/measure-of-circumscribed-angle</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xedc9cfc6.jpg</video:thumbnail_loc><video:title>Tangents of circles problem (example 2)</video:title><video:description>Sal finds a missing angle using the property that tangents are perpendicular to the radius.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ZiqHJwzv_HI.mp4/ZiqHJwzv_HI.mp4</video:content_loc><video:duration>227</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/example-with-tangent-and-radius</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7b77bf0f.jpg</video:thumbnail_loc><video:title>Tangents of circles problem (example 3)</video:title><video:description>Sal finds a missing length using the property that tangents are perpendicular to the radius.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/KjQ1KN5GgoE.mp4/KjQ1KN5GgoE.mp4</video:content_loc><video:duration>154</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/constructing-a-tangent-line-using-compass-and-straightedge</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd131cdd3.jpg</video:thumbnail_loc><video:title>Geometric constructions: circle tangent</video:title><video:description>Sal constructs a line tangent to a circle using compass and straightedge.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/n5cKWjZqpIE.mp4/n5cKWjZqpIE.mp4</video:content_loc><video:duration>350</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/another-example-using-compass-and-straightedge-for-tangent-line</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6b83da1c.jpg</video:thumbnail_loc><video:title>Geometric constructions: circle tangent (example 2)</video:title><video:description>Sal constructs a line tangent to a circle using compass and straightedge.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/g_dStt4st2I.mp4/g_dStt4st2I.mp4</video:content_loc><video:duration>335</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/multiply-complex-graphically-3i</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf2a26e18a5a55bd3.jpg</video:thumbnail_loc><video:title>Multiplying complex numbers graphically example: -3i</video:title><video:description>We can multiply complex numbers graphically on the complex plane by rotating and scaling. Multiplying a complex number z by -3i rotates and scales z.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/fqwR6RNPJgc.mp4/fqwR6RNPJgc.mp4</video:content_loc><video:duration>122</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/multiply-complex-graphically-1-i</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xec05d579abc39d4c.jpg</video:thumbnail_loc><video:title>Multiplying complex numbers graphically example: -1-i</video:title><video:description>We can multiply complex numbers graphically on the complex plane. We rotate an amount equal to the argument and scale by the modulus of the complex number by which we&apos;re multiplying.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ebEwF4kb6pI.mp4/ebEwF4kb6pI.mp4</video:content_loc><video:duration>217</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/using-matrices-to-transform-the-plane-mapping-a-vector</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2abc8976bce511cf.jpg</video:thumbnail_loc><video:title>Using matrices to transform the plane: Mapping a vector</video:title><video:description>2X2 matrices can define transformations for the entire plane. In this worked example, we see how to find the image of a given vector under the transformation defined by a given matrix.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TuDYc-8L2Bw.mp4/TuDYc-8L2Bw.mp4</video:content_loc><video:duration>255</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/using-matrices-to-transform-the-plane-composing-matrices</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdb226d4911f54a41.jpg</video:thumbnail_loc><video:title>Using matrices to transform the plane: Composing matrices</video:title><video:description>2X2 matrices can define transformations for the entire plane. In this worked example, we see how to find a single matrix that defines the same transformation as the composition of two other matrices.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OzoEqs1f1S8.mp4/OzoEqs1f1S8.mp4</video:content_loc><video:duration>317</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/using-matrices-to-represent-data-networks</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8a19e3afa1ae7a58.jpg</video:thumbnail_loc><video:title>Using matrices to represent data: Networks</video:title><video:description>Matrices are basically tables of numeric values. But you may be surprised at how many real-world situations you can model with this structure. Here, for example, we represent a network of bus routes between cities.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/IxmFLAPSx5I.mp4/IxmFLAPSx5I.mp4</video:content_loc><video:duration>340</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/using-matrices-to-represent-data-payoffs</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfd2ba4c6357cffcf.jpg</video:thumbnail_loc><video:title>Using matrices to represent data: Payoffs</video:title><video:description>Matrices are basically tables of numeric values. But you may be surprised at how many real-world situations you can model with this structure. Here, for example, we represent a game&apos;s payoffs: we represent the points each player gets in an elaborate version of rock, paper, scissors.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2ObBIZoZnJ0.mp4/2ObBIZoZnJ0.mp4</video:content_loc><video:duration>403</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/engageny-precalc/v/rendering-5</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x894807a8.jpg</video:thumbnail_loc><video:title>1. Ray tracing intuition</video:title><video:description>First, let&apos;s look at ray tracing in 2D using a simple example. In 2D, an image line is formed from the camera location and the viewing direction. When a pixel&apos;s color is being determined, a ray is built from the camera, through a point on the image line, and off into the scene. Let&apos;s look at the algebra of intersecting a ray with a line segment!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-4s4vYJnIW4.mp4/-4s4vYJnIW4.mp4</video:content_loc><video:duration>148</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/engageny-precalc/v/rendering-6</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x03b6b9b8.jpg</video:thumbnail_loc><video:title>2. Parametric form of a ray</video:title><video:description>This video introduces the parametric form of a ray in 2D. To find the intersection of a two-dimensional ray and a line segment, we use slope intercept form. But this method doesn&apos;t work in three dimensions! In 3D, we can represent a ray using a parametric function. This function, R(t), is a weighted average of two points, and it&apos;s super handy for naming points on the ray. Click here to review weighted averages of two points. Click here to review slope-intercept form of a line.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/oPTRwYdOEAM.mp4/oPTRwYdOEAM.mp4</video:content_loc><video:duration>183</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/engageny-precalc/v/rendering-7</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdd89aa6a.jpg</video:thumbnail_loc><video:title>3. Calculate intersection point</video:title><video:description>Now we are ready to calculate an intersection point using our ray in parametric form and our line in slope-intercept form. Different values of a parameter t locate different points on the ray. The intersection point we&apos;re looking for is one such point, so there&apos;s a value of t, t*, that gives us the intersection point! How do solve for t*?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Mm7ZmL9zfpQ.mp4/Mm7ZmL9zfpQ.mp4</video:content_loc><video:duration>162</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/engageny-precalc/v/rendering-8</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x637f7234.jpg</video:thumbnail_loc><video:title>4. Using the line equation</video:title><video:description>Vertical lines have an undefined slope, so how can we solve for the intersection point? Instead of using slope-intercept form, we need to use the line equation, or implicit form. Click here to see why dividing by zero is bad. Click here to try the interactive program shown in the video.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/b0cgLILc2Eo.mp4/b0cgLILc2Eo.mp4</video:content_loc><video:duration>154</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/engageny-precalc/v/rendering-9</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb97c6b84.jpg</video:thumbnail_loc><video:title>5. 3D ray tracing part 1</video:title><video:description>Now we are ready to ray trace in 3D! We&apos;ll look at the problem of ray triangle intersection. We can break down complex shapes, like characters, into smaller four-sided polygons, which we can then convert into triangles. Click here for more detail on the plane equation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/KCSGeTdjWiI.mp4/KCSGeTdjWiI.mp4</video:content_loc><video:duration>251</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/engageny-precalc/v/half-life</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/423007.jpg</video:thumbnail_loc><video:title>Half-life and carbon dating</video:title><video:description>Carbon dating is a real-life example of a first-order reaction. This video explains half-life in the context of radioactive decay.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9REPnibO4IQ.mp4/9REPnibO4IQ.mp4</video:content_loc><video:duration>751</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/physics/v/wave-interference-pulses</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8a690f5a.jpg</video:thumbnail_loc><video:title>Wave interference</video:title><video:description>Let&apos;s explore wave interference and solve a few examples to find the value of the total wave when two wave pulses overlap.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lpee2Qddqjo.mp4/lpee2Qddqjo.mp4</video:content_loc><video:duration>444</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/permutation-formula</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x26c39251.jpg</video:thumbnail_loc><video:title>Permutation formula</video:title><video:description>Want to learn about the permutation formula and how to apply it to tricky problems? Explore this useful technique by solving seating arrangement problems with factorial notation and a general formula. This video also demonstrates the benefits of deductive reasoning over memorization.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DROZVHObeko.mp4/DROZVHObeko.mp4</video:content_loc><video:duration>455</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/zero-factorial-or-0</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdb036a16.jpg</video:thumbnail_loc><video:title>Zero factorial or 0!</video:title><video:description>Learn all about factorials! Factorials are a quick way to represent multiplying a number by all the smaller positive integers down to one. This video also shows why mathematicians have defined zero factorial as one, instead of zero, to make the formula for permutations work in all cases.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/HGoZfzz6dU0.mp4/HGoZfzz6dU0.mp4</video:content_loc><video:duration>290</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/possible-three-letter-words</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x66bfedb8.jpg</video:thumbnail_loc><video:title>Possible three letter words</video:title><video:description>Sal explains how to find all of the possible three letter words when we can use each letter as many times as we want, and when each letter can only be used once.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/VYbqG2NuOo8.mp4/VYbqG2NuOo8.mp4</video:content_loc><video:duration>339</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/permutations-and-combinations-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/27097.jpg</video:thumbnail_loc><video:title>Ways to arrange colors</video:title><video:description>Thinking about how many ways you can pick four colors from a group of 6</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/oQpKtm5TtxU.mp4/oQpKtm5TtxU.mp4</video:content_loc><video:duration>225</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/permutations-and-combinations-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/27098.jpg</video:thumbnail_loc><video:title>Ways to pick officers</video:title><video:description>How many ways can we pick officers for our organization?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/v9NLtiVt3XY.mp4/v9NLtiVt3XY.mp4</video:content_loc><video:duration>139</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/introduction-to-combinations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe7fa4091.jpg</video:thumbnail_loc><video:title>Intro to combinations</video:title><video:description>Learn the difference between permutations and combinations, using the example of seating six people in three chairs. Permutations count the different arrangements of people in specific chairs, while combinations count the different groups of people, regardless of order or chair.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/iKy-d5_erhI.mp4/iKy-d5_erhI.mp4</video:content_loc><video:duration>378</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/combination-formula</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4a534332.jpg</video:thumbnail_loc><video:title>Combination formula</video:title><video:description>Learn the difference between permutations and combinations, and how to calculate them using factorials. This video also discusses binomial coefficients and the formula for combinations, nCk. Solidify your understanding with an example: how would one seat six people in four chairs?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/p8vIcmr_Pqo.mp4/p8vIcmr_Pqo.mp4</video:content_loc><video:duration>677</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/handshaking-combinations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x70c33285.jpg</video:thumbnail_loc><video:title>Handshaking combinations</video:title><video:description>Sal figures out how different combinations of people can shake hands.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/boH4l1SgJbM.mp4/boH4l1SgJbM.mp4</video:content_loc><video:duration>449</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/permutations-and-combinations-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/27099.jpg</video:thumbnail_loc><video:title>Combination example: 9 card hands</video:title><video:description>Thinking about how many ways we can construct a hand of 9 cards</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/SbpoyXTpC84.mp4/SbpoyXTpC84.mp4</video:content_loc><video:duration>462</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/getting-exactly-two-heads-combinatorics</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/193210641.jpg</video:thumbnail_loc><video:title>Getting exactly two heads (combinatorics)</video:title><video:description>A different way to think about the probability of getting 2 heads in 4 flips</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8TIben0bJpU.mp4/8TIben0bJpU.mp4</video:content_loc><video:duration>600</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/exactly-three-heads-in-five-flips</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/193210640.jpg</video:thumbnail_loc><video:title>Exactly three heads in five flips</video:title><video:description>Probability of exactly 3 heads in 5 flips using combinations</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/udG9KhNMKJw.mp4/udG9KhNMKJw.mp4</video:content_loc><video:duration>411</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/probability-of-dependent-events</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/27101.jpg</video:thumbnail_loc><video:title>Example: Different ways to pick officers</video:title><video:description>Thinking about the different ways we can pick officers in order to find the probability of one situation in particular.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/l9ft9jpriNA.mp4/l9ft9jpriNA.mp4</video:content_loc><video:duration>143</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/probability-of-dependent-events-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/27102.jpg</video:thumbnail_loc><video:title>Example: Combinatorics and probability</video:title><video:description>Probability of getting a set of cards</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ccrYD6iX_SY.mp4/ccrYD6iX_SY.mp4</video:content_loc><video:duration>651</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/permutations-and-combinations-4</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/27100.jpg</video:thumbnail_loc><video:title>Example: Lottery probability</video:title><video:description>What is the probability of winning a 4-number lottery?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DIjlllgq3dc.mp4/DIjlllgq3dc.mp4</video:content_loc><video:duration>310</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/mega-millions-jackpot-probability</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/690344673.jpg</video:thumbnail_loc><video:title>Mega millions jackpot probability</video:title><video:description>Probability of winning the Mega Millions jackpot</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gyqodNhM3EU.mp4/gyqodNhM3EU.mp4</video:content_loc><video:duration>330</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/random-variables</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1203203255.jpg</video:thumbnail_loc><video:title>Random variables</video:title><video:description>Basic idea and definitions of random variables</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3v9w79NhsfI.mp4/3v9w79NhsfI.mp4</video:content_loc><video:duration>332</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/discrete-and-continuous-random-variables</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1202908818.jpg</video:thumbnail_loc><video:title>Discrete and continuous random variables</video:title><video:description>Discrete random variables can only take on a finite number of values. For example, the outcome of rolling a die is a discrete random variable, as it can only land on one of six possible numbers. Continuous random variables, on the other hand, can take on any value in a given interval. For example, the mass of an animal would be a continuous random variable, as it could theoretically be any non-negative number.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/dOr0NKyD31Q.mp4/dOr0NKyD31Q.mp4</video:content_loc><video:duration>717</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/expected-value-profit-lottery-ticket</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf4ac78a7.jpg</video:thumbnail_loc><video:title>Expected profit from lottery ticket</video:title><video:description>Sal multiplies outcomes by probabilities to find the expected value of a lottery ticket.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6vlBOHckmzU.mp4/6vlBOHckmzU.mp4</video:content_loc><video:duration>558</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/expected-value-wager</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfd69eb4f.jpg</video:thumbnail_loc><video:title>Expected value while fishing</video:title><video:description>Sal walks through an example where he multiplies probability by values and sums to find expected value.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/86nb02Bx_5w.mp4/86nb02Bx_5w.mp4</video:content_loc><video:duration>504</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/expected-value-insurance</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb959145f.jpg</video:thumbnail_loc><video:title>Comparing insurance with expected value</video:title><video:description>Sal uses expected value to compare a couple of different insurance policies.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/BveA7JiRGS8.mp4/BveA7JiRGS8.mp4</video:content_loc><video:duration>556</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/financial-mathematics-tx-teks/v/estimating-total-postsecondary-costs</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd20e8eb13d5a526a.jpg</video:thumbnail_loc><video:title>Estimating total postsecondary costs</video:title><video:description>Calculate the total funding required to complete a desired postsecondary education program, accounting for increasing and fixed costs.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/wE_EKGUiJt0.mp4/wE_EKGUiJt0.mp4</video:content_loc><video:duration>205</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/financial-mathematics-tx-teks/v/roi-of-education</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x400018a305393ce1.jpg</video:thumbnail_loc><video:title>ROI of education</video:title><video:description>Calculating education return on investment (ROI) involves dividing the net benefit of a degree by the total investment required. One approach focuses strictly on cash flows, while a more comprehensive method incorporates opportunity costs like foregone wages during years of study. Accurate long-term evaluations should further consider factors such as wage growth, loan interest, and the time value of money.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OJfPASqhLUo.mp4/OJfPASqhLUo.mp4</video:content_loc><video:duration>386</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/financial-mathematics-tx-teks/v/cost-vs-career-comparison</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0f211796d101043c.jpg</video:thumbnail_loc><video:title>Cost vs career comparison</video:title><video:description>To determine if a four-year degree is financially worthwhile, one can use algebra to compare immediate employment earnings against the costs of education followed by a higher salary. This calculation accounts for both tuition expenses and the opportunity cost of lost wages during the years of study.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/dGaILHaNPbc.mp4/dGaILHaNPbc.mp4</video:content_loc><video:duration>285</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/financial-mathematics-tx-teks/v/employment-vocabulary</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8edcfd078dd0b822.jpg</video:thumbnail_loc><video:title>Employment vocabulary</video:title><video:description>When it comes to employment, the main ideas are understanding your wage rights, like minimum wage and overtime pay, and knowing the difference between a W2 employee and a 1099 contractor, which affects how you handle taxes.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LHwIGwc82K0.mp4/LHwIGwc82K0.mp4</video:content_loc><video:duration>372</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/financial-mathematics-tx-teks/v/calculating-gross-pay-with-overtime</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4900282326ac4b7e.jpg</video:thumbnail_loc><video:title>Calculating gross pay with overtime</video:title><video:description>Gross pay with overtime is calculated by paying regular hours at the normal hourly rate and any hours over 40 in a week at 1.5 times that rate. The total gross pay is the sum of regular pay and overtime pay.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qg-8X4JW5uk.mp4/qg-8X4JW5uk.mp4</video:content_loc><video:duration>148</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/financial-mathematics-tx-teks/v/calculating-pay-for-exempt-vs-non-exempt-employees</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x628e22ee67fd141f.jpg</video:thumbnail_loc><video:title>Calculating pay for exempt vs non-exempt employees</video:title><video:description>Sometimes non-exempt employees can earn more than exempt employees because they are paid overtime for extra hours worked. Exempt employees usually earn a fixed salary, so their pay doesn’t increase when they work longer hours.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/HxNI_2lfhJE.mp4/HxNI_2lfhJE.mp4</video:content_loc><video:duration>222</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/financial-mathematics-tx-teks/v/calculating-backpay</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7de0e7a14c8b2235.jpg</video:thumbnail_loc><video:title>Calculating back pay</video:title><video:description>Even when an employee is paid a flat amount, like $200 per week, the employer must ensure that the pay still meets minimum wage requirements based on hours worked. If it doesn’t, the employer is required to provide back pay to cover the shortfall.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LI2o3MNwEJ4.mp4/LI2o3MNwEJ4.mp4</video:content_loc><video:duration>78</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/financial-mathematics-tx-teks/v/calculating-wages-when-earning-tips</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x25213ccf4c424716.jpg</video:thumbnail_loc><video:title>Calculating wages when earning tips</video:title><video:description>When you earn tips, your employer is allowed to pay a lower base hourly wage, assuming tips will make up the difference. However, if your tips plus base pay don’t add up to at least the state minimum wage, your employer is required to cover the gap.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OrLn73I_pI0.mp4/OrLn73I_pI0.mp4</video:content_loc><video:duration>181</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/financial-mathematics-tx-teks/v/cost-of-using-credit-cards</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe7d9c3de014c87f7.jpg</video:thumbnail_loc><video:title>Cost of using credit cards</video:title><video:description>The cost of using a credit card includes more than just interest; it also includes various fees. Some fees are charged simply for having the card, such as an annual fee, while others are triggered by specific actions, such as making a foreign purchase or missing a payment.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pBM7Mf65axo.mp4/pBM7Mf65axo.mp4</video:content_loc><video:duration>232</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/financial-mathematics-tx-teks/v/estimating-life-insurance-needs</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6eab452a49dd7cae.jpg</video:thumbnail_loc><video:title>Estimating life insurance needs</video:title><video:description>Life insurance is essential for supporting your family financially and covering expenses like mortgages, debts, and education in the event of your death. You can estimate your coverage needs by simply multiplying your annual income by 10 to 15, or by precisely calculating your future financial obligations minus current assets.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/U5wgzYwQ6Os.mp4/U5wgzYwQ6Os.mp4</video:content_loc><video:duration>319</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/financial-mathematics-tx-teks/v/marginal-and-effective-tax-rates</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6c4d5767b4f3a2da.jpg</video:thumbnail_loc><video:title>Marginal and effective tax rates</video:title><video:description>Many people think moving into a higher tax bracket means all their income is taxed more. That myth comes from misunderstanding marginal vs. effective tax rates.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5YJcyw3r6Ww.mp4/5YJcyw3r6Ww.mp4</video:content_loc><video:duration>208</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/financial-mathematics-tx-teks/v/capital-gains-tax</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd0ef5b111b83e1ab.jpg</video:thumbnail_loc><video:title>Calculating capital gains tax</video:title><video:description>Capital gains tax is the tax you pay on the profit from selling an asset, such as stocks or real estate. The tax you pay depends on how long you’ve owned the asset. If you hold the asset for one year or less, the gain is short-term, while holding it for more than one year makes it a long-term gain, which is usually taxed at a lower rate.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ZYioN1rIHZE.mp4/ZYioN1rIHZE.mp4</video:content_loc><video:duration>273</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/financial-mathematics-tx-teks/v/calculating-tax-on-interest</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1ba0da35634a5737.jpg</video:thumbnail_loc><video:title>Calculating tax on interest</video:title><video:description>You pay taxes on interest income you earn from sources like savings accounts, bonds, or certificates of deposit. The government includes this interest in your taxable income and applies your regular income tax rate to it.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xrnsCEuEHsI.mp4/xrnsCEuEHsI.mp4</video:content_loc><video:duration>274</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/financial-mathematics-tx-teks/v/calculating-savings-when-paying-pre-tax</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf55d03f83e4f2765.jpg</video:thumbnail_loc><video:title>Calculating savings when paying pre-tax</video:title><video:description>Using pre-tax dollars to pay for expenses allows individuals to avoid paying income tax on that money, resulting in significant savings. This approach is more efficient than using after-tax dollars because it reduces the total amount of gross income needed to cover the same cost.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/QxVKAu-SbrE.mp4/QxVKAu-SbrE.mp4</video:content_loc><video:duration>150</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/financial-mathematics-tx-teks/v/what-determines-if-you-are-getting-a-tax-refund-or-bill</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x843aabca48892ee2.jpg</video:thumbnail_loc><video:title>What determines if you are getting a tax refund or bill?</video:title><video:description>Your employer takes federal income tax out of your paycheck, and that amount appears on your W-2. If they took out more than you actually owe, you get a refund; if they took out less, you have to pay the difference.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/oOwZygUZIN8.mp4/oOwZygUZIN8.mp4</video:content_loc><video:duration>229</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/financial-mathematics-tx-teks/v/charitable-contributions-as-tax-deductions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc3a550762b90ed60.jpg</video:thumbnail_loc><video:title>Charitable contributions as tax deductions</video:title><video:description>You can deduct charitable contributions you make to registered nonprofits or qualified charities, whether you take the standard deduction or itemize. To claim the deduction, add up your eligible donations, make sure you have a receipt for each one, and apply the applicable tax rules on your tax return.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/BfKDwIcFp-4.mp4/BfKDwIcFp-4.mp4</video:content_loc><video:duration>338</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/financial-mathematics-tx-teks/v/calculating-total-purchase-price-of-bonds</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa20073ec40d06ded.jpg</video:thumbnail_loc><video:title>Calculating total purchase price of bonds</video:title><video:description>Buying bonds typically involves more than just their market value, as investors must also account for commissions and accrued interest. This walkthrough explains how to factor in these additional costs to determine the total purchase price for a bulk investment.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7mSGhHarTFw.mp4/7mSGhHarTFw.mp4</video:content_loc><video:duration>283</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/financial-mathematics-tx-teks/v/calculating-proceeds-from-selling-bonds</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x145f36160e36f363.jpg</video:thumbnail_loc><video:title>Calculating proceeds from selling bonds</video:title><video:description>Selling bonds requires factoring in market price, broker commissions, and accrued interest to determine total proceeds. This video guides you through these calculations for corporate bonds, highlighting the industry&apos;s standard 30/360 day-count convention for determining interest earned between payment dates.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5tguTHQReQc.mp4/5tguTHQReQc.mp4</video:content_loc><video:duration>273</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/financial-mathematics-tx-teks/v/calculating-savings-for-financial-independence</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x87c806ba9b358940.jpg</video:thumbnail_loc><video:title>Calculating savings for financial independence</video:title><video:description>To reach financial independence, you calculate a total savings goal based on how much you plan to spend during retirement while accounting for inflation. Once you have that goal, you determine the yearly savings needed by factoring in the growth of your current assets and a steady investment return.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/htZjYFhfI9A.mp4/htZjYFhfI9A.mp4</video:content_loc><video:duration>462</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/financial-mathematics-tx-teks/v/calculating-savings-for-financial-independence-using-tvm-solver</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6b6618a68d4c4037.jpg</video:thumbnail_loc><video:title>Calculating savings for financial independence (using TVM solver)</video:title><video:description>To calculate savings needed for financial independence we can use a TVM (Time Value of Money) solver, available in many financial calculators, including TI-84.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Ytc9sPvgv-o.mp4/Ytc9sPvgv-o.mp4</video:content_loc><video:duration>327</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/financial-mathematics-tx-teks/v/calculating-and-graphing-exponential-functions-for-investing</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x854de0c8e9c62571.jpg</video:thumbnail_loc><video:title>Calculating and graphing exponential functions for investing</video:title><video:description>Starting to save early for retirement provides a significant long-term financial advantage over waiting to start later, even if a person contributes less money per month.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xHfwJ0ycE8s.mp4/xHfwJ0ycE8s.mp4</video:content_loc><video:duration>379</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/financial-mathematics-tx-teks/v/calculating-and-graphing-exponential-functions-for-investing-part-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5259e9adb8784c10.jpg</video:thumbnail_loc><video:title>Calculating and graphing exponential functions for investing (part 2)</video:title><video:description>Graphical analysis of exponential functions when it comes to investing.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/q6Hw5vsSTD4.mp4/q6Hw5vsSTD4.mp4</video:content_loc><video:duration>172</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/financial-mathematics-tx-teks/v/calculating-future-value-of-annuity</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb39e9ccb46201c9a.jpg</video:thumbnail_loc><video:title>Calculating future value of annuity</video:title><video:description>An ordinary annuity involves recurring payments made at the end of each compounding period, while an annuity due involves payments made at the beginning of each period. Because every payment in an annuity due has an extra period to compound interest, its total future value is higher and its growth graph will lie above that of an ordinary annuity.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4oulW0biqqg.mp4/4oulW0biqqg.mp4</video:content_loc><video:duration>348</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/financial-mathematics-tx-teks/v/early-withdrawals-and-penalties</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4e65d489a40eca25.jpg</video:thumbnail_loc><video:title>Early withdrawals and penalties</video:title><video:description>Early withdrawals from a Roth IRA only incur penalties and federal income taxes on the investment gains because the principal contributions consist of post-tax dollars. Conversely, an early withdrawal from a traditional 401(k) requires paying both penalties and income taxes on the entire amount withdrawn since it consists entirely of pre-tax money.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/AbNev7JKgKg.mp4/AbNev7JKgKg.mp4</video:content_loc><video:duration>221</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/euclid-as-the-father-of-geometry</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/611293511.jpg</video:thumbnail_loc><video:title>Euclid as the father of geometry</video:title><video:description>Euclid, often called the father of geometry, changed the way we learn about shapes with his 13-book series, Euclid&apos;s Elements. He used basic ideas called axioms or postulates to create solid proofs and figure out new ideas called theorems and propositions. Studying Euclidean geometry helps us think better and solve problems more effectively.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/WqzK3UAXaHs.mp4/WqzK3UAXaHs.mp4</video:content_loc><video:duration>503</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/geometric-precision-practice</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf56c1db9.jpg</video:thumbnail_loc><video:title>Geometric definitions example</video:title><video:description>Using precise language is important in geometry, as it allows for clear communication and understanding of geometric concepts. This video provides an interactive exercise that emphasizes the significance of accurate definitions, helping learners develop their mathematical communication skills and enhance their grasp of geometry.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/iDQ1foxYf0o.mp4/iDQ1foxYf0o.mp4</video:content_loc><video:duration>526</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/determing-a-translation-between-points</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4435dc5a.jpg</video:thumbnail_loc><video:title>Translation challenge problem</video:title><video:description>A translation acting on the coordinate plane takes the point (-169,434) to point (-203, -68). What are the coordinates of the image of point (31, -529) under this translation?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/nV8taxEW8-0.mp4/nV8taxEW8-0.mp4</video:content_loc><video:duration>194</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/dilating-shapes-shrinking</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7315a4e59ce93066.jpg</video:thumbnail_loc><video:title>Dilating shapes: shrinking</video:title><video:description>Draw the image of the triangle under a dilation with scale factor 1/4 about the center of dilation on the coordinate plane.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xAxgxUHzgaY.mp4/xAxgxUHzgaY.mp4</video:content_loc><video:duration>146</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/dilating-triangles-find-the-error</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd4418350026eb760.jpg</video:thumbnail_loc><video:title>Dilating triangles: find the error</video:title><video:description>Dilating doesn&apos;t just shrink or grow a figure. The scale factor also changes the distance from each point to the center of dilation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Kry9Bhp4PQg.mp4/Kry9Bhp4PQg.mp4</video:content_loc><video:duration>161</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/sequences-of-transformations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x682a7badb97ae737.jpg</video:thumbnail_loc><video:title>Sequences of transformations</video:title><video:description>Determining whether segment lengths and angle measures are preserved under a given sequence of transformations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/KFSBop9TZyI.mp4/KFSBop9TZyI.mp4</video:content_loc><video:duration>279</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/defining-transformations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x47fa972dba5c8314.jpg</video:thumbnail_loc><video:title>Defining transformations</video:title><video:description>Given a description of the effect of a certain transformation, we determine whether that transformation is a translation, a rotation, or a reflection.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4zvwNsou9vU.mp4/4zvwNsou9vU.mp4</video:content_loc><video:duration>385</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/possible-transformations-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x70ee9a30.jpg</video:thumbnail_loc><video:title>Identifying type of transformation</video:title><video:description>Sal is given information about a transformation in terms of a few pairs of points and their corresponding images, and he determines what kind of transformation it can be.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_eAWDuLYVfg.mp4/_eAWDuLYVfg.mp4</video:content_loc><video:duration>281</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/segment-congruence-equivalent-to-having-same-length</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb9c821ecc3070866.jpg</video:thumbnail_loc><video:title>Segment congruence equivalent to having same length</video:title><video:description>Two line segments are congruent if and only if they have equal lengths</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/WDHW-VZK3YI.mp4/WDHW-VZK3YI.mp4</video:content_loc><video:duration>405</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/angle-congruence-equivalent-to-having-same-measure</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x74b58778e74808bf.jpg</video:thumbnail_loc><video:title>Angle congruence equivalent to having same measure</video:title><video:description>Two angles are congruent if and only if they have the same measure.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/t41aV0XkYPQ.mp4/t41aV0XkYPQ.mp4</video:content_loc><video:duration>323</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/proving-the-sss-triangle-congruence-criterion-using-transformations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa38f9384e43310a2.jpg</video:thumbnail_loc><video:title>Proving the SSS triangle congruence criterion using transformations</video:title><video:description>We can prove the side-side-side (SSS) triangle congruence criterion using the rigid transformation definition of congruence.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OIRZd5mDu_o.mp4/OIRZd5mDu_o.mp4</video:content_loc><video:duration>347</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/proving-the-sas-triangle-congruence-criterion-using-transformations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0c3f4d86589e9208.jpg</video:thumbnail_loc><video:title>Proving the SAS triangle congruence criterion using transformations</video:title><video:description>We can prove the side-angle-side (SAS) triangle congruence criterion using the rigid transformation definition of congruence.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/CMTeCNILzwU.mp4/CMTeCNILzwU.mp4</video:content_loc><video:duration>271</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/proving-asa-and-aas-triangle-congruence</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd4ce5ee228f7781f.jpg</video:thumbnail_loc><video:title>Proving the ASA and AAS triangle congruence criteria using transformations</video:title><video:description>We can prove the angle-side-angle (ASA) and angle-angle-side (AAS) triangle congruence criteria using the rigid transformation definition of congruence.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5EX7tYQEB_M.mp4/5EX7tYQEB_M.mp4</video:content_loc><video:duration>444</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/calculating-angle-measures-to-verify-congruence</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xab0f842981801d8c.jpg</video:thumbnail_loc><video:title>Calculating angle measures to verify congruence</video:title><video:description>Calculate missing angle measures to determine which triangles must be congruent.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/i63Ruo2jj1E.mp4/i63Ruo2jj1E.mp4</video:content_loc><video:duration>269</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/proving-triangle-congruence</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xecf8b47700b9c9a3.jpg</video:thumbnail_loc><video:title>Proving triangle congruence</video:title><video:description>Given a figure composed of 2 triangles, prove that the triangles are congruent or determine that there&apos;s not enough information to tell.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Q8EtrFIHJuc.mp4/Q8EtrFIHJuc.mp4</video:content_loc><video:duration>258</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/another-isosceles-example-problem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/281570420.jpg</video:thumbnail_loc><video:title>Finding angles in isosceles triangles</video:title><video:description>The measures of two angles of an isosceles triangle are 3x+5 and x+16. Find all possible values of x.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ceDV0QBpcMA.mp4/ceDV0QBpcMA.mp4</video:content_loc><video:duration>334</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/example-involving-an-isosceles-triangle-and-parallel-lines</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/281570419.jpg</video:thumbnail_loc><video:title>Finding angles in isosceles triangles (example 2)</video:title><video:description>Sal combines what we know about isosceles triangles and parallel lines with the power of algebra to solve the angles of an isosceles triangle.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/CVKAro3HUxQ.mp4/CVKAro3HUxQ.mp4</video:content_loc><video:duration>195</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/geometric-constructions-congruent-angles</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdb60efded6941322.jpg</video:thumbnail_loc><video:title>Geometric constructions: congruent angles</video:title><video:description>We can construct congruent angles with a compass and straight edge. They&apos;re congruent corresponding angles of congruent triangles.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/D9UXfNc1ePs.mp4/D9UXfNc1ePs.mp4</video:content_loc><video:duration>249</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/constructing-parallel-lines</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xca8f02960808bf73.jpg</video:thumbnail_loc><video:title>Geometric constructions: parallel line</video:title><video:description>We can parallel lines with compass and straightedge by creating a pair of congruent corresponding angles on a transversal.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/BHLre3UiIho.mp4/BHLre3UiIho.mp4</video:content_loc><video:duration>123</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/geometric-constructions-perpendicular-line-through-a-point-not-on-the-line</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd06437d8694742d8.jpg</video:thumbnail_loc><video:title>Geometric constructions: perpendicular line through a point not on the line</video:title><video:description>We can construct a perpendicular line through a point off the line. The lines must be perpendicular because a rhombus&apos;s diagonals are perpendicular.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-ltjjKgGY7o.mp4/-ltjjKgGY7o.mp4</video:content_loc><video:duration>162</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/proof-parallel-lines-divide-triangle-sides-proportionally</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7d6e8a3bde72266c.jpg</video:thumbnail_loc><video:title>Proof: Parallel lines divide triangle sides proportionally</video:title><video:description>Prove that a line parallel to one triangle side divides other sides proportionately.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/L1c0SP4W4ro.mp4/L1c0SP4W4ro.mp4</video:content_loc><video:duration>392</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/multi-step-word-problem-with-pythagorean-theorem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6a2de3960f599c04.jpg</video:thumbnail_loc><video:title>Multi-step word problem with Pythagorean theorem</video:title><video:description>Use the Pythagorean theorem and proportional reasoning in context.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jVvpQAIrJ-o.mp4/jVvpQAIrJ-o.mp4</video:content_loc><video:duration>275</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/area-of-a-regular-hexagon</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/353965911.jpg</video:thumbnail_loc><video:title>Area of a regular hexagon</video:title><video:description>Using what we know about triangles to find the area of a regular hexagon</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LrxZMdQ6tiw.mp4/LrxZMdQ6tiw.mp4</video:content_loc><video:duration>471</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/using-similarity-to-estimate-ratio-between-side-lengths</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5dc8769cc2300a48.jpg</video:thumbnail_loc><video:title>Using similarity to estimate ratio between side lengths</video:title><video:description>When two right triangles share an acute angle measure, the ratios of the corresponding side lengths within the triangles are equal.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/M-jQMTWBuzQ.mp4/M-jQMTWBuzQ.mp4</video:content_loc><video:duration>275</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/using-right-triangle-ratios-to-approximate-angle-measure</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe4df20f25da310a0.jpg</video:thumbnail_loc><video:title>Using right triangle ratios to approximate angle measure</video:title><video:description>Because of similarity, all right triangles with a given acute angle measure have equal ratios between their side lengths. So if we know two of the side lengths of a right triangle, we can figure out the angle measures, too!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/fPXQTEYjF-o.mp4/fPXQTEYjF-o.mp4</video:content_loc><video:duration>186</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/example-relating-trig-function-to-side-ratios</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x98eb8563.jpg</video:thumbnail_loc><video:title>Trig challenge problem: trig values &amp; side ratios</video:title><video:description>Sal is given a diagram with multiple right triangles and is asked to match different expressions with different trig values.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/EBKNtjZAjXg.mp4/EBKNtjZAjXg.mp4</video:content_loc><video:duration>564</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/point-relative-to-circle</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4dbb5644.jpg</video:thumbnail_loc><video:title>Points inside/outside/on a circle</video:title><video:description>Sal uses the distance formula to determine whether the point (-6,-6) is inside, outside, or on the circle centered at (-1,-3) with radius 6.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/S6BHQMk8C_A.mp4/S6BHQMk8C_A.mp4</video:content_loc><video:duration>233</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/recognizing-points-on-a-circle</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x93881235.jpg</video:thumbnail_loc><video:title>Challenge problem: Points on two circles</video:title><video:description>Watch Sal solve a challenging problem where he has to determine if points are on both, one, or neither of two circles.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9ASWQi14FlE.mp4/9ASWQi14FlE.mp4</video:content_loc><video:duration>621</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/classfying-a-quadrilateral-on-the-coordinate-plane</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4f7e87ad.jpg</video:thumbnail_loc><video:title>Classifying quadrilaterals on the coordinate plane</video:title><video:description>Watch Sal classify a quadrilateral as a square, rhombus, rectangle, parallelogram, or trapezoid given its four vertices.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vsgrWDLEzcQ.mp4/vsgrWDLEzcQ.mp4</video:content_loc><video:duration>308</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/classifying-figures-with-coordinates</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5bf0f7821a0a4ca2.jpg</video:thumbnail_loc><video:title>Classifying figures with coordinates</video:title><video:description>Use coordinates to determine the slopes of sides of a figure in order to classify it.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2B5SQba9xSo.mp4/2B5SQba9xSo.mp4</video:content_loc><video:duration>417</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/language-and-notation-of-the-circle</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/261106564.jpg</video:thumbnail_loc><video:title>Circles glossary</video:title><video:description>Formal definition of a circle. Tangent and secant lines. Diameters and radii. major and minor arcs</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/U2W7HPyC0cM.mp4/U2W7HPyC0cM.mp4</video:content_loc><video:duration>672</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/radians-as-ratio-of-arc-length-to-radius</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7740664e9e4a71b9.jpg</video:thumbnail_loc><video:title>Radians as ratio of arc length to radius</video:title><video:description>Derive using similarity the fact that the length of the arc intercepted by an angle is proportional to the radius, and define the radian measure of the angle as the constant of proportionality.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9qrx0aqyhS8.mp4/9qrx0aqyhS8.mp4</video:content_loc><video:duration>400</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/dilating-in-3d</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd997f0a2af72c819.jpg</video:thumbnail_loc><video:title>Dilating in 3D</video:title><video:description>The cross sections of 3D shapes are dilations of the original shape, centered at a specific point. The scale factor of the dilation depends on the height of the cross-section or the distance from the point on the base.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3wTy5aI9AF4.mp4/3wTy5aI9AF4.mp4</video:content_loc><video:duration>273</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/rotating-2d-shapes-in-3d</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0c885529.jpg</video:thumbnail_loc><video:title>Rotating 2D shapes in 3D</video:title><video:description>If you rotate a 2D shape about an axis, the shape will define a 3D object. Watch Sal rotating various 2D shapes and see what 3D objects he gets!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vdpyWeiHXmU.mp4/vdpyWeiHXmU.mp4</video:content_loc><video:duration>252</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/area-density</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x878b740b72678000.jpg</video:thumbnail_loc><video:title>Area density</video:title><video:description>Area or surface density is the amount of a quantity (often mass) per unit of area. Density=Quantity/Area</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lqXzyybVh6o.mp4/lqXzyybVh6o.mp4</video:content_loc><video:duration>248</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry/v/volume-density</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2830fa495b885384.jpg</video:thumbnail_loc><video:title>Volume density</video:title><video:description>Volume density is the amount of a quantity (often mass) per unit of volume. Density=Quantity/Volume</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/QoKiCWCsSCo.mp4/QoKiCWCsSCo.mp4</video:content_loc><video:duration>243</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-fl-best/v/conditional-statements-and-logical-equivalence</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9279e643d902029b.jpg</video:thumbnail_loc><video:title>Conditional statements and logical equivalence</video:title><video:description>We assert that a conditional statement is true. Let&apos;s identify the converse, inverse, and contrapositive and determine whether each of them must be true based on the original statement.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5kojy1CHuyI.mp4/5kojy1CHuyI.mp4</video:content_loc><video:duration>344</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-fl-best/v/biconditional-statements</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb3e5f22c8d89d1a3.jpg</video:thumbnail_loc><video:title>Biconditional statements</video:title><video:description>For most conditional statements, swapping the &quot;if&quot; and the &quot;then&quot; parts creates a new statement, and the new statement might not have the same truth value as the original. Biconditional statements are conditional statements that are true regardless of which clause is the &quot;if&quot; and which is the &quot;then&quot; part.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/bs5YLyGHa60.mp4/bs5YLyGHa60.mp4</video:content_loc><video:duration>221</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-fl-best/v/weighted-average-two-points</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0ff0352e.jpg</video:thumbnail_loc><video:title>Weighted average of two points</video:title><video:description>How can we calculate a weighted average between two points? Instead of treating both points equally, we give more weight to one point than the other. For example, if we have two points A and B, and we want to find a point M that is closer to B, we might give B twice as much weight as A. In computer graphics, weighted averages help us find points along a line or curve exactly. This helps animators draw shapes smoothly, rather than guessing points, which might make the shape look jagged.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/SkdYqyCIh5g.mp4/SkdYqyCIh5g.mp4</video:content_loc><video:duration>237</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-fl-best/v/charactermodeling5</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9f3605b8.jpg</video:thumbnail_loc><video:title>Weighted average of three points</video:title><video:description>First, we&apos;ll review weighted averages of two points and extend the idea to three points. Computer graphics use weighted averages to help determine the shape and smoothness of curves. Each point&apos;s weight can influence the curve&apos;s direction and form. It&apos;s like each point is pulling the curve towards itself with a certain strength!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LzkL0Iik2B8.mp4/LzkL0Iik2B8.mp4</video:content_loc><video:duration>222</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math-1-illustrative-math-aligned/v/geometric-constructions-congruent-segments</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x884f0022ddc02a30.jpg</video:thumbnail_loc><video:title>Geometric constructions congruent segments</video:title><video:description>Let&apos;s construct a congruent line segment using a compass and a straightedge. All radii of a given circle are congruent, so we can use the compass to mark possible endpoints for a congruent line segment.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DyzeQO8M9z4.mp4/DyzeQO8M9z4.mp4</video:content_loc><video:duration>90</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math-1-illustrative-math-aligned/v/translations-graph-to-algebraic-rule</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc05f117decdb7326.jpg</video:thumbnail_loc><video:title>Translations: graph to algebraic rule</video:title><video:description>A worked example of going from a graph of a translation to an algebraic rule.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/se4o4QzKkTk.mp4/se4o4QzKkTk.mp4</video:content_loc><video:duration>141</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math-1-illustrative-math-aligned/v/translations-verbal-to-algebraic-rule</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd1beace66e3332dd.jpg</video:thumbnail_loc><video:title>Translations: description to algebraic rule</video:title><video:description>A worked example of going from a verbal description of a translation to an algebraic rule.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vO5d9iXcYtU.mp4/vO5d9iXcYtU.mp4</video:content_loc><video:duration>89</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math-1-illustrative-math-aligned/v/rotations-graph-to-algebraic-rule</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3576e424277c48f8.jpg</video:thumbnail_loc><video:title>Rotations: graph to algebraic rule</video:title><video:description>A worked example of going from a graph of a rotation to an algebraic rule.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/aZnEcR6ZRSw.mp4/aZnEcR6ZRSw.mp4</video:content_loc><video:duration>247</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math-1-illustrative-math-aligned/v/rotations-description-to-algebraic-rule</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x127a8adb0622871e.jpg</video:thumbnail_loc><video:title>Rotations: description to algebraic rule</video:title><video:description>A worked example of going from a verbal description of a rotation to an algebraic rule.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/JIFGwyphKXo.mp4/JIFGwyphKXo.mp4</video:content_loc><video:duration>255</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math-1-illustrative-math-aligned/v/reflections-graph-to-algebraic-rule</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x886cc4ee1c9af919.jpg</video:thumbnail_loc><video:title>Reflections: graph to algebraic rule</video:title><video:description>A worked example of going from a graph of a reflection to an algebraic rule.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/dXxfHjzql2M.mp4/dXxfHjzql2M.mp4</video:content_loc><video:duration>148</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math-1-illustrative-math-aligned/v/reflections-description-to-algebraic-rule</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9b532ca8cda073a2.jpg</video:thumbnail_loc><video:title>Reflections: description to algebraic rule</video:title><video:description>A worked example of going from a verbal description of a reflection to an algebraic rule.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/sJ8XrA4Vb_k.mp4/sJ8XrA4Vb_k.mp4</video:content_loc><video:duration>159</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math-1-illustrative-math-aligned/v/representing-dilations-algebraically-k-greater-than-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xff9c6418c253afd7.jpg</video:thumbnail_loc><video:title>Representing dilations algebraically, k greater than 1</video:title><video:description>Use an algebraic rule to represent a dilation with k &gt; 1.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OuBo1EomJJ8.mp4/OuBo1EomJJ8.mp4</video:content_loc><video:duration>236</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math-1-illustrative-math-aligned/v/representing-dilations-algebraically-k-less-than-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa20b4a4ff0df7bfa.jpg</video:thumbnail_loc><video:title>Representing dilations algebraically, k less than 1</video:title><video:description>Use an algebraic rule to represent a dilation with k less than 1.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/E5ScRFT4zl8.mp4/E5ScRFT4zl8.mp4</video:content_loc><video:duration>208</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-tx/v/rotating-algebraically-about-a-point</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x972c01e6d63db705.jpg</video:thumbnail_loc><video:title>Rotating algebraically about a point</video:title><video:description>Rotate a figure about a point other than the origin on the plane and with algebraic coordinate notation. We can do this by translating the plane so the center of rotation is at the origin, rotating about the origin, and then translating the plane back.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/c1qJuIxXOMY.mp4/c1qJuIxXOMY.mp4</video:content_loc><video:duration>455</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-tx/v/dilating-algebraically-about-a-point</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0ced15701e1c51cc.jpg</video:thumbnail_loc><video:title>Dilating algebraically about a point</video:title><video:description>Dilate a figure about a point other than the origin on the plane and in algebraic coordinate notation. We can do this by translating the plane so the center of dilation is at the origin, dilating about the origin, and then translating the plane back.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/CySwZBgM_j4.mp4/CySwZBgM_j4.mp4</video:content_loc><video:duration>315</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-tx/v/reflecting-over-yx</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xde030f04555404de.jpg</video:thumbnail_loc><video:title>Reflecting over y=x</video:title><video:description>Reflect a figure over the line y = x in the plane and with algebraic coordinate notation. This common transformation swaps the x- and y-coordinates of every point in the figure.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-47SHD2cPAY.mp4/-47SHD2cPAY.mp4</video:content_loc><video:duration>179</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-tx/v/reflecting-over-y-negative-x</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2e314c47dd967bdc.jpg</video:thumbnail_loc><video:title>Reflecting over y=-x</video:title><video:description>Reflect a figure over the line y = -x in the plane and in algebraic coordinate notation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/EydeoSJ3248.mp4/EydeoSJ3248.mp4</video:content_loc><video:duration>244</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math-1-illustrative-math-aligned/v/composing-transformations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2c374acbd5a18fc0.jpg</video:thumbnail_loc><video:title>Composing transformations</video:title><video:description>Graph the image of a ray after the composition of a dilation and a rotation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gYIBbDLYFY0.mp4/gYIBbDLYFY0.mp4</video:content_loc><video:duration>317</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-fl-best/v/trapezoid-midsegment-length</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x22628c7130e06c36.jpg</video:thumbnail_loc><video:title>Trapezoid midsegment length</video:title><video:description>Given the lengths of the 2 bases of a trapezoid (a quadrilateral with a pair of parallel sides), let&apos;s find the length of its midsegment.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Vc7s7Q7yeMg.mp4/Vc7s7Q7yeMg.mp4</video:content_loc><video:duration>93</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-fl-best/v/proof-trapezoid-midsegment-length</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x44b15056e7527831.jpg</video:thumbnail_loc><video:title>Proof: Trapezoid midsegment length</video:title><video:description>Let&apos;s prove that the midsegment of a trapezoid (the segment that joins the midpoints of the 2 legs) has a length equal to the average of the lengths of the two bases. We can use the properties of congruent and similar triangles to support our reasoning. This property holds true whether we define trapezoids has having at least one or exactly one pair of parallel sides.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_HEF49sraFg.mp4/_HEF49sraFg.mp4</video:content_loc><video:duration>419</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-fl-best/v/proof-base-angles-of-isosceles-trapezoids</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x14a9e4aee2dc304d.jpg</video:thumbnail_loc><video:title>Proof: Base angles of isosceles trapezoids</video:title><video:description>Let&apos;s prove that for isosceles trapezoids (quadrilaterals with one pair of parallel sides and one pair of congruent, non-parallel sides), the base angles are congruent. We can use triangle similarity and the properties of isosceles triangles to help us out.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xmdgp7LskQI.mp4/xmdgp7LskQI.mp4</video:content_loc><video:duration>399</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-fl-best/v/opposite-angles-of-isosceles-trapezoid</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x34cbb4f8c50283b7.jpg</video:thumbnail_loc><video:title>Opposite angles of isosceles trapezoid</video:title><video:description>Given one angle measure in an isosceles trapezoid (a quadrilateral with one pair of parallel sides and one pair of congruent, non-parallel sides), find the angle measure of the opposite angle.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/63kIeQgjOIM.mp4/63kIeQgjOIM.mp4</video:content_loc><video:duration>69</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-fl-best/v/trapezoid-diagonals-conjecture</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc658430fb5ef1b4c.jpg</video:thumbnail_loc><video:title>Trapezoid diagonals conjecture</video:title><video:description>What do you notice when you observe the diagonals in several different trapezoids (quadrilaterals with at least one pair of parallel sides)? Let&apos;s form a conjecture.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/uKuzHyUytfg.mp4/uKuzHyUytfg.mp4</video:content_loc><video:duration>261</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-fl-best/v/proof-diagonals-of-isosceles-trapezoid</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x68ea5409cd076556.jpg</video:thumbnail_loc><video:title>Proof: Diagonals of isosceles trapezoid</video:title><video:description>Let&apos;s prove that for isosceles trapezoids (quadrilaterals with exactly one pair of parallel sides and exactly one pair of congruent sides), the diagonals are congruent. We&apos;ll explore how our assumptions affect the generalizability of our proof.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/amfaIdh_QzM.mp4/amfaIdh_QzM.mp4</video:content_loc><video:duration>159</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-tx/v/applying-the-triangle-proportionality-theorem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x11032f25388fe977.jpg</video:thumbnail_loc><video:title>Applying the triangle proportionality theorem</video:title><video:description>Apply the triangle proportionality theorem to determine distances along roads split up by parallel roads.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Fc8JVfHAcQU.mp4/Fc8JVfHAcQU.mp4</video:content_loc><video:duration>278</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-tx/v/applying-similar-triangles</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3138d200955b8fc0.jpg</video:thumbnail_loc><video:title>Applying similar triangles</video:title><video:description>Recognize similar triangles in context and apply them to find a distance. Handle units appropriately.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/MlGOhzYn-QQ.mp4/MlGOhzYn-QQ.mp4</video:content_loc><video:duration>362</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-tx/v/finding-perimeter-of-shape-with-arcs</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7a59ff15ddb11307.jpg</video:thumbnail_loc><video:title>Finding perimeter of shape with arcs</video:title><video:description>Given a figure composed of parts of circles, find the exact perimeter in terms of pi. We can reason about the arc lengths based on the central angles of the arcs.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ybqHUv8cLVk.mp4/ybqHUv8cLVk.mp4</video:content_loc><video:duration>245</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-tx/v/finding-perimeter-of-shape-with-semicircles</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd6940d97dd122186.jpg</video:thumbnail_loc><video:title>Finding perimeter of shape with semicircles</video:title><video:description>Given a figure composed of semicircles, find the exact perimeter in terms of pi. The figure may look unusual, but we can break down the perimeter into very familiar shapes.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/nh56seaS6iA.mp4/nh56seaS6iA.mp4</video:content_loc><video:duration>119</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-tx/v/proof-the-product-of-the-segments-of-intersecting-chords</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xda57be7098fc4d4b.jpg</video:thumbnail_loc><video:title>Proof The product of the segments of intersecting chords</video:title><video:description>Let&apos;s prove the general case that the product of the segments of intersecting chords are equal. We&apos;ll create similar triangles and use the properties of inscribed angles and vertical angles to convince ourselves that this is always true.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3hV7ZXxal7k.mp4/3hV7ZXxal7k.mp4</video:content_loc><video:duration>284</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-tx/v/proof-angle-formed-by-intersecting-chords</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x07af2979a99b576d.jpg</video:thumbnail_loc><video:title>Proof: Angle formed by intersecting chords</video:title><video:description>Let&apos;s prove that the angle formed by intersecting chords is half the sum of the measures of the intercepted arcs. We&apos;ll construct a triangle, then use the properties of inscribed angles to convince ourselves that this is always true.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/nxHUx1o8-sA.mp4/nxHUx1o8-sA.mp4</video:content_loc><video:duration>270</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-fl-best/v/proof-angle-between-a-tangent-and-a-chord</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc7c4467ee35f0c1d.jpg</video:thumbnail_loc><video:title>Proof: Angle between a tangent and a chord</video:title><video:description>Let&apos;s prove that the measure of the angle formed by the intersection of a tangent and a chord is half the measure of the intercepted arc. We&apos;ll construct an isosceles triangle and use the relationship between radii and tangents of a circle to convince ourselves that this is true for both the major and minor arcs formed.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hbdvuygTlMA.mp4/hbdvuygTlMA.mp4</video:content_loc><video:duration>328</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-tx/v/proof-diameter-that-bisects-a-chord</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7949a19d6e45cb88.jpg</video:thumbnail_loc><video:title>Proof: Diameter that bisects a chord</video:title><video:description>Let&apos;s prove that if a diameter of a circle bisects a chord, it is perpendicular to the chord. We&apos;ll construct congruent triangles to convince ourselves that this is always true.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/diQqp7pWxZY.mp4/diQqp7pWxZY.mp4</video:content_loc><video:duration>124</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-tx/v/proof-the-product-of-segments-of-intersecting-secants</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4bb776e0c2237cb0.jpg</video:thumbnail_loc><video:title>Proof: The product of segments of intersecting secants</video:title><video:description>Let&apos;s prove that the product of the length of a secant segment and its external segment is equal to the product of the other secant segment and its external segment from the same point outside the circle. We&apos;ll construct similar triangles and use the properties of inscribed triangles to convince ourselves that this is always true.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/J3FpOlIkH3Q.mp4/J3FpOlIkH3Q.mp4</video:content_loc><video:duration>190</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-tx/v/proof-angle-formed-by-intersecting-secants</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x67af77fb0561fcdf.jpg</video:thumbnail_loc><video:title>Proof: Angle formed by intersecting secants</video:title><video:description>Let&apos;s prove that the measure of the angle formed by 2 secants intersecting at a point outside the circle is half the difference of the measures of the intercepted arcs. We&apos;ll construct a triangle and use the properties of inscribed angles to convince ourselves that this is always true.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/dHP6PxXlrV0.mp4/dHP6PxXlrV0.mp4</video:content_loc><video:duration>272</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-tx/v/proof-the-product-of-segments-of-intersecting-secant-and-tangent</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x75ffbc79aaf64530.jpg</video:thumbnail_loc><video:title>Proof: The product of segments of intersecting secant and tangent</video:title><video:description>Let&apos;s prove that the product of the length of a secant segment and its external segment is equal to the square of the length of the tangent segment intersecting the secant segment at a point outside the circle. We&apos;ll construct a pair of similar triangles and use the properties of inscribed angles, tangents, and chords to convince ourselves that this is always true.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/BnpRSGP4TTE.mp4/BnpRSGP4TTE.mp4</video:content_loc><video:duration>246</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-tx/v/proof-angle-between-a-tangent-and-a-secant</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2f6a05c9eb504b22.jpg</video:thumbnail_loc><video:title>Proof: Angle between a tangent and a secant</video:title><video:description>Prove that the measure of the angle formed by a secant and a tangent intersecting at a point outside the circle is half the difference of the measures of the intercepted arcs. We&apos;ll construct a triangle, then use the properties of inscribed angles, tangents, and chords to convince ourselves that this is always true.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OzeHAwjaG60.mp4/OzeHAwjaG60.mp4</video:content_loc><video:duration>208</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-tx/v/area-between-sector-and-triangle</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x93ae9db2045a25b5.jpg</video:thumbnail_loc><video:title>Area between sector and triangle</video:title><video:description>Find the area of a figure composed subtractively of a sector and special right triangles.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/RlOXnhTujDQ.mp4/RlOXnhTujDQ.mp4</video:content_loc><video:duration>235</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-tx/v/composite-area-related-to-circles</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x98800953c7f04271.jpg</video:thumbnail_loc><video:title>Composite area related to circles</video:title><video:description>Let&apos;s decompose a figure into a square and quarter circles to find its total area.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_cF1cwv2EQU.mp4/_cF1cwv2EQU.mp4</video:content_loc><video:duration>150</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/area-of-an-equilateral-triangle</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/294658865.jpg</video:thumbnail_loc><video:title>Area of equilateral triangle</video:title><video:description>Finding the formula for the area of an equilateral triangle with side s</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/UKQ65tiIQ6o.mp4/UKQ65tiIQ6o.mp4</video:content_loc><video:duration>222</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-tx/v/area-of-regular-polygon-given-side-length</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb114845fdb9afb49.jpg</video:thumbnail_loc><video:title>Area of regular polygon given side length</video:title><video:description>Given the side length of a regular polygon, find its area. The area of a regular polygon is 1/2 * (apothem length) * perimeter. We can split the polygon into congruent right triangles. Then trigonometric ratios help us find the apothem length based on the side length and angle measures.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/a6dbxqVWOf4.mp4/a6dbxqVWOf4.mp4</video:content_loc><video:duration>345</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-tx/v/area-of-regular-polygon-given-radius</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7e3d93cf201c061d.jpg</video:thumbnail_loc><video:title>Area of regular polygon given radius</video:title><video:description>Given the radius of a regular polygon, find its area. The area of a regular polygon is 1/2 * (apothem length) * perimeter. We can split the polygon into congruent right triangles. Then trigonometric ratios help us find the apothem length and side length based on the radius length and angle measures.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9LlgG6l5eXU.mp4/9LlgG6l5eXU.mp4</video:content_loc><video:duration>333</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/area-of-shaded-region-made-from-equilateral-triangles</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd65354b0.jpg</video:thumbnail_loc><video:title>Area of equilateral triangle (advanced)</video:title><video:description>Sal finds a shaded area defined by two equilateral triangles whose side lengths are given.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/QVxqgxVtKbs.mp4/QVxqgxVtKbs.mp4</video:content_loc><video:duration>337</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-fl-best/v/surface-area-of-a-rectangular-pyramid</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xce7d93d890d7a558.jpg</video:thumbnail_loc><video:title>Surface area of a rectangular pyramid</video:title><video:description>Given a right rectangular (non-square) pyramid with the dimensions of the base and the height of the pyramid, let&apos;s find the lateral and total surface area. We&apos;ll use the Pythagorean theorem to find the slant heights of the lateral faces.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/zNL3W-rXbY0.mp4/zNL3W-rXbY0.mp4</video:content_loc><video:duration>338</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-fl-best/v/surface-area-of-a-cone</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x516666bbb90f1329.jpg</video:thumbnail_loc><video:title>Surface area of a cone</video:title><video:description>To find the surface area of a right circular cone, we can draw its net, which looks like a circle and a sector. Let&apos;s build intuition for where the general formulas for lateral surface area and total surface area of a cone come from, then apply them to a specific cone.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9w6qYXatwkM.mp4/9w6qYXatwkM.mp4</video:content_loc><video:duration>376</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-fl-best/v/surface-area-of-an-octagonal-pyramid</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb145ced3d8e9fb95.jpg</video:thumbnail_loc><video:title>Surface area of an octagonal pyramid</video:title><video:description>Given a right pyramid with a regular octagon as the base, let&apos;s find the lateral and total surface area. Since the base is a regular octagon, we can use trigonometric ratios to help find the areas of the base and the lateral faces.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Pfoy2IW7oHw.mp4/Pfoy2IW7oHw.mp4</video:content_loc><video:duration>442</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-fl-best/v/surface-area-of-sphere-computation-and-sense-of-formula</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdb17394461c959ae.jpg</video:thumbnail_loc><video:title>Surface area of sphere: computation and sense of formula</video:title><video:description>Why Is the formula for surface area of sphere equal to 4pir^2? And applying its formula to find the surface area.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/IZ4DpWYO3kY.mp4/IZ4DpWYO3kY.mp4</video:content_loc><video:duration>270</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-8-math-tx/v/scaling-perimeter-and-area-example-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xaa96b0e015db384b.jpg</video:thumbnail_loc><video:title>Scaling perimeter and area example 1</video:title><video:description>Given a dilation and its scale factor, predict the effect of that dilation on the perimeter and area of a figure.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DAt886IH4Cw.mp4/DAt886IH4Cw.mp4</video:content_loc><video:duration>204</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-8-math-tx/v/scaling-perimeter-and-area-example-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x069e25bd8241d871.jpg</video:thumbnail_loc><video:title>Scaling perimeter and area example 2</video:title><video:description>Given a dilation and its scale factor, predict the effect of that dilation on the perimeter and area of a figure.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/bp8DSaYrvF0.mp4/bp8DSaYrvF0.mp4</video:content_loc><video:duration>163</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/identifying-rays</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/372432665.jpg</video:thumbnail_loc><video:title>Identifying rays</video:title><video:description>A ray is a shape that starts at one point and extends forever in one direction. To identify a ray in a picture, look for a line that has one endpoint (the point where the ray starts) and an arrow on the other end (to show that it keeps going).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/w9jEq6dmqPg.mp4/w9jEq6dmqPg.mp4</video:content_loc><video:duration>340</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/measuring-segments</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc6f1d2f0.jpg</video:thumbnail_loc><video:title>Measuring Line Segments</video:title><video:description>In this example of measuring a line segment, the numbers span across the positive and negative. Remember, line segments and points are the foundations of geometry, so this is an important concept.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/y-O_B-wWivQ.mp4/y-O_B-wWivQ.mp4</video:content_loc><video:duration>89</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/congruent-segments</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa1695c23.jpg</video:thumbnail_loc><video:title>Congruent line segments</video:title><video:description>Two line segments on a number line are congruent if they have the same length. To check, you can count the number of units between the two endpoints of each line segment. If the counts are the same, the line segments are congruent.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/bJF9R8_-0O0.mp4/bJF9R8_-0O0.mp4</video:content_loc><video:duration>61</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/the-golden-ratio</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/294676192.jpg</video:thumbnail_loc><video:title>The golden ratio</video:title><video:description>An introduction to one of the most amazing ideas/numbers in mathematics</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5zosU6XTgSY.mp4/5zosU6XTgSY.mp4</video:content_loc><video:duration>882</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/vertical-adjacent-and-linearly-paired-angles</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x40ad80ea.jpg</video:thumbnail_loc><video:title>Angle relationships example</video:title><video:description>Sal finds a linear pair, vertical angles, and adjacent angles from a diagram.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vAlazPPFlyY.mp4/vAlazPPFlyY.mp4</video:content_loc><video:duration>283</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/proof-corresponding-angle-equivalence-implies-parallel-lines</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/265540641.jpg</video:thumbnail_loc><video:title>Parallel lines &amp; corresponding angles proof</video:title><video:description>Proof by contradiction that corresponding angle equivalence implies parallel lines</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9_3OxtdqmqE.mp4/9_3OxtdqmqE.mp4</video:content_loc><video:duration>318</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/ca-geometry-deducing-angle-measures</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24456.jpg</video:thumbnail_loc><video:title>Missing angles (CA geometry)</video:title><video:description>46-50, deducing the measure of angles.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_HJljJuVHLw.mp4/_HJljJuVHLw.mp4</video:content_loc><video:duration>658</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/introduction-to-angles-old</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24939.jpg</video:thumbnail_loc><video:title>Intro to angles (old)</video:title><video:description>What an angle is. Angles in a circle. Complementary and supplementary angles.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2439OIVBgPg.mp4/2439OIVBgPg.mp4</video:content_loc><video:duration>595</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/angles-part-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24941.jpg</video:thumbnail_loc><video:title>Angles (part 2)</video:title><video:description>More on complementary and supplementary angles. Introduction to opposite angles.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/zrqzG6xKa1A.mp4/zrqzG6xKa1A.mp4</video:content_loc><video:duration>544</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/angles-part-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24943.jpg</video:thumbnail_loc><video:title>Angles (part 3)</video:title><video:description>Angles formed when a transversal intersects parallel lines.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/NLg6hfoKKlE.mp4/NLg6hfoKKlE.mp4</video:content_loc><video:duration>587</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/angles-formed-between-transversals-and-parallel-lines</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/2600797.jpg</video:thumbnail_loc><video:title>Angles formed between transversals and parallel lines</video:title><video:description>Angles of parallel lines</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gRKZaojKeP0.mp4/gRKZaojKeP0.mp4</video:content_loc><video:duration>473</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/angles-of-parallel-lines-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/2600798.jpg</video:thumbnail_loc><video:title>Angles of parallel lines 2</video:title><video:description>Angles of parallel lines examples</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0eDwckZOffc.mp4/0eDwckZOffc.mp4</video:content_loc><video:duration>315</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/the-angle-game</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24947.jpg</video:thumbnail_loc><video:title>The angle game</video:title><video:description>Using what we know to solve for angles in the Angle Game.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/kqU_ymV581c.mp4/kqU_ymV581c.mp4</video:content_loc><video:duration>541</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/angle-game-part-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24953.jpg</video:thumbnail_loc><video:title>The angle game (part 2)</video:title><video:description>More examples of the Angle Game.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ko-cYG3d6ec.mp4/ko-cYG3d6ec.mp4</video:content_loc><video:duration>589</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/intro-to-curves-basic-geometrical-ideas-class-6-india-khan-academy</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x73b10c58108327fa.jpg</video:thumbnail_loc><video:title>Intro to curves</video:title><video:description>In daily language, we all use the word curve to mean &quot;not straight&quot; but does the word curve have the same meaning in math? Can a straight line be a curve? Also, what makes a curve a &apos;simple curve&apos;?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/EhmPK6iLz0Q.mp4/EhmPK6iLz0Q.mp4</video:content_loc><video:duration>412</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/polygons-as-special-curves-basic-geometrical-ideas-class-6-india-khan-academy</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x50a7930413204e35.jpg</video:thumbnail_loc><video:title>Polygons as special curves</video:title><video:description>You may have learnt that triangles, rectangles etc. are all examples of polygons but that circles are not. What exactly makes a curve a polygon?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hGRu2Pyl92w.mp4/hGRu2Pyl92w.mp4</video:content_loc><video:duration>193</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/sum-of-interior-angles-of-a-polygon</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/287107579.jpg</video:thumbnail_loc><video:title>Sum of interior angles of a polygon</video:title><video:description>To find the interior angle sum of a polygon, we can use a formula: interior angle sum = (n - 2) x 180°, where n is the number of sides. For example, a pentagon has 5 sides, so its interior angle sum is (5 - 2) x 180° = 3 x 180° = 540°.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qG3HnRccrQU.mp4/qG3HnRccrQU.mp4</video:content_loc><video:duration>550</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/sum-of-the-exterior-angles-of-convex-polygon</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/272207189.jpg</video:thumbnail_loc><video:title>Sum of the exterior angles of a polygon</video:title><video:description>Learn a simple and elegant way to find the sum of the exterior angles of any convex polygon. You will see how to redraw the angles adjacent to each other and form a circle. Then you will discover that the sum of the exterior angles is always 360 degrees. Watch this video to master this important skill in geometry.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/W9B3VYdC5T8.mp4/W9B3VYdC5T8.mp4</video:content_loc><video:duration>324</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/circumcenter-of-a-triangle</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/298421783.jpg</video:thumbnail_loc><video:title>Circumcenter of a triangle</video:title><video:description>To prove that any point on the perpendicular bisector of a segment is equidistant from the endpoints, draw the segment and bisector, and note that the bisector creates two right triangles. By the definition of a perpendicular bisector, the hypotenuses of these triangles are congruent. Using the Pythagorean theorem, show that the two right triangles are congruent, and thus the point on the bisector is equidistant from the two endpoints. Other proofs are also included in the video.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/KXZ6w91DioU.mp4/KXZ6w91DioU.mp4</video:content_loc><video:duration>749</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/circumcenter-of-a-right-triangle</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/298435073.jpg</video:thumbnail_loc><video:title>Circumcenter of a right triangle</video:title><video:description>Showing that the midpoint of the hypotenuse is the circumcenter</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/VejCw2NlE60.mp4/VejCw2NlE60.mp4</video:content_loc><video:duration>342</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/three-points-defining-a-circle</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/309312179.jpg</video:thumbnail_loc><video:title>Three points defining a circle</video:title><video:description>Three points uniquely define a circle. If you circumscribe a circle around a triangle, the circumcenter of that triangle will also be the center of that circle.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4_xhiP6g2ow.mp4/4_xhiP6g2ow.mp4</video:content_loc><video:duration>608</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/area-circumradius-formula-proof</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179257.jpg</video:thumbnail_loc><video:title>Area circumradius formula proof</video:title><video:description>Proof of the formula relating the area of a triangle to its circumradius</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/x_aax6LSRtE.mp4/x_aax6LSRtE.mp4</video:content_loc><video:duration>546</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/2003-aime-ii-problem-7</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179269.jpg</video:thumbnail_loc><video:title>2003 AIME II problem 7</video:title><video:description>Find the area of rhombus ABCD given that the radii of the circles circumscribed about triangles ABD and ACD</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jpKjXtywTlQ.mp4/jpKjXtywTlQ.mp4</video:content_loc><video:duration>793</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/point-line-distance-and-angle-bisectors</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/309312178.jpg</video:thumbnail_loc><video:title>Distance between a point &amp; line</video:title><video:description>Thinking about the distance between a point and a line. Proof that a point on an angle bisector is equidistant to the sides of the angle and a point equidistant to the sides is on an angle bisector.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/yj4oS-27Q3k.mp4/yj4oS-27Q3k.mp4</video:content_loc><video:duration>657</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/inradius-perimeter-and-area</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/311447418.jpg</video:thumbnail_loc><video:title>Inradius, perimeter, &amp; area</video:title><video:description>Showing that area is equal to inradius times semiperimeter</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5NjgcPri07E.mp4/5NjgcPri07E.mp4</video:content_loc><video:duration>449</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/common-orthocenter-and-centroid</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/337196124.jpg</video:thumbnail_loc><video:title>Common orthocenter and centroid</video:title><video:description>If the orthocenter and centroid are the same point, then the triangle is equilateral. This is because the orthocenter is the intersection of the altitudes, which are also the medians and the angle bisectors in an equilateral triangle. The centroid is the intersection of the medians, which divide the triangle into six congruent triangles. Therefore, the orthocenter and the centroid coincide only when the triangle has three equal sides and angles.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pDZIvyeqX1o.mp4/pDZIvyeqX1o.mp4</video:content_loc><video:duration>385</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/review-of-triangle-properties</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/326408404.jpg</video:thumbnail_loc><video:title>Review of triangle properties</video:title><video:description>Comparing perpendicular bisectors to angle bisectors to medians to altitudes.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/KUhdMbx5ges.mp4/KUhdMbx5ges.mp4</video:content_loc><video:duration>597</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/euler-line</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/326395669.jpg</video:thumbnail_loc><video:title>Euler line</video:title><video:description>The magic and mystery of the Euler Line</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tUqyJgmGY7k.mp4/tUqyJgmGY7k.mp4</video:content_loc><video:duration>372</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/euler-s-line-proof</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/334522802.jpg</video:thumbnail_loc><video:title>Euler&apos;s line proof</video:title><video:description>Proving the somewhat mystical result that the circumcenter, centroid, and orthocenter all sit on the same line.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/t_EgAi574sM.mp4/t_EgAi574sM.mp4</video:content_loc><video:duration>590</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/whether-a-special-quadrilateral-can-exist</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/897531450.jpg</video:thumbnail_loc><video:title>Whether a special quadrilateral can exist</video:title><video:description>Proving whether a special quadrilateral can exist or not.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6dIMIBO_2mc.mp4/6dIMIBO_2mc.mp4</video:content_loc><video:duration>308</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/rhombus-diagonals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179268.jpg</video:thumbnail_loc><video:title>Rhombus diagonals</video:title><video:description>To show why the diagonals of a rhombus are perpendicular, we can rotate the rhombus to look like a diamond and draw one diagonal as a horizontal line. Then, we can use the fact that the top and bottom triangles are congruent and isosceles to drop altitudes from the vertices to the horizontal diagonal. These altitudes form the other diagonal, which is perpendicular and bisects the horizontal one. Similarly, the horizontal diagonal bisects the other one.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_QTFeOvPcbY.mp4/_QTFeOvPcbY.mp4</video:content_loc><video:duration>278</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/drawing-polygons-exercise-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x657ad7a6.jpg</video:thumbnail_loc><video:title>Drawing a trapezoid on the coordinate plane example</video:title><video:description>Watch Sal solve an example problem where he draws an isosceles trapezoid on the coordinate plane.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/yZw8z5BIwuQ.mp4/yZw8z5BIwuQ.mp4</video:content_loc><video:duration>162</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/measuring-area-with-partial-unit-squares-math-3rd-grade-khan-academy</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x97dab21a.jpg</video:thumbnail_loc><video:title>Measuring area with partial unit squares</video:title><video:description>Lindsay finds the area of a shape by counting whole and partial unit squares.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/YA7ZrKcbteA.mp4/YA7ZrKcbteA.mp4</video:content_loc><video:duration>196</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/perimeter-and-unit-conversion</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/153770150.jpg</video:thumbnail_loc><video:title>Perimeter and unit conversion</video:title><video:description>Sal converts metric unit to help solve a perimeter problem.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/q9XCrpLPfGk.mp4/q9XCrpLPfGk.mp4</video:content_loc><video:duration>373</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/applying-the-metric-system</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/32.jpg</video:thumbnail_loc><video:title>Applying the metric system to perimeter</video:title><video:description>How do you find width of a rectangle if given a length and a perimeter? First, make sure that your units match. Once the units match, use the formula for the perimeter of a rectangle (2 times the length plus 2 times the width) to solve for the width.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/CDvPPsB3nEM.mp4/CDvPPsB3nEM.mp4</video:content_loc><video:duration>343</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/triangle-area-proofs</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/283213902.jpg</video:thumbnail_loc><video:title>Area of triangle proof</video:title><video:description>Proof that shows that the area of any triangle is 1/2 b x h.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/YOYQys52sPs.mp4/YOYQys52sPs.mp4</video:content_loc><video:duration>623</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/interesting-perimeter-and-area-problems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/283213903.jpg</video:thumbnail_loc><video:title>Challenge problems: perimeter &amp; area</video:title><video:description>Three example problems involving perimeter and area.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vWXMDIazHjA.mp4/vWXMDIazHjA.mp4</video:content_loc><video:duration>493</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/area-of-diagonal-generated-triangles-of-rectangle-are-equal</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/2600582.jpg</video:thumbnail_loc><video:title>Area of diagonal-generated triangles</video:title><video:description>Watch Sal prove that the areas of the pairs of triangles generated by the diagonals of a rectangle are equal.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/YTRimTJ5nX4.mp4/YTRimTJ5nX4.mp4</video:content_loc><video:duration>276</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/conversion-between-metric-units</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/30.jpg</video:thumbnail_loc><video:title>Conversion between metric units</video:title><video:description>Want to learn how to convert between different units of volume using prefixes like kilo, hecto, deka, deci, centi, and milli? In this video, you&apos;ll see how to use these prefixes to compare centiliters and dekaliters, and how to use dimensional analysis to convert one dekaliter to centiliters. You&apos;ll also get some tips on how to check your answers and avoid common mistakes. Watch now and master this useful skill!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/SYkmadc2wOI.mp4/SYkmadc2wOI.mp4</video:content_loc><video:duration>316</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/density-example-blimp</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa13c840d.jpg</video:thumbnail_loc><video:title>Density word problem: blimp</video:title><video:description>Sal solves a word problem about the number of passengers a blimp can carry, using his knowledge of volume and density.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/YbNVUhW-HJM.mp4/YbNVUhW-HJM.mp4</video:content_loc><video:duration>365</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/koch-snowflake-fractal</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/283213904.jpg</video:thumbnail_loc><video:title>Koch snowflake fractal</video:title><video:description>A shape that has an infinite perimeter but finite area</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/azBNsPa1WC4.mp4/azBNsPa1WC4.mp4</video:content_loc><video:duration>551</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/area-of-koch-snowflake-part-1-advanced</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/294677477.jpg</video:thumbnail_loc><video:title>Area of Koch snowflake (1 of 2)</video:title><video:description>Starting to figure out the area of a Koch Snowflake (which has an infinite perimeter). This is an advanced video.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/64bH_27Ehoc.mp4/64bH_27Ehoc.mp4</video:content_loc><video:duration>750</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/area-of-koch-snowflake-part-2-advanced</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/294676175.jpg</video:thumbnail_loc><video:title>Area of Koch snowflake (2 of 2)</video:title><video:description>Summing an infinite geometric series to finally find the finite area of a Koch Snowflake. This is an advanced video.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vBlR2xNAGmo.mp4/vBlR2xNAGmo.mp4</video:content_loc><video:duration>392</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/heron-s-formula</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24971.jpg</video:thumbnail_loc><video:title>Heron&apos;s formula</video:title><video:description>Using Heron&apos;s Formula to determine the area of a triangle while only knowing the lengths of the sides</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-YI6UC4qVEY.mp4/-YI6UC4qVEY.mp4</video:content_loc><video:duration>283</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/part-1-of-proof-of-heron-s-formula</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24973.jpg</video:thumbnail_loc><video:title>Proof of Heron&apos;s formula (1 of 2)</video:title><video:description>Sal proves Heron&apos;s Formula for finding the area of a triangle solely from its side lengths.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/AreOMvPCxv8.mp4/AreOMvPCxv8.mp4</video:content_loc><video:duration>659</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/part-2-of-the-proof-of-heron-s-formula</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24975.jpg</video:thumbnail_loc><video:title>Proof of Heron&apos;s formula (2 of 2)</video:title><video:description>Sal proves Heron&apos;s Formula for finding the area of a triangle solely from its side lengths.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/nZu7IZLhJRI.mp4/nZu7IZLhJRI.mp4</video:content_loc><video:duration>728</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/rotating-about-arbitrary-point</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd2c751b0.jpg</video:thumbnail_loc><video:title>Rotating shapes: center ≠ (0,0)</video:title><video:description>Sal is given a triangle on the coordinate plane and the definition of a rotation about an arbitrary point, and he manually draws the image of that rotation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/uuDQkhx6TAI.mp4/uuDQkhx6TAI.mp4</video:content_loc><video:duration>632</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/translations-of-polygons</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0bee44bd.jpg</video:thumbnail_loc><video:title>Performing translations (old)</video:title><video:description>An older video where Sal uses the interactive widget to find the image of a rectangle under a translation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/u9B-dV6r6rU.mp4/u9B-dV6r6rU.mp4</video:content_loc><video:duration>65</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/rotating-segment-about-orgin-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x68aec32a.jpg</video:thumbnail_loc><video:title>Performing rotations (old)</video:title><video:description>An older video where Sal uses the interactive widget to find the image of a line segment under a rotation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/sQfsql8BPy0.mp4/sQfsql8BPy0.mp4</video:content_loc><video:duration>77</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/reflection-and-mapping-points-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0482ccff.jpg</video:thumbnail_loc><video:title>Performing reflections: rectangle (old)</video:title><video:description>An older video where Sal uses the interactive widget to find the image of a rectangle under a reflection.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Y70TTv5ZLkk.mp4/Y70TTv5ZLkk.mp4</video:content_loc><video:duration>146</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/reflecting-line-across-another-line-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0ed71769.jpg</video:thumbnail_loc><video:title>Performing reflections: line (old)</video:title><video:description>An older video where Sal uses the interactive widget to find the image of a line under a reflection.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0VARkb_n-Bs.mp4/0VARkb_n-Bs.mp4</video:content_loc><video:duration>76</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/determining-a-translation-for-a-shape</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdc65b657.jpg</video:thumbnail_loc><video:title>Determining translations (old)</video:title><video:description>An older video of Sal determining what translation was performed on a shape to result in another shape.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ZhROXmbUVKE.mp4/ZhROXmbUVKE.mp4</video:content_loc><video:duration>46</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/rotation-of-polygons-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd50b8c60.jpg</video:thumbnail_loc><video:title>Rotation examples (old)</video:title><video:description>An older video where Sal finds the images of shapes under various rotations, and where he determines the rotations that take one shape to another.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Hur3v1hrX3U.mp4/Hur3v1hrX3U.mp4</video:content_loc><video:duration>147</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/performing-a-rotation-to-match-figures</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd12e1d3c.jpg</video:thumbnail_loc><video:title>Determining rotations (old)</video:title><video:description>An older video where Sal determines the rotation that takes one shape to another.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/QWX39H9kKvE.mp4/QWX39H9kKvE.mp4</video:content_loc><video:duration>119</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/dilating-one-line-onto-another</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa41fb2ec.jpg</video:thumbnail_loc><video:title>Dilating lines</video:title><video:description>Sal shows how we can use dilations to map a line into another, parallel, line.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jq6WFvMikBQ.mp4/jq6WFvMikBQ.mp4</video:content_loc><video:duration>239</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/example-with-trig-functions-and-ratios</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x835650f9.jpg</video:thumbnail_loc><video:title>Trig challenge problem: verify identities</video:title><video:description>Sal is given a diagram with multiple right triangles and is asked to verify identities relating to trig ratios in those triangles.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TugWqiUjOU4.mp4/TugWqiUjOU4.mp4</video:content_loc><video:duration>307</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/area-of-inscribed-equilateral-triangle-some-basic-trig-used</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24979.jpg</video:thumbnail_loc><video:title>Area of inscribed equilateral triangle</video:title><video:description>A worked example of finding the area of an equilateral triangle inscribed within a circle who&apos;s area is known. This video uses Heron&apos;s formula and some trigonometry.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/UmiZK6Hgm6c.mp4/UmiZK6Hgm6c.mp4</video:content_loc><video:duration>699</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/challenging-perimeter-problem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/283213900.jpg</video:thumbnail_loc><video:title>Challenging perimeter problem</video:title><video:description>Perimeter of rectangle covered by 9 non-overlapping squares. From 2000 American Invitational Math Exam</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1uWZNW5PF-s.mp4/1uWZNW5PF-s.mp4</video:content_loc><video:duration>596</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/ca-geometry-deductive-reasoning</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24434.jpg</video:thumbnail_loc><video:title>CA Geometry: Deductive reasoning</video:title><video:description>1-3, deductive reasoning and congruent angles</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/GluohfOedQE.mp4/GluohfOedQE.mp4</video:content_loc><video:duration>617</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/ca-geometry-proof-by-contradiction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24436.jpg</video:thumbnail_loc><video:title>CA Geometry: Proof by contradiction</video:title><video:description>4-6, proof by contradiction</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/u6O0YHyarlI.mp4/u6O0YHyarlI.mp4</video:content_loc><video:duration>716</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/ca-geometry-more-proofs</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24438.jpg</video:thumbnail_loc><video:title>CA Geometry: More proofs</video:title><video:description>How do you evaluate answer choices about isosceles trapezoids? You start by drawing an isosceles trapezoid and comparing each answer choice against your drawing. The answer will then become obvious.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4PPMnI8-Zsc.mp4/4PPMnI8-Zsc.mp4</video:content_loc><video:duration>732</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/ca-geometry-similar-triangles-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/4802217.jpg</video:thumbnail_loc><video:title>CA Geometry: Similar triangles 1</video:title><video:description>10-14, similar triangles</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/bWTtHKSEcdI.mp4/bWTtHKSEcdI.mp4</video:content_loc><video:duration>775</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/ca-geometry-more-on-congruent-and-similar-triangles</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24444.jpg</video:thumbnail_loc><video:title>CA Geometry: More on congruent and similar triangles</video:title><video:description>17-20, more similar and congruent triangles</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/FVSgVMVZZ-4.mp4/FVSgVMVZZ-4.mp4</video:content_loc><video:duration>671</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/ca-geometry-triangles-and-parallelograms</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24446.jpg</video:thumbnail_loc><video:title>CA Geometry: Triangles and parallelograms</video:title><video:description>21-25, triangles and parallelograms</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/h0FFEBHBufo.mp4/h0FFEBHBufo.mp4</video:content_loc><video:duration>674</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/ca-geometry-area-pythagorean-theorem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24448.jpg</video:thumbnail_loc><video:title>CA Geometry: Area, pythagorean theorem</video:title><video:description>26-30, area, circumference, pythagorean theorem</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jRrRqMJbHKc.mp4/jRrRqMJbHKc.mp4</video:content_loc><video:duration>619</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/ca-geometry-area-circumference-volume</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24450.jpg</video:thumbnail_loc><video:title>CA Geometry: Area, circumference, volume</video:title><video:description>31-35, area, circumference and volume</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/BJSk1joCQsM.mp4/BJSk1joCQsM.mp4</video:content_loc><video:duration>653</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/ca-geometry-pythagorean-theorem-area</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24452.jpg</video:thumbnail_loc><video:title>CA Geometry: Pythagorean theorem, area</video:title><video:description>36-40, Pythagorean Theorem and Area</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vaOXkt7uuac.mp4/vaOXkt7uuac.mp4</video:content_loc><video:duration>644</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/ca-geometry-exterior-angles</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24454.jpg</video:thumbnail_loc><video:title>CA Geometry: Exterior angles</video:title><video:description>41-45, polygons, exterior angles</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Ncg1HB5uVLc.mp4/Ncg1HB5uVLc.mp4</video:content_loc><video:duration>653</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/ca-geometry-pythagorean-theorem-compass-constructions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24458.jpg</video:thumbnail_loc><video:title>CA Geometry: Pythagorean theorem, compass constructions</video:title><video:description>51-55, Pythagorean Theorem, compass constructions</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6EY0E3z-hsU.mp4/6EY0E3z-hsU.mp4</video:content_loc><video:duration>755</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/ca-geometry-compass-construction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24460.jpg</video:thumbnail_loc><video:title>CA Geometry: Compass construction</video:title><video:description>56-60, compass construction, coordinates</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/79lagkER9qY.mp4/79lagkER9qY.mp4</video:content_loc><video:duration>769</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/ca-geometry-basic-trigonometry</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24462.jpg</video:thumbnail_loc><video:title>CA Geometry: Basic trigonometry</video:title><video:description>61-65, basic trigonometry</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/MyvRxKM0xns.mp4/MyvRxKM0xns.mp4</video:content_loc><video:duration>664</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/ca-geometry-more-trig</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24464.jpg</video:thumbnail_loc><video:title>CA Geometry: More trig</video:title><video:description>66-70, more trigonometry</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8YBQQ0GeusM.mp4/8YBQQ0GeusM.mp4</video:content_loc><video:duration>741</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/ca-geometry-circle-area-chords-tangent</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24466.jpg</video:thumbnail_loc><video:title>CA Geometry: Circle area chords tangent</video:title><video:description>71-75, area, chords, tangents of circles</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/FJIZPvE3O1A.mp4/FJIZPvE3O1A.mp4</video:content_loc><video:duration>606</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-home/v/speed-translation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25779.jpg</video:thumbnail_loc><video:title>Speed translation</video:title><video:description>Sal converts feet to inches to help solve a rate problem.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/aTjNDKlz8G4.mp4/aTjNDKlz8G4.mp4</video:content_loc><video:duration>597</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-tx/v/how-sure-are-we</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc4de5f7be17bea94.jpg</video:thumbnail_loc><video:title>How sure are we?</video:title><video:description>In geometry, science, and in many areas of life, we have vocabulary to describe how sure we are. Conjecture: A statement that we believe is always true because we have seen many examples of it and no counterexamples. Postulate: A statement that we believe is always true because people generally agree it is true, but without proof. Theorem: A statement that we believe is always true because we prove it by a series of other definitions, postulates, and theorems.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/a9TUKHWY3TA.mp4/a9TUKHWY3TA.mp4</video:content_loc><video:duration>470</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-tx/v/definitions-and-undefined-terms</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb54ca5d9da4618bc.jpg</video:thumbnail_loc><video:title>Definitions and undefined terms</video:title><video:description>Much of geometry depends on building our ideas from foundational pieces. We use definitions to be very clear about what we mean by a right angle, similar figures, or a line segments. If we go to the very base of even those definitions, we have to agree on some ideas, like what we mean by a point or a line, without being able to simply and clearly define them.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/J_u_ROMJR8U.mp4/J_u_ROMJR8U.mp4</video:content_loc><video:duration>252</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-tx/v/dividing-line-segments-on-number-line</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1ac7ec290ea4af56.jpg</video:thumbnail_loc><video:title>Dividing line segments on number line</video:title><video:description>Given two points on a vertical number line with rational numbers, find the point that is a fractional distance between them.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/aGAmPyfmLRA.mp4/aGAmPyfmLRA.mp4</video:content_loc><video:duration>118</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math-1-illustrative-math-aligned/v/triangle-altitude-equation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc1e9720bd4c91ffc.jpg</video:thumbnail_loc><video:title>Triangle altitude equation</video:title><video:description>Given a triangle on a coordinate plane and a base that is neither horizontal nor vertical, let&apos;s find the equation of the line that contains the altitude of the triangle relative to that base. We can use the fact that the slope of the altitude is perpendicular to the slope of the base. That means the two slopes are opposite reciprocals of each other.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Cb1XT3_hQwM.mp4/Cb1XT3_hQwM.mp4</video:content_loc><video:duration>272</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math-1-illustrative-math-aligned/v/graphing-a-non-similar-pre-image-algebraically</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9995776eb6824399.jpg</video:thumbnail_loc><video:title>Graphing a non similar pre image algebraically</video:title><video:description>Given an image of a geometric figure and the algebraic rule that describes the transformations it is under, graph the pre-image. The composition of transformations the figure is under do not preserve congruence and similarity.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/wkhQNXyW01U.mp4/wkhQNXyW01U.mp4</video:content_loc><video:duration>219</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-tx/v/surface-area-of-combination-of-solids-surface-area-and-volume</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3e873a83e0a930b6.jpg</video:thumbnail_loc><video:title>Area of combination of solids</video:title><video:description>Let&apos;s learn how to find the surface area of combination of solids by breaking them down into cuboids, cylinders, cones, and hemispheres with the help of an example.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/QDQw66_TeaE.mp4/QDQw66_TeaE.mp4</video:content_loc><video:duration>570</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-tx/v/surface-area-of-combination-of-solids-problem-types</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x71bc517f7d43b4be.jpg</video:thumbnail_loc><video:title>Problem types: surface area of combination of solids</video:title><video:description>Let&apos;s look at a few common types of problems involving &apos;surface area of a combination of solids&apos; and look at broad strategies on how to solve them and what mistakes to watch out for.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3CGBz05r1r4.mp4/3CGBz05r1r4.mp4</video:content_loc><video:duration>358</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-tx/v/volume-of-combination-of-solids</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x80ad6049d7bd7c3e.jpg</video:thumbnail_loc><video:title>Volume of combination of solids</video:title><video:description>Let&apos;s learn how to find the volume of a complicated solid by breaking it down into cylinders, cones, hemispheres, and cuboids.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ANc85RET5Fk.mp4/ANc85RET5Fk.mp4</video:content_loc><video:duration>531</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-tx/v/volume-of-combination-solids-problem-types</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4120b3651d8de779.jpg</video:thumbnail_loc><video:title>Problem types: volume of combination of solids</video:title><video:description>Let&apos;s look at a few common types of problems involving &apos;volume of a combination of solids&apos; and look at broad strategies on how to solve them and the mistakes to watch out for.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/feiSEqpPmAA.mp4/feiSEqpPmAA.mp4</video:content_loc><video:duration>207</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-tx/v/curved-surface-area-of-a-frustum-surface-areas-and-volumes</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9a90fe08f4a994e4.jpg</video:thumbnail_loc><video:title>Curved surface area of a frustum</video:title><video:description>Let&apos;s learn how to find the curved surface area of a frustum of a cone through an example. Let&apos;s use the intuitive approach rather than directly plugging into the formula.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Ft-2DJ0UPN8.mp4/Ft-2DJ0UPN8.mp4</video:content_loc><video:duration>454</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-tx/v/volume-of-a-frustum</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3b57ab88f8c04520.jpg</video:thumbnail_loc><video:title>Volume of a frustum</video:title><video:description>Let&apos;s learn how to find the volume of a frustum by looking at an example problem. Let&apos;s use an intuitive approach to find the volume rather than directly applying the formula.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Xn9pHi5u_Fw.mp4/Xn9pHi5u_Fw.mp4</video:content_loc><video:duration>461</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/interpreting-general-multiplication-rule</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xccee087782f2d0dc.jpg</video:thumbnail_loc><video:title>Interpreting general multiplication rule</video:title><video:description>We can express the probability that two events both occur symbolically using the general multiplication rule, and we can interpret probability statements that are expressed symbolically.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/yTJawPRzCzI.mp4/yTJawPRzCzI.mp4</video:content_loc><video:duration>291</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/independent-events-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/27094.jpg</video:thumbnail_loc><video:title>Independent &amp; dependent probability</video:title><video:description>This time around we&apos;re not going to tell you whether we&apos;re working on a dependent or independent probability event problem. You tell us!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Za7G_eWKiF4.mp4/Za7G_eWKiF4.mp4</video:content_loc><video:duration>159</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/factorial-and-counting-seat-arrangements</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc7e724ce.jpg</video:thumbnail_loc><video:title>Factorial and counting seat arrangements</video:title><video:description>Learn how to use permutations to solve problems involving ways to arrange things. Permutations involve using factorials to count all possible arrangements. This video also explores examples including arranging three people in three seats and five people in five seats.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/eoxbgUIYhHo.mp4/eoxbgUIYhHo.mp4</video:content_loc><video:duration>333</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/geometry-tx/v/area-based-probability</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x77208ef925158449.jpg</video:thumbnail_loc><video:title>Finding area-based probabilities</video:title><video:description>Let&apos;s use area models to compare the theoretical probabilities of a dart landing in the shaded area of different dartboard designs. The probability of landing in the shaded region is (area of shaded region)/(total area).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5biGkYiu548.mp4/5biGkYiu548.mp4</video:content_loc><video:duration>478</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/get-ready-for-8th-grade/v/order-of-operations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/2600695.jpg</video:thumbnail_loc><video:title>Order of operations example</video:title><video:description>The order of operations tells us the order to solve steps in expressions with more than one operation. First, we solve any operations inside of parentheses or brackets. Second, we solve any exponents. Third, we solve all multiplication and division from left to right. Fourth, we solve all addition and subtraction from left to right.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/GiSpzFKI5_w.mp4/GiSpzFKI5_w.mp4</video:content_loc><video:duration>267</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/meaningfully-composing-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x467bc55a8fd4e34a.jpg</video:thumbnail_loc><video:title>Meaningfully composing functions</video:title><video:description>Decide which composed functions make sense by checking that the value that one function passes to the other is the right kind of input.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/q9JGGVXdl9I.mp4/q9JGGVXdl9I.mp4</video:content_loc><video:duration>221</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/monty-hall-problem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/878209052.jpg</video:thumbnail_loc><video:title>The Monty Hall problem</video:title><video:description>Here we have a presentation and analysis of the famous thought experiment: the &quot;Monty Hall&quot; problem! This is fun.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Xp6V_lO1ZKA.mp4/Xp6V_lO1ZKA.mp4</video:content_loc><video:duration>443</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/describing-subsets-of-sample-spaces-exercise</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9c78221b.jpg</video:thumbnail_loc><video:title>Subsets of sample spaces</video:title><video:description>Sal solves an example about subsets.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0uHhk7P9SNo.mp4/0uHhk7P9SNo.mp4</video:content_loc><video:duration>344</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/relative-complement-or-difference-between-sets</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4cc5bca0.jpg</video:thumbnail_loc><video:title>Relative complement or difference between sets</video:title><video:description>Sal shows an example finding the relative complement or difference of two sets A and B.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2B4EBvVvf9w.mp4/2B4EBvVvf9w.mp4</video:content_loc><video:duration>375</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/universal-set-and-absolute-complement</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x66808e41.jpg</video:thumbnail_loc><video:title>Universal set and absolute complement</video:title><video:description>Sal moves onto more challenging set ideas and notation like the universal set and absolute complement.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/GVZUpOm3XUg.mp4/GVZUpOm3XUg.mp4</video:content_loc><video:duration>386</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/subset-strict-subset-and-superset</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf762eb2f.jpg</video:thumbnail_loc><video:title>Subset, strict subset, and superset</video:title><video:description>A subset of a set A is any set B such that every element of B is also an element of A. A strict subset is a subset that isn&apos;t equal to the original set (i.e. B must have at least one fewer element than A). A superset of A is any set C such that A is a subset of C.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1wsF9GpGd00.mp4/1wsF9GpGd00.mp4</video:content_loc><video:duration>272</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/bringing-the-set-operations-together</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x614a90bd.jpg</video:thumbnail_loc><video:title>Bringing the set operations together</video:title><video:description>Sal summarizes the set operations that he has discussed in the previous videos.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OCNXS_m1HWU.mp4/OCNXS_m1HWU.mp4</video:content_loc><video:duration>388</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-3-tx-teks/v/decomposing-whole-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6c0238e88ea647fc.jpg</video:thumbnail_loc><video:title>Decomposing whole numbers</video:title><video:description>Sal looks at a number written in standard form and figures out how we can say the number by decomposing the parts.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/JzdD_5SO9ns.mp4/JzdD_5SO9ns.mp4</video:content_loc><video:duration>168</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-3-tx-teks/v/decomposing-whole-numbers-in-word-form</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc68a26c4dd26b66d.jpg</video:thumbnail_loc><video:title>Decomposing whole numbers in word form</video:title><video:description>Sal looks at a number presented in word form and uses a place value chart to put the number together to find the value.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jcRfhk2FAlA.mp4/jcRfhk2FAlA.mp4</video:content_loc><video:duration>184</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-3-tx-teks/v/finding-consecutive-multiples-10-and-100</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8fc0056299fccf07.jpg</video:thumbnail_loc><video:title>Finding consecutive multiples (10 and 100)</video:title><video:description>Sal uses a number line to find the nearest consecutive multiple of a given number.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vuq2HHx9lso.mp4/vuq2HHx9lso.mp4</video:content_loc><video:duration>94</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-3-tx-teks/v/finding-consecutive-multiples-1000-and-10000</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbc4e751b145dc4b8.jpg</video:thumbnail_loc><video:title>Finding consecutive multiples (1,000 and 10,000)</video:title><video:description>Sal uses a number line to determine which of three points is closest to a given number. By using rounding, Sal finds the nearest consecutive multiple to the nearest 10,000.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pkNmgdcb7XY.mp4/pkNmgdcb7XY.mp4</video:content_loc><video:duration>81</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-3-tx-teks/v/creating-picture-and-bar-graphs-indian-accent</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe21eebba75272cb4.jpg</video:thumbnail_loc><video:title>Creating picture and bar graphs</video:title><video:description>Sal creates and interprets bar and picture graphs.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2QrLG7VuAG0.mp4/2QrLG7VuAG0.mp4</video:content_loc><video:duration>279</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-3-tx-teks/v/creating-a-bar-graph-indian-accent</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x115e9fa0847ee23b.jpg</video:thumbnail_loc><video:title>Creating a bar graph</video:title><video:description>Sal creates a bar chart using data from a survey.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DuaUm9dz5HQ.mp4/DuaUm9dz5HQ.mp4</video:content_loc><video:duration>67</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-3-tx-teks/v/what-is-labor-and-income</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x363d781c008685ea.jpg</video:thumbnail_loc><video:title>What is labor and income?</video:title><video:description>Build on students’ understanding that money earned is called income by helping them explain how labor—which includes a person’s skills, education, and training—can affect how much income they earn. Students will explore different jobs, find out how much education or training each one usually requires, and compare the average salaries. They will look for patterns between how long someone goes to school and how much money they might make in different careers.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/nHD2N5gHXj4.mp4/nHD2N5gHXj4.mp4</video:content_loc><video:duration>337</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-3-tx-teks/v/what-is-credit</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4b87a324e5d884bb.jpg</video:thumbnail_loc><video:title>What is credit?</video:title><video:description>Learn all about credit! Credit is used when wants or needs exceed the ability to pay and that it is the borrower&apos;s responsibility to pay it back to the lender, usually with interest.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/zdBrsvkhdeU.mp4/zdBrsvkhdeU.mp4</video:content_loc><video:duration>289</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-3-tx-teks/v/what-is-a-savings-plan</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x870ae54d7c1a8721.jpg</video:thumbnail_loc><video:title>What is a savings plan?</video:title><video:description>What is a savings plane? Understand the reasons to save and find out the benefits of saving (e.g., saving for college, surviving hard financial times, being prepared for unforeseen expenses, setting goals, etc.).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Q4T2ipCuAPo.mp4/Q4T2ipCuAPo.mp4</video:content_loc><video:duration>243</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-3-tx-teks/v/what-are-costs-and-resources</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc24c03ca7fd2572a.jpg</video:thumbnail_loc><video:title>What are costs and resources?</video:title><video:description>Describe the relationship between the availability or scarcity of resources and how that impacts cost. Students learn to analyze data as they explore the relationship between supply and demand.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/dMM2eiK-ejI.mp4/dMM2eiK-ejI.mp4</video:content_loc><video:duration>334</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-3-tx-teks/v/classifying-three-dimensional-shapes</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbcfc1ea87c975ea0.jpg</video:thumbnail_loc><video:title>Classifying three dimensional shapes</video:title><video:description>Identify prisms, pyramids, cones, cylinders, and spheres.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4VgPJkh16_I.mp4/4VgPJkh16_I.mp4</video:content_loc><video:duration>189</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-4-math-tx/v/representing-multi-step-problems-equations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x51b1362bf3c8c4b0.jpg</video:thumbnail_loc><video:title>Representing multi-step problems: equations</video:title><video:description>Practice using equations to represent multi-step word problems.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DGOGterRmp4.mp4/DGOGterRmp4.mp4</video:content_loc><video:duration>160</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-4-math-tx/v/subtracting-decimals-farmers-market</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0c89b404d0ed1364.jpg</video:thumbnail_loc><video:title>Subtracting decimals: farmer&apos;s market</video:title><video:description>Practice solving problems by subtracting decimals.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DpEHVSdiRko.mp4/DpEHVSdiRko.mp4</video:content_loc><video:duration>137</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-4-math-tx/v/input-output-tables-finding-the-output</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x95a19b145d90db2c.jpg</video:thumbnail_loc><video:title>Input &amp; output tables: finding the output</video:title><video:description>Practice using pattern recognition to identify outputs in input and output tables.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9Hdo_OO19uM.mp4/9Hdo_OO19uM.mp4</video:content_loc><video:duration>55</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-4-math-tx/v/input-output-tables-identifying-the-rule</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x43c0a18d96ee68e4.jpg</video:thumbnail_loc><video:title>Input &amp; output tables: identifying the rule</video:title><video:description>Practice using pattern recognition to identify rules in an input and output table.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Y9oW96dhzg0.mp4/Y9oW96dhzg0.mp4</video:content_loc><video:duration>110</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-4-math-tx/v/calculating-profit-with-additions-and-subtraction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xaf77f2e7e2b273be.jpg</video:thumbnail_loc><video:title>Calculating profit with addition and subtraction</video:title><video:description>Explore how to calculate profit using addition and subtraction in this clear, real-world 4th-grade math video with helpful examples.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/kkzQfhQYr_E.mp4/kkzQfhQYr_E.mp4</video:content_loc><video:duration>305</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-4-math-tx/v/calculating-profit-with-multiplication</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdfd83434e77760c9.jpg</video:thumbnail_loc><video:title>Calculating profit with multiplication</video:title><video:description>Learn how to calculate profit using multiplication in this simple 4th grade video with real-world examples and easy math strategies.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/iCA78yjz_HY.mp4/iCA78yjz_HY.mp4</video:content_loc><video:duration>352</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-4-math-tx/v/finding-total-money-saved</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4caac52f7d7d8411.jpg</video:thumbnail_loc><video:title>Finding total money saved</video:title><video:description>Learn how to find the total money saved by adding and multiplying.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3eaTDJKGRqw.mp4/3eaTDJKGRqw.mp4</video:content_loc><video:duration>93</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-4-math-tx/v/calculating-savings</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7c956fe75ee68c37.jpg</video:thumbnail_loc><video:title>Calculating savings</video:title><video:description>Let&apos;s calculate how long it takes to reach a savings goal.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jDRN7fMZ-P4.mp4/jDRN7fMZ-P4.mp4</video:content_loc><video:duration>57</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-5-math-tx/v/estimating-multi-digit-sums</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb11f0227129b67f1.jpg</video:thumbnail_loc><video:title>Estimating multi-digit sums</video:title><video:description>Use estimation to add multi-digit numbers.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/NAXN_dlQ4JA.mp4/NAXN_dlQ4JA.mp4</video:content_loc><video:duration>163</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-5-math-tx/v/estimating-to-subtract-multi-digit-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6925339e71a2d542.jpg</video:thumbnail_loc><video:title>Estimating to subtract multi-digit numbers</video:title><video:description>Practice using estimation as a strategy to subtract multi-digit numbers to find the difference.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/GbosTJIyuSA.mp4/GbosTJIyuSA.mp4</video:content_loc><video:duration>117</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-5-math-tx/v/dividing-2-digit-numbers-by-2-digit-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xef1b342be09bede8.jpg</video:thumbnail_loc><video:title>Dividing 2-digit numbers by 2-digit numbers</video:title><video:description>Practice dividing 2-digit numbers by 2-digit numbers.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/sF1iIsW219s.mp4/sF1iIsW219s.mp4</video:content_loc><video:duration>172</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-5-math-tx/v/dividing-3-digit-numbers-by-2-digit-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x848a8820d51fc4e4.jpg</video:thumbnail_loc><video:title>Dividing 3-digit numbers by 2-digit numbers</video:title><video:description>Practice dividing 3-digit whole numbers by 2-digit whole numbers using different strategies.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/F6BNkk91XKc.mp4/F6BNkk91XKc.mp4</video:content_loc><video:duration>203</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-5-math-tx/v/simplifying-numerical-expressions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb4150d7796fa2444.jpg</video:thumbnail_loc><video:title>Simplifying numerical expressions</video:title><video:description>Practice using brackets and parentheses to simplify numerical expressions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/YrjnKwxdlr4.mp4/YrjnKwxdlr4.mp4</video:content_loc><video:duration>182</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-5-math-tx/v/what-are-taxes</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x39cde83790ec90c6.jpg</video:thumbnail_loc><video:title>What are taxes?</video:title><video:description>Learn about the different types of taxes that impact you daily. Explore income tax, payroll tax, sales tax, and property tax. We can learn the definitions of each tax, while also finding out how they are used!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/kdfk22Ck4nM.mp4/kdfk22Ck4nM.mp4</video:content_loc><video:duration>319</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-5-math-tx/v/gross-and-net-income</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe82cdd26dab9e6f2.jpg</video:thumbnail_loc><video:title>Gross and net income</video:title><video:description>Learn about gross and net income and how they impact the paycheck you would receive if working a job. We will discuss the high level overview of the differences between the two!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/E9ZSeCh1GUE.mp4/E9ZSeCh1GUE.mp4</video:content_loc><video:duration>125</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-5-math-tx/v/financial-record-keeping</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xcd58f7ed01ea960a.jpg</video:thumbnail_loc><video:title>Financial record keeping</video:title><video:description>Sal talks about the importance of financial record keeping and gives advice on how to stay organized - even at a young age!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xHntnwzXA4s.mp4/xHntnwzXA4s.mp4</video:content_loc><video:duration>173</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-5-math-tx/v/balancing-a-budget</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9f74c9e396f15537.jpg</video:thumbnail_loc><video:title>Balancing a budget</video:title><video:description>Learn about how to create a budget! Practice seeing how you can increase your monthly income or decrease your expenses so you have a balanced budget.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/zx98S3XR2KM.mp4/zx98S3XR2KM.mp4</video:content_loc><video:duration>366</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-5-math-tx/v/rounding-decimals-to-the-hundredths-on-the-number-line</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe85ddba2e5d9c560.jpg</video:thumbnail_loc><video:title>Rounding decimals to the hundredths on the number line</video:title><video:description>Practice rounding decimals on a vertical number line. First, start by identifying where a point rounds on a number line given a place value. Then, use a number line with three given points to find which point rounds to a given decimal.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/uu3RrUR-5iE.mp4/uu3RrUR-5iE.mp4</video:content_loc><video:duration>196</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-5-math-tx/v/estimating-decimal-addition-thousandths</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x08de2f914e5faaf0.jpg</video:thumbnail_loc><video:title>Estimating decimal addition (thousandths)</video:title><video:description>Practice using estimation to add decimals to the thousandths. First, practice adding decimals greater than one whole and rounding to the nearest whole number. Then, practice adding two decimals less than one whole and rounding to the nearest tenth.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/j1cY7Upjhbo.mp4/j1cY7Upjhbo.mp4</video:content_loc><video:duration>239</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-5-math-tx/v/adding-decimals-with-thousandths</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x168769d5e2e84754.jpg</video:thumbnail_loc><video:title>Adding decimals with thousandths</video:title><video:description>Practice using place value to line up decimals using the decimal point. Start by adding decimals in the farthest place value column to the right until all place value columns have been added.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_ayXtD83wBA.mp4/_ayXtD83wBA.mp4</video:content_loc><video:duration>245</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-5-math-tx/v/adding-decimals-and-whole-numbers-thousandths</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc7c4e112bea312f4.jpg</video:thumbnail_loc><video:title>Adding decimals and whole numbers (thousandths)</video:title><video:description>Practice adding decimals and whole numbers together using a variety of strategies. First, practice breaking apart the numbers into whole numbers and decimals. Then, line the decimals up by place to add.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/V8LmXU8YiOM.mp4/V8LmXU8YiOM.mp4</video:content_loc><video:duration>169</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-5-math-tx/v/estimating-decimal-subtraction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa5c478a77fc873a2.jpg</video:thumbnail_loc><video:title>Estimating decimal subtraction (thousandths)</video:title><video:description>Practice using estimation on a number line to help as a strategy for multiplying two decimals, up to the thousandths place.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pUsirzVGPrw.mp4/pUsirzVGPrw.mp4</video:content_loc><video:duration>281</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-5-math-tx/v/coordinate-plane-relationships</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7ef797e7831e1967.jpg</video:thumbnail_loc><video:title>Coordinate plane relationships</video:title><video:description>Practice using your understanding of the x- and y-coordinates to determine the relationship between moving up, down, left or right on a coordinate plane.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/oo-2ugRkgAk.mp4/oo-2ugRkgAk.mp4</video:content_loc><video:duration>244</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-5-math-tx/v/additive-and-multiplicative-relationships</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x356555ea0d145787.jpg</video:thumbnail_loc><video:title>Additive and multiplicative relationships</video:title><video:description>Practice using additive and multiplicative relationships to determine patterns within tables.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Iti6JTcijE8.mp4/Iti6JTcijE8.mp4</video:content_loc><video:duration>197</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-5-math-tx/v/constructing-scatterplots</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1440be8c35f36827.jpg</video:thumbnail_loc><video:title>Constructing scatterplots</video:title><video:description>Practice using data given in a table to construct a scatterplot on coordinate grid.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/zgmMOXwDpFI.mp4/zgmMOXwDpFI.mp4</video:content_loc><video:duration>95</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-5-math-tx/v/understanding-scatterplots</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2e23a7b7a2adb73d.jpg</video:thumbnail_loc><video:title>Understanding scatterplots</video:title><video:description>Practice matching a table to a series of scatterplots based on the x- and y-values.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/WaL02i4inE0.mp4/WaL02i4inE0.mp4</video:content_loc><video:duration>121</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/mappers/v/converting-decimals-to-percents-ex-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/915124662.jpg</video:thumbnail_loc><video:title>Converting decimals to percents: 0.601</video:title><video:description>Percents can be written in decimal form. ​Per-cent means per-100. So, we divide the percent by 100 to get an equivalent decimal. Then, we remove the percent sign (%). For example, 65% can be converted to decimal form by solving 65÷100. So, 65%=0.65. Another way to think of dividing by 100 is moving the decimal two places to the left.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5z568fLBQyQ.mp4/5z568fLBQyQ.mp4</video:content_loc><video:duration>156</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/mappers/v/converting-percents-to-decimals-ex-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8959c8e0.jpg</video:thumbnail_loc><video:title>Converting percents to decimals: 113.9%</video:title><video:description>Sal converts 113.9% to a decimal by demonstrating how to move the decimal point</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/T4JKO0OGjpQ.mp4/T4JKO0OGjpQ.mp4</video:content_loc><video:duration>73</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/pre-algebra/v/prime-factorization</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/2600704.jpg</video:thumbnail_loc><video:title>Prime factorization</video:title><video:description>This video explains the concept of prime numbers and how to find the prime factorization of a number using a factorization tree. It also shows how to write the prime factorization using exponential notation. A prime number is a number that is only divisible by itself and one.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ZKKDTfHcsG0.mp4/ZKKDTfHcsG0.mp4</video:content_loc><video:duration>249</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/pre-algebra/v/prime-factorization-exercise</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf27acc45.jpg</video:thumbnail_loc><video:title>Prime factorization exercise</video:title><video:description>Learn to find the prime factorization of any number by breaking it down into its prime factors. Understand the difference between prime and composite numbers. Learn from guided examples of finding the prime factorization of 36, 30, and 73.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/XWq8bplP-_E.mp4/XWq8bplP-_E.mp4</video:content_loc><video:duration>229</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/pre-algebra/v/common-divisibility-examples</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/56195550.jpg</video:thumbnail_loc><video:title>Common divisibility examples</video:title><video:description>Common Divisibility Examples</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/zWcfVC-oCNw.mp4/zWcfVC-oCNw.mp4</video:content_loc><video:duration>475</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-6-math-tx/v/classifying-rational-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x447359e7f4fa1273.jpg</video:thumbnail_loc><video:title>Classifying rational numbers</video:title><video:description>Classify rational numbers including instances using a nested Venn diagram.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/MqLUmHRy1L4.mp4/MqLUmHRy1L4.mp4</video:content_loc><video:duration>176</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-6-math-tx/v/relating-fractions-and-division</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7a135b0e95cc1f76.jpg</video:thumbnail_loc><video:title>Relating fractions and division</video:title><video:description>Practice relating fractions and division.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/yC4yAhU8mNw.mp4/yC4yAhU8mNw.mp4</video:content_loc><video:duration>223</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-6-math-tx/v/dividing-whole-numbers-by-decimals-tenths</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x385e478d72179620.jpg</video:thumbnail_loc><video:title>Dividing whole numbers by decimals (tenths)</video:title><video:description>See worked examples of dividing whole numbers by decimals that are only to the tenths.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pVAmhlmDUMM.mp4/pVAmhlmDUMM.mp4</video:content_loc><video:duration>312</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-6-math-tx/v/dividing-whole-numbers-by-decimals-hundredths-pencils</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdd7b9201948cb15d.jpg</video:thumbnail_loc><video:title>Dividing whole numbers by decimals (hundredths) -pencils</video:title><video:description>See a worked example about the sale of pencils to practice dividing whole numbers by decimals to the hundredths place.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DfnjfYxVdAc.mp4/DfnjfYxVdAc.mp4</video:content_loc><video:duration>223</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-6-math-tx/v/dividing-whole-numbers-by-decimals-hundredths-ice-cream</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfcee8c2b51c6cc8a.jpg</video:thumbnail_loc><video:title>Dividing whole numbers by decimals (hundredths) - ice cream</video:title><video:description>Watch as Sal explains how to divide whole numbers by decimals to the hundredths using an ice cream store example.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/S3MfUqTp0cg.mp4/S3MfUqTp0cg.mp4</video:content_loc><video:duration>208</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-6-math-tx/v/adding-integers-numbers-on-the-number-line-6th-grade-khan-academy</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1df995eab6254590.jpg</video:thumbnail_loc><video:title>Adding integers on the number line</video:title><video:description>Practice adding positive and negative integers using a number line.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/rubKHy5GRvo.mp4/rubKHy5GRvo.mp4</video:content_loc><video:duration>223</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-6-math-tx/v/multiplying-integers-word-problem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x61aca458e6ffc0d3.jpg</video:thumbnail_loc><video:title>Multiplying integers word problem</video:title><video:description>In this video, we&apos;ll explore both positive and negative rates of change through real-world applications.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4eAhLoYGSI0.mp4/4eAhLoYGSI0.mp4</video:content_loc><video:duration>91</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-6-math-tx/v/multiplying-integers-word-problems-temperature</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3d93980180635067.jpg</video:thumbnail_loc><video:title>Multiplying integers word problems (temperature)</video:title><video:description>Watch Sal practice multiplying integers, both negative and positive, using a temperature example.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/p7IfPaQfqus.mp4/p7IfPaQfqus.mp4</video:content_loc><video:duration>68</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-6-math-tx/v/dividing-integers-word-problems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe5ad46306c48945e.jpg</video:thumbnail_loc><video:title>Dividing integers word problems</video:title><video:description>In this video, we&apos;ll examine how quantities change over time to determine the rate of change. We will use division to calculate this rate in real-world contexts, demonstrating a straightforward approach to understanding these changes through practical examples.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/siPU49HmRu0.mp4/siPU49HmRu0.mp4</video:content_loc><video:duration>214</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-6-math-tx/v/problem-solving-with-integers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x10a97b4197dae5a5.jpg</video:thumbnail_loc><video:title>Problem solving with integers</video:title><video:description>In this lesson, we&apos;ll use our understanding of integer operations to solve multi-step word problems.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/STe5t3GPkC4.mp4/STe5t3GPkC4.mp4</video:content_loc><video:duration>125</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-6-math-tx/v/rates-of-change-with-integers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa93d0f4a3df6cb33.jpg</video:thumbnail_loc><video:title>Rates of change with integers</video:title><video:description>Sal practices solving a worked example involving rates of change with integers.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Zu7EupT2pdE.mp4/Zu7EupT2pdE.mp4</video:content_loc><video:duration>390</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-6-math-tx/v/features-and-fees-of-checking-accounts</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5310e6b5d5563cc2.jpg</video:thumbnail_loc><video:title>Features and fees of checking accounts</video:title><video:description>Learn about the features of a checking account.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/HBCsplRQ4Gg.mp4/HBCsplRQ4Gg.mp4</video:content_loc><video:duration>388</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-6-math-tx/v/balancing-a-check-register</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb01a50b5cfd4dbaf.jpg</video:thumbnail_loc><video:title>Balancing a check register</video:title><video:description>Learn how deposits, withdrawals, and transfers affect your account balance.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Tgr3trjhPs8.mp4/Tgr3trjhPs8.mp4</video:content_loc><video:duration>179</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-6-math-tx/v/debit-and-credit-cards</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0e936d0c87cdeb52.jpg</video:thumbnail_loc><video:title>Debit and credit cards</video:title><video:description>Learn the key differences between debit and credit cards in this quick comparison. We&apos;ll cover how each works and what to consider when choosing between them.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_ZVEjFBclFQ.mp4/_ZVEjFBclFQ.mp4</video:content_loc><video:duration>258</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-6-math-tx/v/credit-report-credit-history</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x260f1afe0632c2e6.jpg</video:thumbnail_loc><video:title>Credit report &amp; credit history</video:title><video:description>Explore the essentials of credit reports and credit history. Learn how your credit history affects your financial future, what’s included in a credit report, and how to read it.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OB8bLkRscNc.mp4/OB8bLkRscNc.mp4</video:content_loc><video:duration>268</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-6-math-tx/v/comparing-salaries</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3e63223b18de911d.jpg</video:thumbnail_loc><video:title>Comparing salaries</video:title><video:description>In this video, we&apos;ll compare the salaries of different jobs. We&apos;ll look at how much people earn in certain careers and what affects their pay. This will help you understand which jobs pay more and why, giving you a better idea of what career might interest you.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/EmbQ6s0v1fA.mp4/EmbQ6s0v1fA.mp4</video:content_loc><video:duration>173</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/mappers/v/equivalent-expressions-with-negative-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xedc4e33c.jpg</video:thumbnail_loc><video:title>Equivalent expressions with negative numbers</video:title><video:description>Equivalent expressions with negative numbers</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/fa__960kzVE.mp4/fa__960kzVE.mp4</video:content_loc><video:duration>381</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/reading-pie-graphs-circle-graphs</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/380854780.jpg</video:thumbnail_loc><video:title>Reading pie graphs (circle graphs)</video:title><video:description>Reading Pie Graphs (Circle Graphs)</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4JqH55rLGKY.mp4/4JqH55rLGKY.mp4</video:content_loc><video:duration>189</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-8-math-tx/v/relationships-between-sets-of-rational-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc012ff7e26a8d685.jpg</video:thumbnail_loc><video:title>Relationships between sets of rational numbers</video:title><video:description>A conceptual overview of visually representing relationships between sets of rational numbers (rational numbers, integers, whole numbers, natural numbers).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/j68fKea4Q0M.mp4/j68fKea4Q0M.mp4</video:content_loc><video:duration>229</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-7-math-tx/v/graphing-two-step-equations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe1adb5ebc167138a.jpg</video:thumbnail_loc><video:title>Graphing two-step equations</video:title><video:description>When we have an equation in one variable, we can represent the solution on a number line. Since a two-step linear equation in one variable has a single solution, let&apos;s graph it as a single point.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1JxTtn3WFnQ.mp4/1JxTtn3WFnQ.mp4</video:content_loc><video:duration>163</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-7-math-tx/v/family-budget-calculator</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x600dfff250bd6e4d.jpg</video:thumbnail_loc><video:title>Family budget calculator</video:title><video:description>Use a family budget estimator to determine the minimum household budget and number of hours of work needed for a family to meet its basic needs.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Ady9CqoCNQM.mp4/Ady9CqoCNQM.mp4</video:content_loc><video:duration>308</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-7-math-tx/v/finding-triangle-angles-with-algebra</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdeb1df5d76ec4241.jpg</video:thumbnail_loc><video:title>Finding triangle angles with algebra</video:title><video:description>Solve for the interior angle measures of triangles given linear expressions for each angle measure.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/wQik4r4_sV0.mp4/wQik4r4_sV0.mp4</video:content_loc><video:duration>440</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-7-math-tx/v/identifying-equations-of-proportional-graphs</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x91bbde38b21cb769.jpg</video:thumbnail_loc><video:title>Identifying equations of proportional graphs</video:title><video:description>We can write an equation for a linear graph that represents a proportional relationship in the form y = kx, where k is the constant of proportionality. Let&apos;s make a table of x- and y-coordinates from the graph to find the constant.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hUASd-tVWo4.mp4/hUASd-tVWo4.mp4</video:content_loc><video:duration>174</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-7-math-tx/v/identifying-equations-of-linear-graphs</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1ae2bd6c1011263c.jpg</video:thumbnail_loc><video:title>Identifying equations of linear graphs</video:title><video:description>Verify which equation represents a non-proportional linear graph by testing x-values in the equations. Every point on the graph of a line has an x- and y-coordinate. For an equation to represent the line, then the equation must be true when we substitute in each coordinate pair.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/t9M3Wv0GDwQ.mp4/t9M3Wv0GDwQ.mp4</video:content_loc><video:duration>187</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-7-math-tx/v/modeling-with-linear-tables</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf219cd0ccf69b4b7.jpg</video:thumbnail_loc><video:title>Modeling with linear tables</video:title><video:description>Given a context with an initial starting value and a constant rate of change, complete a table of values for the independent and dependent variables. Using an equation helps us to jump to particular values without needing to create a table for every possible x-value.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/e-Cqegj3ya4.mp4/e-Cqegj3ya4.mp4</video:content_loc><video:duration>348</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-7-math-tx/v/converting-between-measurement-systems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb64cbcb776c444f9.jpg</video:thumbnail_loc><video:title>Converting between measurement systems</video:title><video:description>Create and reason about a proportion to convert a mural measurement from US units to metric units.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TeOESA4r2TQ.mp4/TeOESA4r2TQ.mp4</video:content_loc><video:duration>142</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-8-fl-best/v/orders-of-magnitude-exercise-example-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe58a764b.jpg</video:thumbnail_loc><video:title>Orders of magnitude exercise example 2</video:title><video:description>Orders of magnitude exercise example 2 from 8th grade math (FL B.E.S.T.)</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DaoJmvqU3FI.mp4/DaoJmvqU3FI.mp4</video:content_loc><video:duration>348</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-8-math-tx/v/ordering-rational-numbers-in-context</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0ebf379bf4d66f44.jpg</video:thumbnail_loc><video:title>Ordering rational numbers in context</video:title><video:description>Practice ordering rational numbers in a context.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/T1mc4-_l5Ss.mp4/T1mc4-_l5Ss.mp4</video:content_loc><video:duration>124</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-8-math-tx/v/ordering-rational-numbers-compared-to-an-average</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x01c541b2b45abaec.jpg</video:thumbnail_loc><video:title>Ordering rational numbers compared to an average</video:title><video:description>Given a context with a set of rational numbers in a variety of forms, practice identifying which value represents some characteristic of the set.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jZd_FQdTRMY.mp4/jZd_FQdTRMY.mp4</video:content_loc><video:duration>183</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-8-math-tx/v/simulating-samples-from-populations-example-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x74a809d704f3ca4f.jpg</video:thumbnail_loc><video:title>Simulating samples from populations example 1</video:title><video:description>Practice analyzing samples from populations to see if they are representative of their given population, and why those samples are or are not representative.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4-7u22MrnSs.mp4/4-7u22MrnSs.mp4</video:content_loc><video:duration>141</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-8-math-tx/v/simulating-samples-from-populations-example-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x373aecf3ff58141c.jpg</video:thumbnail_loc><video:title>Simulating samples from populations example 2</video:title><video:description>Practice analyzing samples from populations to see if they are representative of their given population, and why those samples are or are not representative.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7Tio-lJ4kJ4.mp4/7Tio-lJ4kJ4.mp4</video:content_loc><video:duration>124</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-8-math-tx/v/writing-equations-to-represent-geometric-problems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x028f7ed949c7052f.jpg</video:thumbnail_loc><video:title>Writing equations to represent geometric problems</video:title><video:description>Practice writing a one-variable equation with variables on both sides that can be used to represent a geometric problem.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3Xz8IlUgR8o.mp4/3Xz8IlUgR8o.mp4</video:content_loc><video:duration>113</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-8-math-tx/v/writing-equations-to-represent-problems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8968925936471856.jpg</video:thumbnail_loc><video:title>Writing equations to represent problems</video:title><video:description>Explore writing equations to represent real-world problems involving coral samples.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/01I9vY0xOII.mp4/01I9vY0xOII.mp4</video:content_loc><video:duration>118</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-8-math-tx/v/writing-inequalities-to-represent-problems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7c79e16f628ef7fc.jpg</video:thumbnail_loc><video:title>Writing inequalities to represent problems</video:title><video:description>Practice writing a one-variable inequality with variables on both sides that can be used to represent a problem.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/t4QhKsW_yCU.mp4/t4QhKsW_yCU.mp4</video:content_loc><video:duration>163</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-8-math-tx/v/writing-inequalities-to-represent-real-world-problems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x89fcd04be79448d0.jpg</video:thumbnail_loc><video:title>Writing inequalities to represent real-world problems</video:title><video:description>Practice identifying which one-variable inequality with variables on both sides can be used to represent a problem.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/J0tRjEi4pBw.mp4/J0tRjEi4pBw.mp4</video:content_loc><video:duration>169</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-8-math-tx/v/using-similar-triangles-to-reason-about-slope</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfa0c7d9ccf985ed1.jpg</video:thumbnail_loc><video:title>Using similar triangles to reason about slope</video:title><video:description>A conceptual overview video showing that the slope is the same between any two points on the same line.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/JQgmzU23w20.mp4/JQgmzU23w20.mp4</video:content_loc><video:duration>418</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-8-math-tx/v/similar-triangles-and-slope-proportion-of-segments</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7dfa1cfdd60662b5.jpg</video:thumbnail_loc><video:title>Similar triangles &amp; slope: proportion of segments</video:title><video:description>Students use similar triangles to show that the slope is the same between any two points on a line in the coordinate plane. This worked example shows how to write the proportion with the letters for the sides.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/u-r4MwyxdZ8.mp4/u-r4MwyxdZ8.mp4</video:content_loc><video:duration>161</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-8-math-tx/v/similar-triangles-and-slope-proportion-using-coordinates</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x93c70737d6593005.jpg</video:thumbnail_loc><video:title>Similar triangles &amp; slope: proportion using coordinates</video:title><video:description>Students use similar triangles to show that the slope is the same between any two points on a line in the coordinate plane. This worked example shows how to write the proportion using the coordinates and the slope formula.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3TrT1vIR4to.mp4/3TrT1vIR4to.mp4</video:content_loc><video:duration>174</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-8-math-tx/v/locating-y-intercepts-from-graphs</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd5a902fd65cdbfb8.jpg</video:thumbnail_loc><video:title>Locating y-intercepts from graphs</video:title><video:description>Locate the y-intercept from a graph of a line.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Hay980dASAk.mp4/Hay980dASAk.mp4</video:content_loc><video:duration>135</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-8-math-tx/v/relating-unit-rate-to-slope-in-graphs-of-proportional-relationships</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf68f8b44ef2fe784.jpg</video:thumbnail_loc><video:title>Relating unit rate to slope in graphs of proportional relationships</video:title><video:description>Calculate a unit rate and choose which graph has a slope that equals the unit rate.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LCsMxvfeYd4.mp4/LCsMxvfeYd4.mp4</video:content_loc><video:duration>159</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-8-math-tx/v/writing-y-mx-proportional-equations-worked-example-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x906563924c1370cf.jpg</video:thumbnail_loc><video:title>Writing y = mx proportional equations worked example 1</video:title><video:description>Practice writing equations in the form of y = mx to describe proportional relationships.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6h2co0jvTBM.mp4/6h2co0jvTBM.mp4</video:content_loc><video:duration>150</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-8-math-tx/v/writing-y-mx-proportional-equations-worked-example-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4e7ce6d60d149653.jpg</video:thumbnail_loc><video:title>Writing y = mx proportional equations worked example 2</video:title><video:description>Practice writing equations in the form of y = mx to describe proportional relationships.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/XkMA_A7Q94Q.mp4/XkMA_A7Q94Q.mp4</video:content_loc><video:duration>106</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-8-math-tx/v/locating-less-obvious-y-intercepts-on-graphs</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd05fdd36126fe63d.jpg</video:thumbnail_loc><video:title>Locating less obvious y-intercepts on graphs</video:title><video:description>Given a graph of a linear relationship with two points labeled, locate the non-integer y-intercept.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/j7igNR0hRkQ.mp4/j7igNR0hRkQ.mp4</video:content_loc><video:duration>249</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-8-math-tx/v/identifying-proportional-non-proportional-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe81cb8ec6d9fddbc.jpg</video:thumbnail_loc><video:title>Identifying proportional &amp; non-proportional functions</video:title><video:description>Practice identifying examples of proportional and non-proportional functions that arise from mathematical and real-world problems.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gnXCTo6lAnA.mp4/gnXCTo6lAnA.mp4</video:content_loc><video:duration>205</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-8-math-tx/v/identifying-and-verifying-a-solution-to-a-system</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x992e8eefb1dce115.jpg</video:thumbnail_loc><video:title>Identifying and verifying a solution to a system</video:title><video:description>Given a graph of a system of two linear equations, identify and verify the values of x and y that simultaneously satisfy the two linear equations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PQv5yEwXpeg.mp4/PQv5yEwXpeg.mp4</video:content_loc><video:duration>112</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-8-math-tx/v/visually-verifying-a-solution-to-a-system</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x151f92318581943e.jpg</video:thumbnail_loc><video:title>Visually verifying a solution to a system</video:title><video:description>Given a graph of a system of two linear equations, verify if a given value of x is a solution to the system.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Oehhq7kHOM4.mp4/Oehhq7kHOM4.mp4</video:content_loc><video:duration>75</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-8-math-tx/v/equivalent-ratios-in-similar-shapes2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xef175796cca0d417.jpg</video:thumbnail_loc><video:title>Equivalent ratios in similar shapes</video:title><video:description>Relate side lengths within and between similar polygons and dilated shapes using proportion equations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OQlMQ0e4AOs.mp4/OQlMQ0e4AOs.mp4</video:content_loc><video:duration>220</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-8-math-tx/v/finding-equivalent-ratios-in-similar-triangles</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc83a0fd1174eca5c.jpg</video:thumbnail_loc><video:title>Finding equivalent ratios in similar triangles</video:title><video:description>Practice finding equivalent ratios of side lengths in similar shapes.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tgkfytxQjc0.mp4/tgkfytxQjc0.mp4</video:content_loc><video:duration>182</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-8-math-tx/v/finding-equivalent-ratios-in-similar-quadrilaterals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4158161519d1bc16.jpg</video:thumbnail_loc><video:title>Finding equivalent ratios in similar quadrilaterals</video:title><video:description>Practice finding equivalent ratios of side lengths in similar shapes.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/IqjudxRCT40.mp4/IqjudxRCT40.mp4</video:content_loc><video:duration>223</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-8-math-tx/v/lateral-total-surface-area-of-rectangular-prisms</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6718d0fb086ea64a.jpg</video:thumbnail_loc><video:title>Lateral &amp; total surface area of rectangular prisms</video:title><video:description>Practice finding the lateral surface area and total surface area of a rectangular prism using the formulas instead of nets.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/EeaSMjBKRcA.mp4/EeaSMjBKRcA.mp4</video:content_loc><video:duration>295</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-8-math-tx/v/lateral-total-surface-area-of-triangular-prisms</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xae3f73290ead4748.jpg</video:thumbnail_loc><video:title>Lateral &amp; total surface area of triangular prisms</video:title><video:description>Practice finding the lateral surface area and total surface area of a triangular prism using the formulas instead of nets.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/zFPCdP_zaa8.mp4/zFPCdP_zaa8.mp4</video:content_loc><video:duration>404</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-8-math-tx/v/surface-area-of-cylinders-formula</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe3a94a65d9f316ae.jpg</video:thumbnail_loc><video:title>Surface area of cylinders formula</video:title><video:description>Use previous knowledge of surface area to make connections to the formulas for lateral and total surface area of cylinders.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/GOLJkXcrZ2c.mp4/GOLJkXcrZ2c.mp4</video:content_loc><video:duration>240</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/grade-8-math-tx/v/lateral-total-surface-area-of-cylinders</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x01c88af0d33a7057.jpg</video:thumbnail_loc><video:title>Lateral &amp; total surface area of cylinders</video:title><video:description>Use the formulas to find lateral and total surface area of a cylinder.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/QJ69ms9xLU8.mp4/QJ69ms9xLU8.mp4</video:content_loc><video:duration>246</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/vector-introduction-linear-algebra</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbb63d308.jpg</video:thumbnail_loc><video:title>Vector intro for linear algebra</video:title><video:description>A vector has both magnitude and direction. We use vectors to, for example, describe the velocity of moving objects. In this video, you&apos;ll learn how to write and draw vectors.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/br7tS1t2SFE.mp4/br7tS1t2SFE.mp4</video:content_loc><video:duration>349</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/real-coordinate-spaces</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x184489c0.jpg</video:thumbnail_loc><video:title>Real coordinate spaces</video:title><video:description>Real coordinate spaces from Linear algebra</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lCsjJbZHhHU.mp4/lCsjJbZHhHU.mp4</video:content_loc><video:duration>381</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/multiplying-vector-by-scalar</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf85df5ef.jpg</video:thumbnail_loc><video:title>Multiplying a vector by a scalar</video:title><video:description>Watch Sal change the magnitude of a vector by multiplying it by a scalar.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ZN7YaSbY3-w.mp4/ZN7YaSbY3-w.mp4</video:content_loc><video:duration>344</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/linear-algebra-vector-examples</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25221.jpg</video:thumbnail_loc><video:title>Vector examples</video:title><video:description>Visually understanding basic vector operations</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/r4bH66vYjss.mp4/r4bH66vYjss.mp4</video:content_loc><video:duration>1533</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/linear-algebra-parametric-representations-of-lines</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25223.jpg</video:thumbnail_loc><video:title>Parametric representations of lines</video:title><video:description>Parametric Representations of Lines in R2 and R3</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hWhs2cIj7Cw.mp4/hWhs2cIj7Cw.mp4</video:content_loc><video:duration>1486</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/linear-combinations-and-span</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25225.jpg</video:thumbnail_loc><video:title>Linear combinations and span</video:title><video:description>Understanding linear combinations and spans of vectors</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Qm_OS-8COwU.mp4/Qm_OS-8COwU.mp4</video:content_loc><video:duration>1235</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/linear-algebra-introduction-to-linear-independence</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25227.jpg</video:thumbnail_loc><video:title>Introduction to linear independence</video:title><video:description>Introduction to linear dependence and independence</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/CrV1xCWdY-g.mp4/CrV1xCWdY-g.mp4</video:content_loc><video:duration>946</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/more-on-linear-independence</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25229.jpg</video:thumbnail_loc><video:title>More on linear independence</video:title><video:description>More examples determining linear dependence or independence.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Alhcv5d_XOs.mp4/Alhcv5d_XOs.mp4</video:content_loc><video:duration>1058</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/span-and-linear-independence-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25231.jpg</video:thumbnail_loc><video:title>Span and linear independence example</video:title><video:description>Determining whether 3 vectors are linearly independent and/or span R3</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9kW6zFK5E5c.mp4/9kW6zFK5E5c.mp4</video:content_loc><video:duration>1013</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/linear-subspaces</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25233.jpg</video:thumbnail_loc><video:title>Linear subspaces</video:title><video:description>Introduction to linear subspaces of Rn</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pMFv6liWK4M.mp4/pMFv6liWK4M.mp4</video:content_loc><video:duration>1409</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/linear-algebra-basis-of-a-subspace</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25235.jpg</video:thumbnail_loc><video:title>Basis of a subspace</video:title><video:description>Understanding the definition of a basis of a subspace</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/zntNi3-ybfQ.mp4/zntNi3-ybfQ.mp4</video:content_loc><video:duration>1140</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/vector-dot-product-and-vector-length</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25237.jpg</video:thumbnail_loc><video:title>Vector dot product and vector length</video:title><video:description>Definitions of the vector dot product and vector length</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/WNuIhXo39_k.mp4/WNuIhXo39_k.mp4</video:content_loc><video:duration>550</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/proving-vector-dot-product-properties</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25239.jpg</video:thumbnail_loc><video:title>Proving vector dot product properties</video:title><video:description>Proving the &quot;associative&quot;, &quot;distributive&quot; and &quot;commutative&quot; properties for vector dot products.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/rVQ3G9epCjw.mp4/rVQ3G9epCjw.mp4</video:content_loc><video:duration>645</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/proof-of-the-cauchy-schwarz-inequality</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25241.jpg</video:thumbnail_loc><video:title>Proof of the Cauchy-Schwarz inequality</video:title><video:description>Proof of the Cauchy-Schwarz Inequality</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/r2PogGDl8_U.mp4/r2PogGDl8_U.mp4</video:content_loc><video:duration>1015</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/linear-algebra-vector-triangle-inequality</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25243.jpg</video:thumbnail_loc><video:title>Vector triangle inequality</video:title><video:description>Proving the triangle inequality for vectors in Rn</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PsNidCBr5II.mp4/PsNidCBr5II.mp4</video:content_loc><video:duration>1133</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/defining-the-angle-between-vectors</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25245.jpg</video:thumbnail_loc><video:title>Defining the angle between vectors</video:title><video:description>Introducing the idea of an angle between two vectors</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5AWob_z74Ks.mp4/5AWob_z74Ks.mp4</video:content_loc><video:duration>1511</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/defining-a-plane-in-r3-with-a-point-and-normal-vector</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25247.jpg</video:thumbnail_loc><video:title>Defining a plane in R3 with a point and normal vector</video:title><video:description>Determining the equation for a plane in R3 using a point on the plane and a normal vector</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/UJxgcVaNTqY.mp4/UJxgcVaNTqY.mp4</video:content_loc><video:duration>833</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/linear-algebra-cross-product-introduction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25249.jpg</video:thumbnail_loc><video:title>Cross product introduction</video:title><video:description>Introduction to the cross product</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pJzmiywagfY.mp4/pJzmiywagfY.mp4</video:content_loc><video:duration>947</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/proof-relationship-between-cross-product-and-sin-of-angle</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25251.jpg</video:thumbnail_loc><video:title>Proof: Relationship between cross product and sin of angle</video:title><video:description>Proof: Relationship between the cross product and sin of angle between vectors</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7MKA2QlKvHc.mp4/7MKA2QlKvHc.mp4</video:content_loc><video:duration>1089</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/dot-and-cross-product-comparison-intuition</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25253.jpg</video:thumbnail_loc><video:title>Dot and cross product comparison/intuition</video:title><video:description>Dot and Cross Product Comparison/Intuition</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tdwFdzVqito.mp4/tdwFdzVqito.mp4</video:content_loc><video:duration>1154</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/vector-triple-product-expansion-very-optional</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187461.jpg</video:thumbnail_loc><video:title>Vector triple product expansion (very optional)</video:title><video:description>A shortcut for having to evaluate the cross product of three vectors</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/b7JTVLc_aMk.mp4/b7JTVLc_aMk.mp4</video:content_loc><video:duration>865</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/normal-vector-from-plane-equation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187465.jpg</video:thumbnail_loc><video:title>Normal vector from plane equation</video:title><video:description>Figuring out a normal vector to a plane from its equation</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gw-4wltP5tY.mp4/gw-4wltP5tY.mp4</video:content_loc><video:duration>598</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/point-distance-to-plane</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187466.jpg</video:thumbnail_loc><video:title>Point distance to plane</video:title><video:description>Distance between a point and a plane in three dimensions</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7rIFO8hct9g.mp4/7rIFO8hct9g.mp4</video:content_loc><video:duration>732</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/distance-between-planes</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187467.jpg</video:thumbnail_loc><video:title>Distance between planes</video:title><video:description>2010 IIT JEE Paper 1 Problem 51 Distance Between Planes</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/v8plb6V8BQo.mp4/v8plb6V8BQo.mp4</video:content_loc><video:duration>885</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/matrices-reduced-row-echelon-form-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25255.jpg</video:thumbnail_loc><video:title>Solving a system of 3 equations and 4 variables using matrix row-echelon form</video:title><video:description>Sal solves a linear system with 3 equations and 4 variables by representing it with an augmented matrix and bringing the matrix to reduced row-echelon form.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/L0CmbneYETs.mp4/L0CmbneYETs.mp4</video:content_loc><video:duration>1063</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/matrices-reduced-row-echelon-form-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25259.jpg</video:thumbnail_loc><video:title>Using matrix row-echelon form in order to show a linear system has no solutions</video:title><video:description>And another example of solving a system of linear equations by putting an augmented matrix into reduced row echelon form</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/JVDrlTdzxiI.mp4/JVDrlTdzxiI.mp4</video:content_loc><video:duration>728</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/matrix-vector-products</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25261.jpg</video:thumbnail_loc><video:title>Matrix vector products</video:title><video:description>Defining and understanding what it means to take the product of a matrix and a vector</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7Mo4S2wyMg4.mp4/7Mo4S2wyMg4.mp4</video:content_loc><video:duration>1270</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/introduction-to-the-null-space-of-a-matrix</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25263.jpg</video:thumbnail_loc><video:title>Introduction to the null space of a matrix</video:title><video:description>Showing that the Null Space of a Matrix is a valid Subspace</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jCwRV1QL_Xs.mp4/jCwRV1QL_Xs.mp4</video:content_loc><video:duration>623</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/null-space-2-calculating-the-null-space-of-a-matrix</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25265.jpg</video:thumbnail_loc><video:title>Null space 2: Calculating the null space of a matrix</video:title><video:description>Calculating the null space of a matrix</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qvyboGryeA8.mp4/qvyboGryeA8.mp4</video:content_loc><video:duration>787</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/null-space-3-relation-to-linear-independence</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25267.jpg</video:thumbnail_loc><video:title>Null space 3: Relation to linear independence</video:title><video:description>Understanding how the null space of a matrix relates to the linear independence of its column vectors</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-fKh6SNEPr4.mp4/-fKh6SNEPr4.mp4</video:content_loc><video:duration>572</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/column-space-of-a-matrix</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25269.jpg</video:thumbnail_loc><video:title>Column space of a matrix</video:title><video:description>Introduction to the column space of a matrix</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/st6D5OdFV9M.mp4/st6D5OdFV9M.mp4</video:content_loc><video:duration>640</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/null-space-and-column-space-basis</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25271.jpg</video:thumbnail_loc><video:title>Null space and column space basis</video:title><video:description>Figuring out the null space and a basis of a column space for a matrix</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_uTAdf_AsfQ.mp4/_uTAdf_AsfQ.mp4</video:content_loc><video:duration>1513</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/visualizing-a-column-space-as-a-plane-in-r3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25273.jpg</video:thumbnail_loc><video:title>Visualizing a column space as a plane in R3</video:title><video:description>Determining the planar equation for a column space in R3</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/EGNlXtjYABw.mp4/EGNlXtjYABw.mp4</video:content_loc><video:duration>1271</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/proof-any-subspace-basis-has-same-number-of-elements</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25275.jpg</video:thumbnail_loc><video:title>Proof: Any subspace basis has same number of elements</video:title><video:description>Proof: Any subspace basis has same number of elements</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Zn2K8UIT8r4.mp4/Zn2K8UIT8r4.mp4</video:content_loc><video:duration>1295</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/dimension-of-the-null-space-or-nullity</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25277.jpg</video:thumbnail_loc><video:title>Dimension of the null space or nullity</video:title><video:description>Dimension of the Null Space or Nullity</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/abYAUqs_n6I.mp4/abYAUqs_n6I.mp4</video:content_loc><video:duration>839</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/dimension-of-the-column-space-or-rank</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25279.jpg</video:thumbnail_loc><video:title>Dimension of the column space or rank</video:title><video:description>Dimension of the Column Space or Rank</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/JUgrBkPteTg.mp4/JUgrBkPteTg.mp4</video:content_loc><video:duration>768</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/showing-relation-between-basis-cols-and-pivot-cols</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25281.jpg</video:thumbnail_loc><video:title>Showing relation between basis cols and pivot cols</video:title><video:description>Showing that linear independence of pivot columns implies linear independence of the corresponding columns in the original equation</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/BfVjTOjvI30.mp4/BfVjTOjvI30.mp4</video:content_loc><video:duration>513</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/showing-that-the-candidate-basis-does-span-c-a</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25283.jpg</video:thumbnail_loc><video:title>Showing that the candidate basis does span C(A)</video:title><video:description>Showing that just the columns of A associated with the pivot columns of rref(A) do indeed span C(A).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/CkQOCnLWPUA.mp4/CkQOCnLWPUA.mp4</video:content_loc><video:duration>820</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/a-more-formal-understanding-of-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25285.jpg</video:thumbnail_loc><video:title>A more formal understanding of functions</video:title><video:description>A more formal understanding of functions</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/BQMyeQOLvpg.mp4/BQMyeQOLvpg.mp4</video:content_loc><video:duration>961</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/vector-transformations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25287.jpg</video:thumbnail_loc><video:title>Vector transformations</video:title><video:description>Introduction to the notion of vector transformations</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gAbadNuQEjI.mp4/gAbadNuQEjI.mp4</video:content_loc><video:duration>859</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/linear-transformations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25289.jpg</video:thumbnail_loc><video:title>Linear transformations</video:title><video:description>Introduction to linear transformations</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4PCktDZJH8E.mp4/4PCktDZJH8E.mp4</video:content_loc><video:duration>832</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/linear-transformations-as-matrix-vector-products</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25293.jpg</video:thumbnail_loc><video:title>Linear transformations as matrix vector products</video:title><video:description>Showing how ANY linear transformation can be represented as a matrix vector product</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PErhLkQcpZ8.mp4/PErhLkQcpZ8.mp4</video:content_loc><video:duration>1052</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/image-of-a-subset-under-a-transformation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25295.jpg</video:thumbnail_loc><video:title>Image of a subset under a transformation</video:title><video:description>Exploring what happens to a subset of the domain under a transformation</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/MIAmN5kgp3k.mp4/MIAmN5kgp3k.mp4</video:content_loc><video:duration>1091</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/im-t-image-of-a-transformation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25297.jpg</video:thumbnail_loc><video:title>im(T): Image of a transformation</video:title><video:description>Showing that the image of a subspace under a transformation is also a subspace. Definition of the image of a Transformation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hZ827mfh1Jo.mp4/hZ827mfh1Jo.mp4</video:content_loc><video:duration>997</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/preimage-of-a-set</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25299.jpg</video:thumbnail_loc><video:title>Preimage of a set</video:title><video:description>Definition of preimage of a set</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/zVsGtU8lIWs.mp4/zVsGtU8lIWs.mp4</video:content_loc><video:duration>323</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/preimage-and-kernel-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25301.jpg</video:thumbnail_loc><video:title>Preimage and kernel example</video:title><video:description>Example involving the preimage of a set under a transformation. Definition of kernel of a transformation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6yrPU8rYOhs.mp4/6yrPU8rYOhs.mp4</video:content_loc><video:duration>923</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/sums-and-scalar-multiples-of-linear-transformations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25303.jpg</video:thumbnail_loc><video:title>Sums and scalar multiples of linear transformations</video:title><video:description>Sums and Scalar Multiples of Linear Transformations. Definitions of matrix addition and scalar multiplication.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/wHuY97vss18.mp4/wHuY97vss18.mp4</video:content_loc><video:duration>909</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/more-on-matrix-addition-and-scalar-multiplication</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25305.jpg</video:thumbnail_loc><video:title>More on matrix addition and scalar multiplication</video:title><video:description>More on Matrix Addition and Scalar Multiplication</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Z19-ObbmHJE.mp4/Z19-ObbmHJE.mp4</video:content_loc><video:duration>641</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/linear-transformation-examples-scaling-and-reflections</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25307.jpg</video:thumbnail_loc><video:title>Linear transformation examples: Scaling and reflections</video:title><video:description>Creating scaling and reflection transformation matrices (which are diagonal)</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qkfODKmZ-x4.mp4/qkfODKmZ-x4.mp4</video:content_loc><video:duration>913</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/linear-transformation-examples-rotations-in-r2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25309.jpg</video:thumbnail_loc><video:title>Linear transformation examples: Rotations in R2</video:title><video:description>Linear Transformation Examples: Rotations in R2</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lPWfIq5DzqI.mp4/lPWfIq5DzqI.mp4</video:content_loc><video:duration>1072</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/rotation-in-r3-around-the-x-axis</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25311.jpg</video:thumbnail_loc><video:title>Rotation in R3 around the x-axis</video:title><video:description>Construction a rotation transformation in R3</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gkyuLPzfDV0.mp4/gkyuLPzfDV0.mp4</video:content_loc><video:duration>738</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/unit-vectors</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25313.jpg</video:thumbnail_loc><video:title>Unit vectors</video:title><video:description>What unit vectors are and how to construct them</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lQn7fksaDq0.mp4/lQn7fksaDq0.mp4</video:content_loc><video:duration>419</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/introduction-to-projections</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25315.jpg</video:thumbnail_loc><video:title>Introduction to projections</video:title><video:description>Determining the projection of a vector on s line</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/27vT-NWuw0M.mp4/27vT-NWuw0M.mp4</video:content_loc><video:duration>877</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/expressing-a-projection-on-to-a-line-as-a-matrix-vector-prod</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25317.jpg</video:thumbnail_loc><video:title>Expressing a projection on to a line as a matrix vector prod</video:title><video:description>Expressing a Projection on to a line as a Matrix Vector prod</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/JK-8XNIoAkI.mp4/JK-8XNIoAkI.mp4</video:content_loc><video:duration>1000</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/compositions-of-linear-transformations-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25319.jpg</video:thumbnail_loc><video:title>Compositions of linear transformations 1</video:title><video:description>Introduction to compositions of Linear Transformations</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/f_DTiXZpb8M.mp4/f_DTiXZpb8M.mp4</video:content_loc><video:duration>741</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/compositions-of-linear-transformations-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25321.jpg</video:thumbnail_loc><video:title>Compositions of linear transformations 2</video:title><video:description>Providing the motivation for definition of matrix products</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/BuqcKpe5ZQs.mp4/BuqcKpe5ZQs.mp4</video:content_loc><video:duration>990</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/linear-algebra-matrix-product-examples</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25323.jpg</video:thumbnail_loc><video:title>Matrix product examples</video:title><video:description>Example of taking the product of two matrices</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/x1z0hOyjapU.mp4/x1z0hOyjapU.mp4</video:content_loc><video:duration>1094</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/matrix-product-associativity</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25325.jpg</video:thumbnail_loc><video:title>Matrix product associativity</video:title><video:description>Showing that matrix products are associative</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Hhc96U_HvQE.mp4/Hhc96U_HvQE.mp4</video:content_loc><video:duration>719</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/distributive-property-of-matrix-products</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25327.jpg</video:thumbnail_loc><video:title>Distributive property of matrix products</video:title><video:description>Showing that matrix products exhibit the distributive property</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/oMWTMj78cwc.mp4/oMWTMj78cwc.mp4</video:content_loc><video:duration>592</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/linear-algebra-introduction-to-the-inverse-of-a-function</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25329.jpg</video:thumbnail_loc><video:title>Introduction to the inverse of a function</video:title><video:description>Introduction to the inverse of a function</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-eAzhBZgq28.mp4/-eAzhBZgq28.mp4</video:content_loc><video:duration>1133</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/proof-invertibility-implies-a-unique-solution-to-f-x-y</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25331.jpg</video:thumbnail_loc><video:title>Proof: Invertibility implies a unique solution to f(x)=y</video:title><video:description>Proof: Invertibility implies a unique solution to f(x)=y for all y in co-domain of f.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7GEUgRcnfVE.mp4/7GEUgRcnfVE.mp4</video:content_loc><video:duration>1361</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/surjective-onto-and-injective-one-to-one-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25333.jpg</video:thumbnail_loc><video:title>Surjective (onto) and injective (one-to-one) functions</video:title><video:description>Introduction to surjective and injective functions</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xKNX8BUWR0g.mp4/xKNX8BUWR0g.mp4</video:content_loc><video:duration>571</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/relating-invertibility-to-being-onto-and-one-to-one</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25335.jpg</video:thumbnail_loc><video:title>Relating invertibility to being onto and one-to-one</video:title><video:description>Relating invertibility to being onto (surjective) and one-to-one (injective)</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/QIU1daMN8fw.mp4/QIU1daMN8fw.mp4</video:content_loc><video:duration>391</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/determining-whether-a-transformation-is-onto</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25337.jpg</video:thumbnail_loc><video:title>Determining whether a transformation is onto</video:title><video:description>Determining whether a transformation is onto</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/eR8vEdJTvd0.mp4/eR8vEdJTvd0.mp4</video:content_loc><video:duration>1551</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/linear-algebra-exploring-the-solution-set-of-ax-b</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25339.jpg</video:thumbnail_loc><video:title>Exploring the solution set of Ax = b</video:title><video:description>Exploring the solution set of Ax=b (non homogeneous equations)</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1PsNIzUJPkc.mp4/1PsNIzUJPkc.mp4</video:content_loc><video:duration>994</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/linear-algebra-matrix-condition-for-one-to-one-trans</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25341.jpg</video:thumbnail_loc><video:title>Matrix condition for one-to-one transformation</video:title><video:description>Showing that the rank of the of an mxn transformation matrix has to be n for the transformation to be one-to-one (injective)</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/M3FuL9qKTBs.mp4/M3FuL9qKTBs.mp4</video:content_loc><video:duration>1199</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/linear-algebra-simplifying-conditions-for-invertibility</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25343.jpg</video:thumbnail_loc><video:title>Simplifying conditions for invertibility</video:title><video:description>Showing that a transformation is invertible if and only if rref(A) is equal to the identity matrix</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Yz2OosyMTmY.mp4/Yz2OosyMTmY.mp4</video:content_loc><video:duration>397</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/linear-algebra-showing-that-inverses-are-linear</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25345.jpg</video:thumbnail_loc><video:title>Showing that inverses are linear</video:title><video:description>Showing that inverse transformations are also linear</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/mr9Tow8hpCg.mp4/mr9Tow8hpCg.mp4</video:content_loc><video:duration>1285</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/linear-algebra-deriving-a-method-for-determining-inverses</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25347.jpg</video:thumbnail_loc><video:title>Deriving a method for determining inverses</video:title><video:description>Determining a method for constructing inverse transformation matrices</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6DpzCKJBsz0.mp4/6DpzCKJBsz0.mp4</video:content_loc><video:duration>1080</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/linear-algebra-example-of-finding-matrix-inverse</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25349.jpg</video:thumbnail_loc><video:title>Example of finding matrix inverse</video:title><video:description>Example of calculating the inverse of a matrix</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/r9aTLTN16V4.mp4/r9aTLTN16V4.mp4</video:content_loc><video:duration>382</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/linear-algebra-formula-for-2x2-inverse</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25351.jpg</video:thumbnail_loc><video:title>Formula for 2x2 inverse</video:title><video:description>Figuring out the formula for a 2x2 matrix. Defining the determinant.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/eEUK_ThrHuQ.mp4/eEUK_ThrHuQ.mp4</video:content_loc><video:duration>1100</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/linear-algebra-3x3-determinant</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25353.jpg</video:thumbnail_loc><video:title>3 x 3 determinant</video:title><video:description>Determinants: Finding the determinant of a 3x3 matrix</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0c7dt2SQfLw.mp4/0c7dt2SQfLw.mp4</video:content_loc><video:duration>601</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/linear-algebra-nxn-determinant</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25355.jpg</video:thumbnail_loc><video:title>n x n determinant</video:title><video:description>Defining the determinant for nxn matrices. An example of a 4x4 determinant.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/H9BWRYJNIv4.mp4/H9BWRYJNIv4.mp4</video:content_loc><video:duration>1120</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/linear-algebra-determinants-along-other-rows-cols</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25357.jpg</video:thumbnail_loc><video:title>Determinants along other rows/cols</video:title><video:description>Finding the determinant by going along other rows or columns</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/nu87kfmwNfU.mp4/nu87kfmwNfU.mp4</video:content_loc><video:duration>543</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/linear-algebra-rule-of-sarrus-of-determinants</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25359.jpg</video:thumbnail_loc><video:title>Rule of Sarrus of determinants</video:title><video:description>A alternative &quot;short cut&quot; for calculating 3x3 determinants (Rule of Sarrus)</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4xFIi0JF2AM.mp4/4xFIi0JF2AM.mp4</video:content_loc><video:duration>438</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/linear-algebra-determinant-when-row-multiplied-by-scalar</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25361.jpg</video:thumbnail_loc><video:title>Determinant when row multiplied by scalar</video:title><video:description>The determinant when a row is multiplied by a scalar</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/32rdijPB-rA.mp4/32rdijPB-rA.mp4</video:content_loc><video:duration>800</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/linear-algebra-correction-scalar-muliplication-of-row</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25363.jpg</video:thumbnail_loc><video:title>(correction) scalar multiplication of row</video:title><video:description>Correction of last video showing that the determinant when one row is multiplied by a scalar is equal to the scalar times the determinant</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/WY6QG0mZ7uQ.mp4/WY6QG0mZ7uQ.mp4</video:content_loc><video:duration>172</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/linear-algebra-determinant-when-row-is-added</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25365.jpg</video:thumbnail_loc><video:title>Determinant when row is added</video:title><video:description>The determinant when one matrix has a row that is the sum of the rows of other matrices (and every other term is identical in the 3 matrices)</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/VrB3LaSD_uo.mp4/VrB3LaSD_uo.mp4</video:content_loc><video:duration>1015</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/linear-algebra-duplicate-row-determinant</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25367.jpg</video:thumbnail_loc><video:title>Duplicate row determinant</video:title><video:description>Determinant of a matrix with duplicate rows</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gYv8sttBIqs.mp4/gYv8sttBIqs.mp4</video:content_loc><video:duration>499</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/linear-algebra-determinant-after-row-operations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25369.jpg</video:thumbnail_loc><video:title>Determinant after row operations</video:title><video:description>What happens to the determinant when we perform a row operation</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/kpG7xySkivg.mp4/kpG7xySkivg.mp4</video:content_loc><video:duration>625</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/linear-algebra-upper-triangular-determinant</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25371.jpg</video:thumbnail_loc><video:title>Upper triangular determinant</video:title><video:description>The determinant of an upper triangular matrix</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/VX7K8iqoiRc.mp4/VX7K8iqoiRc.mp4</video:content_loc><video:duration>487</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/linear-algebra-simpler-4x4-determinant</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25373.jpg</video:thumbnail_loc><video:title>Simpler 4x4 determinant</video:title><video:description>Calculating a 4x4 determinant by putting in in upper triangular form first.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/QV0jsTiobU4.mp4/QV0jsTiobU4.mp4</video:content_loc><video:duration>553</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/linear-algebra-determinant-and-area-of-a-parallelogram</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25375.jpg</video:thumbnail_loc><video:title>Determinant and area of a parallelogram</video:title><video:description>Realizing that the determinant of a 2x2 matrix is equal to the area of the parallelogram defined by the column vectors of the matrix</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/n-S63_goDFg.mp4/n-S63_goDFg.mp4</video:content_loc><video:duration>1297</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/linear-algebra-determinant-as-scaling-factor</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25377.jpg</video:thumbnail_loc><video:title>Determinant as scaling factor</video:title><video:description>Viewing the determinant of the transformation matrix as a scaling factor of regions</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/g3MqSdO5Ubc.mp4/g3MqSdO5Ubc.mp4</video:content_loc><video:duration>1209</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/linear-algebra-transpose-of-a-matrix</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25379.jpg</video:thumbnail_loc><video:title>Transpose of a matrix</video:title><video:description>Transpose of a matrix</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2t0003_sxtU.mp4/2t0003_sxtU.mp4</video:content_loc><video:duration>517</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/linear-algebra-determinant-of-transpose</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25381.jpg</video:thumbnail_loc><video:title>Determinant of transpose</video:title><video:description>Proof by induction that transposing a matrix does not change its determinant</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/x-GV2v0dRNE.mp4/x-GV2v0dRNE.mp4</video:content_loc><video:duration>850</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/linear-algebra-transpose-of-a-matrix-product</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/178920409.jpg</video:thumbnail_loc><video:title>Transpose of a matrix product</video:title><video:description>Taking the transpose of the product of two matrices</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/UdHgWK13x5I.mp4/UdHgWK13x5I.mp4</video:content_loc><video:duration>530</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/linear-algebra-transposes-of-sums-and-inverses</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25383.jpg</video:thumbnail_loc><video:title>Transposes of sums and inverses</video:title><video:description>Transposes of sums and inverses</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Br_8t58mdeI.mp4/Br_8t58mdeI.mp4</video:content_loc><video:duration>521</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/linear-algebra-transpose-of-a-vector</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25385.jpg</video:thumbnail_loc><video:title>Transpose of a vector</video:title><video:description>Transpose of a column vector. Matrix-matrix products using vectors</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lSoaMCNKfAg.mp4/lSoaMCNKfAg.mp4</video:content_loc><video:duration>726</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/linear-algebra-rowspace-and-left-nullspace</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25387.jpg</video:thumbnail_loc><video:title>Rowspace and left nullspace</video:title><video:description>Rowspace and Left Nullspace</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qBfc57x_RSg.mp4/qBfc57x_RSg.mp4</video:content_loc><video:duration>1398</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/lin-alg-visualizations-of-left-nullspace-and-rowspace</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25389.jpg</video:thumbnail_loc><video:title>Visualizations of left nullspace and rowspace</video:title><video:description>Relationship between left nullspace, rowspace, column space and nullspace.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/GW8ZPjGlk24.mp4/GW8ZPjGlk24.mp4</video:content_loc><video:duration>1190</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/linear-algebra-rank-a-rank-transpose-of-a</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25393.jpg</video:thumbnail_loc><video:title>rank(a) = rank(transpose of a)</video:title><video:description>Rank(A) = Rank(transpose of A)</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tqqVOWm9YsU.mp4/tqqVOWm9YsU.mp4</video:content_loc><video:duration>673</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/lin-alg-showing-that-a-transpose-x-a-is-invertible</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25407.jpg</video:thumbnail_loc><video:title>Showing that A-transpose x A is invertible</video:title><video:description>Showing that (transpose of A)(A) is invertible if A has linearly independent columns</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ESSMQH6Y5OA.mp4/ESSMQH6Y5OA.mp4</video:content_loc><video:duration>754</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/linear-algebra-orthogonal-complements</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25391.jpg</video:thumbnail_loc><video:title>Orthogonal complements</video:title><video:description>Orthogonal Complements as subspaces.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/QOTjdgmNqlg.mp4/QOTjdgmNqlg.mp4</video:content_loc><video:duration>1328</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/linear-algebra-dim-v-dim-orthogonal-complement-of-v-n</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25395.jpg</video:thumbnail_loc><video:title>dim(v) + dim(orthogonal complement of v) = n</video:title><video:description>Showing that if V is a subspace of Rn, then dim(V) + dim(V&apos;s orthogonal complement) = n</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pGhBfkBqok0.mp4/pGhBfkBqok0.mp4</video:content_loc><video:duration>567</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/lin-alg-representing-vectors-in-rn-using-subspace-members</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25397.jpg</video:thumbnail_loc><video:title>Representing vectors in rn using subspace members</video:title><video:description>Showing that any member of Rn can be represented as a unique sum of a vector in subspace V and a vector in the orthogonal complement of V.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/M6lFqkqvUgo.mp4/M6lFqkqvUgo.mp4</video:content_loc><video:duration>1620</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/lin-alg-orthogonal-complement-of-the-orthogonal-complement</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25399.jpg</video:thumbnail_loc><video:title>Orthogonal complement of the orthogonal complement</video:title><video:description>Finding that the orthogonal complement of the orthogonal complement of V is V</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/zlI8mx8Hc8o.mp4/zlI8mx8Hc8o.mp4</video:content_loc><video:duration>738</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/lin-alg-orthogonal-complement-of-the-nullspace</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25401.jpg</video:thumbnail_loc><video:title>Orthogonal complement of the nullspace</video:title><video:description>The orthogonal complement of the nullspace and left nullspace.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LE_aQAur7nI.mp4/LE_aQAur7nI.mp4</video:content_loc><video:duration>207</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/lin-alg-unique-rowspace-solution-to-ax-b</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25403.jpg</video:thumbnail_loc><video:title>Unique rowspace solution to Ax = b</video:title><video:description>Showing that, for any b that is in the column space of A, there is a unique member of the row space that is the &quot;smallest&quot; solution to Ax=b</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/czIYvs9zj2g.mp4/czIYvs9zj2g.mp4</video:content_loc><video:duration>1152</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/linear-alg-rowspace-solution-to-ax-b-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25405.jpg</video:thumbnail_loc><video:title>Rowspace solution to Ax = b example</video:title><video:description>Visualizing the rowspace solution to Ax=b</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qdf2CuMGdKs.mp4/qdf2CuMGdKs.mp4</video:content_loc><video:duration>1178</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/linear-algebra/v/linear-algebra-projections-onto-subspaces</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25409.jpg</video:thumbnail_loc><video:title>Projections onto subspaces</video:title><video:description>Projections onto subspaces</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5B8XluiqdHM.mp4/5B8XluiqdHM.mp4</video:content_loc><video:duration>1046</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
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<url><loc>https://puzzicle.org/math/math-1-illustrative-math-aligned/v/using-geometric-methods-to-solve-design-problems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf455b2d5adac667a.jpg</video:thumbnail_loc><video:title>Using geometric methods to solve design problems</video:title><video:description>Use perpendicular bisectors to create diagrams that solve real-world allocation problems.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/a9LwIWniinw.mp4/a9LwIWniinw.mp4</video:content_loc><video:duration>115</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math-1-illustrative-math-aligned/v/drawing-a-reflection</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6acb123cd5f6990a.jpg</video:thumbnail_loc><video:title>Drawing a reflection</video:title><video:description>Explore reflections on a grid by identifying a line of reflection and drawing reflected images of figures across a given line.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/h83TDyZdBLY.mp4/h83TDyZdBLY.mp4</video:content_loc><video:duration>145</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math-1-illustrative-math-aligned/v/determining-a-reflection</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x89e9b3359f17780b.jpg</video:thumbnail_loc><video:title>Determining a reflection</video:title><video:description>Explore reflections on a grid by identifying a line of reflection and determining the reflected images of figures across a given line.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LNFTDsX_8jE.mp4/LNFTDsX_8jE.mp4</video:content_loc><video:duration>143</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math-1-illustrative-math-aligned/v/defining-translations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x654975c96eea89d6.jpg</video:thumbnail_loc><video:title>Defining translations</video:title><video:description>Explore translations on a grid by specifying a directed line segment and drawing translated images of figures.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/EcwQ1-P0DY4.mp4/EcwQ1-P0DY4.mp4</video:content_loc><video:duration>112</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math-1-illustrative-math-aligned/v/defining-rotations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc3cefac9ffb3111d.jpg</video:thumbnail_loc><video:title>Defining rotations</video:title><video:description>Analyze whether one figure is a rotation of another on a grid.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/sgvD0NoB-jM.mp4/sgvD0NoB-jM.mp4</video:content_loc><video:duration>189</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math-1-illustrative-math-aligned/v/corresponding-parts-of-congruent-triangles-are-congruent-indian-accent</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf53c199a55087caf.jpg</video:thumbnail_loc><video:title>Corresponding parts of congruent triangles are congruent</video:title><video:description>When two triangles are congruent, we can know that all of their corresponding sides and angles are congruent too!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/FpMUWRr4QCY.mp4/FpMUWRr4QCY.mp4</video:content_loc><video:duration>363</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math-1-illustrative-math-aligned/v/the-perpendicular-bisector-theorem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x009012eb37e1dbdc.jpg</video:thumbnail_loc><video:title>The perpendicular bisector theorem</video:title><video:description>Prove the Perpendicular Bisector Theorem and its converse.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PatjYSGbfh8.mp4/PatjYSGbfh8.mp4</video:content_loc><video:duration>465</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/dependent-probability-example-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/94879656.jpg</video:thumbnail_loc><video:title>Dependent probability: coins</video:title><video:description>We&apos;re thinking about how the probability of an event can be dependent on another event occuring in this example problem.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xPUm5SUVzTE.mp4/xPUm5SUVzTE.mp4</video:content_loc><video:duration>541</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/math3/v/types-statistical-studies</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdf317e8d.jpg</video:thumbnail_loc><video:title>Types of statistical studies</video:title><video:description>Types of statistical studies from Integrated math 3</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/z-Qi4w6Xkuc.mp4/z-Qi4w6Xkuc.mp4</video:content_loc><video:duration>592</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/analyzing-statistical-study</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x177c39f1.jpg</video:thumbnail_loc><video:title>Appropriate statistical study example</video:title><video:description>Sal determines if a statistical study was a sample study, an experiment, or an observational study.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/RQPC_rUvHas.mp4/RQPC_rUvHas.mp4</video:content_loc><video:duration>319</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/multivariable-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4aa5be13.jpg</video:thumbnail_loc><video:title>Multivariable functions</video:title><video:description>An introduction to multivariable functions, and a welcome to the multivariable calculus content as a whole.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TrcCbdWwCBc.mp4/TrcCbdWwCBc.mp4</video:content_loc><video:duration>362</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/representing-points-in-3d</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x28725fc4.jpg</video:thumbnail_loc><video:title>Representing points in 3d</video:title><video:description>Learn how to represent and think about points and vectors in three-dimensional space.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/iBgOoaeLUcM.mp4/iBgOoaeLUcM.mp4</video:content_loc><video:duration>399</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/introduction-to-3d-graphs</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4fa0a163.jpg</video:thumbnail_loc><video:title>Introduction to 3d graphs</video:title><video:description>Three-dimensional graphs are a way to represent multi-variable functions with two inputs and one output. They&apos;re visualized by plotting input-output pairs in 3D space, resulting in a surface. Other methods of visualizing multi-variable functions include contour maps, parametric functions, and vector fields.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2DRmfxkH_VI.mp4/2DRmfxkH_VI.mp4</video:content_loc><video:duration>426</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/interpreting-graphs-with-slices</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb967e756.jpg</video:thumbnail_loc><video:title>Interpreting graphs with slices</video:title><video:description>3d graphs can be a lot to take in, but it helps to imagine slicing them with planes parallel to the x-axis or y-axis and relate them with two-dimensional graphs.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/E9bAwP7iK80.mp4/E9bAwP7iK80.mp4</video:content_loc><video:duration>338</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/contour-plots</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3392e50a.jpg</video:thumbnail_loc><video:title>Contour plots</video:title><video:description>An alternative method to representing multivariable functions with a two-dimensional input and a one-dimensional output, contour maps involve drawing purely in the input space.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/WsZj5Rb6do8.mp4/WsZj5Rb6do8.mp4</video:content_loc><video:duration>336</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/parametric-curves</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3b1d7741.jpg</video:thumbnail_loc><video:title>Parametric curves</video:title><video:description>When a function has a one-dimensional input, but a multidimensional output, you can think of it as drawing a curve in space.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/bb4bSCjlFAw.mp4/bb4bSCjlFAw.mp4</video:content_loc><video:duration>351</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/parametric-surfaces</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x826fbf0d.jpg</video:thumbnail_loc><video:title>Parametric surfaces</video:title><video:description>Functions that have a two-dimensional input and a three-dimensional output can be thought of as drawing a surface in three-dimensional space. This is actually pretty cool.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/345SnWfahhY.mp4/345SnWfahhY.mp4</video:content_loc><video:duration>381</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/vector-fields-introduction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8f81fd3c.jpg</video:thumbnail_loc><video:title>Vector fields, introduction</video:title><video:description>Vector fields let you visualize a function with a two-dimensional input and a two-dimensional output. You end up with, well, a field of vectors sitting at various points in two-dimensional space.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5FWAVmwMXWg.mp4/5FWAVmwMXWg.mp4</video:content_loc><video:duration>305</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/fluid-flow-and-vector-fields</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd3b831f4.jpg</video:thumbnail_loc><video:title>Fluid flow and vector fields</video:title><video:description>A neat way to interpret a vector field is to imagine that it represents some kind of fluid flow.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/VJ2ZDLQk3IQ.mp4/VJ2ZDLQk3IQ.mp4</video:content_loc><video:duration>215</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/3d-vector-fields-introduction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd536672f.jpg</video:thumbnail_loc><video:title>3d vector fields, introduction</video:title><video:description>Vector fields can also be three-dimensional, though this can be a bit trickier to visualize.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Go3UvzbsSGo.mp4/Go3UvzbsSGo.mp4</video:content_loc><video:duration>310</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/3d-vector-field-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa91184f2.jpg</video:thumbnail_loc><video:title>3d vector field example</video:title><video:description>See an example of how you can start to understand how the formula for a three-dimensional vector field relates to the way it looks.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ZiMYRBtDB2M.mp4/ZiMYRBtDB2M.mp4</video:content_loc><video:duration>244</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/transformations-part-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xeec906c0.jpg</video:thumbnail_loc><video:title>Transformations, part 1</video:title><video:description>One fun way to think about functions is to imagine that they literally move the points from the input space over to the output space. See what this looks like with some one-dimensional examples.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/roRR6A3TozM.mp4/roRR6A3TozM.mp4</video:content_loc><video:duration>316</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/transformations-part-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x57b38402.jpg</video:thumbnail_loc><video:title>Transformations, part 2</video:title><video:description>More transformations, but this time with a function that maps two dimensions to two dimensions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Rkm0dLTYUuw.mp4/Rkm0dLTYUuw.mp4</video:content_loc><video:duration>278</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/transformations-part-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x75ec9be3.jpg</video:thumbnail_loc><video:title>Transformations, part 3</video:title><video:description>Learn how you can think about a parametric surface as a certain kind of transformation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/U2SQXHMqclc.mp4/U2SQXHMqclc.mp4</video:content_loc><video:duration>209</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/partial-derivatives-introduction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa59f6489.jpg</video:thumbnail_loc><video:title>Partial derivatives, introduction</video:title><video:description>Partial derivatives tell you how a multivariable function changes as you tweak just one of the variables in its input.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/AXqhWeUEtQU.mp4/AXqhWeUEtQU.mp4</video:content_loc><video:duration>656</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/partial-derivatives-and-graphs</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa41cd13a.jpg</video:thumbnail_loc><video:title>Graphical understanding of partial derivatives</video:title><video:description>One of the best ways to think about partial derivatives is by slicing the graph of a multivariable function.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/dfvnCHqzK54.mp4/dfvnCHqzK54.mp4</video:content_loc><video:duration>415</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/formal-definition-of-partial-derivatives</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xba09aabe.jpg</video:thumbnail_loc><video:title>Formal definition of partial derivatives</video:title><video:description>Partial derivatives are formally defined using a limit, much like ordinary derivatives.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/kdMep5GUOBw.mp4/kdMep5GUOBw.mp4</video:content_loc><video:duration>478</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/symmetry-of-second-partial-derivatives</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5637b539.jpg</video:thumbnail_loc><video:title>Symmetry of second partial derivatives</video:title><video:description>There are many ways to take a &quot;second partial derivative&quot;, but some of them secretly turn out to be the same thing.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/J08-L2buigM.mp4/J08-L2buigM.mp4</video:content_loc><video:duration>422</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/gradient</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe92f7935.jpg</video:thumbnail_loc><video:title>Gradient</video:title><video:description>The gradient captures all the partial derivative information of a scalar-valued multivariable function.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tIpKfDc295M.mp4/tIpKfDc295M.mp4</video:content_loc><video:duration>331</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/gradient-and-graphs</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdada919e.jpg</video:thumbnail_loc><video:title>Gradient and graphs</video:title><video:description>Learn how the gradient can be thought of as pointing in the &quot;direction of steepest ascent&quot;. This is a rather important interpretation for the gradient.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_-02ze7tf08.mp4/_-02ze7tf08.mp4</video:content_loc><video:duration>371</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/gradient-and-contour-maps</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2478347d.jpg</video:thumbnail_loc><video:title>Gradient and contour maps</video:title><video:description>Gradient vectors always point perpendicular to contour lines.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ZTbTYEMvo10.mp4/ZTbTYEMvo10.mp4</video:content_loc><video:duration>377</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/directional-derivative</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xaebedeec.jpg</video:thumbnail_loc><video:title>Directional derivative</video:title><video:description>Directional derivatives tell you how a multivariable function changes as you move along some vector in its input space.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/N_ZRcLheNv0.mp4/N_ZRcLheNv0.mp4</video:content_loc><video:duration>434</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/directional-derivative-formal-definition</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9dd381ba.jpg</video:thumbnail_loc><video:title>Directional derivative, formal definition</video:title><video:description>Learn the limit definition of a directional derivative. This helps to clarify what it is really doing.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4RBkIJPG6Yo.mp4/4RBkIJPG6Yo.mp4</video:content_loc><video:duration>399</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/directional-derivatives-and-slope</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0ce88a21.jpg</video:thumbnail_loc><video:title>Directional derivatives and slope</video:title><video:description>The directional derivative can be used to compute the slope of a slice of a graph, but you must be careful to use a unit vector.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4tdyIGIEtNU.mp4/4tdyIGIEtNU.mp4</video:content_loc><video:duration>530</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/why-the-gradient-is-the-direction-of-steepest-ascent</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6a180b72.jpg</video:thumbnail_loc><video:title>Why the gradient is the direction of steepest ascent</video:title><video:description>The way we compute the gradient seems unrelated to its interpretation as the direction of steepest ascent. Here you can see how the two relate.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TEB2z7ZlRAw.mp4/TEB2z7ZlRAw.mp4</video:content_loc><video:duration>632</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/differential-of-a-vector-valued-function</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24320.jpg</video:thumbnail_loc><video:title>Differential of a vector valued function</video:title><video:description>Understanding the differential of a vector valued function</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/FYMn61HLw1k.mp4/FYMn61HLw1k.mp4</video:content_loc><video:duration>304</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/vector-valued-function-derivative-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24322.jpg</video:thumbnail_loc><video:title>Vector valued function derivative example</video:title><video:description>Concrete example of the derivative of a vector valued function to better understand what it means</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vcwvzUVLPw0.mp4/vcwvzUVLPw0.mp4</video:content_loc><video:duration>765</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/multivariable-chain-rule</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x36d3e7c5.jpg</video:thumbnail_loc><video:title>Multivariable chain rule</video:title><video:description>This is the simplest case of taking the derivative of a composition involving multivariable functions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/NO3AqAaAE6o.mp4/NO3AqAaAE6o.mp4</video:content_loc><video:duration>573</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/multivariable-chain-rule-intuition</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9c62350e.jpg</video:thumbnail_loc><video:title>Multivariable chain rule intuition</video:title><video:description>Get a feel for what the multivariable is really saying, and how thinking about various &quot;nudges&quot; in space makes it intuitive.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hFvBZf-Jx28.mp4/hFvBZf-Jx28.mp4</video:content_loc><video:duration>467</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/vector-form-of-the-multivariable-chain-rule</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8e1e9957.jpg</video:thumbnail_loc><video:title>Vector form of the multivariable chain rule</video:title><video:description>The multivariable chain rule is more often expressed in terms of the gradient and a vector-valued derivative. This makes it look very analogous to the single-variable chain rule.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qZlBjnC3iro.mp4/qZlBjnC3iro.mp4</video:content_loc><video:duration>325</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/multivariable-chain-rule-and-directional-derivatives</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xddbd0aaf.jpg</video:thumbnail_loc><video:title>Multivariable chain rule and directional derivatives</video:title><video:description>See how the multivariable chain rule can be expressed in terms of the directional derivative.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/m2mW2FQJgEE.mp4/m2mW2FQJgEE.mp4</video:content_loc><video:duration>401</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/more-formal-treatment-of-multivariable-chain-rule</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x49bfbf51.jpg</video:thumbnail_loc><video:title>More formal treatment of multivariable chain rule</video:title><video:description>For those of you who want to see how the multivariable chain rule looks in the context of the limit definitions of various forms of the derivative.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5mMLaK1ByZc.mp4/5mMLaK1ByZc.mp4</video:content_loc><video:duration>715</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/curvature-intuition</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x97cc1c4f.jpg</video:thumbnail_loc><video:title>Curvature intuition</video:title><video:description>An introduction to curvature, the radius of curvature, and how you can think about each one geometrically.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ugtUGhBSeE0.mp4/ugtUGhBSeE0.mp4</video:content_loc><video:duration>252</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/curvature-formula-part-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x221b8645.jpg</video:thumbnail_loc><video:title>Curvature formula, part 1</video:title><video:description>Curvature is computed by first finding a unit tangent vector function, then finding its derivative with respect to arc length. Here we start thinking about what that means.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gspjhwSNMWs.mp4/gspjhwSNMWs.mp4</video:content_loc><video:duration>366</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/curvature-formula-part-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbecb823e.jpg</video:thumbnail_loc><video:title>Curvature formula, part 2</video:title><video:description>A continuation in explaining how curvature is computed, with the formula for a circle as a guiding example.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Q-BxnC-uWQo.mp4/Q-BxnC-uWQo.mp4</video:content_loc><video:duration>426</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/curvature-formula-part-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdfb610a6.jpg</video:thumbnail_loc><video:title>Curvature formula, part 3</video:title><video:description>Here, this concludes the explanation for how curvature is the derivative of a unit tangent vector with respect to length.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8V4_4M90RfA.mp4/8V4_4M90RfA.mp4</video:content_loc><video:duration>517</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/curvature-formula-part-4</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x55b36872.jpg</video:thumbnail_loc><video:title>Curvature formula, part 4</video:title><video:description>After the last video made reference to an explicit curvature formula, here you can start to get an intuition for why that seemingly unrelated formula describes curvature.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/WmdN_iPhxAI.mp4/WmdN_iPhxAI.mp4</video:content_loc><video:duration>514</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/curvature-formula-part-5</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe8614242.jpg</video:thumbnail_loc><video:title>Curvature formula, part 5</video:title><video:description>Here, we finish the intuition for how the curvature relates to the cross product between the first two derivatives of a parametric function.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8aHUrjgF6s0.mp4/8aHUrjgF6s0.mp4</video:content_loc><video:duration>466</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/curvature-of-a-helix-part-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5c5962e2.jpg</video:thumbnail_loc><video:title>Curvature of a helix, part 1</video:title><video:description>An example of computing curvature by finding the unit tangent vector function, then computing its derivative with respect to arc length.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/AE8NVTyESd8.mp4/AE8NVTyESd8.mp4</video:content_loc><video:duration>388</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/curvature-of-a-helix-part-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x806cbe74.jpg</video:thumbnail_loc><video:title>Curvature of a helix, part 2</video:title><video:description>This finishes up the helix-curvature example started in the last video.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/kjNgXVZ1aZ4.mp4/kjNgXVZ1aZ4.mp4</video:content_loc><video:duration>439</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/curvature-of-a-cycloid</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x025231d3.jpg</video:thumbnail_loc><video:title>Curvature of a cycloid</video:title><video:description>An example of computing curvature with the explicit formula.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/biK6_fWLDRc.mp4/biK6_fWLDRc.mp4</video:content_loc><video:duration>283</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/computing-the-partial-derivative-of-a-vector-valued-function</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfd75feb2.jpg</video:thumbnail_loc><video:title>Computing the partial derivative of a vector-valued function</video:title><video:description>When a function has a multidimensional input, and a multidimensional output, you can take its partial derivative by computing the partial derivative of each component in the output.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ln43wOC3iC4.mp4/ln43wOC3iC4.mp4</video:content_loc><video:duration>138</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/partial-derivative-of-a-parametric-surface-part-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xab9a6baf.jpg</video:thumbnail_loc><video:title>Partial derivative of a parametric surface, part 1</video:title><video:description>When a vector-valued function represents a parametric surface, how do you interpret its partial derivative?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/e7Nel0UoXR8.mp4/e7Nel0UoXR8.mp4</video:content_loc><video:duration>569</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/partial-derivative-of-a-parametric-surface-part-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc71e0dbe.jpg</video:thumbnail_loc><video:title>Partial derivative of a parametric surface, part 2</video:title><video:description>Taking the same example surface used in the last example, we now take a look at the partial derivative in the other direction.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lz8L-0SoMo0.mp4/lz8L-0SoMo0.mp4</video:content_loc><video:duration>423</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/partial-derivatives-of-vector-fields</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x80d8b824.jpg</video:thumbnail_loc><video:title>Partial derivatives of vector fields</video:title><video:description>How do you intepret the partial derivatives of the function which defines a vector field?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ar9SeJpbPI8.mp4/ar9SeJpbPI8.mp4</video:content_loc><video:duration>514</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/partial-derivatives-of-vector-fields-component-by-component</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xccb57798.jpg</video:thumbnail_loc><video:title>Partial derivatives of vector fields, component by component</video:title><video:description>Here we step through each partial derivative of each component in a vector field, and understand what each means geometrically.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/VhtFSSq3lXo.mp4/VhtFSSq3lXo.mp4</video:content_loc><video:duration>451</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/divergence-intuition-part-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x044f3f1d.jpg</video:thumbnail_loc><video:title>Divergence intuition, part 1</video:title><video:description>Vector fields can be thought of as representing fluid flow, and divergence is all about studying the change in fluid density during that flow.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/c0MR-vWiUPU.mp4/c0MR-vWiUPU.mp4</video:content_loc><video:duration>381</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/divergence-intuition-part-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbdd5f10c.jpg</video:thumbnail_loc><video:title>Divergence intuition, part 2</video:title><video:description>In preparation for finding the formula for divergence, we start getting an intuition for what points of positive, negative and zero divergence should look like.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Yeie-aJT2eU.mp4/Yeie-aJT2eU.mp4</video:content_loc><video:duration>328</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/divergence-formula-part-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x32a14878.jpg</video:thumbnail_loc><video:title>Divergence formula, part 1</video:title><video:description>How does the x-component of a vector field relate to the divergence?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/uOX7SijjH9w.mp4/uOX7SijjH9w.mp4</video:content_loc><video:duration>219</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/divergence-formula-part-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0f86b891.jpg</video:thumbnail_loc><video:title>Divergence formula, part 2</video:title><video:description>Here we finish the line of reasoning which leads to the formula for divergence in two dimensions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TKlpZ0UUJTQ.mp4/TKlpZ0UUJTQ.mp4</video:content_loc><video:duration>364</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/divergence-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1b43cae4.jpg</video:thumbnail_loc><video:title>Divergence example</video:title><video:description>An example of computing and interpreting the divergence of a two-dimensional vector field.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/AlXVrAOls-8.mp4/AlXVrAOls-8.mp4</video:content_loc><video:duration>251</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/divergence-notation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb60334f1.jpg</video:thumbnail_loc><video:title>Divergence notation</video:title><video:description>Learn how divergence is expressed using the same upsidedown triangle symbols that the gradient uses.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TyYlBXNETZE.mp4/TyYlBXNETZE.mp4</video:content_loc><video:duration>289</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/2d-curl-intuition</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc5160b5d.jpg</video:thumbnail_loc><video:title>2d curl intuition</video:title><video:description>A description of how vector fields relate to fluid rotation, laying the intuition for what the operation of curl represents.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/eEwZeY51mT0.mp4/eEwZeY51mT0.mp4</video:content_loc><video:duration>234</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/2d-curl-formula</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0deab6bd.jpg</video:thumbnail_loc><video:title>2d curl formula</video:title><video:description>Here we build up to the formula for computing the two-dimensional curl of a vector field, reasoning through what partial derivative information corresponds to fluid rotation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qF9Kz37Ksq0.mp4/qF9Kz37Ksq0.mp4</video:content_loc><video:duration>343</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/2d-curl-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x58b7877a.jpg</video:thumbnail_loc><video:title>2d curl example</video:title><video:description>A worked example of computing and interpreting two-dimensional curl.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/cAAEMza4GvQ.mp4/cAAEMza4GvQ.mp4</video:content_loc><video:duration>339</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/2d-curl-nuance</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7dcabd7d.jpg</video:thumbnail_loc><video:title>2d curl nuance</video:title><video:description>The meaning of positive curl in a fluid flow can sometimes look a bit different from the clear cut rotation-around-a-point examples discussed in previous videos.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/szLkF7isbI0.mp4/szLkF7isbI0.mp4</video:content_loc><video:duration>300</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/describing-rotation-in-3d-with-a-vector</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x62ccb697.jpg</video:thumbnail_loc><video:title>Describing rotation in 3d with a vector</video:title><video:description>Learn how a three-dimensional vector can be used to describe three-dimensional rotation. This is important for understanding three-dimensional curl.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/h5BmWo5_sc8.mp4/h5BmWo5_sc8.mp4</video:content_loc><video:duration>366</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/3d-curl-intuition-part-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7f3a9ecf.jpg</video:thumbnail_loc><video:title>3d curl intuition, part 1</video:title><video:description>Here we start transitioning from the understanding of two-dimensional curl into an understanding of three-dimensional curl.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/erMopRd-MXg.mp4/erMopRd-MXg.mp4</video:content_loc><video:duration>350</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/3d-curl-intuition-part-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbf11198c.jpg</video:thumbnail_loc><video:title>3d curl intuition, part 2</video:title><video:description>Continuing the intuition for how three-dimensional curl represents rotation in three-dimensional fluid flow.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4yzV8m8X3Kk.mp4/4yzV8m8X3Kk.mp4</video:content_loc><video:duration>497</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/3d-curl-formula-part-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xca7d2a0c.jpg</video:thumbnail_loc><video:title>3d curl formula, part 1</video:title><video:description>How to compute a three-dimensional curl, imagined as a cross product of sorts.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/a_49iMi10kg.mp4/a_49iMi10kg.mp4</video:content_loc><video:duration>461</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/3d-curl-formula-part-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x29cb7d34.jpg</video:thumbnail_loc><video:title>3d curl formula, part 2</video:title><video:description>This finishes the demonstration of how to compute three-dimensional curl using a certain determinant.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0k4tWeI3R0Y.mp4/0k4tWeI3R0Y.mp4</video:content_loc><video:duration>372</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/3d-curl-computation-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5d1b79ea.jpg</video:thumbnail_loc><video:title>3d curl computation example</video:title><video:description>A worked example of a three-dimensional curl computation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/GRuEOLcdWjo.mp4/GRuEOLcdWjo.mp4</video:content_loc><video:duration>335</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/laplacian-intuition</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x60573c87.jpg</video:thumbnail_loc><video:title>Laplacian intuition</video:title><video:description>A visual understanding for how the Laplace operator is an extension of the second derivative to multivariable functions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/EW08rD-GFh0.mp4/EW08rD-GFh0.mp4</video:content_loc><video:duration>331</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/laplacian-computation-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4c3be4fb.jpg</video:thumbnail_loc><video:title>Laplacian computation example</video:title><video:description>A worked example of computing the laplacian of a two-variable function.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/XbCvGRjjzgg.mp4/XbCvGRjjzgg.mp4</video:content_loc><video:duration>321</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/explicit-laplacian-formula</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x20f5346f.jpg</video:thumbnail_loc><video:title>Explicit Laplacian formula</video:title><video:description>This is another way you might see the Laplace operator written.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6cMn1F6bNPU.mp4/6cMn1F6bNPU.mp4</video:content_loc><video:duration>243</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/harmonic-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0fad04bf.jpg</video:thumbnail_loc><video:title>Harmonic Functions</video:title><video:description>If the Laplacian of a function is zero everywhere, it is called Harmonic. Harmonic functions arise all the time in physics, capturing a certain notion of &quot;stability&quot;, whenever one point in space is influenced by its neighbors.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/JQSC0lCPG24.mp4/JQSC0lCPG24.mp4</video:content_loc><video:duration>656</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/jacobian-prerequisite-knowledge</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x89ac6576e2c8a11f.jpg</video:thumbnail_loc><video:title>Jacobian prerequisite knowledge</video:title><video:description>Before jumping into the Jacobian, it&apos;s important to make sure we all know how to think about matrices geometrically. This is targetted towards those who have seen linear algebra but may need a quick refresher.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/VmfTXVG9S0U.mp4/VmfTXVG9S0U.mp4</video:content_loc><video:duration>562</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/local-linearity-for-a-multivariable-function</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc561d674a3d5a959.jpg</video:thumbnail_loc><video:title>Local linearity for a multivariable function</video:title><video:description>A visual representation of local linearity for a function with a 2d input and a 2d output, in preparation for learning about the Jacobian matrix.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Vnga_psnCAo.mp4/Vnga_psnCAo.mp4</video:content_loc><video:duration>323</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/the-jacobian-matrix</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb3c8591f3af73e71.jpg</video:thumbnail_loc><video:title>The Jacobian matrix</video:title><video:description>An introduction to how the jacobian matrix represents what a multivariable function looks like locally, as a linear transformation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/bohL918kXQk.mp4/bohL918kXQk.mp4</video:content_loc><video:duration>382</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/computing-a-jacobian-matrix</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x15de8d5d7d1c48b6.jpg</video:thumbnail_loc><video:title>Computing a Jacobian matrix</video:title><video:description>This finishes the introduction of the Jacobian matrix, working out the computations for the example shown in the last video.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/CGbBbH1e7Yw.mp4/CGbBbH1e7Yw.mp4</video:content_loc><video:duration>233</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/the-jacobian-determinant</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe42b23090e815198.jpg</video:thumbnail_loc><video:title>The Jacobian Determinant</video:title><video:description>How to interpret the determinant of a Jacobian matrix, along with some examples.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/p46QWyHQE6M.mp4/p46QWyHQE6M.mp4</video:content_loc><video:duration>533</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/what-is-a-tangent-plane</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3297f1fe.jpg</video:thumbnail_loc><video:title>What is a tangent plane</video:title><video:description>The &quot;tangent plane&quot; of the graph of a function is, well, a two-dimensional plane that is tangent to this graph. Here you can see what that looks like.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/cHNT7_F8m1Y.mp4/cHNT7_F8m1Y.mp4</video:content_loc><video:duration>200</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/controlling-a-plane-in-space</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0b636b91.jpg</video:thumbnail_loc><video:title>Controlling a plane in space</video:title><video:description>How can you describe a specified plane in space as the graph of a function?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/H2hOwKszKRo.mp4/H2hOwKszKRo.mp4</video:content_loc><video:duration>640</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/computing-a-tangent-plane</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8763b3e1.jpg</video:thumbnail_loc><video:title>Computing a tangent plane</video:title><video:description>Here you can see how to use the control over functions whose graphs are planes, as introduced in the last video, to find the tangent plane to a function graph.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/QL6qb1h65hg.mp4/QL6qb1h65hg.mp4</video:content_loc><video:duration>581</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/local-linearization</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc8af53b7.jpg</video:thumbnail_loc><video:title>Local linearization</video:title><video:description>A &quot;local linearization&quot; is the generalization of tangent plane functions; one that can apply to multivariable functions with any number of inputs.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/o7_zS7Bx2VA.mp4/o7_zS7Bx2VA.mp4</video:content_loc><video:duration>553</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/what-do-quadratic-approximations-look-like</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa0c2bd39.jpg</video:thumbnail_loc><video:title>What do quadratic approximations look like</video:title><video:description>After learning about local linearizations of multivariable functions, the next step is to understand how to approximate a function even more closely with a quadratic approximation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/80bJA_tSbo4.mp4/80bJA_tSbo4.mp4</video:content_loc><video:duration>282</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/quadratic-approximation-formula-part-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x48b93c30.jpg</video:thumbnail_loc><video:title>Quadratic approximation formula, part 1</video:title><video:description>How to create a quadratic function that approximates an arbitrary two-variable function.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/UV5yj5A3QIM.mp4/UV5yj5A3QIM.mp4</video:content_loc><video:duration>429</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/quadratic-approximation-formula-part-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfd5eae14.jpg</video:thumbnail_loc><video:title>Quadratic approximation formula, part 2</video:title><video:description>A continuation from the previous video, leading to the full formula for the quadratic approximation of a two-variable function.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/szHMvVXxp-g.mp4/szHMvVXxp-g.mp4</video:content_loc><video:duration>590</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/quadratic-approximation-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf188596e.jpg</video:thumbnail_loc><video:title>Quadratic approximation example</video:title><video:description>A worked example for finding the quadratic approximation of a two-variable function.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/fW3snxnCPEY.mp4/fW3snxnCPEY.mp4</video:content_loc><video:duration>729</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/the-hessian-matrix</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5346e9fe.jpg</video:thumbnail_loc><video:title>The Hessian matrix</video:title><video:description>The Hessian matrix is a way of organizing all the second partial derivative information of a multivariable function.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LbBcuZukCAw.mp4/LbBcuZukCAw.mp4</video:content_loc><video:duration>370</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/expressing-a-quadratic-form-with-a-matrix</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfa25e3b4.jpg</video:thumbnail_loc><video:title>Expressing a quadratic form with a matrix</video:title><video:description>How to write an expression like ax^2 + bxy + cy^2 using matrices and vectors.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0yEiCV-xEWQ.mp4/0yEiCV-xEWQ.mp4</video:content_loc><video:duration>500</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/vector-form-of-multivariable-quadratic-approximation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xcad2e826.jpg</video:thumbnail_loc><video:title>Vector form of multivariable quadratic approximation</video:title><video:description>This is the more general form of a quadratic approximation for a scalar-valued multivariable function. It is analogous to a quadratic Taylor polynomial in the single-variable world.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ClFrIg0PpnM.mp4/ClFrIg0PpnM.mp4</video:content_loc><video:duration>515</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/multivariable-maxima-and-minima</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xadaf4e40.jpg</video:thumbnail_loc><video:title>Multivariable maxima and minima</video:title><video:description>A description of maxima and minima of multivariable functions, what they look like, and a little bit about how to find them.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ux7EQ3ip2DU.mp4/ux7EQ3ip2DU.mp4</video:content_loc><video:duration>484</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/saddle-points</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5993ca15.jpg</video:thumbnail_loc><video:title>Saddle points</video:title><video:description>Just because the tangent plane to a multivariable function is flat, it doesn&apos;t mean that point is a local minimum or a local maximum. There is a third possibility, new to multivariable calculus, called a &quot;saddle point&quot;.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8aAU4r_pUUU.mp4/8aAU4r_pUUU.mp4</video:content_loc><video:duration>350</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/warm-up-to-the-second-partial-derivative-test</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4affaf47.jpg</video:thumbnail_loc><video:title>Warm up to the second partial derivative test</video:title><video:description>An example of looking for local minima in a multivariable function by finding where tangent planes are flat, along with some of the intuitions that will underly the second partial derivative test.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/nRJM4mY-Pq0.mp4/nRJM4mY-Pq0.mp4</video:content_loc><video:duration>697</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/second-partial-derivative-test</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2cfadbec.jpg</video:thumbnail_loc><video:title>Second partial derivative test</video:title><video:description>How to determine if the critical point of a two-variable function is a local minimum, a local maximum, or a saddle point.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/m1FhUjMMv30.mp4/m1FhUjMMv30.mp4</video:content_loc><video:duration>712</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/second-partial-derivative-test-intuition</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd786588e.jpg</video:thumbnail_loc><video:title>Second partial derivative test intuition</video:title><video:description>The second partial derivative test is based on a formula which seems to come out of nowhere. Here, you can see a little more intuition for why it looks the way it does.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/sJo7D74PAak.mp4/sJo7D74PAak.mp4</video:content_loc><video:duration>643</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/second-partial-derivative-test-example-part-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3affa5ce.jpg</video:thumbnail_loc><video:title>Second partial derivative test example, part 1</video:title><video:description>A worked example of finding a classifying critical points of a two-variable function.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/shWXeUn5BHk.mp4/shWXeUn5BHk.mp4</video:content_loc><video:duration>371</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/second-partial-derivative-test-example-part-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x88eeefe9.jpg</video:thumbnail_loc><video:title>Second partial derivative test example, part 2</video:title><video:description>Continuing the worked example from the previous video, now classifying each critical point.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TqslX-bUTD8.mp4/TqslX-bUTD8.mp4</video:content_loc><video:duration>463</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/constrained-optimization-introduction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf123b6a166983b0e.jpg</video:thumbnail_loc><video:title>Constrained optimization introduction</video:title><video:description>The Lagrange multiplier technique is how we take advantage of the observation made in the last video, that the solution to a constrained optimization problem occurs when the contour lines of the function being maximized are tangent to the constraint curve.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vwUV2IDLP8Q.mp4/vwUV2IDLP8Q.mp4</video:content_loc><video:duration>389</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/lagrange-multipliers-using-tangency-to-solve-constrained-optimization</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9645cf61a8256d54.jpg</video:thumbnail_loc><video:title>Lagrange multipliers, using tangency to solve constrained optimization</video:title><video:description>The Lagrange multiplier technique is how we take advantage of the observation made in the last video, that the solution to a constrained optimization problem occurs when the contour lines of the function being maximized are tangent to the constraint curve.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/yuqB-d5MjZA.mp4/yuqB-d5MjZA.mp4</video:content_loc><video:duration>523</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/finishing-the-intro-lagrange-multiplier-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xee1132860c2a5d35.jpg</video:thumbnail_loc><video:title>Finishing the intro lagrange multiplier example</video:title><video:description>Working out the algebra for the final solution the the example from the previous two videos.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/aep6lwPqm6I.mp4/aep6lwPqm6I.mp4</video:content_loc><video:duration>399</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/lagrange-multiplier-example-part-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbabfa1cb9a42466b.jpg</video:thumbnail_loc><video:title>Lagrange multiplier example, part 1</video:title><video:description>A Lagrange multipliers example of maximizing revenues subject to a budgetary constraint.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/BSKtQcLQLWU.mp4/BSKtQcLQLWU.mp4</video:content_loc><video:duration>470</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/lagrange-multiplier-example-part-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8b06c88b2bcfc0c9.jpg</video:thumbnail_loc><video:title>Lagrange multiplier example, part 2</video:title><video:description>Finishing off the example from the previous video</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5gCx5YCmXbI.mp4/5gCx5YCmXbI.mp4</video:content_loc><video:duration>411</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/the-lagrangian</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x046926e43a1c2f91.jpg</video:thumbnail_loc><video:title>The Lagrangian</video:title><video:description>How a special function, called the &quot;Lagrangian&quot;, can be used to package together all the steps needed to solve a constrained optimization problem.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hQ4UNu1P2kw.mp4/hQ4UNu1P2kw.mp4</video:content_loc><video:duration>748</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/meaning-of-lagrange-multiplier</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3c5c1012d0728ba3.jpg</video:thumbnail_loc><video:title>Meaning of the Lagrange multiplier</video:title><video:description>In the previous videos on Lagrange multipliers, the Lagrange multiplier itself has just been some proportionality constant that we didn&apos;t care about. Here, you can see what its real meaning is.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/m-G3K2GPmEQ.mp4/m-G3K2GPmEQ.mp4</video:content_loc><video:duration>608</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/proof-for-the-meaning-of-lagrange-multipliers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x39e4f4907a5382bc.jpg</video:thumbnail_loc><video:title>Proof for the meaning of Lagrange multipliers</video:title><video:description>Here, you can see a proof of the fact shown in the last video, that the Lagrange multiplier gives information about how altering a constraint can alter the solution to a constrained maximization problem. Note, this is somewhat technical</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/b9B2FZ5cqbM.mp4/b9B2FZ5cqbM.mp4</video:content_loc><video:duration>1039</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/introduction-to-the-line-integral</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24308.jpg</video:thumbnail_loc><video:title>Introduction to the line integral</video:title><video:description>Introduction to the Line Integral</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_60sKaoRmhU.mp4/_60sKaoRmhU.mp4</video:content_loc><video:duration>1128</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/line-integral-example-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24310.jpg</video:thumbnail_loc><video:title>Line integral example 1</video:title><video:description>Concrete example using a line integral</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/uXjQ8yc9Pdg.mp4/uXjQ8yc9Pdg.mp4</video:content_loc><video:duration>782</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/line-integral-example-2-part-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24312.jpg</video:thumbnail_loc><video:title>Line integral example 2 (part 1)</video:title><video:description>Line integral over a closed path (part 1)</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/wyTjyQMVvc4.mp4/wyTjyQMVvc4.mp4</video:content_loc><video:duration>773</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/line-integral-example-2-part-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24314.jpg</video:thumbnail_loc><video:title>Line integral example 2 (part 2)</video:title><video:description>Part 2 of an example of taking a line integral over a closed path</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Qqanbd3gLhw.mp4/Qqanbd3gLhw.mp4</video:content_loc><video:duration>598</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/line-integrals-and-vector-fields</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24324.jpg</video:thumbnail_loc><video:title>Line integrals and vector fields</video:title><video:description>Using line integrals to find the work done on a particle moving through a vector field</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/t3cJYNdQLYg.mp4/t3cJYNdQLYg.mp4</video:content_loc><video:duration>1006</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/using-a-line-integral-to-find-the-work-done-by-a-vector-field-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24326.jpg</video:thumbnail_loc><video:title>Using a line integral to find work</video:title><video:description>Using a line integral to find the work done by a vector field example</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/AFF8FXxt5os.mp4/AFF8FXxt5os.mp4</video:content_loc><video:duration>692</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/parametrization-of-a-reverse-path</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24328.jpg</video:thumbnail_loc><video:title>Parametrization of a reverse path</video:title><video:description>Understanding how to parametrize a reverse path for the same curve.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/eGRZKkmI_fo.mp4/eGRZKkmI_fo.mp4</video:content_loc><video:duration>446</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/scalar-field-line-integral-independent-of-path-direction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24330.jpg</video:thumbnail_loc><video:title>Scalar field line integral independent of path direction</video:title><video:description>Showing that the line integral of a scalar field is independent of path direction</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/99pD1-6ZpuM.mp4/99pD1-6ZpuM.mp4</video:content_loc><video:duration>982</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/vector-field-line-integrals-dependent-on-path-direction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24332.jpg</video:thumbnail_loc><video:title>Vector field line integrals dependent on path direction</video:title><video:description>Showing that, unlike line integrals of scalar fields, line integrals over vector fields are path direction dependent</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/fuSOY9r1R6w.mp4/fuSOY9r1R6w.mp4</video:content_loc><video:duration>951</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/path-independence-for-line-integrals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24334.jpg</video:thumbnail_loc><video:title>Path independence for line integrals</video:title><video:description>Showing that if a vector field is the gradient of a scalar field, then its line integral is path independent</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/K_fgnCJOI8I.mp4/K_fgnCJOI8I.mp4</video:content_loc><video:duration>1034</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/closed-curve-line-integrals-of-conservative-vector-fields</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24336.jpg</video:thumbnail_loc><video:title>Closed curve line integrals of conservative vector fields</video:title><video:description>Showing that the line integral along closed curves of conservative vector fields is zero</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/I2dbzp0zHuw.mp4/I2dbzp0zHuw.mp4</video:content_loc><video:duration>505</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/example-of-closed-line-integral-of-conservative-field</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24338.jpg</video:thumbnail_loc><video:title>Example of closed line integral of conservative field</video:title><video:description>Example of taking a closed line integral of a conservative field</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Q9t1LghwdGc.mp4/Q9t1LghwdGc.mp4</video:content_loc><video:duration>662</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/second-example-of-line-integral-of-conservative-vector-field</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24340.jpg</video:thumbnail_loc><video:title>Second example of line integral of conservative vector field</video:title><video:description>Using path independence of a conservative vector field to solve a line integral</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LpY8Qa3IP1w.mp4/LpY8Qa3IP1w.mp4</video:content_loc><video:duration>619</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/double-integral-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24288.jpg</video:thumbnail_loc><video:title>Double integral 1</video:title><video:description>Introduction to the double integral</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/85zGYB-34jQ.mp4/85zGYB-34jQ.mp4</video:content_loc><video:duration>629</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/double-integrals-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24290.jpg</video:thumbnail_loc><video:title>Double integrals 2</video:title><video:description>Figuring out the volume under z=xy^2</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TdLD2Zh-nUQ.mp4/TdLD2Zh-nUQ.mp4</video:content_loc><video:duration>590</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/double-integrals-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24292.jpg</video:thumbnail_loc><video:title>Double integrals 3</video:title><video:description>Let&apos;s integrate dy first!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/z8BM6cHifPA.mp4/z8BM6cHifPA.mp4</video:content_loc><video:duration>483</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/double-integrals-4</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24294.jpg</video:thumbnail_loc><video:title>Double integrals 4</video:title><video:description>Another way to conceptualize the double integral.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/twT-WZChfZ8.mp4/twT-WZChfZ8.mp4</video:content_loc><video:duration>564</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/double-integrals-5</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24296.jpg</video:thumbnail_loc><video:title>Double integrals 5</video:title><video:description>Finding the volume when we have variable boundaries.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hrIPO8mQqtw.mp4/hrIPO8mQqtw.mp4</video:content_loc><video:duration>591</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/double-integrals-6</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24298.jpg</video:thumbnail_loc><video:title>Double integrals 6</video:title><video:description>Let&apos;s evaluate the double integrals with y=x^2 as one of the boundaries.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0pv0QtOi5l8.mp4/0pv0QtOi5l8.mp4</video:content_loc><video:duration>598</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/polar-coordinates-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf16db78cc1c9b015.jpg</video:thumbnail_loc><video:title>Polar coordinates</video:title><video:description>Introduction to polar coordinates</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jexMSlSDubM.mp4/jexMSlSDubM.mp4</video:content_loc><video:duration>620</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/triple-integrals-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24300.jpg</video:thumbnail_loc><video:title>Triple integrals 1</video:title><video:description>Introduction to the triple integral</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vr0sTKbV7lI.mp4/vr0sTKbV7lI.mp4</video:content_loc><video:duration>638</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/triple-integrals-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24302.jpg</video:thumbnail_loc><video:title>Triple integrals 2</video:title><video:description>Using a triple integral to find the mass of a volume of variable density.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vxQvL_WhBGU.mp4/vxQvL_WhBGU.mp4</video:content_loc><video:duration>446</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/triple-integrals-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24304.jpg</video:thumbnail_loc><video:title>Triple integrals 3</video:title><video:description>Figuring out the boundaries of integration.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ZN2PfqZ4ihM.mp4/ZN2PfqZ4ihM.mp4</video:content_loc><video:duration>708</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/introduction-to-parametrizing-a-surface-with-two-parameters</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/2505283.jpg</video:thumbnail_loc><video:title>Parametrizing a surface, part 1</video:title><video:description>Introduction to Parametrizing a Surface with Two Parameters</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/owKAHXf1y1A.mp4/owKAHXf1y1A.mp4</video:content_loc><video:duration>1142</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/determining-a-position-vector-valued-function-for-a-parametrization-of-two-param</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/2542218.jpg</video:thumbnail_loc><video:title>Determining a position vector-valued function for a parametrization of two parameters</video:title><video:description>Determining a Position Vector-Valued Function for a Parametrization of Two Parameters</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/bJ_09eoCmag.mp4/bJ_09eoCmag.mp4</video:content_loc><video:duration>992</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/partial-derivatives-of-vector-valued-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/2565195.jpg</video:thumbnail_loc><video:title>Partial derivatives of vector-valued functions</video:title><video:description>Partial Derivatives of Vector-Valued Functions</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/c7ByaI3T7Dc.mp4/c7ByaI3T7Dc.mp4</video:content_loc><video:duration>607</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/introduction-to-the-surface-integral</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24356.jpg</video:thumbnail_loc><video:title>Introduction to the surface integral</video:title><video:description>Introduction to the surface integral</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9k97m8oWnaY.mp4/9k97m8oWnaY.mp4</video:content_loc><video:duration>1334</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/example-of-calculating-a-surface-integral-part-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24358.jpg</video:thumbnail_loc><video:title>Example of calculating a surface integral part 1</video:title><video:description>Example of calculating a surface integral part 1</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7sQCcGlK2bY.mp4/7sQCcGlK2bY.mp4</video:content_loc><video:duration>645</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/example-of-calculating-a-surface-integral-part-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24360.jpg</video:thumbnail_loc><video:title>Example of calculating a surface integral part 2</video:title><video:description>Example of calculating a surface integral part 2</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qQAhhithHa8.mp4/qQAhhithHa8.mp4</video:content_loc><video:duration>629</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/example-of-calculating-a-surface-integral-part-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24362.jpg</video:thumbnail_loc><video:title>Example of calculating a surface integral part 3</video:title><video:description>Example of calculating a surface integral part 3</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/s2_NTiISZl4.mp4/s2_NTiISZl4.mp4</video:content_loc><video:duration>594</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/surface-integral-example-part-1-parameterizing-the-unit-sphere</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/809362246.jpg</video:thumbnail_loc><video:title>Surface integral example, part 1</video:title><video:description>Visualizing a suitable parameterization</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/E_Hwhp74Rhc.mp4/E_Hwhp74Rhc.mp4</video:content_loc><video:duration>665</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/surface-integral-example-part-2-calculating-the-surface-differential</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/809263849.jpg</video:thumbnail_loc><video:title>Surface integral example part 2</video:title><video:description>Taking the cross product to calculate the surface differential in terms of the parameters</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tyVCA_8MUV4.mp4/tyVCA_8MUV4.mp4</video:content_loc><video:duration>771</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/surface-integral-example-part-3-the-home-stretch</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/809327989.jpg</video:thumbnail_loc><video:title>Surface integral example part 3: The home stretch</video:title><video:description>Using a few trigonometric identities to finally calculate the value of the surface integral</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/uzOXGgAgmPs.mp4/uzOXGgAgmPs.mp4</video:content_loc><video:duration>759</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/surface-integral-ex2-part-1-parameterizing-the-surface</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/815244209.jpg</video:thumbnail_loc><video:title>Surface integral ex2 part 1</video:title><video:description>Parametrizing a surface that can be explictly made a function of x and y.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PpUWpxAb39w.mp4/PpUWpxAb39w.mp4</video:content_loc><video:duration>310</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/surface-integral-ex2-part-2-evaluating-integral</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/815252175.jpg</video:thumbnail_loc><video:title>Surface integral ex2 part 2</video:title><video:description>Evaluating the surface integral</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ItW5CxLsLSo.mp4/ItW5CxLsLSo.mp4</video:content_loc><video:duration>591</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/surface-integral-ex3-part-1-parameterizing-the-outside-surface</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/815198581.jpg</video:thumbnail_loc><video:title>Surface integral ex3 part 1</video:title><video:description>Breaking apart a larger surface into its components</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/EOpzN8ZHqpU.mp4/EOpzN8ZHqpU.mp4</video:content_loc><video:duration>540</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/surface-integral-ex3-part-2-evaluating-the-outside-surface</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/815059993.jpg</video:thumbnail_loc><video:title>Surface integral ex3 part 2</video:title><video:description>Evaluating the surface integral over the outside of the chopped cylinder</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xGiILI906C4.mp4/xGiILI906C4.mp4</video:content_loc><video:duration>550</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/surface-integral-ex3-part-3-top-surface</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/815160761.jpg</video:thumbnail_loc><video:title>Surface integral ex3 part 3</video:title><video:description>Parametrizing the top surface</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/wiVWafc3JBM.mp4/wiVWafc3JBM.mp4</video:content_loc><video:duration>761</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/surface-integral-ex3-part-4-home-stretch</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/815201348.jpg</video:thumbnail_loc><video:title>Surface integral ex3 part 4</video:title><video:description>Evaluating the third surface integral and coming to the final answer</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/bhrmEy0wvD0.mp4/bhrmEy0wvD0.mp4</video:content_loc><video:duration>242</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/conceputal-understanding-of-flux-in-three-dimensions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/815159721.jpg</video:thumbnail_loc><video:title>Conceptual understanding of flux</video:title><video:description>Conceptual understanding of flux across a two-dimensional surface</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ivg3dLTarbs.mp4/ivg3dLTarbs.mp4</video:content_loc><video:duration>503</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/constructing-a-unit-normal-vector-to-a-surface</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/815232513.jpg</video:thumbnail_loc><video:title>Constructing a unit normal vector</video:title><video:description>Deriving a unit normal vector from the surface parametrization</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/usH9VUi2-Xg.mp4/usH9VUi2-Xg.mp4</video:content_loc><video:duration>383</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/vector-representation-of-a-surface-integral</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/815106014.jpg</video:thumbnail_loc><video:title>Vector representation of a surface integral</video:title><video:description>Different ways of representing a flux integral</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/NCwwfvPEVn8.mp4/NCwwfvPEVn8.mp4</video:content_loc><video:duration>575</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/green-s-theorem-proof-part-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24342.jpg</video:thumbnail_loc><video:title>Green&apos;s theorem proof (part 1)</video:title><video:description>Part 1 of the proof of Green&apos;s Theorem</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/l5zJvZKfMYE.mp4/l5zJvZKfMYE.mp4</video:content_loc><video:duration>866</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/green-s-theorem-proof-part-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24344.jpg</video:thumbnail_loc><video:title>Green&apos;s theorem proof (part 2)</video:title><video:description>Part 2 of the proof of Green&apos;s Theorem</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qdFD-0OWBRo.mp4/qdFD-0OWBRo.mp4</video:content_loc><video:duration>1166</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/green-s-theorem-example-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24346.jpg</video:thumbnail_loc><video:title>Green&apos;s theorem example 1</video:title><video:description>Using Green&apos;s Theorem to solve a line integral of a vector field</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gGXnILbrhsM.mp4/gGXnILbrhsM.mp4</video:content_loc><video:duration>631</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/green-s-theorem-example-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24348.jpg</video:thumbnail_loc><video:title>Green&apos;s theorem example 2</video:title><video:description>Another example applying Green&apos;s Theorem</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/sSyPAAyL8nQ.mp4/sSyPAAyL8nQ.mp4</video:content_loc><video:duration>427</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/constructing-a-unit-normal-vector-to-a-curve</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/809395096.jpg</video:thumbnail_loc><video:title>Constructing a unit normal vector to a curve</video:title><video:description>Figuring out a unit normal vector at any point along a curve defined by a position vector function</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_9x2cqO7-Ig.mp4/_9x2cqO7-Ig.mp4</video:content_loc><video:duration>608</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/2-d-divergence-theorem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/809321651.jpg</video:thumbnail_loc><video:title>2D divergence theorem</video:title><video:description>Using Green&apos;s Theorem to establish a two dimensional version of the Divergence Theorem</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/eoJGBr-tJXo.mp4/eoJGBr-tJXo.mp4</video:content_loc><video:duration>884</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/conceptual-clarification-for-2-d-divergence-theorem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/809302581.jpg</video:thumbnail_loc><video:title>Conceptual clarification for 2D divergence theorem</video:title><video:description>Understanding the line integral as flux through a boundary</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qs0hRHfnzTQ.mp4/qs0hRHfnzTQ.mp4</video:content_loc><video:duration>568</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/stokes-theorem-intuition</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/873691665.jpg</video:thumbnail_loc><video:title>Stokes&apos; theorem intuition</video:title><video:description>Conceptual understanding of why the curl of a vector field along a surface would relate to the line integral around the surface&apos;s boundary</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9iaYNaENVH4.mp4/9iaYNaENVH4.mp4</video:content_loc><video:duration>732</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/green-s-and-stokes-theorem-relationship</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/873865593.jpg</video:thumbnail_loc><video:title>Green&apos;s and Stokes&apos; theorem relationship</video:title><video:description>Seeing that Green&apos;s Theorem is just a special case of Stokes&apos; Theorem</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TPov_v9mLWc.mp4/TPov_v9mLWc.mp4</video:content_loc><video:duration>415</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/orienting-boundary-with-surface</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/873764943.jpg</video:thumbnail_loc><video:title>Orienting boundary with surface</video:title><video:description>Determining the proper orientation of the boundary given the orientation of the surface</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/84NkvxfMPtM.mp4/84NkvxfMPtM.mp4</video:content_loc><video:duration>209</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/orientation-and-stokes</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/874076304.jpg</video:thumbnail_loc><video:title>Orientation and stokes</video:title><video:description>Determining the proper orientation of a boundary given the orientation of the normal vector</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/U6U4HhR3Fqc.mp4/U6U4HhR3Fqc.mp4</video:content_loc><video:duration>266</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/conditions-for-stokes-theorem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/878103964.jpg</video:thumbnail_loc><video:title>Conditions for stokes theorem</video:title><video:description>Understanding when you can use Stokes. Piecewise-smooth lines and surfaces</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/yDB-191sa2M.mp4/yDB-191sa2M.mp4</video:content_loc><video:duration>284</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/stokes-example-part-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/878112005.jpg</video:thumbnail_loc><video:title>Stokes example part 1</video:title><video:description>Starting to apply Stokes theorem to solve a line integral</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/E2MRMdaPKcc.mp4/E2MRMdaPKcc.mp4</video:content_loc><video:duration>190</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/part-2-parameterizing-the-surface</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/878163443.jpg</video:thumbnail_loc><video:title>Stokes example part 2</video:title><video:description>Parameterizing the surface</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9bwy85M1Zxg.mp4/9bwy85M1Zxg.mp4</video:content_loc><video:duration>242</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/stokes-example-part-3-surface-to-double-integral</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/878196180.jpg</video:thumbnail_loc><video:title>Stokes example part 3</video:title><video:description>Converting the surface integral to a double integral</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/VPz4bCQDGgk.mp4/VPz4bCQDGgk.mp4</video:content_loc><video:duration>485</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/stokes-example-part-4-curl-and-final-answer</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/878133910.jpg</video:thumbnail_loc><video:title>Stokes example part 4</video:title><video:description>Finding the curl of the vector field and then evaluating the double integral in the parameter domain</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/clL2jLXtX4I.mp4/clL2jLXtX4I.mp4</video:content_loc><video:duration>414</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/evaluating-line-integral-directly-part-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1254589677.jpg</video:thumbnail_loc><video:title>Evaluating line integral directly - part 1</video:title><video:description>Showing that we didn&apos;t need to use Stokes&apos; Theorem to evaluate this line integral</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/A57_63yP1UU.mp4/A57_63yP1UU.mp4</video:content_loc><video:duration>464</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/evaluating-line-integral-directly-part-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1254590705.jpg</video:thumbnail_loc><video:title>Evaluating line integral directly - part 2</video:title><video:description>Finishing up the line integral with a little trigonometric integration</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Jhu1M53AF0E.mp4/Jhu1M53AF0E.mp4</video:content_loc><video:duration>383</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/3-d-divergence-theorem-intuition</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1254611464.jpg</video:thumbnail_loc><video:title>3D divergence theorem intuition</video:title><video:description>Intuition behind the Divergence Theorem in three dimensions</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/XyiQ2dwJHXE.mp4/XyiQ2dwJHXE.mp4</video:content_loc><video:duration>554</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/divergence-theorem-example-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1254640190.jpg</video:thumbnail_loc><video:title>Divergence theorem example 1</video:title><video:description>Example of calculating the flux across a surface by using the Divergence Theorem</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/asyIsn59Lnc.mp4/asyIsn59Lnc.mp4</video:content_loc><video:duration>645</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/why-we-got-zero-flux-in-divergence-theorem-example-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1254539389.jpg</video:thumbnail_loc><video:title>Explanation of example 1</video:title><video:description>Intuition as to why we got no net flux in the last worked example</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/iFpyKTuC7jY.mp4/iFpyKTuC7jY.mp4</video:content_loc><video:duration>214</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/stokes-theorem-proof-part-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1254599500.jpg</video:thumbnail_loc><video:title>Stokes&apos; theorem proof part 1</video:title><video:description>The beginning of a proof of Stokes&apos; theorem for a special class of surfaces. Finding the curl of our vector field.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qIBqvr5_QqQ.mp4/qIBqvr5_QqQ.mp4</video:content_loc><video:duration>314</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/stokes-theorem-proof-part-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1254626652.jpg</video:thumbnail_loc><video:title>Stokes&apos; theorem proof part 2</video:title><video:description>Figuring out a parameterization of our surface and representing dS</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/apWQoMKVmW4.mp4/apWQoMKVmW4.mp4</video:content_loc><video:duration>459</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/stokes-theorem-proof-part-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1254632405.jpg</video:thumbnail_loc><video:title>Stokes&apos; theorem proof part 3</video:title><video:description>Writing our surface integral as a double integral over the domain of our parameters</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4o4P7KrkzXg.mp4/4o4P7KrkzXg.mp4</video:content_loc><video:duration>251</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/stokes-theorem-proof-part-4</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1254257997.jpg</video:thumbnail_loc><video:title>Stokes&apos; theorem proof part 4</video:title><video:description>Starting to work on the line integral about the surface</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1og25U-d3_8.mp4/1og25U-d3_8.mp4</video:content_loc><video:duration>439</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/stokes-theorem-proof-part-5</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1254588379.jpg</video:thumbnail_loc><video:title>Stokes&apos; theorem proof part 5</video:title><video:description>Working on the integrals...</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/a29qZSRDBdE.mp4/a29qZSRDBdE.mp4</video:content_loc><video:duration>328</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/stokes-theorem-proof-part-6</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1254528847.jpg</video:thumbnail_loc><video:title>Stokes&apos; theorem proof part 6</video:title><video:description>More manipulating the integrals...</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/02gVmoObrjM.mp4/02gVmoObrjM.mp4</video:content_loc><video:duration>327</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/stokes-theorem-proof-part-7</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1254530460.jpg</video:thumbnail_loc><video:title>Stokes&apos; theorem proof part 7</video:title><video:description>Using Green&apos;s Theorem to complete the proof</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/YT6XwkcPcsw.mp4/YT6XwkcPcsw.mp4</video:content_loc><video:duration>709</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/type-i-regions-in-three-dimensions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1254699123.jpg</video:thumbnail_loc><video:title>Type I regions in three dimensions</video:title><video:description>Definition of Type 1 regions. Visualizing what is and isn&apos;t a Type I region</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/A11AfJ2-3rE.mp4/A11AfJ2-3rE.mp4</video:content_loc><video:duration>519</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/type-ii-regions-in-three-dimensions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1254469905.jpg</video:thumbnail_loc><video:title>Type II regions in three dimensions</video:title><video:description>Definition and intuition for Type 2 Regions</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pZ_2bATPi2I.mp4/pZ_2bATPi2I.mp4</video:content_loc><video:duration>449</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/type-iii-regions-in-three-dimensions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1254671407.jpg</video:thumbnail_loc><video:title>Type III regions in three dimensions</video:title><video:description>Definition and intuition for type 3 regions</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/bxGnbVOtRYo.mp4/bxGnbVOtRYo.mp4</video:content_loc><video:duration>393</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/divergence-theorem-proof-part-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1254638405.jpg</video:thumbnail_loc><video:title>Divergence theorem proof (part 1)</video:title><video:description>Setting up the proof for the divergence theorem</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vCAFlt4pQSQ.mp4/vCAFlt4pQSQ.mp4</video:content_loc><video:duration>509</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/divergence-theorem-proof-part-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1254358889.jpg</video:thumbnail_loc><video:title>Divergence theorem proof (part 2)</video:title><video:description>Breaking up the surface integral</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OM3e-J3euXo.mp4/OM3e-J3euXo.mp4</video:content_loc><video:duration>450</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/divergence-theorem-proof-part-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1254688165.jpg</video:thumbnail_loc><video:title>Divergence theorem proof (part 3)</video:title><video:description>Evaluating the surface integral</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3_W6bGuTfzU.mp4/3_W6bGuTfzU.mp4</video:content_loc><video:duration>381</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/divergence-theorem-proof-part-4</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1254709098.jpg</video:thumbnail_loc><video:title>Divergence theorem proof (part 4)</video:title><video:description>More evaluation of the surface integral</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lUD7ti47IQc.mp4/lUD7ti47IQc.mp4</video:content_loc><video:duration>489</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/multivariable-calculus/v/divergence-theorem-proof-part-5</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1254605394.jpg</video:thumbnail_loc><video:title>Divergence theorem proof (part 5)</video:title><video:description>Home stretch. Proving the Type I part</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DrRsXhln4S8.mp4/DrRsXhln4S8.mp4</video:content_loc><video:duration>192</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/cosine-sine-and-tangent-of-6-and-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xaa39178f36038ef7.jpg</video:thumbnail_loc><video:title>Cosine, sine and tangent of π/6 and π/3</video:title><video:description>With the unit circle and the Pythagorean theorem, we can find the exact sine, cosine, and tangent of the angles π/6 and π/3.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Tt_ATh5mCGw.mp4/Tt_ATh5mCGw.mp4</video:content_loc><video:duration>528</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/cosine-equation-algebraic-solution-set</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6fa2fde28005f2a5.jpg</video:thumbnail_loc><video:title>Cosine equation algebraic solution set</video:title><video:description>Solve a cosine equation with an infinite number of solutions. Use trig identities to represent the whole solution set.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/JoOfBpdaAiw.mp4/JoOfBpdaAiw.mp4</video:content_loc><video:duration>373</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/cosine-equation-solution-set-in-an-interval</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4f1bc4c6751cd4c4.jpg</video:thumbnail_loc><video:title>Cosine equation solution set in an interval</video:title><video:description>Given the algebraic solution set for a cosine equation, find which solutions fall within an interval.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0_4uTKBI99o.mp4/0_4uTKBI99o.mp4</video:content_loc><video:duration>382</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/sine-equation-algebraic-solution-set</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x096d3067db0caafb.jpg</video:thumbnail_loc><video:title>Sine equation algebraic solution set</video:title><video:description>Solve a sine equation with an infinite number of solutions. Use trig identities to represent the whole solution set.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ES15mSuqHM8.mp4/ES15mSuqHM8.mp4</video:content_loc><video:duration>336</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/proof-of-the-tangent-angle-sum-and-difference-identities</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2b010b5c159918fd.jpg</video:thumbnail_loc><video:title>Proof of the tangent angle sum and difference identities</video:title><video:description>Using the sine and cosine of the sum or difference of two angles, we can prove: tan(x+y)=(tan(x)+tan(y))/(1-tan(x)tan(y))</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/nUlElr4LXz8.mp4/nUlElr4LXz8.mp4</video:content_loc><video:duration>415</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/using-the-tangent-angle-addition-identity</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa5b3c26ba3b1a2e0.jpg</video:thumbnail_loc><video:title>Using the tangent angle addition identity</video:title><video:description>Find the tangent of 13pi/12 without a calculator using the tangent angle addition identity.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4nPMCRuts9o.mp4/4nPMCRuts9o.mp4</video:content_loc><video:duration>389</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/complex-numbers-same-modulus</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2b266422dad332be.jpg</video:thumbnail_loc><video:title>Complex numbers with the same modulus (absolute value)</video:title><video:description>Sal shows how to determine which members in a set of complex numbers have the same modulus (or absolute value). He also shows how to visualize all of the complex numbers with a given modulus as a circle centered at the origin on the complex plane, since all points on such a circle are the same distance from the origin.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/uB5QDraFefs.mp4/uB5QDraFefs.mp4</video:content_loc><video:duration>172</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/multiply-complex-numbers-polar</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd88b64481289c668.jpg</video:thumbnail_loc><video:title>Multiplying complex numbers in polar form</video:title><video:description>We can multiply two complex numbers in polar form by multiplying their moduli and adding their arguments.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/VkdXztTFsvM.mp4/VkdXztTFsvM.mp4</video:content_loc><video:duration>147</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/divide-complex-polar</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x34e958aff90c3f66.jpg</video:thumbnail_loc><video:title>Dividing complex numbers in polar form</video:title><video:description>We can divide two complex numbers in polar form by dividing their moduli and subtracting their arguments.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lyWaNZ1ERMw.mp4/lyWaNZ1ERMw.mp4</video:content_loc><video:duration>190</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/visualizing-powers-complex-number</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd60fc5c65ef997ae.jpg</video:thumbnail_loc><video:title>Taking and visualizing powers of a complex number</video:title><video:description>Given a complex number in rectangular form, we can convert it to polar form to show how to visualize powers of the complex number by scaling and rotating it by its own modulus and argument.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/VZmnLQ3CMbE.mp4/VZmnLQ3CMbE.mp4</video:content_loc><video:duration>381</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/parallelogram-rule-for-vector-addition</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x64f19fb133aa602b.jpg</video:thumbnail_loc><video:title>Parallelogram rule for vector addition</video:title><video:description>The parallelogram rule says that if we place two vectors so they have the same initial point, and then complete the vectors into a parallelogram, then the sum of the vectors is the directed diagonal that starts at the same point as the vectors.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Mep0foZMOCg.mp4/Mep0foZMOCg.mp4</video:content_loc><video:duration>140</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/subtracting-vectors-with-parallelogram-rule</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa18760e499aacad7.jpg</video:thumbnail_loc><video:title>Subtracting vectors with parallelogram rule</video:title><video:description>The parallelogram rule says that if we place two vectors so they have the same initial point, and then complete the vectors into a parallelogram, then the sum of the vectors is the directed diagonal that starts at the same point as the vectors. To subtract two vectors, we simply add the first vector and the opposite of the second vector, i.e., a+b=a+(-b).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4mRDJf6tShs.mp4/4mRDJf6tShs.mp4</video:content_loc><video:duration>166</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/vector-word-problem-resultant-velocity</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x689490466c9eb9af.jpg</video:thumbnail_loc><video:title>Vector word problem: resultant velocity</video:title><video:description>When an object, say, a boat, travels at a certain velocity, and the medium through which it travels, say, a river, has its own velocity, we can find the resultant velocity of the object by adding the two velocities. In this example, we find the resultant velocity vector of a boat.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Neon4dpvmUk.mp4/Neon4dpvmUk.mp4</video:content_loc><video:duration>617</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/vector-word-problem-resultant-force</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x87912fdee3fc278a.jpg</video:thumbnail_loc><video:title>Vector word problem: resultant force</video:title><video:description>When two different forces act on the same object, we can find the resultant force acting on the object by adding the two separate forces. In this example, we find a resultant force vector using geometry, specifically the laws of sines and the laws of cosines.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Ga1Di84GcgM.mp4/Ga1Di84GcgM.mp4</video:content_loc><video:duration>432</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/matrices-as-transformations-of-the-plane</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x77c3c0ec61006c97.jpg</video:thumbnail_loc><video:title>Matrices as transformations of the plane</video:title><video:description>We can think of a 2X2 matrix as describing a special kind of transformation of the plane (called &quot;linear transformation&quot;). By telling us where the vectors [1,0] and [0,1] are mapped to, we can figure out where any other vector is mapped to.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PtjdhADnJi4.mp4/PtjdhADnJi4.mp4</video:content_loc><video:duration>492</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/working-with-matrices-as-transformations-of-the-plane</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5a4b500a33b2766d.jpg</video:thumbnail_loc><video:title>Working with matrices as transformations of the plane</video:title><video:description>Once we know how 2X2 matrices define transformations of the plane, we can connect geometric transformations like rotations, reflections, and dilations to specific matrices.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vCkvVAvmJwY.mp4/vCkvVAvmJwY.mp4</video:content_loc><video:duration>255</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/intro-to-determinants</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa2f9e84b3bcb95a7.jpg</video:thumbnail_loc><video:title>Intro to determinant notation and computation</video:title><video:description>Matrix determinants are easy to define and hard to understand. So let&apos;s start with defining them and introducing related notation. In other videos we will learn what they mean and how to use them.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ZAkmBOCiNqU.mp4/ZAkmBOCiNqU.mp4</video:content_loc><video:duration>206</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/interpreting-determinants-in-terms-of-area</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc5e499ea08b67bdc.jpg</video:thumbnail_loc><video:title>Interpreting determinants in terms of area</video:title><video:description>The determinant of a 2X2 matrix tells us what the area of the image of a unit square would be under the matrix transformation. This, in turn, allows us to tell what the area of the image of any figure would be under the transformation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ER_96Mx-KEE.mp4/ER_96Mx-KEE.mp4</video:content_loc><video:duration>259</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/finding-area-of-figure-after-transformation-using-determinant</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa9ae3dc81e2633f3.jpg</video:thumbnail_loc><video:title>Finding area of figure after transformation using determinant</video:title><video:description>In this worked example, Sal finds the area of the image of a rectangle after a transformation defined by a given matrix. This is done by finding the area of the pre-image and multiplying by the matrix&apos;s determinant.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/aVuCoUxt3vc.mp4/aVuCoUxt3vc.mp4</video:content_loc><video:duration>127</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/proof-matrix-determinant-gives-area-of-image-of-unit-square-under-mapping</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe5735d39a2f26ed7.jpg</video:thumbnail_loc><video:title>Proof: Matrix determinant gives area of image of unit square under mapping</video:title><video:description>Proof that the determinant of a 2X2 matrix gives the area of the image of the unit square under the mapping defined by the matrix.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_OiMiQGKvvc.mp4/_OiMiQGKvvc.mp4</video:content_loc><video:duration>259</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/using-matrices-to-transform-a-4d-vector</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x218b7462a2078e66.jpg</video:thumbnail_loc><video:title>Using matrices to transform a 4D vector</video:title><video:description>4X4 matrices can define transformations of the 4D space. In this worked example, we see how to find the image of a given 4D vector under the transformation defined by a given matrix.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Foy8cAMqnAo.mp4/Foy8cAMqnAo.mp4</video:content_loc><video:duration>379</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/composing-3x3-matrices</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9b5bb488dbd2fa0b.jpg</video:thumbnail_loc><video:title>Composing 3x3 matrices</video:title><video:description>3X3 matrices can define transformations of the 3D space. In this worked example, we see how to find the matrix transformation that is the composition of two other matrices.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2O18RbWmrYA.mp4/2O18RbWmrYA.mp4</video:content_loc><video:duration>218</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/inverse-matrix-introduction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x954f4bbe019f355a.jpg</video:thumbnail_loc><video:title>Inverse matrix introduction</video:title><video:description>The inverse of a square matrix is another matrix (of the same dimensions), where the multiplication (or composition) of the two matrices results in the identity matrix. This is analogous to inverse functions (if we think of matrices as functions) or reciprocal numbers (if we think of matrices as special numbers). Fascinating!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/sT9IgHjjhiY.mp4/sT9IgHjjhiY.mp4</video:content_loc><video:duration>410</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/invertible-matrices-and-determinants</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x056893a13619a4b9.jpg</video:thumbnail_loc><video:title>Invertible matrices and determinants</video:title><video:description>An invertible matrix is a matrix that has an inverse. In this video, we investigate the relationship between a matrix&apos;s determinant, and whether that matrix is invertible.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/GuFvSwriy1Q.mp4/GuFvSwriy1Q.mp4</video:content_loc><video:duration>282</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/invertible-matrices-and-transformations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x678a9c56ef091bcf.jpg</video:thumbnail_loc><video:title>Invertible matrices and transformations</video:title><video:description>An invertible matrix is a matrix that has an inverse. In this video, we compare the effect of two transformations, one defined by an invertible matrix and one by a non-invertible matrix. We see that the non-invertible matrix map the entire plane onto a single line.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/S278zOWSsZM.mp4/S278zOWSsZM.mp4</video:content_loc><video:duration>368</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/inverse-matrices-and-matrix-equations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x80af5561a2fc6840.jpg</video:thumbnail_loc><video:title>Inverse matrices and matrix equations</video:title><video:description>In other videos, we&apos;ve seen how matrices can represent systems of equations, and we&apos;ve also seen how matrices whose determinant is zero don&apos;t have an inverse. In this video, we connect this two understanding, and by doing that way we understand how we can solve systems of equations with matrices.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/a2S0kuXO3gE.mp4/a2S0kuXO3gE.mp4</video:content_loc><video:duration>450</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/probability-using-combinations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25851.jpg</video:thumbnail_loc><video:title>Probability using combinations</video:title><video:description>Probability of getting exactly 3 heads in 8 flips of a fair coin.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Xqfcy1rqMbI.mp4/Xqfcy1rqMbI.mp4</video:content_loc><video:duration>550</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/probability-permutations-combinations-taste-testing</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4d467bb2723d85e4.jpg</video:thumbnail_loc><video:title>Probability with permutations &amp; combinations example: taste testing</video:title><video:description>We can use combinations (when order does not matter) and permutations (when order does matter) to find probabilities.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/C6gQZ7qKtdM.mp4/C6gQZ7qKtdM.mp4</video:content_loc><video:duration>226</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/probability-combinations-choosing-groups</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x14d325c1d92be14a.jpg</video:thumbnail_loc><video:title>Probability with combinations example: choosing groups</video:title><video:description>We can use two combinations (when order does not matter) to find the probability of someone being included in the group that&apos;s chosen at random from a larger group.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gy8E0-wf4a0.mp4/gy8E0-wf4a0.mp4</video:content_loc><video:duration>219</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/probability-combinations-example-choosing-cards</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xafc50db74d0782e4.jpg</video:thumbnail_loc><video:title>Probability with combinations example: choosing cards</video:title><video:description>We can use combinations (when order does not matter) to find the probability of drawing two aces and two kings in a draw of four cards.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Tp-SjgG11G8.mp4/Tp-SjgG11G8.mp4</video:content_loc><video:duration>149</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/probability-distributions-empirical-data</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbbfc533d3121f47e.jpg</video:thumbnail_loc><video:title>Probability distributions from empirical data</video:title><video:description>We can approximate a probability distribution by using empirical or observed data.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/wztjEa7893c.mp4/wztjEa7893c.mp4</video:content_loc><video:duration>172</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/probabilities-fair-decisions-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5b6ea363f742d41d.jpg</video:thumbnail_loc><video:title>Using probabilities to make fair decisions example</video:title><video:description>We can determine whether or not probabilities are being used to make a fair decision. In this example, we look at whether different outcomes have the same probability or not when we roll two dice to make a decision.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Z_5f3kys52o.mp4/Z_5f3kys52o.mp4</video:content_loc><video:duration>214</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/expected-payoff-example-lottery</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x395fecff8361ddc2.jpg</video:thumbnail_loc><video:title>Expected payoff example: lottery ticket</video:title><video:description>We can find the expected payoff (or the expected net gain) of a certain lottery ticket by taking the weighted average the outcomes.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Ay1bVzqTKzg.mp4/Ay1bVzqTKzg.mp4</video:content_loc><video:duration>244</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus/v/expected-payoff-example-protection-plan</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8a8f30a531ad189f.jpg</video:thumbnail_loc><video:title>Expected payoff example: protection plan</video:title><video:description>We can find the expected payoff (or the expected net gain) of a protection plan offered by a store by taking the weighted average of the outcomes.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/mKPeuVjPDo0.mp4/mKPeuVjPDo0.mp4</video:content_loc><video:duration>158</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus-tx/v/interpreting-a-transformed-polynomial-functions-graph-precalculus-khan-academy</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5cacfd43c8c54839.jpg</video:thumbnail_loc><video:title>Interpreting a transformed polynomial function&apos;s graph</video:title><video:description>Given a function and a transformed version of this function, interpret the new meaning of the key features in context.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Ftz3jDAEPfo.mp4/Ftz3jDAEPfo.mp4</video:content_loc><video:duration>184</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus-tx/v/solving-polynomial-functions-using-their-graphs-precalculus-khan-academy</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9e2110e526bfb84e.jpg</video:thumbnail_loc><video:title>Solving polynomial functions using their graphs</video:title><video:description>Find the values of x when a function takes on certain y-values.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/H-N4QpKJQoY.mp4/H-N4QpKJQoY.mp4</video:content_loc><video:duration>195</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus-tx/v/solving-polynomials-using-a-table-precalculus-khan-academy</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x75e4a03990e669d6.jpg</video:thumbnail_loc><video:title>Solving polynomials using a table</video:title><video:description>Finding zeroes of a polynomial function from a table and estimating where a zero may live if it is not on the table.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/R4l_ySDoZJ8.mp4/R4l_ySDoZJ8.mp4</video:content_loc><video:duration>203</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus-tx/v/solving-polynomial-inequalities-in-factored-form</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6f4a831b2f62952a.jpg</video:thumbnail_loc><video:title>Solving polynomial inequalities in factored form</video:title><video:description>Learn how to solve a polynomial inequality when provided factored form.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4DUipIIwFfc.mp4/4DUipIIwFfc.mp4</video:content_loc><video:duration>414</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus-tx/v/solving-applications-of-polynomial-inequalities-precalculus-khan-academy</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7329f07b37bbce3c.jpg</video:thumbnail_loc><video:title>Solving applications of polynomial inequalities</video:title><video:description>Learn how to apply knowledge of polynomial inequalities to real world contexts and apply solving skills to answer questions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7AOvarRJy5w.mp4/7AOvarRJy5w.mp4</video:content_loc><video:duration>342</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus-tx/v/solving-factored-form-rational-inequalities</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x928b9c2467a894dc.jpg</video:thumbnail_loc><video:title>Solving factored form rational inequalities by testing intervals</video:title><video:description>Identify when a rational inequality provided in factored form is true in terms of zero by testing intervals.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hER6MasSSww.mp4/hER6MasSSww.mp4</video:content_loc><video:duration>482</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus-tx/v/solving-rational-inequalities-with-rational-expressions-on-both-sides</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9515899b84d4fb45.jpg</video:thumbnail_loc><video:title>Solving rational inequalities with rational expressions on both sides</video:title><video:description>Learn how to solve rational inequalities where there is a rational expression on both sides of the inequality sign.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/eQT08EvLW1k.mp4/eQT08EvLW1k.mp4</video:content_loc><video:duration>479</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus-tx/v/recursive-formula-for-geometric-sequence</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2000d28fbb4e08c2.jpg</video:thumbnail_loc><video:title>Recursive formula for geometric sequences</video:title><video:description>Write the recursive formula for a geometric sequence by finding the common ratio and designated initial term.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/GVLPBC-T2vU.mp4/GVLPBC-T2vU.mp4</video:content_loc><video:duration>137</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus-tx/v/equations-of-sequence-patterns</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26788.jpg</video:thumbnail_loc><video:title>Sequences word problem: growth pattern</video:title><video:description>Sal finds the equation that describes a growth pattern of shapes made of squares.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_3BnyEr5fG4.mp4/_3BnyEr5fG4.mp4</video:content_loc><video:duration>516</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus-tx/v/using-the-quotient-identities-to-prove-trig-identities</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x93f600e314e538af.jpg</video:thumbnail_loc><video:title>Using the quotient identities to prove trig identities</video:title><video:description>Using the quotient identities to prove trig identities.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vcFiReQah40.mp4/vcFiReQah40.mp4</video:content_loc><video:duration>122</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus-tx/v/identifying-if-a-parabola-exists-from-given-key-features</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x577a85716c650fd9.jpg</video:thumbnail_loc><video:title>Identifying if a parabola exists from given key features</video:title><video:description>Use the distance formula to identify if a parabola can exist when provided a point, focus and directrix.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/HyirU1YnzX0.mp4/HyirU1YnzX0.mp4</video:content_loc><video:duration>279</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus-tx/v/identifying-if-a-ellipse-or-hyperbola-exists-from-given-key-features</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x91e69c663864316b.jpg</video:thumbnail_loc><video:title>Identifying if an ellipse or hyperbola exists from given key features</video:title><video:description>Identify if the provided points and foci can exist on an ellipse or hyperbola, or both.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/NGKCekLhErg.mp4/NGKCekLhErg.mp4</video:content_loc><video:duration>302</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus-tx/v/identifying-the-foci-of-an-ellipse-using-the-radii</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xed05297687a9eb01.jpg</video:thumbnail_loc><video:title>Identifying the foci of an ellipse using the radii</video:title><video:description>Using the graph of an ellipse to identify the foci by identifying the radii on the major and minor axes.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/wGHqt0RwHxY.mp4/wGHqt0RwHxY.mp4</video:content_loc><video:duration>150</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/precalculus-tx/v/proving-the-formula-for-focal-length-of-an-ellipse</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x34d88ec81133a03f.jpg</video:thumbnail_loc><video:title>Proving the formula for focal length of an ellipse</video:title><video:description>Sal proves how to write the formula used for focal length of an ellipse.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ze-ij372f88.mp4/ze-ij372f88.mp4</video:content_loc><video:duration>194</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/reading-pictographs</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/380860451.jpg</video:thumbnail_loc><video:title>Reading pictographs</video:title><video:description>Common sense tells you that a pictograph must be some kind of....picture. Yes! A pictograph is basically a way to represent data with pictures that relate to the data. Let&apos;s look at this word problem that asks to interpret a pictograph.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qrVvpYt3Vl0.mp4/qrVvpYt3Vl0.mp4</video:content_loc><video:duration>141</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/reading-bar-graphs</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/380854778.jpg</video:thumbnail_loc><video:title>Reading bar graphs</video:title><video:description>Reading Bar Graphs.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/kiQ6MUQZHSs.mp4/kiQ6MUQZHSs.mp4</video:content_loc><video:duration>179</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/reading-bar-charts-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb3b8475c.jpg</video:thumbnail_loc><video:title>Reading bar charts: putting it together with central tendency</video:title><video:description>Let&apos;s combine some learning! Here we looking at bar charts and using the information to determine the measures of central tendency.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DGZNaKnbQo0.mp4/DGZNaKnbQo0.mp4</video:content_loc><video:duration>281</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/histograms</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23768.jpg</video:thumbnail_loc><video:title>Histograms</video:title><video:description>Here&apos;s how we make a histogram: 1. Collect your data and decide on the number and size of bins (categories) you want to divide your data into. 2. Count the number of data points that fall within each bin. 3. Draw a graph with the bins as the x-axis and the frequency counts as the y-axis. 4. Draw vertical bars to represent the frequency count for each bin.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4eLJGG2Ad30.mp4/4eLJGG2Ad30.mp4</video:content_loc><video:duration>368</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/u08-l1-t2-we2-reading-line-graphs</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/380860452.jpg</video:thumbnail_loc><video:title>Reading line graphs</video:title><video:description>A line graph is way to visually represent data, especially data that changes over time. Let&apos;s take a look at an example.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/36v2EXZRzUE.mp4/36v2EXZRzUE.mp4</video:content_loc><video:duration>141</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/misleading-line-graphs</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/380855564.jpg</video:thumbnail_loc><video:title>Misleading line graphs</video:title><video:description>Misleading Line Graphs</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gs-OPF3KEGU.mp4/gs-OPF3KEGU.mp4</video:content_loc><video:duration>293</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/statistics-alternate-variance-formulas</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26181.jpg</video:thumbnail_loc><video:title>Statistics: Alternate variance formulas</video:title><video:description>Sal explains a different variance formula and why it works! For a population, the variance is calculated as σ² = ( Σ (x-μ)² ) / N. Another equivalent formula is σ² = ( (Σ x²) / N ) - μ². If we need to calculate variance by hand, this alternate formula is easier to work with.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/sRVGcYGjUk8.mp4/sRVGcYGjUk8.mp4</video:content_loc><video:duration>737</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/range-and-mid-range</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/380854781.jpg</video:thumbnail_loc><video:title>Range and mid-range</video:title><video:description>The range is the difference between the largest and smallest data points in a set of numerical data. The midrange is the average of the largest and smallest data points. Range is an easy to calculate measure of variability, while midrange is an easy to calculate measure of central tendency.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7DtWXEPB_AI.mp4/7DtWXEPB_AI.mp4</video:content_loc><video:duration>123</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/ck12-org-exercise-standard-normal-distribution-and-the-empirical-rule</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26204.jpg</video:thumbnail_loc><video:title>Standard normal distribution and the empirical rule (from ck12.org)</video:title><video:description>Using the Empirical Rule with a standard normal distribution</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2fzYE-Emar0.mp4/2fzYE-Emar0.mp4</video:content_loc><video:duration>496</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/ck12-org-more-empirical-rule-and-z-score-practice</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26206.jpg</video:thumbnail_loc><video:title>More empirical rule and z-score practice (from ck12.org)</video:title><video:description>More Empirical Rule and Z-score practice</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/itQEwESWDKg.mp4/itQEwESWDKg.mp4</video:content_loc><video:duration>357</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/introduction-to-the-normal-distribution</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26196.jpg</video:thumbnail_loc><video:title>Deep definition of the normal distribution</video:title><video:description>We take an extremely deep dive into the normal distribution to explore the parent function that generates normal distributions, and how to modify parameters in the function to produce a normal distribution with any given mean and standard deviation. We also look at relative frequency as area under the normal distribution.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hgtMWR3TFnY.mp4/hgtMWR3TFnY.mp4</video:content_loc><video:duration>1584</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/normal-distribution-excel-exercise</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/26194.jpg</video:thumbnail_loc><video:title>Normal distribution excel exercise</video:title><video:description>(Long-26 minutes) Presentation on spreadsheet to show that the normal distribution approximates the binomial distribution for a large number of trials.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/yTGEMoaWDCQ.mp4/yTGEMoaWDCQ.mp4</video:content_loc><video:duration>1564</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/standard-deviation-of-residuals-or-root-mean-square-error-rmsd</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa5ebe5224c12ce0f.jpg</video:thumbnail_loc><video:title>Standard deviation of residuals or Root-mean-square error (RMSD)</video:title><video:description>Calculating the standard deviation of residuals (or root-mean-square error (RMSD) or root-mean-square deviation (RMSD)) to measure disagreement between a linear regression model and a set of data.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/zMFdb__sUpw.mp4/zMFdb__sUpw.mp4</video:content_loc><video:duration>403</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/squared-error-of-regression-line</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187292.jpg</video:thumbnail_loc><video:title>Squared error of regression line</video:title><video:description>Introduction to the idea that one can find a line that minimizes the squared distances to the points</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6OvhLPS7rj4.mp4/6OvhLPS7rj4.mp4</video:content_loc><video:duration>407</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/proof-part-1-minimizing-squared-error-to-regression-line</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187293.jpg</video:thumbnail_loc><video:title>Proof (part 1) minimizing squared error to regression line</video:title><video:description>Proof (Part 1) Minimizing Squared Error to Regression Line</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/mIx2Oj5y9Q8.mp4/mIx2Oj5y9Q8.mp4</video:content_loc><video:duration>635</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/proof-part-2-minimizing-squared-error-to-line</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187297.jpg</video:thumbnail_loc><video:title>Proof (part 2) minimizing squared error to regression line</video:title><video:description>Proof Part 2 Minimizing Squared Error to Line</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/f6OnoxctvUk.mp4/f6OnoxctvUk.mp4</video:content_loc><video:duration>594</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/proof-part-3-minimizing-squared-error-to-regression-line</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187294.jpg</video:thumbnail_loc><video:title>Proof (part 3) minimizing squared error to regression line</video:title><video:description>Proof (Part 3) Minimizing Squared Error to Regression Line</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/u1HhUB3NP8g.mp4/u1HhUB3NP8g.mp4</video:content_loc><video:duration>654</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/proof-part-4-minimizing-squared-error-to-regression-line</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187295.jpg</video:thumbnail_loc><video:title>Proof (part 4) minimizing squared error to regression line</video:title><video:description>Proof (Part 4) Minimizing Squared Error to Regression Line</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8RSTQl0bQuw.mp4/8RSTQl0bQuw.mp4</video:content_loc><video:duration>258</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/regression-line-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187296.jpg</video:thumbnail_loc><video:title>Regression line example</video:title><video:description>Regression Line Example</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/GAmzwIkGFgE.mp4/GAmzwIkGFgE.mp4</video:content_loc><video:duration>567</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/second-regression-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187299.jpg</video:thumbnail_loc><video:title>Second regression example</video:title><video:description>Second Regression Example</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ww_yT9ckPWw.mp4/ww_yT9ckPWw.mp4</video:content_loc><video:duration>555</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/calculating-r-squared</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187300.jpg</video:thumbnail_loc><video:title>Calculating R-squared</video:title><video:description>Calculating R-Squared to see how well a regression line fits data</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Fc5t_5r_7IU.mp4/Fc5t_5r_7IU.mp4</video:content_loc><video:duration>585</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/covariance-and-the-regression-line</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187301.jpg</video:thumbnail_loc><video:title>Covariance and the regression line</video:title><video:description>Covariance, Variance and the Slope of the Regression Line</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ualmyZiPs9w.mp4/ualmyZiPs9w.mp4</video:content_loc><video:duration>908</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/probability-decisions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9ecaa35a.jpg</video:thumbnail_loc><video:title>Picking fairly</video:title><video:description>Sal determines if a few different methods of a magician choosing a volunteer are fair.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vst006REeTQ.mp4/vst006REeTQ.mp4</video:content_loc><video:duration>419</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/frequency-probability-and-unfair-coins</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/191769947.jpg</video:thumbnail_loc><video:title>Probability without equally likely events</video:title><video:description>Up until now, we&apos;ve looked at probabilities surrounding only equally likely events. What about probabilities when we don&apos;t have equally likely events? Say, we have unfair coins?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/RI874OSJp1U.mp4/RI874OSJp1U.mp4</video:content_loc><video:duration>538</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/independent-events-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/27096.jpg</video:thumbnail_loc><video:title>Die rolling probability with independent events</video:title><video:description>We hope you&apos;re not a gambler, but if you had to bet on whether you can roll even numbers three times in a row, you might want to figure this probability first.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2MYA8Ba2PvM.mp4/2MYA8Ba2PvM.mp4</video:content_loc><video:duration>148</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/dependent-probability-example-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/94879657.jpg</video:thumbnail_loc><video:title>Dependent probability example</video:title><video:description>It&apos;s important to practice these probability problems as they get more complex eventually. Take a stab on this one...with our help, of course.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7BkcNLOf56w.mp4/7BkcNLOf56w.mp4</video:content_loc><video:duration>394</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/analyzing-dependent-probability</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x850f9277.jpg</video:thumbnail_loc><video:title>Dependent probability</video:title><video:description>Sal finds dependent probabilities like P(A | B) using an example rolling dice.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8iKsY8C5VW8.mp4/8iKsY8C5VW8.mp4</video:content_loc><video:duration>570</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/probability-and-combinations-part-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25853.jpg</video:thumbnail_loc><video:title>Probability &amp; combinations (2 of 2)</video:title><video:description>Making at least 3 out of 5 free throws.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/W7DmsJKLoxc.mp4/W7DmsJKLoxc.mp4</video:content_loc><video:duration>636</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/generalizing-with-binomial-coefficients-bit-advanced</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/193210639.jpg</video:thumbnail_loc><video:title>Generalizing with binomial coefficients (bit advanced)</video:title><video:description>Conceptual understanding of where the formula for binomial coefficients come from</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/AOsWph2FNLw.mp4/AOsWph2FNLw.mp4</video:content_loc><video:duration>700</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/conditional-probability-and-combinations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25855.jpg</video:thumbnail_loc><video:title>Conditional probability and combinations</video:title><video:description>Probability that I picked a fair coin given that I flipped 4 heads out of 6 tosses.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xw6utjoyMi4.mp4/xw6utjoyMi4.mp4</video:content_loc><video:duration>1012</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/birthday-probability-problem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25857.jpg</video:thumbnail_loc><video:title>Birthday probability problem</video:title><video:description>The probability that at least 2 people in a room of 30 share the same birthday.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9G0w61pZPig.mp4/9G0w61pZPig.mp4</video:content_loc><video:duration>796</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/probability-density-functions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25861.jpg</video:thumbnail_loc><video:title>Probability density functions</video:title><video:description>Probability density functions for continuous random variables.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Fvi9A_tEmXQ.mp4/Fvi9A_tEmXQ.mp4</video:content_loc><video:duration>602</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/binomial-distribution</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xaf13e4df.jpg</video:thumbnail_loc><video:title>Binomial distribution</video:title><video:description>Sal introduces the binomial distribution with an example.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/WWv0RUxDfbs.mp4/WWv0RUxDfbs.mp4</video:content_loc><video:duration>712</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/visualizing-a-binomial-distribution</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0f59b8e3.jpg</video:thumbnail_loc><video:title>Visualizing a binomial distribution</video:title><video:description>Sal walks through graphing a binomial distribution and connects it back to how to calculate binomial probabilities.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/NF0lrkqXIkQ.mp4/NF0lrkqXIkQ.mp4</video:content_loc><video:duration>567</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/mean-and-variance-of-bernoulli-distribution-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/6022798.jpg</video:thumbnail_loc><video:title>Mean and variance of Bernoulli distribution example</video:title><video:description>Sal calculates the mean and variance of a Bernoulli distribution (in this example the responses are either favorable or unfavorable).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/O8vB1eInP_8.mp4/O8vB1eInP_8.mp4</video:content_loc><video:duration>500</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/bernoulli-distribution-mean-and-variance-formulas</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/6022799.jpg</video:thumbnail_loc><video:title>Bernoulli distribution mean and variance formulas</video:title><video:description>Sal continues on from the previous video to derive the mean and variance formulas for the Bernoulli distribution.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ry81_iSHt6E.mp4/ry81_iSHt6E.mp4</video:content_loc><video:duration>419</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/empirical-data-expected-value</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x63d8573a.jpg</video:thumbnail_loc><video:title>Getting data from expected value</video:title><video:description>Expected value refers to the average outcome you would expect from repeating an experiment over and over. It is calculated by multiplying each possible outcome by its probability of occurring, and summing those products together. If we know the expected value, we can go backwards and solve for frequency.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gHpl5UcgRkI.mp4/gHpl5UcgRkI.mp4</video:content_loc><video:duration>592</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/law-of-large-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25879.jpg</video:thumbnail_loc><video:title>Law of large numbers</video:title><video:description>Sal introduces the magic behind the law of large numbers.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/VpuN8vCQ--M.mp4/VpuN8vCQ--M.mp4</video:content_loc><video:duration>539</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/poisson-process-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25875.jpg</video:thumbnail_loc><video:title>Poisson process 1</video:title><video:description>Introduction to Poisson Processes and the Poisson Distribution.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3z-M6sbGIZ0.mp4/3z-M6sbGIZ0.mp4</video:content_loc><video:duration>661</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/poisson-process-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25877.jpg</video:thumbnail_loc><video:title>Poisson process 2</video:title><video:description>More of the derivation of the Poisson Distribution.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Jkr4FSrNEVY.mp4/Jkr4FSrNEVY.mp4</video:content_loc><video:duration>761</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/confidence-interval-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/6022802.jpg</video:thumbnail_loc><video:title>Confidence interval example</video:title><video:description>Sal calculates a 99% confidence interval for the proportion of teachers who felt computers are an essential tool.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/SeQeYVJZ2gE.mp4/SeQeYVJZ2gE.mp4</video:content_loc><video:duration>1116</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/margin-of-error-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/6022800.jpg</video:thumbnail_loc><video:title>Margin of error 1</video:title><video:description>Finding the 95% confidence interval for the proportion of a population voting for a candidate.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OwPSuHXmiPw.mp4/OwPSuHXmiPw.mp4</video:content_loc><video:duration>902</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/margin-of-error-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/6022801.jpg</video:thumbnail_loc><video:title>Margin of error 2</video:title><video:description>Finding the 95% confidence interval for the proportion of a population voting for a candidate.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/YclQE2XtaLw.mp4/YclQE2XtaLw.mp4</video:content_loc><video:duration>605</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/sample-size-for-a-given-margin-of-error-for-a-mean</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xeddcb5225895f2fd.jpg</video:thumbnail_loc><video:title>Sample size for a given margin of error for a mean</video:title><video:description>Calculate the approximate sample size required to obtain a desired margin of error in a confidence interval for a mean.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/FSVDJoHZ3rM.mp4/FSVDJoHZ3rM.mp4</video:content_loc><video:duration>462</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/t-statistic-confidence-interval</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/6022809.jpg</video:thumbnail_loc><video:title>T-statistic confidence interval</video:title><video:description>Sal computes a confidence interval for the emission from an engine with a new design.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hV4pdjHCKuA.mp4/hV4pdjHCKuA.mp4</video:content_loc><video:duration>707</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/small-sample-size-confidence-intervals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/6022803.jpg</video:thumbnail_loc><video:title>Small sample size confidence intervals</video:title><video:description>Constructing small sample size confidence intervals using t-distributions</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/K4KDLWENXm0.mp4/K4KDLWENXm0.mp4</video:content_loc><video:duration>671</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/simple-hypothesis-testing</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb0f85f82.jpg</video:thumbnail_loc><video:title>Simple hypothesis testing</video:title><video:description>Sal walks through an example about who should do the dishes that gets at the idea behind hypothesis testing.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5D1gV37bKXY.mp4/5D1gV37bKXY.mp4</video:content_loc><video:duration>385</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/type-1-errors</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/6022807.jpg</video:thumbnail_loc><video:title>Type 1 errors</video:title><video:description>A Type 1 error occurs when the null hypothesis is true, but we reject it because of an usual sample result.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/EowIec7Y8HM.mp4/EowIec7Y8HM.mp4</video:content_loc><video:duration>204</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/hypothesis-testing-and-p-values</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/6022804.jpg</video:thumbnail_loc><video:title>Hypothesis testing and p-values</video:title><video:description>Sal walks through an example about a neurologist testing the effect of a drug to discuss hypothesis testing and p-values.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-FtlH4svqx4.mp4/-FtlH4svqx4.mp4</video:content_loc><video:duration>686</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/one-tailed-and-two-tailed-tests</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/6022805.jpg</video:thumbnail_loc><video:title>One-tailed and two-tailed tests</video:title><video:description>Sal continues his discussion of the effect of a drug to one-tailed and two-tailed hypothesis tests.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/mvye6X_0upA.mp4/mvye6X_0upA.mp4</video:content_loc><video:duration>394</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/z-statistics-vs-t-statistics</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/6022806.jpg</video:thumbnail_loc><video:title>Z-statistics vs. T-statistics</video:title><video:description>Sal breaks down the difference between Z-statistics and T-statistics.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5ABpqVSx33I.mp4/5ABpqVSx33I.mp4</video:content_loc><video:duration>399</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/small-sample-hypothesis-test</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/6022808.jpg</video:thumbnail_loc><video:title>Small sample hypothesis test</video:title><video:description>Sal walks through an example of a hypothesis test where he determines if there is sufficient evidence to conclude that a new type of engine meets emission requirements.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/D2sMsmL0ScQ.mp4/D2sMsmL0ScQ.mp4</video:content_loc><video:duration>544</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/large-sample-proportion-hypothesis-testing</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/6022810.jpg</video:thumbnail_loc><video:title>Large sample proportion hypothesis testing</video:title><video:description>Sal uses a large sample to test if more than 30% of US households have internet access.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1JT9oODsClE.mp4/1JT9oODsClE.mp4</video:content_loc><video:duration>870</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/comparing-population-proportions-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/6022816.jpg</video:thumbnail_loc><video:title>Comparing population proportions 1</video:title><video:description>Sal uses an election example to compare population proportions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/a1Ye5RcWOqg.mp4/a1Ye5RcWOqg.mp4</video:content_loc><video:duration>647</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/comparing-population-proportions-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/6022817.jpg</video:thumbnail_loc><video:title>Comparing population proportions 2</video:title><video:description>Sal continues the election example for population proportions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/MNbat1lrJW4.mp4/MNbat1lrJW4.mp4</video:content_loc><video:duration>600</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/hypothesis-test-comparing-population-proportions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/6022840.jpg</video:thumbnail_loc><video:title>Hypothesis test comparing population proportions</video:title><video:description>Once again, Sal continues the discussion of election results to run a hypothesis test comparing population proportions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/dvSa_tx04hw.mp4/dvSa_tx04hw.mp4</video:content_loc><video:duration>973</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/statistical-significance-on-bus-speeds</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5e1b1135.jpg</video:thumbnail_loc><video:title>Statistical significance on bus speeds</video:title><video:description>Sal determines if the results of an experiment about bus speeds are statistically significant.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/W3C07uH-b9o.mp4/W3C07uH-b9o.mp4</video:content_loc><video:duration>696</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/difference-of-sample-means-distribution</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/6022812.jpg</video:thumbnail_loc><video:title>Difference of sample means distribution</video:title><video:description>Sal walks through the difference of sample means distribution.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TcIDXqmt74A.mp4/TcIDXqmt74A.mp4</video:content_loc><video:duration>738</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/confidence-interval-of-difference-of-means</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/6022813.jpg</video:thumbnail_loc><video:title>Confidence interval of difference of means</video:title><video:description>Sal uses a confidence interval to help figure out if a low-fat diet helps obese people lose weight.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hxZ6uooEJOk.mp4/hxZ6uooEJOk.mp4</video:content_loc><video:duration>949</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/clarification-of-confidence-interval-of-difference-of-means</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/6022814.jpg</video:thumbnail_loc><video:title>Clarification of confidence interval of difference of means</video:title><video:description>Clarification of Confidence Interval of Difference of Means</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/yQsCMnz9wO8.mp4/yQsCMnz9wO8.mp4</video:content_loc><video:duration>161</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/hypothesis-test-for-difference-of-means</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/6022815.jpg</video:thumbnail_loc><video:title>Hypothesis test for difference of means</video:title><video:description>Hypothesis Test for Difference of Means</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/N984XGLjQfs.mp4/N984XGLjQfs.mp4</video:content_loc><video:duration>606</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/chi-square-distribution-introduction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187302.jpg</video:thumbnail_loc><video:title>Chi-square distribution introduction</video:title><video:description>Chi-Square Distribution Introduction</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/dXB3cUGnaxQ.mp4/dXB3cUGnaxQ.mp4</video:content_loc><video:duration>623</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/pearson-s-chi-square-test-goodness-of-fit</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187303.jpg</video:thumbnail_loc><video:title>Pearson&apos;s chi square test (goodness of fit)</video:title><video:description>Sal uses the chi square test to the hypothesis that the owner&apos;s distribution is correct.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2QeDRsxSF9M.mp4/2QeDRsxSF9M.mp4</video:content_loc><video:duration>708</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/frequency-table-independent-events</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4a98d13d.jpg</video:thumbnail_loc><video:title>Filling out frequency table for independent events</video:title><video:description>Give the row and column totals, Sal fills in the cells of a frequency table so that the events are independent.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TQJQeTpH_lw.mp4/TQJQeTpH_lw.mp4</video:content_loc><video:duration>296</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/contingency-table-chi-square-test</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187304.jpg</video:thumbnail_loc><video:title>Contingency table chi-square test</video:title><video:description>Sal uses the contingency table chi-square test to see if a couple of different herbs prevent people from getting sick.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hpWdDmgsIRE.mp4/hpWdDmgsIRE.mp4</video:content_loc><video:duration>1057</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/anova-1-calculating-sst-total-sum-of-squares</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187305.jpg</video:thumbnail_loc><video:title>ANOVA 1: Calculating SST (total sum of squares)</video:title><video:description>Analysis of Variance 1 - Calculating SST (Total Sum of Squares)</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/EFdlFoHI_0I.mp4/EFdlFoHI_0I.mp4</video:content_loc><video:duration>459</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/anova-2-calculating-ssw-and-ssb-total-sum-of-squares-within-and-between-avi</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187306.jpg</video:thumbnail_loc><video:title>ANOVA 2: Calculating SSW and SSB (total sum of squares within and between)</video:title><video:description>Analysis of Variance 2 - Calculating SSW and SSB (Total Sum of Squares Within and Between)</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/j9ZPMlVHJVs.mp4/j9ZPMlVHJVs.mp4</video:content_loc><video:duration>800</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-probability/v/anova-3-hypothesis-test-with-f-statistic</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187307.jpg</video:thumbnail_loc><video:title>ANOVA 3: Hypothesis test with F-statistic</video:title><video:description>Analysis of Variance 3 -Hypothesis Test with F-Statistic</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Xg8_iSkJpAE.mp4/Xg8_iSkJpAE.mp4</video:content_loc><video:duration>614</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-tx/v/comparing-methods-for-determining-best-fit</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6ae5f31302da057e.jpg</video:thumbnail_loc><video:title>Comparing methods for determining best fit</video:title><video:description>In this video, Sal compares and contrasts different methods used to determine a line of best fit, including least squares, median-median, and least absolute value regression.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/QkRX8vSmSJc.mp4/QkRX8vSmSJc.mp4</video:content_loc><video:duration>127</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-tx/v/determining-if-slope-or-y-intercept-is-reasonable</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc524b331fecdd48e.jpg</video:thumbnail_loc><video:title>Determining if slope or y-intercept is reasonable</video:title><video:description>In this video, Sal shows how to determine if the slope or y-intercept of a linear model is reasonable in context.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tZxAWJTPveo.mp4/tZxAWJTPveo.mp4</video:content_loc><video:duration>120</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-tx/v/identifying-sources-of-variability</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0c2d1b8eb3b824db.jpg</video:thumbnail_loc><video:title>Identifying sources of variability</video:title><video:description>Sal examines two pairs of scenarios, and identifies which scenario exhibits a specific source of variability and why.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/cjiBPL0HJTc.mp4/cjiBPL0HJTc.mp4</video:content_loc><video:duration>246</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-tx/v/independent-events-example-test-taking-indian-accent</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x72ce2672bff96e0c.jpg</video:thumbnail_loc><video:title>Independent events example: test taking</video:title><video:description>Have you ever taken a test and discovered you have no choice but to guess on a couple of problems? In this example problem, we are considering the probability of two independent events occurring.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DtQzDcIQYsw.mp4/DtQzDcIQYsw.mp4</video:content_loc><video:duration>236</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-tx/v/constructing-distributions-from-simulations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xcc38c0762f4dc943.jpg</video:thumbnail_loc><video:title>Constructing distributions from simulations</video:title><video:description>In this video, Sal examines a simulation context to identify random variables and their possible values, organize simulation data into frequency tables, and choose an appropriate data representation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1LnzkYvI6Fs.mp4/1LnzkYvI6Fs.mp4</video:content_loc><video:duration>322</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-tx/v/identifying-mathematical-and-statistical-models</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0d7a5487ad0dd846.jpg</video:thumbnail_loc><video:title>Identifying mathematical and statistical models</video:title><video:description>In this video, Sal explains how to distinguish between mathematical models (exact, deterministic relationships) and statistical models (relationships based on data, with variation and uncertainty).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OBBbgvA5euc.mp4/OBBbgvA5euc.mp4</video:content_loc><video:duration>198</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-tx/v/comparing-simulated-and-theoretical-sampling-distributions-proportions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xce4ef334fd8c22ce.jpg</video:thumbnail_loc><video:title>Comparing simulated and theoretical sampling distributions - proportions</video:title><video:description>In this video, Sal uses information about a population and the results of a simulated sampling distribution for a proportion to determine whether the simulation is consistent with the theoretical sampling distribution for that population.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3xo-3TogBcE.mp4/3xo-3TogBcE.mp4</video:content_loc><video:duration>262</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/statistics-tx/v/comparing-simulated-and-theoretical-sampling-distributions-means</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfff8a1f4961f0ecc.jpg</video:thumbnail_loc><video:title>Comparing simulated and theoretical sampling distributions - means</video:title><video:description>In this video, Sal uses information about a population and the results of a simulated sampling distribution for a mean to determine whether the simulation is consistent with the theoretical sampling distribution for that population.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1nV77gNOPW4.mp4/1nV77gNOPW4.mp4</video:content_loc><video:duration>209</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/teacher-resources-tx-teks-science/v/how-to-use-teks-aligned-unit-guides-on-khan-academy</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x90f5d0a59e0c4bd2.jpg</video:thumbnail_loc><video:title>How to use TEKS-aligned unit guides on Khan Academy</video:title><video:description>Join Jennifer, the Texas Professional Learning Specialist with Khan Academy as she introduces our TEKS-aligned Unit Guides to help you navigate the Texas Essential Knowledge and Skills (TEKS) standards more effectively. These comprehensive Unit Guides are designed to streamline your planning process. They outline key concepts and skills for each unit, helping you align your instruction with TEKS standards. With detailed overviews, objectives, standards, teaching tips, and best practices, these guides empower you to make a meaningful impact on your students’ learning experience.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/IVjfIQbVGhk.mp4/IVjfIQbVGhk.mp4</video:content_loc><video:duration>143</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/trigonometry/v/pythagorean-trig-identity-from-soh-cah-toa</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x10c52471.jpg</video:thumbnail_loc><video:title>Intro to the Pythagorean trig identity</video:title><video:description>Sal introduces and proves the identity (sinθ)^2+(cosθ)^2=1, which arises from the Pythagorean theorem!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/HnDvUaVjQ1I.mp4/HnDvUaVjQ1I.mp4</video:content_loc><video:duration>256</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/trigonometry/v/tau-versus-pi</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/145890679.jpg</video:thumbnail_loc><video:title>Tau versus pi</video:title><video:description>Why Tau might be a better number to look at than Pi</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1jDDfkKKgmc.mp4/1jDDfkKKgmc.mp4</video:content_loc><video:duration>982</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/trigonometry/v/pi-is-still-wrong</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/538086220.jpg</video:thumbnail_loc><video:title>Pi is (still) wrong</video:title><video:description>Please excuse the simple math and spelling errors. You shouldn&apos;t believe anything I say without double-checking even at the best of times. Go here: http://tauday.com/ and here: http://www.math.utah.edu/~palais/pi.html Me: http://vihart.com</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jG7vhMMXagQ.mp4/jG7vhMMXagQ.mp4</video:content_loc><video:duration>317</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/trigonometry/v/2003-aime-ii-problem-11-avi</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179281.jpg</video:thumbnail_loc><video:title>Trig challenge problem: area of a triangle</video:title><video:description>Sal solves a very complicated geometrical trig problem that appeared as problem 11 in the 2003 AIME II exam.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/smtrrefmC40.mp4/smtrrefmC40.mp4</video:content_loc><video:duration>995</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/trigonometry/v/2003-aime-ii-problem-14</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179282.jpg</video:thumbnail_loc><video:title>Trig challenge problem: area of a hexagon</video:title><video:description>Sal solves a very complicated geometrical trig problem that appeared as problem 14 in the 2003 AIME II exam.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Ec-BKdC8vOo.mp4/Ec-BKdC8vOo.mp4</video:content_loc><video:duration>1098</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/trigonometry/v/cosine-angle-addition-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6130cff9.jpg</video:thumbnail_loc><video:title>Trig challenge problem: cosine of angle-sum</video:title><video:description>Sal is given cos(θ) and cos(φ) and he finds cos(θ+φ). To do that, he must first find sin(θ) and sin(φ) using the Pythagorean identity.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/XGpEHj43kcc.mp4/XGpEHj43kcc.mp4</video:content_loc><video:duration>434</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/trigonometry/v/iit-jee-trigonometry-problem-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187432.jpg</video:thumbnail_loc><video:title>Trig challenge problem: arithmetic progression</video:title><video:description>Sal solves a very complicated algebraic trig problem that appeared as problem 29 in the 2010 IIT JEE Paper I exam.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/X7GT9JKoAbo.mp4/X7GT9JKoAbo.mp4</video:content_loc><video:duration>913</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/trigonometry/v/iit-jee-trigonometric-maximum</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187460.jpg</video:thumbnail_loc><video:title>Trig challenge problem: maximum value</video:title><video:description>Sal solves a very complicated algebraic trig problem that appeared as problem 48 in the 2010 IIT JEE Paper I exam.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tzR9jUCSniQ.mp4/tzR9jUCSniQ.mp4</video:content_loc><video:duration>594</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/trigonometry/v/iit-jee-trigonometric-constraints</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187459.jpg</video:thumbnail_loc><video:title>Trig challenge problem: multiple constraints</video:title><video:description>Sal solves a very complicated algebraic trig problem that appeared as problem 47 in the 2010 IIT JEE Paper I exam.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/EjtjdJZ2x8w.mp4/EjtjdJZ2x8w.mp4</video:content_loc><video:duration>769</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/math/trigonometry/v/trigonometric-system-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187470.jpg</video:thumbnail_loc><video:title>Trig challenge problem: system of equations</video:title><video:description>Sal solves a very complicated algebraic trig problem that appeared as problem 55 in the 2010 IIT JEE Paper I exam.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Y2ed-g8Lpdc.mp4/Y2ed-g8Lpdc.mp4</video:content_loc><video:duration>662</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/hydrogen-bonding-in-water</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc28468ba.jpg</video:thumbnail_loc><video:title>Hydrogen bonding in water</video:title><video:description>Water is made up of two hydrogens and one oxygen atom, arranged in a tetrahedral shape. Oxygen is highly electronegative, which creates a partial negative charge on one end of the molecule, and a partial positive charge on the other. So, water molecules are able to form hydrogen bonds with one another, giving water many of its unique properties.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6G1evL7ELwE.mp4/6G1evL7ELwE.mp4</video:content_loc><video:duration>407</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/capillary-action-and-why-we-see-a-meniscus</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x451fa8cc.jpg</video:thumbnail_loc><video:title>Capillary action and why we see a meniscus</video:title><video:description>A meniscus is a curved liquid surface that results from the interplay of adhesion (the liquid&apos;s attraction to its container) and cohesion (the liquid&apos;s attraction to itself). Adhesion also drives capillary action, which draws a liquid up a narrow tube.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/eQXGpturk3A.mp4/eQXGpturk3A.mp4</video:content_loc><video:duration>506</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/surface-tension</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x097b2cfb.jpg</video:thumbnail_loc><video:title>Surface tension</video:title><video:description>Water molecules are held together by hydrogen bonds, which give water its unique properties. At the surface of water, molecules are more densely packed because they are not being pulled from above, resulting in stronger intermolecular forces. This creates surface tension, which allows for phenomena such as water droplets maintaining a round shape and insects walking on water.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_RTF0DAHBBM.mp4/_RTF0DAHBBM.mp4</video:content_loc><video:duration>271</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/water-as-a-solvent</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x139c1eb0.jpg</video:thumbnail_loc><video:title>Water as a solvent</video:title><video:description>Water—due to its polarity—acts as a fantastic solvent, especially for polar substances and ions. This is because the positive and negative ends of water molecules are attracted to ions, allowing them to dissolve. This property is crucial for chemical interactions within cells. However, non-polar substances like hydrocarbons do not dissolve well in water and are termed hydrophobic.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lCvBp73ZJ-A.mp4/lCvBp73ZJ-A.mp4</video:content_loc><video:duration>552</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/carbon-as-a-building-block-of-life</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6f46b5d3.jpg</video:thumbnail_loc><video:title>Carbon as a building block of life</video:title><video:description>Carbon is essential to life because its four valence electrons allow it to form four covalent bonds and create many different molecular structures. Carbon forms hydrocarbons such as methane as well as important biological molecules including DNA, proteins, glucose, and ATP. Its flexible bonding makes carbon a key building block of living organisms.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/JgYlogdtJDo.mp4/JgYlogdtJDo.mp4</video:content_loc><video:duration>542</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/functional-groups</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7d3ab1b9.jpg</video:thumbnail_loc><video:title>Functional groups</video:title><video:description>Various functional groups can be attached to hydrocarbons, affecting chemical properties. Hydroxyl groups are polar, turn molecules into alcohols, and allow molecules to dissolve in water. Carboxyl groups can donate hydrogen ions, so they make molecules acidic. Amino groups can pick up hydrogen ions from the surroundings, so they make molecules basic. Other functional groups include sulfhydryl, carbonyl, methyl, and phosphate groups.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/iuaYuCreEPk.mp4/iuaYuCreEPk.mp4</video:content_loc><video:duration>611</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/elemental-building-blocks-of-biological-molecules</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbf070c5199e6197f.jpg</video:thumbnail_loc><video:title>Elemental building blocks of biological molecules</video:title><video:description>Biological molecules share many of the same elemental building blocks, including carbon, hydrogen, oxygen, nitrogen, and phosphorus. These elements combine to form amino acids, ATP, fats, and DNA. Despite the complexity of living systems, their molecules use similar components, including sugars, phosphates, and nitrogenous bases, that ultimately come from the environment.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vnsrBHkYTq4.mp4/vnsrBHkYTq4.mp4</video:content_loc><video:duration>271</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/dehydration-synthesis-or-a-condensation-reaction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc324ac4d.jpg</video:thumbnail_loc><video:title>Dehydration synthesis or a condensation reaction</video:title><video:description>The monosaccharide glucose can be used as a building block for more complex sugars and carbohydrates. Two glucose molecules can be linked together through a dehydration synthesis reaction to form a disaccharide called maltose. This process can be repeated to form polysaccharides, such as starch and glycogen.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/FEAXI5XeJ4M.mp4/FEAXI5XeJ4M.mp4</video:content_loc><video:duration>603</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/hydrolysis</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5ff00476.jpg</video:thumbnail_loc><video:title>Hydrolysis</video:title><video:description>Polysaccharides (such as starch, chitin, glycogen, and cellulose) can be broken down into monosaccharides. This occurs through the process of hydrolysis, which uses water to break the bonds between monosaccharides.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/SOQyiM6V3RQ.mp4/SOQyiM6V3RQ.mp4</video:content_loc><video:duration>509</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/introduction-to-carbohydrates</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x05e30a4e3b15fddb.jpg</video:thumbnail_loc><video:title>Introduction to carbohydrates</video:title><video:description>A carbohydrate is a type of molecule that contains carbon, hydrogen, and oxygen. Carbohydrates can be simple sugars (monosaccharides) like glucose, or they can be made up of multiple sugar units (polysaccharides) like glycogen. They are important in biology as a source of energy and as structural components in plants.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6o4WL5jlpn0.mp4/6o4WL5jlpn0.mp4</video:content_loc><video:duration>268</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/molecular-structure-of-triglycerides-fats</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x989f9684.jpg</video:thumbnail_loc><video:title>Molecular structure of triglycerides (fats)</video:title><video:description>Triglycerides (or fats) are formed from the combination of glycerol and three fatty acid molecules. Triglycerides are formed through dehydration reactions. Another word for triglyceride is triacylglycerol. Fats can be solid (such as coconut oil) or liquid (such as vegetable oil) at room temperature.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OpyTJbzA7Fk.mp4/OpyTJbzA7Fk.mp4</video:content_loc><video:duration>664</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/saturated-fats-unsaturated-fats-and-trans-fats</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc3236192.jpg</video:thumbnail_loc><video:title>Saturated fats, unsaturated fats, and trans fats</video:title><video:description>A triglyceride is a type of lipid (or fat) molecule. It is made up of three fatty acid chains attached to a glycerol backbone. Triglycerides can be classified as saturated (having no double bonds) or unsaturated (having double bonds). Trans fats are a type of unsaturated fat that is produced artificially and can be unhealthy to consume.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/O9lL2KStW9s.mp4/O9lL2KStW9s.mp4</video:content_loc><video:duration>537</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/dna-deoxyribonucleic-acid</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x983f0c01.jpg</video:thumbnail_loc><video:title>DNA</video:title><video:description>DNA (or deoxyribonucleic acid) is the molecular basis for inheritance, discovered in the mid-1800s and understood in 1953 with the double helix structure. Composed of a sugar-phosphate backbone and base pairs (adenine-thymine, guanine-cytosine), DNA stores genetic information, replicates, and expresses traits. The human genome contains 6 billion base pairs across 46 chromosomes, making it a compact and efficient information storage system.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/AmOO4j0E408.mp4/AmOO4j0E408.mp4</video:content_loc><video:duration>782</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/molecular-structure-of-dna</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5f5151df.jpg</video:thumbnail_loc><video:title>Molecular structure of DNA</video:title><video:description>DNA (deoxyribonucleic acid) consists of nucleotides forming a double helix structure. Nucleotides contain a phosphate group, deoxyribose sugar, and a nitrogenous base. The bases adenine, thymine, cytosine, and guanine pair up through hydrogen bonds, creating the rungs of the DNA ladder.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/L677-Fl0joY.mp4/L677-Fl0joY.mp4</video:content_loc><video:duration>781</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/antiparallel-structure-of-dna-strands</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb0f3c430.jpg</video:thumbnail_loc><video:title>Antiparallel structure of DNA strands</video:title><video:description>DNA structure consists of two strands, each with a backbone of alternating phosphate and sugar groups. These strands are linked by complementary nitrogenous bases, forming a ladder-like structure. The strands are antiparallel, meaning they run in opposite directions, which is crucial for DNA replication.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0CQ5ls3Uc2Q.mp4/0CQ5ls3Uc2Q.mp4</video:content_loc><video:duration>597</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/molecular-structure-of-rna</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x44533ed0.jpg</video:thumbnail_loc><video:title>Molecular structure of RNA</video:title><video:description>DNA and RNA have different sugar backbones: deoxyribose for DNA and ribose for RNA. Notably, RNA has uracil instead of thymine as a nitrogenous base. RNA plays various roles in cells, including messenger RNA (mRNA), transfer RNA (tRNA), ribosomal RNA (rRNA), and microRNA, and it is a vital part of processes such as transcription, translation, and cellular functions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jUUJSOM1ihU.mp4/jUUJSOM1ihU.mp4</video:content_loc><video:duration>690</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/introduction-to-amino-acids</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe81203a5.jpg</video:thumbnail_loc><video:title>Introduction to amino acids</video:title><video:description>Amino acids are the building blocks of proteins, molecules that perform many essential functions in organisms. Each amino acid contains an amino group, a carboxyl group, and a variable R group. These R groups affect properties such as polarity and help determine protein shape. Amino acids connect through peptide bonds to form polypeptide chains.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Pk4d9lY48GI.mp4/Pk4d9lY48GI.mp4</video:content_loc><video:duration>594</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/overview-of-protein-structure</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3759e606.jpg</video:thumbnail_loc><video:title>Overview of protein structure</video:title><video:description>Protein structure determines how proteins function in living systems. Primary structure describes the amino acid sequence, while secondary structure includes alpha helices and beta-pleated sheets formed through backbone interactions. Side-chain interactions create tertiary structure, and proteins with multiple polypeptide chains have quaternary structure. Together, these levels produce specific three-dimensional shapes and functions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/MODnIkQvyz0.mp4/MODnIkQvyz0.mp4</video:content_loc><video:duration>598</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/introduction-to-the-cell</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x42878b6111bb5bb2.jpg</video:thumbnail_loc><video:title>Introduction to the cell</video:title><video:description>Cells are the most basic unit of life. All cells have a membrane that separates them from the outside world. Although cells are small, they are not simple. Cells contain different components, such as the cytoplasm, ribosomes, and genetic information in the form of DNA.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5KfHxF6Vhps.mp4/5KfHxF6Vhps.mp4</video:content_loc><video:duration>352</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/organelles-in-eukaryotic-cells</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9fee9f7cbfade35f.jpg</video:thumbnail_loc><video:title>Organelles in eukaryotic cells</video:title><video:description>Eukaryotic cells have membrane-bound organelles. The nucleus stores DNA. The endoplasmic reticulum and Golgi body are involved in protein maturation and transport. Mitochondria generate usable energy for the cell. Chloroplasts carry out photosynthesis. Vacuoles are storage compartments that sequester waste and help maintain water balance. Lysosomes contain enzymes that help break down waste.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/bWPQvxElpLY.mp4/bWPQvxElpLY.mp4</video:content_loc><video:duration>578</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/endoplasmic-reticulum-and-golgi-bodies</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3b506ff8.jpg</video:thumbnail_loc><video:title>Endoplasmic reticulum and Golgi bodies</video:title><video:description>During protein synthesis, proteins meant for use within the cell are translated by free ribosomes. Proteins meant to be embedded in the cell membrane or used outside the cell are translated by ribosomes attached to the rough endoplasmic reticulum. These proteins are then transported to the Golgi body for further maturation and sorting before being released.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6UqtgH_Zy1Y.mp4/6UqtgH_Zy1Y.mp4</video:content_loc><video:duration>700</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/endomembrane-system</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa41115fb.jpg</video:thumbnail_loc><video:title>Endomembrane system</video:title><video:description>The endomembrane system in eukaryotic cells includes cell membrane, nuclear envelope, endoplasmic reticulum, Golgi apparatus, vesicles, vacuoles, and lysosomes. These parts (made of phospholipid bilayers) work together for protein and lipid synthesis, modification, transport, and recycling within the cell.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vC-cEWJxDRY.mp4/vC-cEWJxDRY.mp4</video:content_loc><video:duration>380</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/scale-of-cells</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0086be61.jpg</video:thumbnail_loc><video:title>Scale of cells</video:title><video:description>Even though molecules, proteins, viruses, and cells are all tiny, there are significant size differences between them. The diameter of a water molecule is roughly 0.28 nanometers. The diameter of the protein hemoglobin is roughly 5 nanometers. The diameter of the HIV virus is roughly 120 nanometers. A red blood cell is 6-8 micrometers.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xKJ3txXIuQk.mp4/xKJ3txXIuQk.mp4</video:content_loc><video:duration>440</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/cell-size</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xffe5513f.jpg</video:thumbnail_loc><video:title>Cell size</video:title><video:description>Cells range from tiny bacteria to much larger human egg cells, but their size has limits. Cells must be large enough to contain DNA and cellular machinery. As cells grow, volume increases faster than surface area, making nutrient and waste exchange less efficient. Cell shapes and adaptations can increase surface area and support efficient transport.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6xx5v3PKZZM.mp4/6xx5v3PKZZM.mp4</video:content_loc><video:duration>536</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/introduction-to-cilia-flagella-and-pseudopodia</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xea5cff3f26fe7652.jpg</video:thumbnail_loc><video:title>Introduction to cilia, flagella, and pseudopodia</video:title><video:description>Amoebas use pseudopods (&quot;false feet&quot;) for movement and capturing prey, demonstrating the complexity of cellular structures. Unicellular organisms like Oxytricha trifallax use cilia (hair-like structures) for movement and have unique mating processes. Chlamydomonas (a green algae) uses a flagellum (tail-like structure) for movement. These examples highlight the intricate machinery of cells.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/E0D1H74PMmI.mp4/E0D1H74PMmI.mp4</video:content_loc><video:duration>265</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/surface-area-to-volume-ratio-of-cells</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc2739ff2ca2f7492.jpg</video:thumbnail_loc><video:title>Surface area to volume ratio of cells</video:title><video:description>In order to stay alive, cells exchange resources, waste, and energy with their environments. This exchange happens across the cell membrane. As the volume of a cell increases, the ratio of surface area to volume decreases, making these exchanges less efficient. Some cells have folds in their membranes, which increase their surface area to volume ratio.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/uu9eHX6Tu8Q.mp4/uu9eHX6Tu8Q.mp4</video:content_loc><video:duration>312</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/fluid-mosaic-model-of-cell-membranes</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0c4fbd1d.jpg</video:thumbnail_loc><video:title>Fluid mosaic model of cell membranes</video:title><video:description>The fluid mosaic model explains the structure of cell membranes. These membranes are composed of phospholipids, forming a bilayer with hydrophilic heads facing outwards and hydrophobic tails facing inwards. Proteins, glycolipids, glycoproteins, and cholesterol are embedded within this bilayer, creating a diverse &quot;mosaic&quot;. The &quot;fluid&quot; aspect refers to the flexibility and movement within the membrane, maintaining separation between the cell&apos;s interior and exterior.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/cP8iQu57dQo.mp4/cP8iQu57dQo.mp4</video:content_loc><video:duration>527</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/cell-membrane-proteins</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe53e7da2.jpg</video:thumbnail_loc><video:title>Cell membrane proteins</video:title><video:description>Membrane proteins help cells transport substances, communicate, and maintain homeostasis. Integral and peripheral proteins differ in how they attach to the phospholipid bilayer. Channel and carrier proteins move ions and molecules across the membrane, sometimes using ATP, while glycoproteins combine sugars and proteins to support cell signaling and recognition.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0emD1AmfdjY.mp4/0emD1AmfdjY.mp4</video:content_loc><video:duration>491</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/cell-membrane-introduction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3af34ed1.jpg</video:thumbnail_loc><video:title>Cell membrane introduction</video:title><video:description>The cell membrane is made up of phospholipids, which have a hydrophilic phosphate head, a glycerol backbone, and two hydrophobic fatty acid tails. The phospholipids form a bilayer with the hydrophilic heads facing outward. This bilayer is semi-permeable meaning that it allows some substances to pass through while blocking others.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/QpcACa39YtA.mp4/QpcACa39YtA.mp4</video:content_loc><video:duration>532</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/cell-membrane-overview-fluid-mosaic-model</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb7ad5d15.jpg</video:thumbnail_loc><video:title>Cell membrane overview and the fluid mosaic model</video:title><video:description>The cell membrane protects cells and controls interactions with their surroundings. Its phospholipid bilayer contains cholesterol, which helps maintain fluidity, and proteins that support communication and transport. Carbohydrates help cells recognize one another. Together, these moving components form the fluid mosaic model, reflecting the membrane&apos;s flexible, dynamic structure.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LXaPt9i9hqk.mp4/LXaPt9i9hqk.mp4</video:content_loc><video:duration>532</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/plant-cell-walls</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x927ae556.jpg</video:thumbnail_loc><video:title>Plant cell walls</video:title><video:description>The cell wall surrounds the plant cell, providing both structure and protection. Plant cell walls are made up mostly of cellulose, and also include hemicellulose and pectin. Plant cells connect directly to one another via tunnels in their cell walls called plasmodesmata.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/zdvKhaQxvag.mp4/zdvKhaQxvag.mp4</video:content_loc><video:duration>463</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/introduction-to-passive-and-active-transport</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xceb2019f52466dba.jpg</video:thumbnail_loc><video:title>Introduction to passive and active transport</video:title><video:description>Active transport requires energy to move substances against a concentration or electrical gradient, like a canoeist paddling upstream. Passive transport, on the other hand, does not require energy as substances move along their gradient, similar to a canoeist drifting downstream. The sodium-potassium pump is a key example of active transport.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TsoAA7zOyj8.mp4/TsoAA7zOyj8.mp4</video:content_loc><video:duration>486</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/passive-transport-and-selective-permeability</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6525e15d.jpg</video:thumbnail_loc><video:title>Passive transport and selective permeability</video:title><video:description>Passive transport describes the movement of substances across a cell membrane down their concentration gradients, which does not require energy. Cell membranes are selectively permeable, so only certain substances can passively diffuse directly across the membrane. These substances include small, nonpolar molecules such as carbon dioxide and molecular oxygen.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jQN07Hvq6WI.mp4/jQN07Hvq6WI.mp4</video:content_loc><video:duration>420</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/endocytosis-phagocytosis-and-pinocytosis</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf31b726a.jpg</video:thumbnail_loc><video:title>Endocytosis, phagocytosis, and pinocytosis</video:title><video:description>Phagocytosis is the process by which a cell engulfs and internalizes a large particle, such as a bacterium, by extending its membrane around it. Pinocytosis is similar, but instead the cell engulfs droplets of extracellular fluid, taking in any dissolved substances within. Both phagocytosis and pinocytosis are forms of endocytosis.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/QspmZf_yWyU.mp4/QspmZf_yWyU.mp4</video:content_loc><video:duration>278</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/exocytosis</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb8a748cc.jpg</video:thumbnail_loc><video:title>Exocytosis</video:title><video:description>Exocytosis is a form of bulk transport during which large numbers of molecules are transported out of the cell. In exocytosis, a vesicle (a small, membrane-bound compartment) containing the molecules to be released fuses with the cell membrane, and the contents of the vesicle are expelled. Exocytosis is important for the transport of neurotransmitters.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/VOzV4d0HKis.mp4/VOzV4d0HKis.mp4</video:content_loc><video:duration>257</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/facilitated-diffusion</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x32334dc8.jpg</video:thumbnail_loc><video:title>Facilitated diffusion</video:title><video:description>Facilitated diffusion is a type of passive transport that uses specialized proteins, such as channel proteins and carrier proteins, to help molecules move across a cell membrane. In this process, molecules can move down their concentration gradient without requiring any energy input from the cell.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8HlVy__J8XA.mp4/8HlVy__J8XA.mp4</video:content_loc><video:duration>395</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/diffusion-and-osmosis</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23984.jpg</video:thumbnail_loc><video:title>Diffusion and osmosis</video:title><video:description>Diffusion refers to the movement of molecules from an area of high concentration to an area of lower concentration. Osmosis is a type of diffusion specifically for water molecules moving across a semi-permeable membrane. A concentration gradient is the difference in concentration of a substance between two areas, which drives diffusion or osmosis.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/aubZU0iWtgI.mp4/aubZU0iWtgI.mp4</video:content_loc><video:duration>1139</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/uniporters-symporters-and-antiporters</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x94a43831.jpg</video:thumbnail_loc><video:title>Uniporters, symporters, and antiporters</video:title><video:description>Passive transport is the movement of substances across a cell membrane without the use of energy. Examples include diffusion and facilitated diffusion. Active transport describes the use of energy to move molecules across a cell membrane, usually against their concentration gradients. Membrane proteins involved in active transport include symporters, antiporters, and the sodium-potassium pump.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-aGYytZ7K7M.mp4/-aGYytZ7K7M.mp4</video:content_loc><video:duration>433</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/osmosis</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc57249c4.jpg</video:thumbnail_loc><video:title>Osmosis</video:title><video:description>Osmosis is a process where water molecules move from an area of low solute concentration to high solute concentration through a semipermeable membrane. This movement can be influenced by factors like solute size and charge. Understanding osmosis helps us grasp how cells maintain balance and control their internal environment.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/rCNlG_j_gSM.mp4/rCNlG_j_gSM.mp4</video:content_loc><video:duration>484</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/hypotonic-isotonic-and-hypertonic-solutions-tonicity</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf9dc3289.jpg</video:thumbnail_loc><video:title>Hypotonic, isotonic, and hypertonic solutions (tonicity)</video:title><video:description>Cells react differently in hypotonic, isotonic, and hypertonic solutions. In a hypotonic solution, water rushes into the cell causing it to expand or even burst. In an isotonic solution, there is no net flow of water, keeping the cell stable. In a hypertonic solution, water leaves the cell, causing it to shrivel. These reactions are due to the semipermeable nature of cell membranes and the concentration of solutes.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/afWnU10ZNfg.mp4/afWnU10ZNfg.mp4</video:content_loc><video:duration>390</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/water-potential-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc83d63fab651905c.jpg</video:thumbnail_loc><video:title>Water potential example</video:title><video:description>Water potential helps explain how water moves into and out of plant cells through osmosis. By finding the sucrose concentration where a potato cube has no change in mass, its water potential can be calculated using solute potential. Concentration, temperature, and the ionization constant determine the final water potential in bars.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/BsnJDe4Tl-4.mp4/BsnJDe4Tl-4.mp4</video:content_loc><video:duration>405</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/electrochemical-gradient-and-secondary-active-transport</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xcf4785aa.jpg</video:thumbnail_loc><video:title>Electrochemical gradients and secondary active transport</video:title><video:description>Electrochemical gradients combine differences in ion concentration and electric charge across a cell membrane. The sodium-potassium pump creates a sodium gradient that stores potential energy. A sodium-glucose symporter uses this energy to move glucose against its concentration gradient, an example of secondary active transport that helps cells bring in needed molecules.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/wbWL2wfvsM8.mp4/wbWL2wfvsM8.mp4</video:content_loc><video:duration>317</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/sodium-potassium-pump-video</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9c826aa6.jpg</video:thumbnail_loc><video:title>Sodium potassium pump</video:title><video:description>The sodium-potassium pump is a trans-membrane protein that helps establish the resting membrane potential of cells, particularly neurons. In a process that requires ATP, the pump moves three sodium ions out of the cell for every two potassium ions it brings in. This contributes to the electric potential difference between the inside and outside of the cell.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vh166DKxYiM.mp4/vh166DKxYiM.mp4</video:content_loc><video:duration>438</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/prokaryotic-and-eukaryotic-cells</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xed3c4701.jpg</video:thumbnail_loc><video:title>Prokaryotic and eukaryotic cells</video:title><video:description>Eukaryotic cells contain membrane-bound organelles (such as the nucleus and mitochondria), while prokaryotic cells do not. DNA in eukaryotic cells is found inside the nucleus, while DNA in prokaryotic cells is located in the cytoplasm. Eukaryotic cells are generally larger and more complex than prokaryotic cells. Eukaryotic organisms include animals, plants, fungi, and paramecia. Prokaryotic organisms include bacteria and archaea.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xTnNv7YplSo.mp4/xTnNv7YplSo.mp4</video:content_loc><video:duration>410</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/endosymbiosis-theory</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5b44a315947b0f34.jpg</video:thumbnail_loc><video:title>Endosymbiosis theory</video:title><video:description>Certain characteristics of mitochondria and chloroplasts support the endosymbiotic theory, which posits that eukaryotic cells evolved from simpler prokaryotic cells that merged together. Lynn Margulis was a key figure in developing this theory. Margulis&apos;s work was at first met with skepticism, but now the endosymbiotic theory is widely accepted in the scientific community.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/eCWwKrJyKxA.mp4/eCWwKrJyKxA.mp4</video:content_loc><video:duration>250</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/enzymes</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x32f1ee82.jpg</video:thumbnail_loc><video:title>Enzymes</video:title><video:description>Enzymes are biological catalysts that speed up reactions. The active site is where substrates bind to the enzyme. Induced fit occurs when the enzyme changes shape to better accommodate substrates, facilitating the reaction. Enzymes can be used multiple times and are affected by factors such as temperature and pH.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/A90HKrgUOg0.mp4/A90HKrgUOg0.mp4</video:content_loc><video:duration>493</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/enzyme-reaction-velocity-and-ph</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf648b619f7355779.jpg</video:thumbnail_loc><video:title>Enzyme reaction velocity and pH</video:title><video:description>Enzymes are proteins that catalyze reactions in biological systems. The pH of an enzyme&apos;s surroundings affects the bonds that maintain the enzyme&apos;s structure, which can also affect the enzyme&apos;s activity. Different enzymes have optimal activity at different pH levels, with some enzymes working best in acidic environments and others in neutral or basic environments.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LtGCHzKAf8w.mp4/LtGCHzKAf8w.mp4</video:content_loc><video:duration>403</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/competitive-inhibition</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7fa5fd48.jpg</video:thumbnail_loc><video:title>Competitive inhibition</video:title><video:description>Enzymes catalyze reactions by binding substrates to their active sites. Inhibition can occur competitively (when a molecule competes for the active site) or non-competitively (when a molecule binds somewhere else on the enzyme, altering the enzyme&apos;s shape). Allosteric regulation describes any case where an enzyme&apos;s function at one site is affected by the binding of a molecule at another site.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/O23i38B2EmA.mp4/O23i38B2EmA.mp4</video:content_loc><video:duration>390</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/noncompetitive-inhibition</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf7618e41.jpg</video:thumbnail_loc><video:title>Noncompetitive inhibition</video:title><video:description>Noncompetitive inhibition occurs when an inhibitor reduces an enzyme&apos;s activity without preventing the substrate from binding. Both the substrate and inhibitor can bind to the enzyme at the same time, often at different sites. However, when the inhibitor is present, the enzyme cannot catalyze the reaction, distinguishing this process from competitive inhibition.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4xOsAuj0QZg.mp4/4xOsAuj0QZg.mp4</video:content_loc><video:duration>295</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/first-law-of-thermodynamics-introduction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x15363e45.jpg</video:thumbnail_loc><video:title>First law of thermodynamics introduction</video:title><video:description>The first law of thermodynamics states that energy cannot be created or destroyed, only converted from one form to another. For example, kinetic energy may be converted into thermal energy, or potential energy may be converted into kinetic energy. Energy is never &quot;lost&quot;; instead, it is transferred or converted in some way.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vny1qUaToHw.mp4/vny1qUaToHw.mp4</video:content_loc><video:duration>558</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/second-law-of-thermodynamics-and-entropy</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x618d2187.jpg</video:thumbnail_loc><video:title>Second law of thermodynamics and entropy</video:title><video:description>Entropy is a measure of disorder or randomness in a system. It represents the number of possible states or configurations that a system can take on. According to the second law of thermodynamics, entropy tends to increase over time, meaning that systems naturally progress towards a more disordered or random state.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/axG9HuqViDY.mp4/axG9HuqViDY.mp4</video:content_loc><video:duration>512</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/reaction-coupling-to-create-glucose-6-phosphate</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf7bec56a.jpg</video:thumbnail_loc><video:title>Reaction coupling to create glucose-6-phosphate</video:title><video:description>Reaction coupling is a process in which two reactions are linked together, with one providing the energy needed for the other to occur. In coupled reactions, an energetically favorable reaction (exergonic) releases energy, which is then used to drive an energetically unfavorable reaction (endergonic). This allows the overall coupled reaction to be exergonic, meaning it can happen spontaneously.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/L8ifD4I1o38.mp4/L8ifD4I1o38.mp4</video:content_loc><video:duration>419</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/introduction-to-metabolism-anabolism-and-catabolism</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6f1c22d2.jpg</video:thumbnail_loc><video:title>Introduction to metabolism: Anabolism and catabolism</video:title><video:description>Metabolism refers to the set of chemical reactions that occur within living organisms to maintain life. Anabolism is the process of building up larger, more complex molecules from smaller ones. This process requires energy. Catabolism is the process of breaking down larger molecules into smaller ones. This process releases energy that can be used by the organism.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/KwNe9x0eChs.mp4/KwNe9x0eChs.mp4</video:content_loc><video:duration>607</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/conceptual-overview-of-light-dependent-reactions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2ef70f81.jpg</video:thumbnail_loc><video:title>Conceptual overview of light-dependent reactions</video:title><video:description>During the light-dependent reactions of photosynthesis, light energy excites electrons, which then move through a series of molecules in the thylakoid membrane of chloroplasts. As the electrons move to lower energy states, they help pump hydrogen ions into the thylakoid lumen, creating a concentration gradient. This gradient powers ATP synthase to produce ATP.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vEsAtC9d_MQ.mp4/vEsAtC9d_MQ.mp4</video:content_loc><video:duration>545</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/photosynthesis-evolution</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x19dd2b55504b41ad.jpg</video:thumbnail_loc><video:title>Photosynthesis evolution</video:title><video:description>Ancient cyanobacteria produced oxygen as a byproduct of photosynthesis, changing the composition of the atmosphere over time in the Great Oxygenation Event. These cyanobacteria also led to the evolution of chloroplasts when they started living inside other cells, a process called endosymbiosis. The cyanobacteria provided the larger cell with sugars from photosynthesis, and the larger cell gave protection and nutrients.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/RnHCOBDSSfA.mp4/RnHCOBDSSfA.mp4</video:content_loc><video:duration>488</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/mitochondria-video</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7d4cfad5.jpg</video:thumbnail_loc><video:title>Mitochondria</video:title><video:description>Mitochondria are organelles that contain their own DNA, and have both inner and outer membranes. Mitochondria are often referred to as the &quot;powerhouses of the cell&quot; because they are responsible for producing most of the cell&apos;s energy in the form of ATP. According to the endosymbiont theory, mitochondria began as separate bacteria that were absorbed into another cell for their energy-producing capabilities.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/i1dAnpSFbyI.mp4/i1dAnpSFbyI.mp4</video:content_loc><video:duration>861</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/introduction-to-cellular-respiration</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23954.jpg</video:thumbnail_loc><video:title>Cellular respiration introduction</video:title><video:description>Cellular respiration is the process by which cells derive energy from glucose. The chemical reaction for cellular respiration involves glucose and oxygen as inputs, and produces carbon dioxide, water, and energy (ATP) as outputs. There are three stages to cellular respiration: glycolysis, the Krebs cycle, and the electron transport chain.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2f7YwCtHcgk.mp4/2f7YwCtHcgk.mp4</video:content_loc><video:duration>859</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/overview-of-cellular-respiration</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x19cf920e.jpg</video:thumbnail_loc><video:title>Overview of cellular respiration</video:title><video:description>Cellular respiration is how cells get energy from glucose. The process has three main parts: Glycolysis happens in the cytosol and breaks glucose into two pyruvate, producing 2 ATPs and 2 NADHs. The Krebs cycle occurs in the mitochondrial matrix, where pyruvate is turned into acetyl-CoA, which then goes through a series of reactions, producing ATP, NADH, and FADH2. Finally, oxidative phosphorylation uses NADH and FADH2 to create a proton gradient, which helps make more ATP.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9zoS5WGsmpc.mp4/9zoS5WGsmpc.mp4</video:content_loc><video:duration>791</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/oxidative-phosphorylation-and-the-electon-transport-chain</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5769d931.jpg</video:thumbnail_loc><video:title>Oxidative phosphorylation and the electron transport chain</video:title><video:description>Oxidative phosphorylation produces ATP (energy) in our cells. NADH, a molecule produced during cellular respiration, gets oxidized and releases electrons. These electrons pass through a series of acceptors in the electron transport chain, releasing energy. This energy pumps hydrogen protons across a membrane, creating a gradient. Finally, the enzyme ATP synthase uses this gradient to produce ATP.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/J30zpvbmw7s.mp4/J30zpvbmw7s.mp4</video:content_loc><video:duration>937</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/atp-synthase</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xcf231b1f0cb6bdde.jpg</video:thumbnail_loc><video:title>ATP synthase</video:title><video:description>ATP synthase is a membrane-bound enzyme that uses the flow of protons (H+) across a membrane to drive the synthesis of ATP from ADP and phosphate. It is found in mitochondria and chloroplasts, and plays a crucial role in cellular energy production and photosynthesis.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/rg8gpzFLQ-E.mp4/rg8gpzFLQ-E.mp4</video:content_loc><video:duration>267</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/cellular-communication</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0f31c982.jpg</video:thumbnail_loc><video:title>Cellular communication</video:title><video:description>Cell communication is crucial for complex organisms. Cells can communicate directly through contact or indirectly via chemical signaling. This communication can occur over short distances, such as between neurons, or long distances, like hormonal signaling in the endocrine system. Understanding these interactions is key to grasping biological complexity.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5MoIg5lWLXA.mp4/5MoIg5lWLXA.mp4</video:content_loc><video:duration>397</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/overview-of-cell-signaling</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc8b3fbfd.jpg</video:thumbnail_loc><video:title>Overview of cell signaling</video:title><video:description>Cell communication is a crucial biological process where cells interact directly or signal over distances. Direct contact involves gap junctions or complementary surface proteins. Paracrine communication happens over short distances, while endocrine signaling involves hormones traveling through the bloodstream for long-distance communication. Autocrine processes allow a cell to signal itself.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/FQFBygnIONU.mp4/FQFBygnIONU.mp4</video:content_loc><video:duration>529</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/intro-to-the-endocrine-system</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/221376883.jpg</video:thumbnail_loc><video:title>Introduction to the endocrine system</video:title><video:description>Endocrinology focuses on hormones, the body&apos;s chemical messengers. These hormones originate in one part of the body and journey to another to stimulate activity. They communicate through various methods, from direct contact to long-distance signaling. Crucial glands such as the pituitary, thyroid, and pancreas play significant roles in this process, regulating aspects like metabolism and growth.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/f_Z1zsR9lFM.mp4/f_Z1zsR9lFM.mp4</video:content_loc><video:duration>577</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/membrane-receptors</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6589e16e.jpg</video:thumbnail_loc><video:title>Membrane receptors</video:title><video:description>Membrane receptors, integral proteins in the cell membrane, enable cells to communicate with the outside environment. They bind with specific signaling molecules or ligands, triggering changes inside the cell. This process, known as signal transduction, influences cell behavior. The specificity of ligand-receptor binding is crucial in body functions and pharmaceutical drug design.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8Otn9DVkm-g.mp4/8Otn9DVkm-g.mp4</video:content_loc><video:duration>479</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/g-protein-coupled-receptors</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7e31c319.jpg</video:thumbnail_loc><video:title>G-protein coupled receptors</video:title><video:description>G-protein coupled receptors (GPCRs) are a large, diverse group of membrane receptors in eukaryotes that respond to a wide range of external signals. When a ligand binds to a GPCR, it triggers a complex chain of events involving G-proteins and second messengers, influencing various cell functions. This process is key to many bodily functions, from sensation to growth to hormone response.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ZBSo_GFN3qI.mp4/ZBSo_GFN3qI.mp4</video:content_loc><video:duration>768</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/cellular-mechanism-hormone-action</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd4489fab.jpg</video:thumbnail_loc><video:title>Cellular mechanism of hormone action</video:title><video:description>Hormones communicate with target cells via two primary methods: secondary messengers and primary messengers. Secondary messengers, such as cAMP, are released inside the cell after a hormone binds to a receptor, triggering a chain reaction. Primary messengers, such as steroid and thyroid hormones, can cross the cell membrane and directly affect transcription or translation. These processes enable efficient and amplified cellular responses.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TNGSzt2v4xY.mp4/TNGSzt2v4xY.mp4</video:content_loc><video:duration>503</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/example-of-signal-transduction-pathway</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x91f39d63.jpg</video:thumbnail_loc><video:title>Example of a signal transduction pathway</video:title><video:description>Signal transduction is a complex process where cells communicate through chemical signals. This involves a ligand binding to a receptor, initiating a cascade of events that can alter cell behavior. The Map kinase pathway, crucial in cell differentiation and replication, is a key player in this process. Mutations in this pathway can lead to diseases like cancer.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/i7z7f-wnews.mp4/i7z7f-wnews.mp4</video:content_loc><video:duration>395</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/cell-signaling-in-yeast-reproduction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x512026aa.jpg</video:thumbnail_loc><video:title>Cell signaling in yeast reproduction</video:title><video:description>Yeast can reproduce sexually through a signaling pathway known as the mating factor pathway. In this process, two haploid yeast cells combine to form a diploid cell. Yeast cells secrete a signal molecule called mating factor that attracts them to their mates. Once the mating factor of one yeast binds to the receptor on another yeast, an outgrowth called a &quot;shmoo&quot; forms, which allows the yeast cells to fuse together.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DJfNr8WoXW4.mp4/DJfNr8WoXW4.mp4</video:content_loc><video:duration>482</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/activation-and-inhibition-of-signal-transduction-pathways</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa2d9f762996b1eb6.jpg</video:thumbnail_loc><video:title>Activation and inhibition of signal transduction pathways</video:title><video:description>The cholera toxin triggers a signal transduction pathway. This process starts when molecules outside the cell interact with cell receptors, setting off a chain of events. G-proteins, acting like molecular switches, play a key role here. Mutations or disruptions can affect the signaling pathway, leading to changes in how the cell responds.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/zYX5a65LrXs.mp4/zYX5a65LrXs.mp4</video:content_loc><video:duration>356</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/homeostasis</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1262562541.jpg</video:thumbnail_loc><video:title>Homeostasis</video:title><video:description>Homeostasis, or maintaining a steady body temperature, is achieved through feedback mechanisms. Exposure to extreme temperatures triggers physiological responses like shivering or sweating, ensuring a constant core temperature. Homeostasis also extends to regulating blood pressure and sugar levels.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/rSBbnHLR_cg.mp4/rSBbnHLR_cg.mp4</video:content_loc><video:duration>220</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/hormone-concentration-metabolism-negative-feedback</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xcdd0a401.jpg</video:thumbnail_loc><video:title>Hormone concentration metabolism and negative feedback</video:title><video:description>Hormone concentration in our bodies is tightly regulated through metabolism, excretion, and feedback loops. The liver, kidneys, and sweat glands help remove excess hormones. Negative feedback loops, where hormone action suppresses further hormone release, play a crucial role in maintaining hormonal balance and homeostasis.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/RycF0ub2Al0.mp4/RycF0ub2Al0.mp4</video:content_loc><video:duration>287</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/interphase</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x78f186b2.jpg</video:thumbnail_loc><video:title>Interphase</video:title><video:description>A cell spends most of its life in interphase, which has three phases: G1, S, and G2. In the G1 phase, the cell grows and takes in nutrients. In the S phase, the cell&apos;s DNA is replicated. Each replicated chromosome consists of two sister chromatids connected at the centromere. The G2 phase is another growth phase, after which the cell is ready for mitosis.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/VXLSTd_dlKg.mp4/VXLSTd_dlKg.mp4</video:content_loc><video:duration>508</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/mitosis</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x385762f9.jpg</video:thumbnail_loc><video:title>Mitosis</video:title><video:description>Mitosis, a key part of the cell cycle, involves a series of stages (prophase, metaphase, anaphase, and telophase) that facilitate cell division and genetic information transmission. Centrosomes and microtubules play pivotal roles in orchestrating this complex process, ensuring the successful replication of cells.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TKGcfbyFXsw.mp4/TKGcfbyFXsw.mp4</video:content_loc><video:duration>732</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/cell-cycle-control</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4662267b.jpg</video:thumbnail_loc><video:title>Cell cycle control</video:title><video:description>The cell cycle is tightly regulated by checkpoints between the G1 and S phase, and between the G2 and mitosis. Key proteins, cyclin-dependent kinases and cyclins, control this process. Cyclins are produced at specific times, activating the kinases and allowing progression through the cell cycle. This regulation prevents unchecked cell division, a hallmark of cancer.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/542CMooowNY.mp4/542CMooowNY.mp4</video:content_loc><video:duration>249</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/loss-of-cell-cycle-control-in-cancer</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x49a016da.jpg</video:thumbnail_loc><video:title>Loss of cell cycle control in cancer</video:title><video:description>Proteins like p53 and RB play a crucial role in regulating the cell cycle. These proteins, known as tumor suppressor genes, prevent uncontrolled cell division, potentially leading to cancer. The case of p21 is intriguing, as its absence can surprisingly trigger limb regeneration in mice.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/UgZIULiNRoo.mp4/UgZIULiNRoo.mp4</video:content_loc><video:duration>225</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/fertilization-haploid-diploid-gamete-zygote-homologous</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x49fa677e.jpg</video:thumbnail_loc><video:title>Fertilization terminology</video:title><video:description>Sperm and egg cells, known as gametes, fuse during fertilization to create a zygote. Gametes have half the chromosomes (haploid) of a typical body cell, while zygotes have the full set (diploid). Homologous chromosomes from each parent determine traits, including sex. Understanding haploid and diploid numbers is essential in studying cell division and genetics.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/dNp7vErqlaA.mp4/dNp7vErqlaA.mp4</video:content_loc><video:duration>627</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/phases-of-meiosis-i</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x103b28b6.jpg</video:thumbnail_loc><video:title>Phases of meiosis I</video:title><video:description>In meiosis I, cells go through four phases: prophase I, metaphase I, anaphase I, and telophase I. During prophase I, chromosomes pair up and exchange genetic material, creating more variation. In metaphase I, chromosomes line up in the middle of the cell. Anaphase I separates homologous pairs, while telophase I forms two new cells with a haploid number of chromosomes.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/XGWL9jfPHJ8.mp4/XGWL9jfPHJ8.mp4</video:content_loc><video:duration>585</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/phases-of-meiosis-ii</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xcc05c922.jpg</video:thumbnail_loc><video:title>Phases of meiosis II</video:title><video:description>Meiosis II is a process that helps cells divide and create gametes, which are needed for sexual reproduction. It starts with prophase II, where the nuclear envelope dissolves and chromosomes condense. Then, in metaphase II, chromosomes line up along the cell&apos;s middle. During anaphase II, sister chromatids separate and move to opposite ends of the cell. Finally, in telophase II, the nuclear envelope reforms, and the cell splits into four new cells, each with a haploid number of chromosomes.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/mMCcBsSAlF4.mp4/mMCcBsSAlF4.mp4</video:content_loc><video:duration>658</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/comparing-mitosis-and-meiosis</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9d72f94c.jpg</video:thumbnail_loc><video:title>Comparing mitosis and meiosis</video:title><video:description>Mitosis and meiosis are two different types of cell division. Mitosis occurs in somatic cells and results in two identical daughter cells with a diploid (2n) number of chromosomes. This process is essential for growth and repair in the body. On the other hand, meiosis occurs in germ cells and produces four non-identical gametes with a haploid (n) number of chromosomes. These gametes, such as sperm and egg cells, are crucial for sexual reproduction and genetic diversity.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/IQJ4DBkCnco.mp4/IQJ4DBkCnco.mp4</video:content_loc><video:duration>351</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/chromosomal-crossover-in-meiosis-i</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1cc0f1a3.jpg</video:thumbnail_loc><video:title>Chromosomal crossover in meiosis I</video:title><video:description>Meiosis is a process where germ cells divide to produce gametes, such as sperm and egg cells. In prophase I of meiosis, chromosomes condense and homologous recombination takes place, leading to genetic variation through chromosomal crossover. This forms a tetrad, which is made up of four chromatids (two sister chromatids per chromosome).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/04gQ0bQu6xk.mp4/04gQ0bQu6xk.mp4</video:content_loc><video:duration>736</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/variation-in-a-species</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23926.jpg</video:thumbnail_loc><video:title>Variation in a species</video:title><video:description>Natural selection relies on genetic variation within a species. Mutations alone aren&apos;t sufficient for creating diversity; sexual reproduction plays a crucial role as well. By combining genetic material from two parents, offspring inherit a unique mix of traits, resulting in vast potential for variation. This process allows for more efficient adaptation and survival, making sexual reproduction a widespread biological strategy.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DuArVnT1i-E.mp4/DuArVnT1i-E.mp4</video:content_loc><video:duration>1191</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/introduction-to-heredity</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23940.jpg</video:thumbnail_loc><video:title>Introduction to heredity</video:title><video:description>Genetics is a fascinating world, focusing on the inheritance of traits from parents to offspring. Gregor Mendel, the father of classical genetics, made significant contributions to our understanding of this process. Dominant and recessive traits play a crucial role in determining an individual&apos;s characteristics. The difference between genotype and phenotype is also a key concept, illustrated here through the example of eye color.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/eEUvRrhmcxM.mp4/eEUvRrhmcxM.mp4</video:content_loc><video:duration>1047</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/alleles-and-genes</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5155c0f0.jpg</video:thumbnail_loc><video:title>Alleles and genes</video:title><video:description>Genes and alleles are key players in heredity. Genes are sections of DNA that code for specific proteins or functional RNA. Alleles, on the other hand, are different versions of the same gene. They can lead to variations in traits like eye color. Understanding these differences is crucial to studying inheritance patterns.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/P0nMnPPdW_k.mp4/P0nMnPPdW_k.mp4</video:content_loc><video:duration>498</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/punnett-square-fun</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23942.jpg</video:thumbnail_loc><video:title>Worked example: Punnett squares</video:title><video:description>Punnett squares help predict offspring traits by showing possible gene combinations from parents. In addition, Punnett squares can illustrate trends among dominant and recessive traits, incomplete dominance, codominance, and dihybrid crosses. Punnett squares are useful for understanding genetics and inheritance patterns.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/D5ymMYcLtv0.mp4/D5ymMYcLtv0.mp4</video:content_loc><video:duration>1516</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/boveri-sutton-chromosome-theory</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xefeb7dbf.jpg</video:thumbnail_loc><video:title>Boveri-Sutton chromosome theory</video:title><video:description>Gregor Mendel&apos;s groundbreaking 1866 work on heritable traits laid the foundation for modern genetics. His laws of segregation, independent assortment, and dominance provided a framework for understanding how traits pass from parents to offspring. However, it wasn&apos;t until the early 1900s that the Boveri-Sutton Chromosome Theory linked Mendel&apos;s laws to the behavior of chromosomes during meiosis, solidifying the molecular basis of inheritance.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/rV6O3rGulaY.mp4/rV6O3rGulaY.mp4</video:content_loc><video:duration>659</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/pedigrees</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xec86dfc45c44c9c2.jpg</video:thumbnail_loc><video:title>Pedigrees</video:title><video:description>Pedigrees are a useful method to model the inheritance patterns of traits within families. By using symbols and analyzing phenotypes, we can infer genotypes and understand the role of autosomal dominant traits. The trait of freckles serves as a practical example here and shows the complex world of genetic inheritance patterns.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/11s5Biyi9q4.mp4/11s5Biyi9q4.mp4</video:content_loc><video:duration>368</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/thomas-hunt-morgan-and-fruit-flies</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc4865c52.jpg</video:thumbnail_loc><video:title>Thomas Hunt Morgan and fruit flies</video:title><video:description>The groundbreaking work of Thomas Hunt Morgan in the early 1900s provided substantial evidence for the chromosome theory of inheritance. Using fruit flies as a model organism, Morgan discovered a mutant white-eyed male fly and traced its inheritance pattern, revealing a connection between the X sex chromosome and the gene for eye color. This pioneering research earned Morgan a Nobel Prize and cemented the role of chromosomes in genetic inheritance.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/huDDaj0PjLU.mp4/huDDaj0PjLU.mp4</video:content_loc><video:duration>640</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/pedigree-for-determining-probability-of-exhibiting-sex-linked-recessive-trait</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe9b4a7a106de559a.jpg</video:thumbnail_loc><video:title>Pedigree for determining probability of exhibiting sex-linked recessive trait</video:title><video:description>Pedigree charts can be used to determine the probability of offspring exhibiting an X-linked recessive trait, such as color blindness. By scrutinizing genotypes and utilizing a Punnett square, the probability of color blindness in offspring can be calculated.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DzP7XO0Qg_Y.mp4/DzP7XO0Qg_Y.mp4</video:content_loc><video:duration>319</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/extranuclear-inheritance-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3ce4eef4.jpg</video:thumbnail_loc><video:title>Extranuclear inheritance</video:title><video:description>Certain organelles, like mitochondria and chloroplasts, have their own DNA and can replicate independently outside of the nucleus. This is called extranuclear inheritance and both mitochondria and chloroplasts show maternal inheritance. Mitochondria and chloroplasts are also involved in making energy (ATP) and food (glucose) for cells.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/yyM0yIOJ2yE.mp4/yyM0yIOJ2yE.mp4</video:content_loc><video:duration>434</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/phenotype-plasticity</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7300199cf7c3dc96.jpg</video:thumbnail_loc><video:title>Phenotype plasticity</video:title><video:description>Identical twin astronauts, Mark Kelly and Scott Kelly, help illustrate differences between genotype (genetic info) and phenotype (observable traits). Despite their identical genotypes, environmental factors like the time Scott spent in space led to differences in the phenotypes of the twins, showcasing the concept of phenotype plasticity.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Mh3QXbVU6Eo.mp4/Mh3QXbVU6Eo.mp4</video:content_loc><video:duration>197</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/gene-environment-interaction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x777976b6.jpg</video:thumbnail_loc><video:title>Gene environment interaction</video:title><video:description>Genes and environment interact to influence behavior, and the term &quot;nature through nurture&quot; captures this relationship. The genetic condition phenylketonuria (PKU) is an example of how a genetic condition can be managed through environmental factors, like a specialized diet, to prevent negative outcomes.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/sMyZO9YDlk8.mp4/sMyZO9YDlk8.mp4</video:content_loc><video:duration>269</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/introduction-to-nucleic-acids-and-nucleotides</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6c61c97a15e29d9c.jpg</video:thumbnail_loc><video:title>Introduction to nucleic acids and nucleotides</video:title><video:description>Nucleic acids, crucial macromolecules for life, were first discovered in cell nuclei and exhibit acidic properties. DNA and RNA, composed of nucleotide building blocks, store hereditary information. These polymers have a backbone of alternating ribose and phosphate groups, with nitrogenous bases forming ladder rungs. The sequence of nucleotides encodes genetic information, making nucleic acids fundamental to life.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hI4v7v8AdfI.mp4/hI4v7v8AdfI.mp4</video:content_loc><video:duration>355</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/leading-and-lagging-strands-in-dna-replication</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5f21e0dd.jpg</video:thumbnail_loc><video:title>Leading and lagging strands in DNA replication</video:title><video:description>DNA replication is a precise process where DNA unwinds and splits into two strands. Each strand then serves as a template for a new DNA molecule. The leading strand is built continuously, while the lagging strand is built in fragments, called Okazaki fragments.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/eM7arWJJ3zk.mp4/eM7arWJJ3zk.mp4</video:content_loc><video:duration>619</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/speed-and-precision-of-dna-replication</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5e58fede.jpg</video:thumbnail_loc><video:title>Speed and precision of DNA replication</video:title><video:description>DNA replication is a complex, fast, and precise process involving enzymes like topoisomerase, helicase, and polymerase. In E. coli, polymerase can replicate up to 700+ base pairs per second. Initially, one mistake occurs for every 10 million nucleotides, but proofreading reduces errors to one in a billion. This amazing cellular machinery keeps our DNA accurate and functional.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PSl6IXUCNuw.mp4/PSl6IXUCNuw.mp4</video:content_loc><video:duration>235</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/semi-conservative-replication</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xcdf631f4.jpg</video:thumbnail_loc><video:title>Semi-conservative replication</video:title><video:description>DNA replication has three possible methods: conservative, dispersive, and semi-conservative. Here, we focus on the Meselson-Stahl experiment, which proved DNA replication is semi-conservative. In this process, each new DNA pair consists of one old strand and one new strand, ensuring accurate genetic information transfer.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jaJ3NlqK5dA.mp4/jaJ3NlqK5dA.mp4</video:content_loc><video:duration>132</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/transcription-and-mrna-processing</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9ad4c3f8.jpg</video:thumbnail_loc><video:title>Transcription and mRNA processing</video:title><video:description>Transcription involves rewriting genetic information from DNA to mRNA, with RNA polymerase playing a crucial role. In eukaryotic cells, DNA to mRNA transcription occurs within the nucleus, producing pre-mRNA. This pre-mRNA undergoes processing, including the addition of a 5&apos; cap, a poly-A tail, and splicing out introns, resulting in mature mRNA, which then leaves the nucleus for protein translation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/JQIwwJqF5D0.mp4/JQIwwJqF5D0.mp4</video:content_loc><video:duration>625</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/post-translational-regulation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x11cb2084.jpg</video:thumbnail_loc><video:title>Post-transcriptional regulation</video:title><video:description>Post-transcriptional regulation occurs in eukaryotes, stabilizing mRNA for translation. DNA transcribes into RNA, with exons coding for proteins and introns removed by spliceosomes. The mRNA acquires a 5&apos; cap and 3&apos; poly-A tail for protection and translation promotion. RNA editing, a rare process, alters RNA sequences through insertion, deletion, or base substitution, impacting viral enzymes and functions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/nz5rbvt64kE.mp4/nz5rbvt64kE.mp4</video:content_loc><video:duration>368</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/translation-mrna-to-protein</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb510c64f.jpg</video:thumbnail_loc><video:title>Translation (mRNA to protein)</video:title><video:description>Translation is the process whereby mRNA is converted into proteins by ribosomes. Translation occurs in ribosomes, which are cellular structures made of proteins and ribosomal RNA (rRNA). Here, mRNA is converted into amino acid sequences, forming polypeptides. Transfer RNA (tRNA) carries amino acids and matches them with mRNA codons, allowing ribosomes to synthesize proteins.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ocAAkB32Hqs.mp4/ocAAkB32Hqs.mp4</video:content_loc><video:duration>850</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/rna-transcription-and-translation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4626c3c0.jpg</video:thumbnail_loc><video:title>DNA replication and RNA transcription and translation</video:title><video:description>DNA serves as the molecular basis of heredity through replication, expression, and translation processes. Replication creates identical DNA strands, while transcription converts DNA into messenger RNA (mRNA). Translation then decodes mRNA into amino acids, forming proteins essential for life functions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6gUY5NoX1Lk.mp4/6gUY5NoX1Lk.mp4</video:content_loc><video:duration>924</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/differences-in-translation-between-prokaryotes-and-eukaryotes</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfee29e2b.jpg</video:thumbnail_loc><video:title>Differences in translation between prokaryotes and eukaryotes</video:title><video:description>The process of mRNA translation differs between prokaryotes and eukaryotes. Prokaryotic mRNA has a Shine-Dalgarno sequence for ribosome binding, while eukaryotic mRNA has a 5&apos; cap and poly-A tail for protection and ribosome binding. The first amino acid also differs: formylmethionine in prokaryotes and methionine in eukaryotes.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/WNZf4ip_R9s.mp4/WNZf4ip_R9s.mp4</video:content_loc><video:duration>396</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/retroviruses</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa3a3b196.jpg</video:thumbnail_loc><video:title>Retroviruses</video:title><video:description>Retroviruses, like HIV, have a unique replication process combining lytic and lysogenic elements. They enter cells through direct fusion and use reverse transcriptase to create complementary DNA (cDNA) from their RNA. Integrase integrates viral DNA into the host genome, forming a provirus. Viral mRNA is produced, translated into proteins, and assembled into new viruses that bud off with an envelope. Protease matures the viruses before they infect other cells.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/KhdX5eX4dMM.mp4/KhdX5eX4dMM.mp4</video:content_loc><video:duration>448</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/dna-and-chromatin-regulation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4f8acd81.jpg</video:thumbnail_loc><video:title>DNA and chromatin regulation</video:title><video:description>Gene regulation controls when and how much a gene is expressed. Chromatin regulation and DNA methylation are two ways to regulate genes. Chromatin regulation involves histone modifications, while DNA methylation adds methyl groups. Both are examples of epigenetic regulation and are crucial for proper cell function.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OqRt723t33o.mp4/OqRt723t33o.mp4</video:content_loc><video:duration>321</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/regulation-of-transcription</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9fd7ee93.jpg</video:thumbnail_loc><video:title>Regulation of transcription</video:title><video:description>Gene regulation controls cell functions by determining which genes are transcribed. This process involves transcription factors, activators, enhancers, repressors, and silencers. Prokaryotes rely on gene regulation for environmental adaptation, while eukaryotes have more complex interactions and a nuclear envelope for added control. Understanding gene expression is crucial for studying cellular processes and responses.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ypH-hDKpCY0.mp4/ypH-hDKpCY0.mp4</video:content_loc><video:duration>407</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/operons-and-gene-regulation-in-bacteria</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x565e1bd2.jpg</video:thumbnail_loc><video:title>Operons and gene regulation in bacteria</video:title><video:description>DNA regulation controls gene expression in cells, allowing different cell types to perform unique functions despite having the same DNA. Prokaryotes, like bacteria, use operons, which consist of a promoter and multiple genes. Repressors, corepressors, activators, and inducers can influence transcription by binding to regulatory DNA sequences, enabling cells to adapt to their environment.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/N7_K0yl0Egk.mp4/N7_K0yl0Egk.mp4</video:content_loc><video:duration>610</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/lac-operon</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe8bc037d.jpg</video:thumbnail_loc><video:title>Lac operon</video:title><video:description>The lac operon in E. coli regulates lactose metabolism. It consists of three genes (lacZ, lacY, and lacA) and is controlled by a promoter, operator, and CAP site. Lactose presence triggers allolactose production, which inhibits the lac repressor, allowing transcription. Glucose levels impact transcription through cyclic AMP and the catabolite activator protein.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LuOaEe89_HE.mp4/LuOaEe89_HE.mp4</video:content_loc><video:duration>665</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/trp-operon</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3bbb0a1a.jpg</video:thumbnail_loc><video:title>Trp operon</video:title><video:description>The Trp operon plays a crucial role in tryptophan production, an essential amino acid. In E. Coli, the operon consists of genes and regulatory DNA sequences, including the promoter and operator. Tryptophan acts as a co-repressor, binding to the Trp repressor and inhibiting transcription when abundant. Additionally, feedback inhibition occurs, where tryptophan directly inhibits enzyme activity. This regulation ensures efficient resource use and tryptophan biosynthesis.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/EvLy_1_Y3tk.mp4/EvLy_1_Y3tk.mp4</video:content_loc><video:duration>396</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/cellular-specialization-differentiation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb0aae61c.jpg</video:thumbnail_loc><video:title>Cellular specialization (differentiation)</video:title><video:description>Stem cells differentiate into specialized cells through gene expression, influenced by internal and external cues. Asymmetric segregation of cellular determinants and inductive signaling guide this process. Transcription factors activate genes, while induction involves cell-to-cell communication. These mechanisms shape cell specialization, forming diverse body parts during development.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/YtvL-LQlPrU.mp4/YtvL-LQlPrU.mp4</video:content_loc><video:duration>511</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/non-coding-rna-ncrna</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xcd2b2b61.jpg</video:thumbnail_loc><video:title>Non-coding RNA (ncRNA)</video:title><video:description>Non-coding RNAs (ncRNAs) are functional RNA molecules that do not translate into proteins. They play vital roles in cellular processes, including transcription and translation. Key examples include micro RNAs (miRNAs), ribosomal RNAs, transfer RNAs, small nucleolar RNAs (snow RNAs), and small nuclear RNAs (snRNAs). These ncRNAs help regulate gene expression, protein synthesis, and maintain cellular structures.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9YrS35wxE7o.mp4/9YrS35wxE7o.mp4</video:content_loc><video:duration>280</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/an-introduction-to-genetic-mutations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa20533ca.jpg</video:thumbnail_loc><video:title>An introduction to genetic mutations</video:title><video:description>Genetic mutations originate at the DNA level, affecting protein synthesis. Mutations can be inherited from parents or occur spontaneously due to factors like replication errors or environmental influences. Sickle-cell disease exemplifies how a single amino acid change can impact protein function, leading to health complications.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/g02RnGXCXrQ.mp4/g02RnGXCXrQ.mp4</video:content_loc><video:duration>324</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/mutagens-and-carcinogens</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x149a9fec.jpg</video:thumbnail_loc><video:title>Mutagens and carcinogens</video:title><video:description>Mutagens and carcinogens can cause DNA damage, affecting protein production. Mutagens, either endogenous or exogenous, increase genetic mutation probability. Endogenous mutagens, like reactive oxygen species (ROS), are produced by the body. Exogenous mutagens include intercalators and base analogs. Carcinogens lead to cancer, and while some are mutagenic, not all are. Examples include tobacco, asbestos, and UV radiation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4mrp5uI9anE.mp4/4mrp5uI9anE.mp4</video:content_loc><video:duration>337</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/the-effects-of-mutations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x735334d0.jpg</video:thumbnail_loc><video:title>The effects of mutations</video:title><video:description>Mutations in DNA can lead to abnormal protein production, affecting organisms in various ways. These genetic changes can be advantageous, deleterious, or neutral, depending on factors like the environment. Examples include antibiotic-resistant bacteria, cystic fibrosis, and sickle-cell disease, which demonstrate the complex nature of mutations and their impact on living beings.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/JxC2phkdY8Y.mp4/JxC2phkdY8Y.mp4</video:content_loc><video:duration>251</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/impact-of-mutations-on-translation-into-amino-acids</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8d81330713137fa1.jpg</video:thumbnail_loc><video:title>Impact of mutations on translation into amino acids</video:title><video:description>DNA transcription and RNA translation are key processes in converting genetic information into proteins. Amino acid translation tables help determine the resulting amino acids, while point mutations and frameshift mutations can impact protein synthesis. Mutations play a crucial role in providing variation and driving evolution in populations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1Dk0_-fyyDI.mp4/1Dk0_-fyyDI.mp4</video:content_loc><video:duration>532</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/mutation-as-a-source-of-variation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4775ddb6119931e5.jpg</video:thumbnail_loc><video:title>Mutation as a source of variation</video:title><video:description>Natural selection relies on variation in populations, driving evolution. Variation arises from sexual reproduction, shuffling gene combinations, and mutations, creating new alleles or genes. Phenotypes, observable traits, stem from genotypes, genetic information. Mutations can be neutral, advantageous, or detrimental, influencing the survival and reproduction of an organism.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LZCE-4q5f9c.mp4/LZCE-4q5f9c.mp4</video:content_loc><video:duration>366</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/introduction-to-genetic-engineering</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb42c5cd2ce121bdc.jpg</video:thumbnail_loc><video:title>Introduction to genetic engineering</video:title><video:description>Genetic engineering, although a recent concept, has roots in ancient human practices like selective breeding of animals and plants. Today, recombinant DNA technology enables precise gene manipulation, creating genetically modified organisms (GMOs) with enhanced traits. While offering benefits like robust crops and new medicines, it raises bioethical concerns, especially regarding human genome modification.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/JNgONZ8Dq9I.mp4/JNgONZ8Dq9I.mp4</video:content_loc><video:duration>391</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/dna-cloning-and-recombinant-dna</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfe0194fc.jpg</video:thumbnail_loc><video:title>DNA cloning and recombinant DNA</video:title><video:description>DNA cloning involves creating identical copies of a specific gene using restriction enzymes to cut the desired gene, pasting it into a plasmid, and inserting it into bacteria like E. coli. The bacteria replicate the gene and can produce proteins, such as insulin. Antibiotic resistance genes in plasmids help select bacteria containing the desired gene.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5ffl-0OYVQU.mp4/5ffl-0OYVQU.mp4</video:content_loc><video:duration>668</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/the-polymerase-chain-reaction-pcr</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x72f7bdcd.jpg</video:thumbnail_loc><video:title>Polymerase chain reaction (PCR)</video:title><video:description>PCR (Polymerase Chain Reaction) is a vital technique in molecular biology, enabling researchers to amplify specific DNA fragments exponentially. Essential for cloning, forensics, and medical diagnostics, PCR involves three main steps: denaturation, annealing, and extension. By using heat-resistant Taq polymerase and repeating cycles, scientists can generate billions of DNA copies within hours, significantly enhancing their ability to study and manipulate genetic material.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/nHi-3jP6Mvc.mp4/nHi-3jP6Mvc.mp4</video:content_loc><video:duration>594</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/gel-electrophoresis-dna</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5921c437.jpg</video:thumbnail_loc><video:title>Gel electrophoresis</video:title><video:description>Gel electrophoresis is a technique used to separate DNA, RNA, or protein fragments by size. It involves a gel, electric charge, and migration of molecules. DNA samples are placed in wells within an agarose gel, and an electric field is applied. Smaller molecules move faster through the gel, allowing for separation and estimation of fragment lengths using a DNA ladder as a reference. Ethidium bromide or other dyes are used to visualize the separated fragments under UV light.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_EYsykjsfiY.mp4/_EYsykjsfiY.mp4</video:content_loc><video:duration>660</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/dna-sequencing</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1baa728e.jpg</video:thumbnail_loc><video:title>DNA sequencing</video:title><video:description>DNA sequencing involves three main steps: 1) using PCR to amplify DNA fragments, 2) introducing dideoxynucleotides that halt DNA strand elongation, and 3) employing a computer to analyze the fluorescent labels on the DNA fragments to determine the sequence.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Jnk_4Maf5Fk.mp4/Jnk_4Maf5Fk.mp4</video:content_loc><video:duration>281</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/applications-of-dna-technologies</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x37c99fd7.jpg</video:thumbnail_loc><video:title>Applications of DNA technologies</video:title><video:description>DNA technology revolutionizes medicine, forensics, and agriculture. Recombinant DNA creates insulin and growth hormones, improves vaccine safety, and helps solve crimes through genome analysis. Genetically modified crops enhance resistance, delay ripening, and support farmers, feeding more people and boosting the economy.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gqMqYYcJgz4.mp4/gqMqYYcJgz4.mp4</video:content_loc><video:duration>301</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/introduction-to-evolution-and-natural-selection</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23916.jpg</video:thumbnail_loc><video:title>Introduction to evolution and natural selection</video:title><video:description>Natural selection is a mechanism of evolution and explains how species adapt to their environment over time through variations in traits. Examples include the peppered moth adapting to industrial pollution, yearly flu virus changes, and antibiotic-resistant bacteria. Understanding natural selection is essential for studying living systems.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/GcjgWov7mTM.mp4/GcjgWov7mTM.mp4</video:content_loc><video:duration>1059</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/natural-selection-and-the-owl-butterfly</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23922.jpg</video:thumbnail_loc><video:title>Natural selection and the owl butterfly</video:title><video:description>Intricate patterns, such as the owl butterfly&apos;s eye-like wing markings, evolve through natural selection. Over thousands of generations, small variations in wing patterns offer slight survival advantages, leading to the dominance of beneficial traits. This gradual process allows complex designs to emerge from random genetic mutations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/dR_BFmDMRaI.mp4/dR_BFmDMRaI.mp4</video:content_loc><video:duration>809</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/biodiversity-and-natural-selection-two</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x29f3228a.jpg</video:thumbnail_loc><video:title>Biodiversity and natural selection</video:title><video:description>The patterns and processes of evolution play a crucial role in biodiversity. Natural selection, adaptation, and inheritance serve as key mechanisms driving diversity. Examining relationships among organisms, genealogical trees, and environmental factors provides insight into the complex interplay shaping Earth&apos;s rich biodiversity.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/sNgsCT0E7Es.mp4/sNgsCT0E7Es.mp4</video:content_loc><video:duration>543</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/molecular-variation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe10e4777e8df7ebc.jpg</video:thumbnail_loc><video:title>Molecular variation</video:title><video:description>Molecular variation in cells allows organisms to respond to a wider range of environmental stimuli, and allows populations to adapt to a wider range of environmental conditions. Examples of molecular variation include the different types of hemoglobin proteins, and the different forms of chlorophyll produced in cells.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/RYz3d1meQQc.mp4/RYz3d1meQQc.mp4</video:content_loc><video:duration>373</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/artificial-selection-and-domestication</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xcadbfc6f4f94806e.jpg</video:thumbnail_loc><video:title>Artificial selection and domestication</video:title><video:description>Artificial selection and domestication are processes where humans influence the evolution of species. Dogs, farm animals, and crops have all been shaped by these methods. Humans select which individuals reproduce based on desired traits, accelerating changes that would take much longer in natural selection. This has led to the diverse breeds of dogs and varieties of crops we see today.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hFjGQXcwYIk.mp4/hFjGQXcwYIk.mp4</video:content_loc><video:duration>251</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/genetic-drift-bottleneck-effect-and-founder-effect</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8c483d3a.jpg</video:thumbnail_loc><video:title>Genetic drift, bottleneck effect, and founder effect</video:title><video:description>Evolution has multiple mechanisms, including genetic drift, which involves random changes in trait frequency. In particular, genetic drift is more likely in small populations. Examples include the bottleneck effect, where a disaster reduces population size, and the founder effect, where a small group starts a new population; both result in less genetic variation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/IRTn0iNkAHI.mp4/IRTn0iNkAHI.mp4</video:content_loc><video:duration>647</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/dna-spells-evolution</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe9279bc7.jpg</video:thumbnail_loc><video:title>DNA spells evolution</video:title><video:description>Genetic mutations lead to variations in traits. These variations can provide survival advantages, resulting in new species over generations. For example, brown bears evolved into polar bears due to beneficial mutations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/uI_Q1kjmfxo.mp4/uI_Q1kjmfxo.mp4</video:content_loc><video:duration>134</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/allele-frequency</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf2057c13.jpg</video:thumbnail_loc><video:title>Allele frequency</video:title><video:description>Allele frequency describes how often an allele (a variant of a gene) appears in a population. In this video, eye color is used as an example, with brown (B) eyes being dominant and blue (b) eyes being recessive. Allele frequency (or genotype frequency) can also differ from phenotype frequency.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Bc9bhLk_AhI.mp4/Bc9bhLk_AhI.mp4</video:content_loc><video:duration>447</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/hardy-weinberg</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5628ee19.jpg</video:thumbnail_loc><video:title>Hardy-Weinberg equation</video:title><video:description>The Hardy-Weinberg equilibrium is a principle that helps to predict allele frequencies in a population. It assumes no selection, no mutation, no geneflow, random mating, and large populations for stable allele frequencies. The Hardy-Weinberg equation calculates probabilities of homozygous dominant, heterozygous, and homozygous recessive genotypes.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/oc9fJCAIRJs.mp4/oc9fJCAIRJs.mp4</video:content_loc><video:duration>494</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/applying-hardy-weinberg</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x15272d4a.jpg</video:thumbnail_loc><video:title>Applying the Hardy-Weinberg equation</video:title><video:description>The Hardy-Weinberg equation can help to estimate allele frequencies in a population. Dominant (p) and recessive (q) allele frequencies and genotype frequencies can be calculated using the equation. In this video, eye color is used as an example to determine allele frequencies and genotype distribution.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/D5NVlAaT-OA.mp4/D5NVlAaT-OA.mp4</video:content_loc><video:duration>330</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/discussions-of-conditions-for-hardy-weinberg</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x88d56ee0.jpg</video:thumbnail_loc><video:title>Discussions of conditions for Hardy-Weinberg</video:title><video:description>The Hardy-Weinberg equation assumes stable allele frequencies in a population. Key conditions include no mutation, random mating, no gene flow, infinite population size, and no selection. Diploid organisms with sexual reproduction are also assumed. Although real-world populations may not strictly adhere to these conditions, the equation remains a useful approximation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Q618DALi2eo.mp4/Q618DALi2eo.mp4</video:content_loc><video:duration>414</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/evidence-for-evolution</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6bd5a4dc.jpg</video:thumbnail_loc><video:title>Evidence for evolution</video:title><video:description>Three types of evidence support evolution and natural selection: structural, microbiological, and direct observation. Structural evidence encompasses homologous structures and the fossil record. Microbiological evidence involves DNA similarities and shared processes across species. Direct observation showcases evolution in action, such as antibiotic resistance in bacteria.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Q-aGAX27SIo.mp4/Q-aGAX27SIo.mp4</video:content_loc><video:duration>779</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/fossils-rocking-the-earth</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1cf8e423.jpg</video:thumbnail_loc><video:title>Fossils: Rocking the Earth</video:title><video:description>Fossils reveal connections between ancient and modern organisms, providing strong evidence for evolution. The fossil record shows gradual evolutionary change, physical proof of extinction, species splitting, and transitional forms. By studying fossils, we can trace the development of features in living organisms and understand how life on Earth has evolved over time.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/rSWwmN5ozQ0.mp4/rSWwmN5ozQ0.mp4</video:content_loc><video:duration>134</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/biogeography-where-life-lives</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x22546072.jpg</video:thumbnail_loc><video:title>Biogeography: Where life lives</video:title><video:description>Biogeography explores the distribution of plants, animals, and organisms across Earth. New islands form habitats for unique species, like Galapagos finches and Hawaiian honeycreepers. Continental drift explains related species on different continents, with Pangaea&apos;s breakup separating organisms. Phylogenetic trees help trace species&apos; movements, revealing Earth&apos;s dynamic biodiversity.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2UQC5ts6hUs.mp4/2UQC5ts6hUs.mp4</video:content_loc><video:duration>110</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/molecular-evidence-for-evolutionary-relationships-examples</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb4f57f93bafc053f.jpg</video:thumbnail_loc><video:title>Molecular evidence for evolutionary relationships: Examples</video:title><video:description>This investigation focuses on determining the closest plant species to an unknown species by analyzing enzyme presence, amino acid sequence differences, and gel electrophoresis banding patterns. Plant species with the most similarities in these factors are considered closely related. The method also applies to finch species, using molecular evidence to establish evolutionary relationships.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/mHH0sSm2cK8.mp4/mHH0sSm2cK8.mp4</video:content_loc><video:duration>365</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/carbon-14-dating-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187416.jpg</video:thumbnail_loc><video:title>Carbon-14 dating: Part 1</video:title><video:description>Carbon-14 forms in the atmosphere through cosmic rays interacting with nitrogen-14, creating a small fraction of carbon-14 in living organisms. When an organism dies, its carbon-14 decays back into nitrogen-14 at a known rate, called a half-life (5,730 years). By measuring the remaining carbon-14 in fossils, scientists can estimate their age, helping us understand the history of life on Earth.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8wYvKeSK1IY.mp4/8wYvKeSK1IY.mp4</video:content_loc><video:duration>603</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/cellular-evidence-of-common-ancestry</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc5a0515c015fc65d.jpg</video:thumbnail_loc><video:title>Cellular evidence of common ancestry</video:title><video:description>All living organisms share a common ancestor, evidenced by cellular similarities like DNA, RNA, and glycolysis. Evolutionary trees depict these relationships, with branches representing different species. Eukaryotes, a distinct group, possess membrane-bound organelles, linear chromosomes, and introns. DNA and RNA sequencing refines our understanding of these connections, enabling more precise evolutionary tree construction.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/BwwElHbjTGo.mp4/BwwElHbjTGo.mp4</video:content_loc><video:duration>229</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/taxonomy-and-the-tree-of-life</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/351477593.jpg</video:thumbnail_loc><video:title>Taxonomy and the tree of life</video:title><video:description>Carl Linnaeus, the father of modern taxonomy, developed a system for classifying living organisms into categories like species, genus, order, class, and kingdom. This tree of life helps us understand relationships between organisms. Taxonomy is both an art and a science, with DNA analysis now playing a significant role. Humans are also classified within this system, highlighting our connections to other life forms.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/oHvLlS_Sc54.mp4/oHvLlS_Sc54.mp4</video:content_loc><video:duration>761</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/discovering-the-tree-of-life</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd6f10a27.jpg</video:thumbnail_loc><video:title>Discovering the tree of life</video:title><video:description>The study of evolutionary lineages involves analyzing biodiversity over time. Phylogenetic systematics are a method to study the tree of life. By examining unique features in organisms, scientists can trace shared evolutionary histories and relationships. Modern techniques, such as DNA analysis, enhance our understanding of these connections, allowing us to better protect Earth&apos;s threatened biodiversity.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/AjvLQJ6PIiU.mp4/AjvLQJ6PIiU.mp4</video:content_loc><video:duration>470</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/understanding-and-building-phylogenetic-trees-or-cladograms</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc14e1283.jpg</video:thumbnail_loc><video:title>Understanding and building phylogenetic trees</video:title><video:description>Constructing a phylogenetic tree involves hypothesizing evolutionary relationships among species based on observable traits and genetic evidence. By practicing parsimony, we aim for the simplest explanation. This graphical representation helps determine relatedness and common ancestors, allowing us to understand the evolutionary history of different species.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6_XMKmFQ_w8.mp4/6_XMKmFQ_w8.mp4</video:content_loc><video:duration>657</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/species</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/351477592.jpg</video:thumbnail_loc><video:title>Species</video:title><video:description>Taxonomy comes to life through the exploration of species, defined as groups of animals that can interbreed to produce fertile offspring. Examples of species include lions, tigers, and horses. Hybrids are the offspring of different species, which are usually infertile. Examples of hybrids include mules and ligers.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Tmt4zrDK3dA.mp4/Tmt4zrDK3dA.mp4</video:content_loc><video:duration>529</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/allopatric-and-sympatric-speciation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1a6232a5.jpg</video:thumbnail_loc><video:title>Speciation</video:title><video:description>Speciation occurs when populations become different enough that they no longer interbreed and produce fertile offspring. Allopatric speciation results from geographic separation, while sympatric speciation can occur without a physical barrier. Natural selection, genetic drift, behavior, and changes in chromosome number can contribute to the formation of new species.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gnku5AksWvU.mp4/gnku5AksWvU.mp4</video:content_loc><video:duration>647</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/reproductive-isolation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2c49b090.jpg</video:thumbnail_loc><video:title>Reproductive isolation</video:title><video:description>Species are groups of organisms that can reproduce together; reproductive isolation keeps species separate. Pre-zygotic isolation prevents mating or fertilization (through temporal, habitat, behavioral, or mechanical isolation), while post-zygotic isolation affects zygotes or hybrids (via zygote mortality, hybrid inviability, or hybrid sterility). Although sexually-reproducing species are easier to classify, the species problem makes classifying asexually-reproducing organisms difficult.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vmgKC2IJjOI.mp4/vmgKC2IJjOI.mp4</video:content_loc><video:duration>299</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/new-localities-lead-to-new-biodiversity</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xee15c10e.jpg</video:thumbnail_loc><video:title>New localities lead to new biodiversity</video:title><video:description>Dispersal is the process by which species move and expand their ranges. It can lead to speciation, or new species forming. Islands represent excellent case studies; organisms on islands often experience isolation and restricted gene flow, resulting in unique speciation patterns (called island biogeography). Factors like distance, time, area, habitat, location, and serendipity influence the rate of colonization and speciation on islands.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ACxH7ZVUOLk.mp4/ACxH7ZVUOLk.mp4</video:content_loc><video:duration>630</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/environmental-change-and-adaptation-in-galapagos-finches</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9dcd3b63fb2e570b.jpg</video:thumbnail_loc><video:title>Environmental change and adaptation in Galápagos finches</video:title><video:description>Adaptation by natural selection is one important process by which species change over time. After an environmental change, traits that support successful survival and reproduction in the new environment become more common; those that do not become less common. Thus, the distribution of traits in a population changes.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0G2uDKYBX-c.mp4/0G2uDKYBX-c.mp4</video:content_loc><video:duration>141</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/population-diversity-and-resilience</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xac52938959819e0e.jpg</video:thumbnail_loc><video:title>Population diversity and resilience</video:title><video:description>Biodiversity plays a critical role in the survival of populations, with genetic diversity providing resilience against environmental changes. The higher the genetic diversity in a population, the more resilient the population is to environmental change. This resilience ensures the survival and reproduction of populations, underscoring the importance of biodiversity and ecosystem conservation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3NdTUkjwehs.mp4/3NdTUkjwehs.mp4</video:content_loc><video:duration>269</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/earth-formation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179297.jpg</video:thumbnail_loc><video:title>Earth formation</video:title><video:description>Earth ​was formed approximately 4.6 billion years ago, likely as the result of a supernova (star explosion). The debris from this explosion began to collapse in on itself due to gravity, forming the sun. Gravity continued to draw the remaining particles together, clumping them into larger bodies, ultimately forming Earth and the other planets in our solar system.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/VbNXh0GaLYo.mp4/VbNXh0GaLYo.mp4</video:content_loc><video:duration>608</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/beginnings-of-life</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179298.jpg</video:thumbnail_loc><video:title>Beginnings of life</video:title><video:description>The Archean Eon marks an early chapter in Earth&apos;s history when simple prokaryotic life existed in the oceans. Early organisms were likely anaerobic, but some bacteria evolved photosynthesis and began producing oxygen. This major change gradually transformed Earth&apos;s environment, setting the stage for oxygen-breathing organisms to evolve much later.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/nYFuxTXDj90.mp4/nYFuxTXDj90.mp4</video:content_loc><video:duration>626</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/origins-of-life</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x24f81a83.jpg</video:thumbnail_loc><video:title>Origins of life</video:title><video:description>The origin of life remains an open scientific question. Evidence suggests that simple molecules on early Earth could form organic molecules such as amino acids and nucleotides without life. Hypotheses including the RNA world and metabolism first explore how increasingly complex molecules and chemical processes may have eventually developed into the earliest life forms.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/rMuj2MGeIAc.mp4/rMuj2MGeIAc.mp4</video:content_loc><video:duration>632</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/originoflife</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2d33c6b3.jpg</video:thumbnail_loc><video:title>The RNA origin of life</video:title><video:description>The RNA world hypothesis proposes that RNA may have played a key role in the origin of life. Unlike DNA or proteins alone, RNA can store genetic information and perform cellular functions. Scientists hypothesize that early self-replicating RNA molecules evolved over time, eventually contributing to the development of proteins, DNA, and more complex life.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/VYQQD0KNOis.mp4/VYQQD0KNOis.mp4</video:content_loc><video:duration>190</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/animal-communication</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6ae75632.jpg</video:thumbnail_loc><video:title>Animal communication</video:title><video:description>Animal communication encompasses a diverse range of methods, including nonverbal and visual cues, to convey information within and among species, and even with humans. Key functions of animal communication include mating rituals, territorial proclamations, food discovery, and alarm signals. It is crucial to avoid anthropomorphizing animals by attributing human emotions and thoughts to their behaviors, as their primary goal is survival and adaptation within their environment.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1kbZ1JAoi5o.mp4/1kbZ1JAoi5o.mp4</video:content_loc><video:duration>262</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/animal-behavior-foraging</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xda926539.jpg</video:thumbnail_loc><video:title>Animal behavior: Foraging</video:title><video:description>Foraging—a crucial animal behavior—involves searching for food and balancing energy costs. Two primary strategies exist: solitary foraging (where animals hunt alone) and group foraging (where animals cooperate). While genetics play a significant role, animals also learn foraging techniques by observing and mimicking others in their group.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OrCoshLAOiQ.mp4/OrCoshLAOiQ.mp4</video:content_loc><video:duration>134</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/organism-life-history-and-fecundity</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0312bee7.jpg</video:thumbnail_loc><video:title>Life history strategies and fecundity</video:title><video:description>Species exhibit diverse life histories, lifespans, and reproduction rates, as seen in elephants, rabbits, and salmon. Fecundity measures reproduction rate, while semelparity and iteroparity describe single or multiple reproductive events. Natural selection influences these traits based on factors like energy availability, predation, and disease, leading species to make trade-offs between growth, reproduction, and survival.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/mAdUjImDx58.mp4/mAdUjImDx58.mp4</video:content_loc><video:duration>707</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/k-selected-and-r-selected-population-growth-strategies</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2d6cda30fa6cbafb.jpg</video:thumbnail_loc><video:title>r-selected and K-selected population growth strategies</video:title><video:description>r and K are two extremes for a range of population growth strategies. K-selected species, like elephants, are typically larger, live longer, and produce fewer offspring. Conversely, r-selected species, such as frogs, are generally smaller, have shorter lifespans, and produce a larger number of offspring. These strategies are shaped by various factors, including environmental conditions and the level of competition for resources.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ey4FTyYjiPw.mp4/ey4FTyYjiPw.mp4</video:content_loc><video:duration>400</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/flow-of-energy-and-matter-through-ecosystems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe5f09d743abf7323.jpg</video:thumbnail_loc><video:title>Flow of energy and matter through ecosystems</video:title><video:description>Energy flows and matter recycles in ecosystems, with the Sun as the primary energy source. Plants, as primary producers, convert sunlight into energy-storing biomolecules. Consumers, like animals, obtain energy by eating plants or other animals. Decomposers break down dead organisms, recycling matter and nutrients. Energy is conserved but often released as heat, while matter constantly cycles through the ecosystem.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TitrRpMUt0I.mp4/TitrRpMUt0I.mp4</video:content_loc><video:duration>626</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/impact-of-changes-to-trophic-pyramids</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xadb4c9cef7f5b2bb.jpg</video:thumbnail_loc><video:title>Impact of changes to trophic pyramids</video:title><video:description>The trophic pyramid illustrates energy transfer within ecosystems, highlighting primary producers, consumers, and decomposers. Energy from the sun is stored as biomass, with only 10% transferred between trophic levels. Ecosystem changes, such as reduced sunlight or pesticide use, can impact the entire pyramid, emphasizing the interconnectedness of ecosystems and the importance of energy cycling.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/sV-KQ91Fnck.mp4/sV-KQ91Fnck.mp4</video:content_loc><video:duration>432</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/the-water-cycle</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x46df8fd3c0a2c721.jpg</video:thumbnail_loc><video:title>The water cycle</video:title><video:description>The water cycle—powered by the sun—involves water moving in various forms between sources and sinks. It starts with evaporation from bodies of water, condensation into clouds, and precipitation back to the earth. This cycle also includes transpiration from plants and sublimation from ice to vapor. The majority of Earth&apos;s water is saltwater, with only a small percentage being freshwater in lakes, rivers, and groundwater.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jFjI6y46QRk.mp4/jFjI6y46QRk.mp4</video:content_loc><video:duration>494</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/carbon-cycle</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x33bc098853d5090c.jpg</video:thumbnail_loc><video:title>The carbon cycle</video:title><video:description>Carbon is crucial for life, forming molecules like glucose, ATP, amino acids, and DNA. The carbon cycle involves plants taking in carbon dioxide, fixing carbon, and creating organic molecules. Animals eat plants, metabolize the molecules, and release carbon dioxide. This cycle keeps carbon circulating in the biosphere.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_dYkByQ9Kmg.mp4/_dYkByQ9Kmg.mp4</video:content_loc><video:duration>517</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/phosphorous-cycle</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc07f92006e35dfec.jpg</video:thumbnail_loc><video:title>The phosphorus cycle</video:title><video:description>The phosphorus cycle, essential for life, involves the movement of phosphorus atoms from rocks and soil into plants and animals. Unlike carbon or nitrogen, phosphorus doesn&apos;t exist in the atmosphere. It&apos;s often a limiting factor for plant growth, making it a key ingredient in fertilizers. Human activities like mining and farming can disrupt this cycle, leading to environmental consequences.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tm2LG5ScT1g.mp4/tm2LG5ScT1g.mp4</video:content_loc><video:duration>331</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/exponential-and-logistic-growth-in-populations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x32a950e6.jpg</video:thumbnail_loc><video:title>Exponential and logistic growth in populations</video:title><video:description>Rabbit populations grow exponentially when not limited by resources, space, or predators. Exponential growth has time in the exponent, causing a rapid increase in population size. In real-world situations, logistic growth is more accurate due to environmental constraints. Logistic growth models population growth with a natural carrying capacity, creating an S-shaped curve.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/KyAKEisg2PQ.mp4/KyAKEisg2PQ.mp4</video:content_loc><video:duration>452</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/population-growth-rate-based-on-birth-and-death-rates</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc6c411beaccb5407.jpg</video:thumbnail_loc><video:title>Population growth rate based on birth and death rates</video:title><video:description>Calculating population growth rate is simpler than it seems. By comparing birth and death rates, we can intuitively find the growth rate. Here, we show the formula to calculate population growth rate, using calculus notation. Although this formula may look intimidating, it represents a straightforward concept, making it easy to grasp and apply in biology.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/R2yPeLJsPOo.mp4/R2yPeLJsPOo.mp4</video:content_loc><video:duration>194</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/per-capita-population-growth-and-exponential-growth</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1bf413fba7f31c36.jpg</video:thumbnail_loc><video:title>Per capita population growth and exponential growth</video:title><video:description>Population growth rate represents the net increase in population based on birth and death rates. Per capita population growth rate measures the average growth rate per individual. Exponential growth equations describe unconstrained population growth, while environmental carrying capacity sets real-world limits.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/B_qsI4Q1nNk.mp4/B_qsI4Q1nNk.mp4</video:content_loc><video:duration>525</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/density-dependent-and-density-independent-population-regulation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x19eaca00.jpg</video:thumbnail_loc><video:title>Population regulation</video:title><video:description>There are two types of population regulation: density-dependent and density-independent. Density-dependent factors, like competition for resources, predation, disease, and waste accumulation, limit population growth based on population density. Density-independent factors, such as natural disasters, affect populations regardless of density. Understanding these factors helps us consider human population growth and potential carrying capacity.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6IS_M6CX7FE.mp4/6IS_M6CX7FE.mp4</video:content_loc><video:duration>633</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/logistic-growth-versus-exponential-growth</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xab6648aeea47abe1.jpg</video:thumbnail_loc><video:title>Logistic growth versus exponential growth</video:title><video:description>Exponential growth presumes infinite resources, resulting in unrestrained population expansion. Conversely, logistic growth considers resource limitations and a carrying capacity (K): the maximum sustainable population. The logistic growth model modifies the exponential growth equation by including a factor that decelerates population growth as it nears the carrying capacity.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jfIPQ5_71Mc.mp4/jfIPQ5_71Mc.mp4</video:content_loc><video:duration>602</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/interactions-between-populations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4b4b2de6.jpg</video:thumbnail_loc><video:title>Interactions between populations</video:title><video:description>Interspecific interactions are the relationships and interactions between different species living together in a shared habitat, such as competition, predation, and symbiosis. Competition involves species vying for resources, while predation entails one species consuming another. Symbiosis involves long-term relationships, including parasitism (one benefits, the other is harmed), mutualism (both benefit), and commensalism (one benefits, the other remains unaffected).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/q2zdiLn3gSE.mp4/q2zdiLn3gSE.mp4</video:content_loc><video:duration>492</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/predator-prey-cycle</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3d85d1d2.jpg</video:thumbnail_loc><video:title>Predator-prey cycles</video:title><video:description>The predator-prey cycle demonstrates how populations of predators and prey interact and influence each other&apos;s growth. As predator numbers increase, prey populations decline, leading to a decrease in predators. This allows prey populations to recover, restarting the cycle. The snowshoe hare and Canadian lynx exemplify this ecological relationship through observed population fluctuations over time.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/NYq2078_xqc.mp4/NYq2078_xqc.mp4</video:content_loc><video:duration>309</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/exploring-ecosystems-tropical-rainforest-diversity-california-academy-of-science</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xee183dd2.jpg</video:thumbnail_loc><video:title>Tropical rainforest diversity</video:title><video:description>Tropical rainforests are among the most diverse, energy-rich ecosystems on the planet and host a vast array of species within distinct vertical layers. Researchers study these ecosystems&apos; structure and diversity, focusing on species richness and evenness. Diverse ecological communities are more stable and resilient, helping rainforests adapt to disturbances like deforestation and climate change. Unraveling the mysteries of tropical rainforests can aid in their conservation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LHPuo0rwM1w.mp4/LHPuo0rwM1w.mp4</video:content_loc><video:duration>244</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/simpsons-index-of-diversity</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x88701f3862b56814.jpg</video:thumbnail_loc><video:title>Simpson&apos;s index of diversity</video:title><video:description>Learn how to calculate Simpson&apos;s diversity index, a valuable tool for quantifying species diversity in communities. By comparing two communities with equal populations but different species distributions, the index reveals that a more evenly distributed community exhibits higher diversity. This mathematical method offers one way to evaluate biodiversity.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/bfxhh7l-LQw.mp4/bfxhh7l-LQw.mp4</video:content_loc><video:duration>343</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/biodiversity-ecosystems-and-ecological-networks</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4baff49e.jpg</video:thumbnail_loc><video:title>Ecosystems and ecological networks</video:title><video:description>Biodiversity, specifically species richness, plays a crucial role in ecosystem stability and resilience. The emerging field of biodiversity-ecosystem function (BEF) studies these interactions. Higher biodiversity spreads interactions among more species, reducing the chance of ecological collapse. Ecosystems with more species and interactions are less likely to suffer negative impacts from disturbances, as crucial components are less likely to be removed.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-bE-Pydad7U.mp4/-bE-Pydad7U.mp4</video:content_loc><video:duration>536</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/introduced-species-and-biodiversity</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x96adeb74.jpg</video:thumbnail_loc><video:title>Introduced species and biodiversity</video:title><video:description>Introduced species, also known as exotic species, can disrupt ecosystems and harm native species. While some introduced species benefit humans and native species, invasive species outcompete natives, causing ecological damage. Invasive species often lack natural predators and can introduce diseases, parasites, and pathogens. It is important to recognize and mitigate the impact of invasive species on ecosystems to preserve biodiversity and maintain healthy ecological functions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/J-ftiWffNTc.mp4/J-ftiWffNTc.mp4</video:content_loc><video:duration>596</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/human-activities-that-threaten-biodiversity</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd1385475.jpg</video:thumbnail_loc><video:title>Human activities that threaten biodiversity</video:title><video:description>Biodiversity is threatened by human population growth and resource utilization, leading to decreased species richness. Local factors contributing to biodiversity loss include land-use changes, pollution, resource exploitation, and introduction of exotic species. Balancing human needs with ecosystem health requires doing more with less and preserving species richness for a sustainable future.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2RC3Hsk90t8.mp4/2RC3Hsk90t8.mp4</video:content_loc><video:duration>771</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/how-does-climate-change-affect-biodiversity</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3f29eda1.jpg</video:thumbnail_loc><video:title>How does climate change affect biodiversity?</video:title><video:description>Global warming, caused by increasing greenhouse gas emissions, threatens biodiversity. As temperatures rise, species struggle to adapt, leading to extinctions and ecosystem disruptions. Melting ice contributes to sea level rise, endangering low-lying habitats. Additionally, increased carbon dioxide levels affect plant growth and biodiversity, potentially exacerbating climate change through feedback loops. Urgent action is needed to address these challenges and protect our planet&apos;s diverse ecosystems.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/XFmovUAWQUQ.mp4/XFmovUAWQUQ.mp4</video:content_loc><video:duration>727</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/biodiversity-and-extinction-then-and-now</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x778c92a4.jpg</video:thumbnail_loc><video:title>Biodiversity and extinction, then and now</video:title><video:description>Extinctions may occur because of direct, natural phenomena or the inability of species to adapt quickly enough to changing environmental conditions or ecological interactions. Five major mass extinctions have happened on Earth. A sixth mass extinction is currently underway and is driven by human activity, which underscores the need to learn from the past to safeguard our future.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/v8PPsI0LqOY.mp4/v8PPsI0LqOY.mp4</video:content_loc><video:duration>742</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/how-did-dinosaurs-go-extinct</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7e9ef16a.jpg</video:thumbnail_loc><video:title>How did all dinosaurs except birds go extinct?</video:title><video:description>The non-avian dinosaur extinction, excluding birds, remains a captivating mystery for paleontologists. The leading theory suggests an asteroid impact 66 million years ago caused tsunamis, blocked sunlight, halted photosynthesis, and induced freezing temperatures, acid rain, and global warming. Concurrently, immense lava flows in southwest India may have produced similar effects. While the asteroid impact is considered the final straw, both events likely contributed to the extinction.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/mCKeogDioWE.mp4/mCKeogDioWE.mp4</video:content_loc><video:duration>115</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/dinosaur-decline</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc6e48ef4.jpg</video:thumbnail_loc><video:title>Were dinosaurs undergoing long-term decline before mass extinction?</video:title><video:description>Were dinosaurs already undergoing a long-term decline before an asteroid hit at the end of the Cretaceous about 65.5 million years ago? A study led by museum scientists gives a multifaceted answer. Results suggest that (in general) large-bodied, bulk-feeding herbivores were declining during the last 12 million years of the Cretaceous Period. However, carnivorous dinosaurs and mid-sized herbivores were not.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/cgGnvH0Ozvk.mp4/cgGnvH0Ozvk.mp4</video:content_loc><video:duration>164</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-biology/v/introduction-to-simulation-based-exercises</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa74da60b1d66487b.jpg</video:thumbnail_loc><video:title>Introduction to simulation-based exercises</video:title><video:description>Khan Academy’s simulation-based exercises let students explore real-world phenomena through interactive experiments, data analysis, and evidence-based reasoning. Aligned to the Next Generation Science Standards or AP course CEDs, these engaging tools bring key concepts to life—helping students think and investigate like professional scientists.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/JO68D_EieXA.mp4/JO68D_EieXA.mp4</video:content_loc><video:duration>148</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/mass-spectrometry</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8a15ff9cea78f965.jpg</video:thumbnail_loc><video:title>Mass spectrometry</video:title><video:description>In the analytical technique of mass spectrometry, atoms or molecules are ionized using a high-energy electron beam and then separated based on their mass-to-charge ratios (m/z). The results are presented as a mass spectrum, which shows the relative abundances of the ions on the y-axis and their m/z ratios on the x-axis. This data can be used to calculate the exact masses of the atoms or molecules in the sample.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/myolF-h1kKI.mp4/myolF-h1kKI.mp4</video:content_loc><video:duration>258</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/worked-example-identifying-element-from-mass-spectrum</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdeff1bb75f94717d.jpg</video:thumbnail_loc><video:title>Worked example: Identifying an element from its mass spectrum</video:title><video:description>Using mass spectrometry data, we can estimate an element&apos;s average atomic mass and determine its identity.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vU7MDe4ph5A.mp4/vU7MDe4ph5A.mp4</video:content_loc><video:duration>201</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/worked-example-calculating-mass-of-substance-in-mixture</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x66735a2a3d420f6d.jpg</video:thumbnail_loc><video:title>Worked example: Calculating the mass of a substance in a mixture</video:title><video:description>Elemental analysis can be used to determine the amounts of substances in a mixture. For example, if elemental analysis tells us that a potassium supplement contains 22% K by mass, and we know that the K is present as KCl, we can calculate the grams of KCl in the supplement.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Zy3Y3ZbJ2xs.mp4/Zy3Y3ZbJ2xs.mp4</video:content_loc><video:duration>321</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/worked-example-analyzing-purity-of-a-mixture</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfe065fa1d26a5da0.jpg</video:thumbnail_loc><video:title>Worked example: Analyzing the purity of a mixture</video:title><video:description>Elemental analysis can be used to analyze the purity of a sample. For example, a pure sample of NaCl should contain 61% chlorine by mass. If elemental analysis tells us that the sample actually contains 73% chlorine by mass, this suggests that our sample has been contaminated by a compound containing a higher mass percent of chlorine.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/K5HPsKdgxsI.mp4/K5HPsKdgxsI.mp4</video:content_loc><video:duration>401</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/hs-chemistry/v/orbitals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/425003.jpg</video:thumbnail_loc><video:title>Shells, subshells, and orbitals</video:title><video:description>The electrons in an atom are arranged in shells that surround the nucleus, with each successive shell being farther from the nucleus. Electron shells consist of one or more subshells, and subshells consist of one or more atomic orbitals. Electrons in the same subshell have the same energy, while electrons in different shells or subshells have different energies.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/26PF9Ctch9Y.mp4/26PF9Ctch9Y.mp4</video:content_loc><video:duration>581</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/hs-chemistry/v/introduction-to-electron-configurations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x946fe5f16f5f9997.jpg</video:thumbnail_loc><video:title>Introduction to electron configurations</video:title><video:description>Electron configurations describe where electrons are located around the nucleus of an atom. For example, the electron configuration of lithium, 1s²2s¹, tells us that lithium has two electrons in the 1s subshell and one electron in the 2s subshell.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LyFzELsUgBU.mp4/LyFzELsUgBU.mp4</video:content_loc><video:duration>308</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/hs-chemistry/v/the-aufbau-principle</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xed4472ca473f626c.jpg</video:thumbnail_loc><video:title>The Aufbau principle</video:title><video:description>The Aufbau principle states that electrons fill lower-energy atomic orbitals before filling higher-energy ones (Aufbau is German for &quot;building-up&quot;). By following this rule, we can predict the electron configurations for atoms or ions. The Aufbau principle is most useful for the first 20 elements: from Sc on, the Aufbau principle does not accurately predict the order of electron filling in atoms.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Zersl0Ji3P0.mp4/Zersl0Ji3P0.mp4</video:content_loc><video:duration>473</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/valence-electrons</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa911bccf76ea72ea.jpg</video:thumbnail_loc><video:title>Valence electrons</video:title><video:description>Valence electrons are the electrons in the outermost shell, or energy level, of an atom. For example, oxygen has six valence electrons, two in the 2s subshell and four in the 2p subshell. We can write the configuration of oxygen&apos;s valence electrons as 2s²2p⁴.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/cZTdBsAjPPk.mp4/cZTdBsAjPPk.mp4</video:content_loc><video:duration>311</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/hs-chemistry/v/electron-configurations-of-ions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfbba214cd1e413f4.jpg</video:thumbnail_loc><video:title>Electron configurations of ions</video:title><video:description>To find the electron configuration for an ion, first identify the configuration for the neutral atom. Then, add or remove electrons depending on the ion&apos;s charge. For example, to find the configuration for the lithium ion (Li⁺), start with neutral lithium (1s²2s¹). Then, since the lithium ion has one less electron, remove an electron from the 2s subshell to get 1s².</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/oCajIGPK-WM.mp4/oCajIGPK-WM.mp4</video:content_loc><video:duration>236</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/electron-configurations-in-the-3d-orbitals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4d6604e9.jpg</video:thumbnail_loc><video:title>Electron configurations of the 3d transition metals</video:title><video:description>The Aufbau principle predicts that the 4s orbital is always filled before the 3d orbitals, but this is actually not true for most elements! From Sc on, the 3d orbitals are actually lower in energy than the 4s orbital, which means that electrons enter the 3d orbitals first. In this video, we’ll discuss this in more depth and walk through all of the electron configurations for the 3d transition metals.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ddNsfv8iaps.mp4/ddNsfv8iaps.mp4</video:content_loc><video:duration>753</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/periodic-trends-and-coulombs-law</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3fd61bc1b1bf6d93.jpg</video:thumbnail_loc><video:title>Periodic trends and Coulomb&apos;s law</video:title><video:description>Periodic trends (such as electronegativity, electron affinity, atomic and ionic radii, and ionization energy) can be understood in terms of Coulomb&apos;s law, which is Fₑ = (q₁q₂)/r². For example, consider first ionization energy: Coulomb&apos;s law tells us that the greater the nuclear charge (q₁) and the shorter the distance between the nucleus and the outermost electron (r), the stronger the attraction between the nucleus and the electron. As a result, the electron will require more energy to remove.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gi2Y-kbrjCw.mp4/gi2Y-kbrjCw.mp4</video:content_loc><video:duration>643</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/group-trend-for-ionization-energy</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe2b4547d.jpg</video:thumbnail_loc><video:title>Ionization energy: group trend</video:title><video:description>An element&apos;s first ionization energy is the energy required to remove the outermost, or least bound, electron from a neutral atom of the element. On the periodic table, first ionization energy generally decreases as you move down a group. This is because the outermost electron is, on average, farther from the nucleus, meaning it is held less tightly and requires less energy to remove.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vQLcxlvK7Ik.mp4/vQLcxlvK7Ik.mp4</video:content_loc><video:duration>619</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/period-trend-for-ionization-energy</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdb3555d5.jpg</video:thumbnail_loc><video:title>Ionization energy: period trend</video:title><video:description>An element&apos;s first ionization energy is the energy required to remove the outermost, or least bound, electron from a neutral atom of the element. On the periodic table, first ionization energy generally increases as you move left to right across a period. This is due to increasing nuclear charge, which results in the outermost electron being more strongly bound to the nucleus.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/649ZlWMp0LE.mp4/649ZlWMp0LE.mp4</video:content_loc><video:duration>603</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/first-and-second-ionization-energy</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4562bba6.jpg</video:thumbnail_loc><video:title>First and second ionization energy</video:title><video:description>An element&apos;s second ionization energy is the energy required to remove the outermost, or least bound, electron from a 1+ ion of the element. Because positive charge binds electrons more strongly, the second ionization energy of an element is always higher than the first.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/uVWquWFjnCw.mp4/uVWquWFjnCw.mp4</video:content_loc><video:duration>455</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/worked-example-identifying-element-from-successive-ionization-energies</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8881d65fba31ef25.jpg</video:thumbnail_loc><video:title>Worked example: Identifying an element from successive ionization energies</video:title><video:description>When electrons are removed in succession from an element, the transition from removing valence electrons to removing core electrons results in a large jump in ionization energy. By looking for this large jump in energy, we can determine how many valence electrons an element has, which in turn can help us identify the element.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PfL-gzDdOBo.mp4/PfL-gzDdOBo.mp4</video:content_loc><video:duration>151</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/electron-affinity</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb9779c70.jpg</video:thumbnail_loc><video:title>Electron affinity: period trend</video:title><video:description>Electron affinity is the energy change that results from adding an electron to a gaseous atom. For example, when a fluorine atom in the gaseous state gains an electron to form F⁻(g), the associated energy change is -328 kJ/mol. Because this value is negative (energy is released), we say that the electron affinity of fluorine is favorable.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6WIBa32o63Q.mp4/6WIBa32o63Q.mp4</video:content_loc><video:duration>786</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/hs-chemistry/v/electronegativity-trends</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8dafd3b7.jpg</video:thumbnail_loc><video:title>Electronegativity</video:title><video:description>Electronegativity is a measure of an atom&apos;s ability to attract shared electrons to itself. On the periodic table, electronegativity generally increases as you move from left to right across a period and decreases as you move down a group. As a result, the most electronegative elements are found on the top right of the periodic table, while the least electronegative elements are found on the bottom left.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Rr7LhdSKMxY.mp4/Rr7LhdSKMxY.mp4</video:content_loc><video:duration>594</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/introduction-to-photoelectron-spectroscopy</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x56731103acf29061.jpg</video:thumbnail_loc><video:title>Introduction to photoelectron spectroscopy</video:title><video:description>In the analytical technique of photoelectron spectroscopy (PES), a sample is ionized using high-energy radiation, and the kinetic energies of the ejected electrons (called photoelectrons) are measured. From this, we can determine the binding or ionization energy of each electron in the atom or molecule. The results are presented as a PES spectrum, which shows the photoelectron count on the y-axis and binding energy on the x-axis.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/UaTWrOTh4qU.mp4/UaTWrOTh4qU.mp4</video:content_loc><video:duration>504</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/hs-chemistry/v/predicting-bond-type-electronegativity</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8e340c87a1c11fc7.jpg</video:thumbnail_loc><video:title>Predicting bond type (electronegativity)</video:title><video:description>One way to predict the type of bond that forms between two elements is to compare the electronegativities of the elements. In general, large differences in electronegativity result in ionic bonds, while smaller differences result in covalent bonds.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/AHUHpVQXRsw.mp4/AHUHpVQXRsw.mp4</video:content_loc><video:duration>283</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/bond-length-and-bond-energy</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4c2d3d6896637625.jpg</video:thumbnail_loc><video:title>Bond length and bond energy</video:title><video:description>A diatomic molecule can be represented using a potential energy curve, which graphs potential energy versus the distance between the two atoms (called the internuclear distance). From this graph, we can determine the equilibrium bond length (the internuclear distance at the potential energy minimum) and the bond energy (the energy required to separate the two atoms).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/EMCWvehKpd4.mp4/EMCWvehKpd4.mp4</video:content_loc><video:duration>402</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/worked-example-interpreting-potential-energy-curves-of-diatomic-molecules</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdf2d44737d97e6c5.jpg</video:thumbnail_loc><video:title>Worked example: Interpreting potential energy curves of diatomic molecules</video:title><video:description>The length and energy of a bond are influenced by both the bond order and the size of the atoms in the bond. In general, the higher the bond order and the smaller the atoms, the shorter and stronger the bond. As shown in this video, we can use these relationships to match diatomic molecules to their potential energy curves.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-mZAsdJnnMM.mp4/-mZAsdJnnMM.mp4</video:content_loc><video:duration>321</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/lattice-energy</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xec4d836b71d6b63a.jpg</video:thumbnail_loc><video:title>Lattice energy</video:title><video:description>The energy required to separate the ions in a crystal lattice into individual gaseous ions is known as lattice energy. Lattice energy depends on the strength of interactions between cations and anions in the lattice, which we can estimate using Coulomb&apos;s law: Fₑ = (q₁q₂)/r². According to this equation, stronger interactions occur between ions with larger charges and smaller radii.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/paXRIINiYlQ.mp4/paXRIINiYlQ.mp4</video:content_loc><video:duration>490</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/drawing-lewis-diagrams</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x91256a3f5999fc0d.jpg</video:thumbnail_loc><video:title>Drawing Lewis diagrams</video:title><video:description>A Lewis diagram shows how the valence electrons are distributed around the atoms in a molecule. Shared pairs of electrons are drawn as lines between atoms, while lone pairs of electrons are drawn as dots next to atoms. When constructing a Lewis diagram, keep in mind the octet rule, which refers to the tendency of atoms to gain, lose, or share electrons until they are surrounded by eight valence electrons (an octet).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9BZFphoY-vo.mp4/9BZFphoY-vo.mp4</video:content_loc><video:duration>428</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/worked-example-lewis-diagram-of-formaldehyde</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5b2a84d197de4686.jpg</video:thumbnail_loc><video:title>Worked example: Lewis diagram of formaldehyde (CH₂O)</video:title><video:description>The Lewis diagram of a molecule can be constructed using the following stepwise procedure: (1) Find the number of valence electrons in the molecule. (2) Draw single bonds between bonded atoms. (3) Distribute the remaining electrons throughout the molecule, keeping in mind the duet and octet rules. In this video, we&apos;ll use these steps to construct the Lewis diagram of formaldehyde (CH₂O).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/s0VM7WKnPeA.mp4/s0VM7WKnPeA.mp4</video:content_loc><video:duration>368</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/worked-example-lewis-diagram-of-cyanide-ion</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc6e8f2162d590bfc.jpg</video:thumbnail_loc><video:title>Worked example: Lewis diagram of the cyanide ion (CN⁻)</video:title><video:description>We can draw Lewis structures for polyatomic ions (ions containing multiple atoms) using the same stepwise procedure as for neutral molecules. In this video, we&apos;ll see how to construct the Lewis diagram of the cyanide ion (CN⁻).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Y8p4cthWB8I.mp4/Y8p4cthWB8I.mp4</video:content_loc><video:duration>268</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/exceptions-to-the-octet-rule</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8266112775363add.jpg</video:thumbnail_loc><video:title>Exceptions to the octet rule</video:title><video:description>While most atoms obey the duet and octet rules, there are some exceptions. For example, elements such as boron or beryllium often form compounds in which the central atom is surrounded by fewer than eight electrons (e.g., BF₃ or BeH₂). In contrast, many elements in the third-row and beyond have been observed to exceed the octet rule, forming compounds in which the central atom is surrounded by more than eight electrons (e.g. ICl₄⁻ or PF₅).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Tkb1OemB2KI.mp4/Tkb1OemB2KI.mp4</video:content_loc><video:duration>430</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/worked-example-lewis-diagram-of-xenon-difluoride</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x702bc808ee12c27c.jpg</video:thumbnail_loc><video:title>Worked example: Lewis diagram of xenon difluoride (XeF₂)</video:title><video:description>In some molecules, the central atom exceeds the octet rule (is surrounded by more than eight electrons). See an example of a molecule that violates the octet rule (XeF₂) and learn how to draw its Lewis diagram in this video.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/kfTm72uWt9o.mp4/kfTm72uWt9o.mp4</video:content_loc><video:duration>191</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/introduction-to-resonance</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf0c549357879a0f5.jpg</video:thumbnail_loc><video:title>Resonance</video:title><video:description>Resonance arises when more than one valid Lewis structure can be drawn for a molecule or ion. The overall electronic structure of the molecule or ion is given by the weighted average of these resonance structures and is referred to as the resonance hybrid.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/XRM9o1Sq5hg.mp4/XRM9o1Sq5hg.mp4</video:content_loc><video:duration>444</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/formal-charge</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6c97c569abdf4021.jpg</video:thumbnail_loc><video:title>Formal charge</video:title><video:description>The formal charge of an atom in a molecule is the charge that would reside on the atom if all of the bonding electrons were shared equally. We can calculate an atom&apos;s formal charge using the equation FC = VE - [LPE - ½(BE)], where VE = the number of valence electrons on the free atom, LPE = the number of lone pair electrons on the atom in the molecule, and BE = the number of bonding (shared) electrons around the atom in the molecule.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Kv5y3t9jsi4.mp4/Kv5y3t9jsi4.mp4</video:content_loc><video:duration>423</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/worked-example-using-formal-charges-to-evaluate-nonequivalent-resonance-structur</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb31c81c773ae3ea6.jpg</video:thumbnail_loc><video:title>Worked example: Using formal charges to evaluate nonequivalent resonance structures</video:title><video:description>When a molecule has nonequivalent resonance structures, one structure may contribute more to the resonance hybrid than another. In terms of formal charge, a structure generally contributes more when (1) the formal charges on the atoms are minimized and (2) any negative formal charges are on more electronegative atoms and any positive charges are on more electropositive atoms. In this video, we use these guidelines to evaluate the nonequivalent resonance structures of SCN⁻.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/N8qKGrChGC4.mp4/N8qKGrChGC4.mp4</video:content_loc><video:duration>482</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/vsepr-for-2-electron-clouds</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x072a19ee.jpg</video:thumbnail_loc><video:title>VSEPR for 2 electron clouds</video:title><video:description>The valence shell electron-pair repulsion (VSEPR) model is used to predict the shapes of molecules and polyatomic ions. VSEPR is based on the idea that the “groups” or “clouds” of electrons surrounding an atom will adopt an arrangement that minimizes the repulsions between them. In this video, we look at examples of molecules in which there are two groups of electrons around the central atom.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/97POZGcfoY8.mp4/97POZGcfoY8.mp4</video:content_loc><video:duration>484</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/vsepr-for-3-electron-clouds</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdf5e267d.jpg</video:thumbnail_loc><video:title>VSEPR for 3 electron clouds</video:title><video:description>In this video, we apply VSEPR theory to molecules and ions with three groups or “clouds” of electrons around the central atom. To minimize repulsions, three electron clouds will always adopt a trigonal planar electron geometry. If none of the clouds is a lone pair, the molecular geometry will also be trigonal planar. If one of the clouds is a lone pair, the molecular geometry will be bent.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3RDytvJYehY.mp4/3RDytvJYehY.mp4</video:content_loc><video:duration>753</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/vsepr-for-4-electron-clouds</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x13e2fe6f.jpg</video:thumbnail_loc><video:title>VSEPR for 4 electron clouds</video:title><video:description>In this video, we apply VSEPR theory to molecules and ions with four groups or “clouds” of electrons around the central atom. To minimize repulsions, four electron clouds will always adopt a tetrahedral electron geometry. Depending on how many of the clouds are lone pairs, the molecular geometry will be tetrahedral (no lone pairs), trigonal pyramidal (one lone pair), or bent (two lone pairs).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ka8Yt4bTODs.mp4/ka8Yt4bTODs.mp4</video:content_loc><video:duration>605</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/vsepr-for-5-electron-clouds</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6968389f.jpg</video:thumbnail_loc><video:title>VSEPR for 5 electron clouds (part 1)</video:title><video:description>In this video, we apply VSEPR theory to molecules and ions with five groups or “clouds” of electrons around the central atom. To minimize repulsions, five electron clouds will always adopt a trigonal bipyramidal electron geometry. Depending on how many of the clouds are lone pairs, the molecular geometry will be trigonal bipyramidal (no lone pairs), seesaw (one lone pair), T-shaped (two lone pairs), or linear (three lone pairs). This video focuses on the first two molecular geometries, trigonal bipyramidal and seesaw.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0na0xtIHkXA.mp4/0na0xtIHkXA.mp4</video:content_loc><video:duration>898</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/vsepr-for-5-electron-clouds-continued</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x14b19da7.jpg</video:thumbnail_loc><video:title>VSEPR for 5 electron clouds (part 2)</video:title><video:description>In this video, we continue exploring VSEPR theory for molecules and ions with five regions or “clouds” of electrons around the central atom, focusing on examples where the molecular geometry is T-shaped (two of the clouds are lone pairs) or linear (three of the clouds are lone pairs).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ufzlgOyWBHE.mp4/ufzlgOyWBHE.mp4</video:content_loc><video:duration>648</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/vsepr-for-6-electron-clouds</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0795dd14.jpg</video:thumbnail_loc><video:title>VSEPR for 6 electron clouds</video:title><video:description>In this video, we apply VSEPR theory to molecules and ions with six groups or “clouds” of electrons around the central atom. To minimize repulsions, six electron clouds will always adopt a octahedral electron geometry. Depending on how many of the clouds are lone pairs, the molecular geometry will be octahedral (no lone pairs), square pyramidal (one lone pair), or square planer (two lone pairs).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/WEoml1Fs26I.mp4/WEoml1Fs26I.mp4</video:content_loc><video:duration>749</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/dipole-moment</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x03aa879e.jpg</video:thumbnail_loc><video:title>Molecular polarity</video:title><video:description>Like bonds, molecules can also be polar. In a polar molecule, electron density is unevenly distributed throughout the molecule, resulting in regions of partial negative charge and regions of partial positive charge. Molecular polarity depends on both individual bond polarities and molecular geometry, the latter of which we can predict using VSEPR theory.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/q3g3jsmCOEQ.mp4/q3g3jsmCOEQ.mp4</video:content_loc><video:duration>562</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/sp3-hybrid-orbital-jay-final</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x67a13ebc.jpg</video:thumbnail_loc><video:title>sp³ hybridization</video:title><video:description>In sp³ hybridization, one s orbital and three p orbitals hybridize to form four sp³ orbitals, each consisting of 25% s character and 75% p character. This type of hybridization is required whenever an atom is surrounded by four groups of electrons.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/JHgTNNX01r4.mp4/JHgTNNX01r4.mp4</video:content_loc><video:duration>643</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/steric-number-sp3-hybridization</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0213e20b.jpg</video:thumbnail_loc><video:title>Steric number</video:title><video:description>One way to determine the hybridization of an atom is to calculate its steric number, which is equal to the number of sigma bonds surrounding the atom plus the number of lone pairs on the atoms. In this video, we focus on atoms with a steric number of 4, which corresponds to sp³ hybridization.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/BM-My1AheLw.mp4/BM-My1AheLw.mp4</video:content_loc><video:duration>587</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/sp2-hybridization-jay-final</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3f29bc33.jpg</video:thumbnail_loc><video:title>sp² hybridization</video:title><video:description>In sp² hybridization, one s orbital and two p orbitals hybridize to form three sp² orbitals, each consisting of 33% s character and 67% p character. This type of hybridization is required whenever an atom is surrounded by three groups of electrons.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ROzkyTgscGg.mp4/ROzkyTgscGg.mp4</video:content_loc><video:duration>762</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/sp-hybridization-jay-final</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3fb4948a.jpg</video:thumbnail_loc><video:title>sp hybridization</video:title><video:description>In sp hybridization, one s orbital and one p orbital hybridize to form two sp orbitals, each consisting of 50% s character and 50% p character. This type of hybridization is required whenever an atom is surrounded by two groups of electrons.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/BRHfy7envyQ.mp4/BRHfy7envyQ.mp4</video:content_loc><video:duration>660</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/organic-hybridization-practice</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xafb6fb15.jpg</video:thumbnail_loc><video:title>Worked examples: Finding the hybridization of atoms in organic molecules</video:title><video:description>We can find the hybridization of an atom in a molecule by either looking at the types of bonds surrounding the atom or by calculating its steric number. In this video, we use both of these methods to determine the hybridizations of atoms in various organic molecules.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/GuaozMpFS3w.mp4/GuaozMpFS3w.mp4</video:content_loc><video:duration>621</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/london-dispersion-forces</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5c6a3803891c1d03.jpg</video:thumbnail_loc><video:title>London dispersion forces</video:title><video:description>London dispersion forces result from the coulombic interactions between instantaneous dipoles. Dispersion forces are present between all molecules (and atoms) and are typically greater for heavier, more polarizable molecules and molecules with larger surface areas.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5OT5l-NZS24.mp4/5OT5l-NZS24.mp4</video:content_loc><video:duration>578</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/hs-chemistry/v/dipole-dipole-forces</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x68bf4a5bf43a24d0.jpg</video:thumbnail_loc><video:title>Dipole–dipole forces</video:title><video:description>Dipole-dipole forces occur between molecules with permanent dipoles (i.e., polar molecules). For molecules of similar size and mass, the strength of these forces increases with increasing polarity. Polar molecules can also induce dipoles in nonpolar molecules, resulting in dipole–induced dipole forces.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hg7jN32q9A0.mp4/hg7jN32q9A0.mp4</video:content_loc><video:duration>406</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/hs-chemistry/v/hydrogen-bonding</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2e43aa15619f9940.jpg</video:thumbnail_loc><video:title>Hydrogen bonding</video:title><video:description>Hydrogen bonding is a special type of dipole-dipole interaction that occurs between the lone pair of a highly electronegative atom (typically N, O, or F) and the hydrogen atom in a N–H, O–H, or F–H bond. Hydrogen bonds can form between different molecules (intermolecular hydrogen bonding) or between different parts of the same molecule (intramolecular hydrogen bonding).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ltxqQbiI6-o.mp4/ltxqQbiI6-o.mp4</video:content_loc><video:duration>399</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/ion-dipole-forces</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x69b4fbdc3ec5950c.jpg</video:thumbnail_loc><video:title>Ion–dipole forces</video:title><video:description>Ion–dipole forces occur between ions and polar molecules. The relative strength of these forces can be understood in terms of Coulomb&apos;s law, which tells us that the electrostatic attraction between ion and dipole is directly related to the magnitudes of the ion charge and the dipole and inversely related to the distance between them.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7HCAGSkK1Do.mp4/7HCAGSkK1Do.mp4</video:content_loc><video:duration>280</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/hs-chemistry/v/intermolecular-forces-and-vapor-pressure</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x400a8568b0d2774a.jpg</video:thumbnail_loc><video:title>Intermolecular forces and vapor pressure</video:title><video:description>A liquid’s vapor pressure is directly related to the intermolecular forces present between its molecules. The stronger these forces, the lower the rate of evaporation and the lower the vapor pressure.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/eubN8DwUh48.mp4/eubN8DwUh48.mp4</video:content_loc><video:duration>364</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/ideal-gas-equation-pv-nrt</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/408019.jpg</video:thumbnail_loc><video:title>The ideal gas law (PV = nRT)</video:title><video:description>The ideal gas law (PV = nRT) relates the macroscopic properties of ideal gases. An ideal gas is a gas in which the particles (a) do not attract or repel one another and (b) take up no space (have no volume). No gas is truly ideal, but the ideal gas law does provide a good approximation of real gas behavior under many conditions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qObcdZj8YTM.mp4/qObcdZj8YTM.mp4</video:content_loc><video:duration>379</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/worked-example-using-the-ideal-gas-law-to-calculate-number-of-moles</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2db232c8e659bd0c.jpg</video:thumbnail_loc><video:title>Worked example: Using the ideal gas law to calculate number of moles</video:title><video:description>The ideal gas law relates four macroscopic properties of ideal gases (pressure, volume, number of moles, and temperature). If we know the values of three of these properties, we can use the ideal gas law to solve for the fourth. In this video, we&apos;ll use the ideal gas law to solve for the number of moles (and ultimately molecules) in a sample of gas.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/KnWEhXmJwdU.mp4/KnWEhXmJwdU.mp4</video:content_loc><video:duration>437</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/hs-chemistry/v/worked-example-using-the-ideal-gas-law-to-calculate-a-change-in-volume</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4b331a3152ed2cc0.jpg</video:thumbnail_loc><video:title>Worked example: Using the ideal gas law to calculate a change in volume</video:title><video:description>The ideal gas law can be used to describe a change in state for an ideal gas. In this video, we&apos;ll apply the ideal gas law to the initial and final states of a gas to see how changes in temperature and pressure affect the volume of the gas.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/bQ5vHcFlT78.mp4/bQ5vHcFlT78.mp4</video:content_loc><video:duration>392</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/hs-chemistry/v/introduction-to-partial-pressure</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xed32e0e7.jpg</video:thumbnail_loc><video:title>Gas mixtures and partial pressures</video:title><video:description>For a mixture of ideal gases, the total pressure exerted by the mixture equals the sum of the pressures that each gas would exert on its own. This observation, known as Dalton&apos;s law of partial pressures, can be written as follows: P (total) = P ₁ + P ₂ + P ₃ + ... where P ₁, P ₂, and P ₃ are the partial pressures of the different gases in the mixture, and P (total) is the total pressure of the mixture.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/A2xi-jEqpmg.mp4/A2xi-jEqpmg.mp4</video:content_loc><video:duration>383</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/partial-pressure</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/428007.jpg</video:thumbnail_loc><video:title>Worked example: Calculating partial pressures</video:title><video:description>In a mixture of ideal gases, each gas behaves independently of the other gases. As a result, we can use the ideal gas law to calculate the partial pressure of each gas in the mixture. Once we know the partial pressures of all of the gases, we can sum them using Dalton&apos;s law to find the total pressure of the mixture.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6jaMJHiza4s.mp4/6jaMJHiza4s.mp4</video:content_loc><video:duration>483</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/hs-chemistry/v/the-kinetic-molecular-theory-of-gases</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe5baf4192ba83421.jpg</video:thumbnail_loc><video:title>The kinetic molecular theory of gases</video:title><video:description>The kinetic molecular theory (KMT) describes the behavior of ideal gases at the particle level. The five main postulates of the KMT are as follows: (1) the particles in a gas are in constant, random motion, (2) the combined volume of the particles is negligible, (3) the particles exert no forces on one another, (4) any collisions between the particles are completely elastic, and (5) the average kinetic energy of the particles is proportional to the temperature in kelvins.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/HkSXiHz9vUc.mp4/HkSXiHz9vUc.mp4</video:content_loc><video:duration>384</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/hs-chemistry/v/kinetic-molecular-theory-and-the-gas-laws</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf8c4d2a22bf83fdd.jpg</video:thumbnail_loc><video:title>Kinetic molecular theory and the gas laws</video:title><video:description>The kinetic molecular theory (KMT) can be used to explain the macroscopic behavior of ideal gases. In this video, we&apos;ll see how the KMT accounts for the properties of gases as described by the various gas laws (Boyle&apos;s law, Gay-Lussac&apos;s law, Charles&apos;s law, Avogadro&apos;s law, and Dalton&apos;s law of partial pressures).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/F6lhYxV6gEY.mp4/F6lhYxV6gEY.mp4</video:content_loc><video:duration>491</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/real-gas-vs-ideal-gas</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbd1a207f43dbb8bf.jpg</video:thumbnail_loc><video:title>Introduction to real gases</video:title><video:description>Real gases do not always follow the assumptions of the kinetic molecular theory. While the particles of an ideal gas are assumed to occupy no volume and experience no interparticle attractions, the particles of a real gas do have finite volumes and do attract one another. As a result, real gases are often observed to deviate from ideal behavior.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/yDZcVKy52LM.mp4/yDZcVKy52LM.mp4</video:content_loc><video:duration>201</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/real-gases-deviations-from-ideal-behavior</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5bc9e8e5be862592.jpg</video:thumbnail_loc><video:title>Real gases: Deviations from ideal behavior</video:title><video:description>In this video, we examine the conditions under which real gases are most likely to deviate from ideal behavior: low temperatures and high pressures (small volumes). At low temperatures, attractions between gas particles cause the particles to collide less often with the container walls, resulting in a pressure lower than the ideal gas value. At high pressures (small volumes), finite particle volumes lower the actual volume available to the gas particles, resulting in a pressure higher than the ideal gas value.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/UABFOI1sb7A.mp4/UABFOI1sb7A.mp4</video:content_loc><video:duration>258</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/types-of-mixtures</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x98e653184f76d83b.jpg</video:thumbnail_loc><video:title>Types of mixtures</video:title><video:description>A mixture is composed of one or more pure substances in varying composition. There are two types of mixtures: heterogeneous and homogeneous. Heterogeneous mixtures have visually distinguishable components, while homogeneous mixtures appear uniform throughout. The most common type of homogenous mixture is a solution, which can be a solid, liquid, or gas.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/HgD6a4TVxLY.mp4/HgD6a4TVxLY.mp4</video:content_loc><video:duration>375</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/dilution</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x47c67af7b90ba658.jpg</video:thumbnail_loc><video:title>Dilution</video:title><video:description>A common method of making a solution of a given concentration involves taking a more concentration solution and adding water until the desired concentration is reached. This process is known as dilution. We can relate the concentrations and volumes before and after a dilution using the following equation: M₁V₁ = M₂V₂ where M₁ and V₁ represent the molarity and volume of the initial concentrated solution and M₂ and V₂ represent the molarity and volume of the final diluted solution.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/T3H7YZ6-fto.mp4/T3H7YZ6-fto.mp4</video:content_loc><video:duration>353</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/representing-solutions-using-particulate-models</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x056db2fcf75670c9.jpg</video:thumbnail_loc><video:title>Representing solutions using particulate models</video:title><video:description>A solution is a homogeneous mixture composed of two or more pure substances. In this video, we&apos;ll learn how to represent the relative concentrations of the substances in a solution as well as the interactions between the substances using a particulate model.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/NFcSRjLgDTk.mp4/NFcSRjLgDTk.mp4</video:content_loc><video:duration>466</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/distillation-curves</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd66334de72193c5e.jpg</video:thumbnail_loc><video:title>Distillation curves</video:title><video:description>The progress of a distillation can be represented using a distillation curve, which plots temperature versus volume of distillate collected. In this video, we&apos;ll learn how to interpret the various regions of a distillation curve for the fractional distillation of a 1:1 mixture of methyl and propyl acetate.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Aaz99lyLBf8.mp4/Aaz99lyLBf8.mp4</video:content_loc><video:duration>384</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/thin-layer-chromatography-tlc</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xaf737a53fee16ba5.jpg</video:thumbnail_loc><video:title>Thin-layer chromatography (TLC)</video:title><video:description>Thin-layer chromatography (TLC) is a technique used to separate mixtures of compounds based on differences in polarity. In TLC, a glass plate coated with a stationary phase (typically silica gel) is spotted with the mixture to be separated. The plate is then placed in a mobile phase (solvent), which travels up the plate by capillary action. The rate at which each compound in the mixture moves up the plate depends on its relative attractions to the stationary and mobile phases.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/GOWUw0-SEDE.mp4/GOWUw0-SEDE.mp4</video:content_loc><video:duration>368</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/column-chromatography-intro</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2bfff36aef54f50e.jpg</video:thumbnail_loc><video:title>Column chromatography</video:title><video:description>Column chromatography applies the same principles as TLC on a larger scale. In column chromatography, a glass column is filled with a stationary phase (typically silica gel), and the mixture of compounds to be separated is placed on top. Then, a mobile phase (solvent) is passed through the column from top to bottom. As with TLC, the rate at which each compound in the mixture moves down the column depends on its relative attractions to the stationary and mobile phases.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/UHF1HXdkrZQ.mp4/UHF1HXdkrZQ.mp4</video:content_loc><video:duration>240</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/hs-chemistry/v/solubility-and-intermolecular-forces</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/410034.jpg</video:thumbnail_loc><video:title>Solubility and intermolecular forces</video:title><video:description>Substances with similar polarities tend to be soluble in one another (&quot;like dissolves like&quot;). Nonpolar substances are generally more soluble in nonpolar solvents, while polar and ionic substances are generally more soluble in polar solvents.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ccDKr4TIWfk.mp4/ccDKr4TIWfk.mp4</video:content_loc><video:duration>263</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/introduction-to-spectroscopy</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x911639f72a122a76.jpg</video:thumbnail_loc><video:title>Introduction to spectroscopy</video:title><video:description>Spectroscopy is the study of the interaction of light and matter. Many types of spectroscopy rely on the ability of atoms and molecules to absorb or emit electromagnetic (EM) radiation. The absorption or emission of different forms of EM radiation is related to different types of transitions. Microwave radiation is associated with molecular rotational transitions, infrared radiation is associated with molecular vibrational transitions, and UV/visible radiation is associated with electronic transitions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LYseY0y2tgg.mp4/LYseY0y2tgg.mp4</video:content_loc><video:duration>294</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/electronic-transitions-and-energy</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x69960b6824c7681d.jpg</video:thumbnail_loc><video:title>Electronic transitions and energy</video:title><video:description>Electronic transitions occur in atoms and molecules due to the absorption or emission of electromagnetic radiation (typically UV or visible). The energy change associated with a transition is related to the frequency of the electromagnetic wave by Planck&apos;s equation, E = h𝜈. In turn, the frequency of the wave is related to its wavelength and the speed of light by the equation c = 𝜆𝜈.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ukYSvaRyE3c.mp4/ukYSvaRyE3c.mp4</video:content_loc><video:duration>472</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/worked-example-calculating-the-maximum-wavelength-capable-of-ionization</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x774545dc9cee7a62.jpg</video:thumbnail_loc><video:title>Worked example: Calculating the maximum wavelength capable of ionization</video:title><video:description>If a photon has enough energy, it can completely remove an electron from an atom or molecule. In this video, we&apos;ll use the light equations (E = h𝜈 and c = 𝜆𝜈) to calculate the longest photon wavelength capable of removing an electron from a single atom of silver.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/BR7Svm1s8fs.mp4/BR7Svm1s8fs.mp4</video:content_loc><video:duration>380</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/spectrophotometry-introduction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/6022723.jpg</video:thumbnail_loc><video:title>Spectrophotometry and the Beer–Lambert Law</video:title><video:description>Spectrophotometry is a technique that uses light absorption to measure the concentration of an analyte in solution. The amount of light absorbed by a solution is related to the analyte concentration by the Beer–Lambert law, which is expressed as follows: A = εbc, where ε is the molar absorptivity of the analyte, b is the path length (the distance the light travels through the solution), and c is the concentration of the analyte.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/fJRJLUYZe9c.mp4/fJRJLUYZe9c.mp4</video:content_loc><video:duration>623</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/spectrophotometry-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/6022724.jpg</video:thumbnail_loc><video:title>Worked example: Calculating concentration using the Beer–Lambert law</video:title><video:description>The Beer–Lambert law relates the absorption of light by a solution to the properties of the solution according to the following equation: A = εbc, where ε is the molar absorptivity of the absorbing species, b is the path length, and c is the concentration of the absorbing species. In this video, we&apos;ll use the Beer–Lambert law to calculate the concentration of KMnO₄ in an unknown solution.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pbbHg_9zFbI.mp4/pbbHg_9zFbI.mp4</video:content_loc><video:duration>228</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/visualizing-chemical-equations-using-particulate-models</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfcbe0400bafdb1b1.jpg</video:thumbnail_loc><video:title>Visualizing chemical equations using particulate models</video:title><video:description>A balanced chemical equation can be visualized using a particulate diagram, in which each of the atoms involved in the reaction is represented using a circle or a sphere. To be consistent with the law of conservation of mass, the diagram should depict the same numbers and types of atoms on each side of the reaction arrow.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3UoxWEZuwp8.mp4/3UoxWEZuwp8.mp4</video:content_loc><video:duration>242</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/drawing-particulate-models-of-reaction-mixtures</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3a91038e40cef60e.jpg</video:thumbnail_loc><video:title>Drawing particulate models of reaction mixtures</video:title><video:description>A given chemical reaction can be represented using a particulate diagram, in which the reaction mixture is depicted both before the reaction occurs and after the reaction has proceeded completely as possible. To be consistent with the law of conservation of mass, the &quot;before reaction&quot; and &quot;after reaction&quot; visualizations should each contain the same numbers and types of atoms.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/kCkyk4YNUyY.mp4/kCkyk4YNUyY.mp4</video:content_loc><video:duration>189</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/worked-example-calculating-the-amount-of-product-formed-from-a-limiting-reactant</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9e62d02e4448deea.jpg</video:thumbnail_loc><video:title>Worked example: Calculating the amount of product formed from a limiting reactant</video:title><video:description>In a chemical reaction, the reactant that is consumed first and limits how much product can be formed is called the limiting reactant (or limiting reagent). In this video, we&apos;ll determine the limiting reactant for a given reaction and use this information to calculate the theoretical yield of product.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/cVqEfuJBVd8.mp4/cVqEfuJBVd8.mp4</video:content_loc><video:duration>382</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/worked-example-relating-reaction-stoichiometry-and-the-ideal-gas-law</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1ef7e362142729c4.jpg</video:thumbnail_loc><video:title>Worked example: Relating reaction stoichiometry and the ideal gas law</video:title><video:description>By combining stoichiometric calculations with the ideal gas law, we can calculate amounts of reactants and products for chemical reactions involving gases.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/FRNTJmqMko8.mp4/FRNTJmqMko8.mp4</video:content_loc><video:duration>378</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/balance-and-redox-reactions1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7e2a500f.jpg</video:thumbnail_loc><video:title>Worked example: Balancing a redox equation in acidic solution</video:title><video:description>When balancing equations for redox reactions occurring in acidic solution, it is often necessary to add H⁺ ions or the H⁺/H₂O pair to fully balance the equation. In this video, we&apos;ll walk through this process for the reaction between dichromate (Cr₂O₇²⁻) and chloride (Cl⁻) ions in acidic solution.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4tLrbMstfm8.mp4/4tLrbMstfm8.mp4</video:content_loc><video:duration>724</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/balancing-redox-reactions1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1cd3b06b.jpg</video:thumbnail_loc><video:title>Worked example: Balancing a redox equation in basic solution</video:title><video:description>When balancing equations for redox reactions occurring in basic solution, it is often necessary to add OH⁻ ions or the OH⁻/H₂O pair to fully balance the equation. In this video, we&apos;ll walk through this process for the reaction between ClO⁻ and Cr(OH)₄⁻ in basic solution.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Vjs8uK2ovQE.mp4/Vjs8uK2ovQE.mp4</video:content_loc><video:duration>842</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/conjugate-acid-base-pairs-acids-and-bases-chemistry-khan-academy</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6dc05b65.jpg</video:thumbnail_loc><video:title>Conjugate acid–base pairs</video:title><video:description>In the Brønsted–Lowry definition of acids and bases, a conjugate acid–base pair consists of two substances that differ only by the presence of a proton (H⁺). A conjugate acid is formed when a proton is added to a base, and a conjugate base is formed when a proton is removed from an acid.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4441EyWBPt8.mp4/4441EyWBPt8.mp4</video:content_loc><video:duration>506</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/rate-law-and-reaction-order</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xba36c390.jpg</video:thumbnail_loc><video:title>Rate law and reaction order</video:title><video:description>A rate law shows how the rate of a chemical reaction depends on reactant concentration. For a reaction such as aA → products, the rate law generally has the form rate = k[A]ⁿ, where k is a proportionality constant called the rate constant and n is the order of the reaction with respect to A. The value of n is not related to the reaction stoichiometry and must be determined by experiment.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6Ng8ayarWHw.mp4/6Ng8ayarWHw.mp4</video:content_loc><video:duration>639</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/experimental-determination-of-rate-laws</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa3c0f3cf.jpg</video:thumbnail_loc><video:title>Worked example: Determining a rate law using initial rates data</video:title><video:description>The rate law for a chemical reaction can be determined using the method of initial rates, which involves measuring the initial reaction rate at several different initial reactant concentrations. In this video, we&apos;ll use initial rates data to determine the rate law, overall order, and rate constant for the reaction between nitrogen dioxide and hydrogen gas.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Ad0aaYixFJg.mp4/Ad0aaYixFJg.mp4</video:content_loc><video:duration>748</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/finding-units-of-rate-constant-k</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6edd0754.jpg</video:thumbnail_loc><video:title>Units of the rate constant</video:title><video:description>The units of the rate constant, k, depend on the overall reaction order. The units of k for a zero-order reaction are M/s, the units of k for a first-order reaction are 1/s, and the units of k for a second-order reaction are 1/(M·s).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/fLL8xxjhDPI.mp4/fLL8xxjhDPI.mp4</video:content_loc><video:duration>309</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/first-order-reactions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe9b629531cb38ffa.jpg</video:thumbnail_loc><video:title>First-order reactions</video:title><video:description>The integrated rate law for the first-order reaction A → products is ln[A]_t = -kt + ln[A]_0. Because this equation has the form y = mx + b, a plot of the natural log of [A] as a function of time yields a straight line. The rate constant for the reaction can be determined from the slope of the line, which is equal to -k.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PVqWOehVTOg.mp4/PVqWOehVTOg.mp4</video:content_loc><video:duration>464</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/half-life-of-a-first-order-reaction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfce7e24d.jpg</video:thumbnail_loc><video:title>Half-life of a first-order reaction</video:title><video:description>The half-life of a reaction is the time required for a reactant to reach one-half its initial concentration or pressure. For a first-order reaction, the half-life is independent of concentration and constant over time.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/e4qci9b2d3U.mp4/e4qci9b2d3U.mp4</video:content_loc><video:duration>496</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/first-order-reaction-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf66a9476.jpg</video:thumbnail_loc><video:title>Worked example: Using the first-order integrated rate law and half-life equations</video:title><video:description>In this video, we&apos;ll use the first-order integrated rate law to calculate the concentration of a reactant after a given amount of time. We&apos;ll also calculate the amount of time it takes for the concentration to decrease to a certain value. Finally, we&apos;ll use the first-order half-life equation to calculate the half-life of the reaction.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/fCdT2z0JcU8.mp4/fCdT2z0JcU8.mp4</video:content_loc><video:duration>620</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/second-order-reactions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x43cc063e2c16cee8.jpg</video:thumbnail_loc><video:title>Second-order reactions</video:title><video:description>The integrated rate law for the second-order reaction A → products is 1/[A]_t = kt + 1/[A]_0. Because this equation has the form y = mx + b, a plot of the inverse of [A] as a function of time yields a straight line. The rate constant for the reaction can be determined from the slope of the line, which is equal to k.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/YgWmHssKVvQ.mp4/YgWmHssKVvQ.mp4</video:content_loc><video:duration>463</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/zero-order-reactions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8426e58b1baf8027.jpg</video:thumbnail_loc><video:title>Zero-order reactions</video:title><video:description>The integrated rate law for the zero-order reaction A → products is [A]_t = -kt + [A]_0. Because this equation has the form y = mx + b, a plot of the concentration of A as a function of time yields a straight line. The rate constant for the reaction can be determined from the slope of the line, which is equal to -k.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/aXf3e8a1teo.mp4/aXf3e8a1teo.mp4</video:content_loc><video:duration>282</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/kinetics-of-radioactive-decay</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x221fa86002de41cb.jpg</video:thumbnail_loc><video:title>Kinetics of radioactive decay</video:title><video:description>The nuclei of radioactive elements decay according to first-order kinetics. As a result, the half-life equation and integrated rate law for radioactive decay processes can be derived from the rate laws for first-order reactions. The resulting equations can be used to find the rate constant k for a decay process and determine the amount of radioactive isotope remaining after a certain time period.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Xnu--929bo4.mp4/Xnu--929bo4.mp4</video:content_loc><video:duration>473</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/elementary-rate-laws</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xde3ff69d.jpg</video:thumbnail_loc><video:title>Elementary reactions</video:title><video:description>An elementary reaction is a reaction that occurs in a single step. The rate law for an elementary reaction can be derived from the coefficients of the reactants in the balanced equation. For example, the rate law for the elementary reaction 2A + B → products is rate = k[A]²[B].</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vIZ0LnLo3jE.mp4/vIZ0LnLo3jE.mp4</video:content_loc><video:duration>335</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/mechanisms-and-the-rate-determining-step</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3f370583.jpg</video:thumbnail_loc><video:title>Reaction mechanism and rate law</video:title><video:description>A reaction mechanism is the sequence of elementary steps by which a chemical reaction occurs. Many reaction mechanisms contain one step that is much slower than the others; this step is known as the rate-determining step. If the rate-determining step is the first step in a mechanism, the rate law for the overall reaction can be derived directly from the stoichiometry of the step&apos;s balanced equation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ShzW1LoQgoc.mp4/ShzW1LoQgoc.mp4</video:content_loc><video:duration>522</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/the-pre-equilibrium-approximation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5ce9cf605ad7a313.jpg</video:thumbnail_loc><video:title>The pre-equilibrium approximation</video:title><video:description>The pre-equilibrium approximation is used to find the rate law for a reaction with a fast and reversible initial step. In this method, we first write the rate law based on the slow (rate-determining) step. Then, to eliminate any intermediates from the rate law, we use the fast initial step to solve for the intermediate concentration(s) in terms of reactant and/or product concentrations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4czm7qIbUjA.mp4/4czm7qIbUjA.mp4</video:content_loc><video:duration>443</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/arrhenius-equation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x81933fd6.jpg</video:thumbnail_loc><video:title>The Arrhenius equation</video:title><video:description>The Arrhenius equation is k = Ae^(-Ea/RT), where A is the frequency or pre-exponential factor and e^(-Ea/RT) represents the fraction of collisions that have enough energy to overcome the activation barrier (i.e., have energy greater than or equal to the activation energy Ea) at temperature T. This equation can be used to understand how the rate of a chemical reaction depends on temperature.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/zjhepBLtqug.mp4/zjhepBLtqug.mp4</video:content_loc><video:duration>564</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/multistep-reaction-energy-profiles</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9a07606446767ae4.jpg</video:thumbnail_loc><video:title>Multistep reaction energy profiles</video:title><video:description>Many chemical reactions have mechanisms that consist of multiple elementary steps. The energy profile for a multistep reaction can be used to compare the activation energies of the different steps and identify the rate-determining step. The energy profile can also be used to determine the overall change in energy for the reaction.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/l4VCiJulLKw.mp4/l4VCiJulLKw.mp4</video:content_loc><video:duration>467</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/types-of-catalysts</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa5de288495055b1e.jpg</video:thumbnail_loc><video:title>Types of catalysts</video:title><video:description>Catalysts can be categorized as homogeneous, heterogeneous, or enzymatic. Homogeneous catalysts exist in the same phase as the reactants, whereas heterogeneous catalysts exist in a different phase than the reactants. Enzymes are biological catalysts that speed up biochemical reactions in living organisms, often by many orders of magnitude.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5Tw9Yp-YuVU.mp4/5Tw9Yp-YuVU.mp4</video:content_loc><video:duration>299</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/heat-transfer-and-thermal-equilibrium</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x402b475eea799166.jpg</video:thumbnail_loc><video:title>Heat transfer and thermal equilibrium</video:title><video:description>The particles in a warmer object have a greater average kinetic energy than the particles in a cooler object. When two objects of different temperatures come into contact with one another, the particles at the surface of each object collide, resulting in the transfer of energy as heat. This process continues until thermal equilibrium is reached, at which point the average kinetic energies of the particles—and therefore the temperatures of the objects—is the same.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7jAPitc0bkY.mp4/7jAPitc0bkY.mp4</video:content_loc><video:duration>189</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/heat-capacity</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1216e754323fa94e.jpg</video:thumbnail_loc><video:title>Heat capacity</video:title><video:description>Heat capacity is the amount of heat required to change the temperature of a given amount of matter by 1°C. The heat capacity of 1 gram of a substance is called its specific heat capacity (or specific heat), while the heat capacity of 1 mole of a substance is called its molar heat capacity. The amount of heat gained or lost by a sample (q) can be calculated using the equation q = mcΔT, where m is the mass of the sample, c is the specific heat, and ΔT is the temperature change.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/QlusUNM1ehA.mp4/QlusUNM1ehA.mp4</video:content_loc><video:duration>521</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/hs-chemistry/v/constant-pressure-calorimetry</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbce4b4dee42adb49.jpg</video:thumbnail_loc><video:title>Constant-pressure calorimetry</video:title><video:description>Constant-pressure calorimetry is used to measure the change in enthalpy, ΔH, for a physical or chemical process. In this technique, a process is carried out in solution in a coffee cup calorimeter, an inexpensive device composed of two Styrofoam cups. The amount of heat transferred in the process (q) can be calculated from the mass, specific heat, and temperature change of the solution. Because the calorimeter is at constant (atmospheric) pressure, q is equal to ΔH for the process.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/SkMeY6RBJZY.mp4/SkMeY6RBJZY.mp4</video:content_loc><video:duration>560</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/worked-example-measuring-the-energy-content-of-foods-using-soda-can-calorimetry</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6ae8224cece922c3.jpg</video:thumbnail_loc><video:title>Worked example: Measuring the energy content of foods using soda-can calorimetry</video:title><video:description>Calorimetry is often used to evaluate the energy content of different foods. In this video, we&apos;ll see how data from a soda-can calorimetry experiment can be used to calculate the energy content of a marshmallow in Calories per gram.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1Zx71Il5jaM.mp4/1Zx71Il5jaM.mp4</video:content_loc><video:duration>466</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/constant-volume-calorimetry</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9dfabe8a466adac7.jpg</video:thumbnail_loc><video:title>Constant-volume calorimetry</video:title><video:description>Constant-volume calorimetry is used to measure the change in internal energy, ΔE, for a combustion reaction. In this technique, a sample is burned under constant volume in a device called a bomb calorimeter. The amount of heat released in the reaction can be calculated using the equation q = -CΔT, where C is the heat capacity of the calorimeter and ΔT is the temperature change. Because the combustion occurs at constant volume, q is equal to ΔE for the reaction.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1NueJQpqkuc.mp4/1NueJQpqkuc.mp4</video:content_loc><video:duration>478</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/heating-curve-for-water</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf98674bfa32150a0.jpg</video:thumbnail_loc><video:title>Heating curve for water</video:title><video:description>The heating curve for water shows how the temperature of a given quantity of water changes as heat is added at a constant rate. During a phase change, the temperature of the water remains constant, resulting in a plateau on the graph. We can use the heating curve to calculate the amount of heat required to raise the temperature of the water sample by a certain amount, such as from -25°C (when the water is present as a solid) to 125°C (when the water is present as a gas).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/MqAVc_XaIXQ.mp4/MqAVc_XaIXQ.mp4</video:content_loc><video:duration>631</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/enthalpy-of-reaction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4a20fdc9722c1a28.jpg</video:thumbnail_loc><video:title>Enthalpy of reaction</video:title><video:description>The enthalpy change that accompanies a chemical reaction is referred to as the enthalpy of reaction and is abbreviated ΔH_rxn. The value of ΔH_rxn depends on how the balanced equation for the reaction is written and is typically given in units of kJ/mol-rxn.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/cEzN33gfgVs.mp4/cEzN33gfgVs.mp4</video:content_loc><video:duration>257</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/worked-example-measuring-enthalpy-of-reaction-using-coffee-cup-calorimetry</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1474d84a9ab0d884.jpg</video:thumbnail_loc><video:title>Worked example: Measuring enthalpy of reaction using coffee-cup calorimetry</video:title><video:description>Constant-pressure calorimetry is often used to determine the changes in enthalpy for aqueous reactions. In this video, we&apos;ll see how data from a coffee-cup calorimetry experiment can be used to calculate ΔH_rxn for the reaction between AgNO₃(aq) and NaCl(aq).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pDCcRU5OGmA.mp4/pDCcRU5OGmA.mp4</video:content_loc><video:duration>456</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/hess-s-law-intro</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7e9abacd182248a6.jpg</video:thumbnail_loc><video:title>Hess&apos;s law</video:title><video:description>Hess&apos;s law states that if a process can be expressed as the sum of two or more steps, the enthalpy change for the overall process is the sum of the ΔH values for each step. To use Hess&apos;s law, two principles must be understood: one, if an equation is reversed, the sign of the ΔH value is also reversed. Two, if an equation is multiplied by a coefficient, the ΔH value is multiplied by the same coefficient.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/QU3zVec5I_M.mp4/QU3zVec5I_M.mp4</video:content_loc><video:duration>344</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/hess-s-law-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/6022728.jpg</video:thumbnail_loc><video:title>Worked example: Using Hess&apos;s law to calculate enthalpy of reaction</video:title><video:description>Hess&apos;s law can be used to calculate enthalpy changes that are difficult to measure directly. In this video, we&apos;ll use Hess&apos;s law to calculate the enthalpy change for the formation of methane, CH₄, from solid carbon and hydrogen gas, a reaction that occurs too slowly to be measured in the laboratory.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8bCL8TQZFKo.mp4/8bCL8TQZFKo.mp4</video:content_loc><video:duration>728</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/enthalpy-of-formation-intro</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9a645835a14c858d.jpg</video:thumbnail_loc><video:title>Enthalpy of formation</video:title><video:description>The standard enthalpy of formation of a substance is the enthalpy change that occurs when 1 mole of the substance is formed from its constituent elements in their standard states. A pure element in its standard state has a standard enthalpy of formation of zero. For any chemical reaction, the standard enthalpy change is the sum of the standard enthalpies of formation of the products minus the sum of the standard enthalpies of formation of the reactants.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TNwGNHqwHxc.mp4/TNwGNHqwHxc.mp4</video:content_loc><video:duration>565</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/writing-equilibrium-constant-and-reaction-quotient-expressions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5ba6c83b65f6f515.jpg</video:thumbnail_loc><video:title>Writing equilibrium constant and reaction quotient expressions</video:title><video:description>The equilibrium constant, K, describes the relative amounts of reaction species at equilibrium. The expression for K is equal to the concentrations (or partial pressures) of the products raised to their stoichiometric coefficients divided by the concentrations (or partial pressures) of the reactants raised to their stoichiometric coefficients. The reaction quotient, Q, has the same form as K but describes the relative amounts of reaction species at any point in time.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lG8tCeNzEjY.mp4/lG8tCeNzEjY.mp4</video:content_loc><video:duration>423</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/worked-examples-calculating-equilibrium-constants-from-equilibrium-concentration</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8e80cf5c2d1b7d81.jpg</video:thumbnail_loc><video:title>Worked examples: Calculating equilibrium constants</video:title><video:description>In this video, we&apos;ll calculate equilibrium constants using measurements of concentration and partial pressures at equilibrium. First, we&apos;ll find Kc for an equilibrium system using equilibrium concentrations. Then, we&apos;ll find Kp for a different system using equilibrium partial pressures.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5HZbCNg9mIw.mp4/5HZbCNg9mIw.mp4</video:content_loc><video:duration>492</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/magnitude-of-the-equilibrium-constant</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5b0c897613efccfb.jpg</video:thumbnail_loc><video:title>Magnitude of the equilibrium constant</video:title><video:description>The magnitude of the equilibrium constant provides information about the relative amounts of reactants and products at equilibrium. A large K value (greater than 1) indicates that there are more products than reactants at equilibrium, while a small K value (less than 1) indicates that there are more reactants than products at equilibrium.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/CoRawW0_Kns.mp4/CoRawW0_Kns.mp4</video:content_loc><video:duration>364</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/properties-of-the-equilibrium-constant</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xae35ca847266af38.jpg</video:thumbnail_loc><video:title>Properties of the equilibrium constant</video:title><video:description>The equilibrium constant for a reaction depends on how the balanced equation is written. If the equation is reversed, K is inverted. If the equation is multiplied by a factor n, K is raised to the nth power. If multiple equations are added together, K for the overall equation is the product of the K values for the equations that were summed.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/U39OqCEMjto.mp4/U39OqCEMjto.mp4</video:content_loc><video:duration>396</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/worked-example-calculating-an-equilibrium-constant-from-initial-and-equilibrium-</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xda43fd0e7a843470.jpg</video:thumbnail_loc><video:title>Worked example: Calculating an equilibrium constant from initial and equilibrium pressures</video:title><video:description>Given an initial partial pressure and the total pressure at equilibrium, we can use Dalton&apos;s law to determine the equilibrium partial pressures of the gases in a reaction mixture. Once we know the equilibrium partial pressures, we can calculate the equilibrium constant for the reaction.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/MKt3X0SGrtw.mp4/MKt3X0SGrtw.mp4</video:content_loc><video:duration>291</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/worked-example-calculating-equilibrium-concentrations-from-initial-concentration</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x89e5acafaf8b5cef.jpg</video:thumbnail_loc><video:title>Worked example: Calculating equilibrium concentrations from initial concentrations</video:title><video:description>In this video, we&apos;ll learn how to use initial concentrations along with the equilibrium constant to calculate the concentrations of reaction species at equilibrium.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/l81swfmUaek.mp4/l81swfmUaek.mp4</video:content_loc><video:duration>329</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/using-the-reaction-quotient-ap</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfe3339a8f31de97a.jpg</video:thumbnail_loc><video:title>Using the reaction quotient</video:title><video:description>By comparing the reaction quotient to the equilibrium constant, we can predict the direction a reaction will proceed to reach equilibrium. If Q &lt; K, the reaction will proceed towards the products. If Q &gt; K, the reaction will proceed towards the reactants. If Q = K, the reaction is already at equilibrium and will not change.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/JDUNQMj9Yk0.mp4/JDUNQMj9Yk0.mp4</video:content_loc><video:duration>470</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/worked-example-using-the-reaction-quotient-to-find-equilibrium-partial-pressures</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6f1ad9382238d63e.jpg</video:thumbnail_loc><video:title>Worked example: Using the reaction quotient to find equilibrium partial pressures</video:title><video:description>In some equilibrium problems, we first need to use the reaction quotient to predict the direction a reaction will proceed to reach equilibrium. Once we know this, we can build an ICE table, which we can then use to calculate the concentrations or partial pressures of the reaction species at equilibrium.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/U7U3e0r_8y8.mp4/U7U3e0r_8y8.mp4</video:content_loc><video:duration>391</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/comparing-q-vs-k-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb4136c2e.jpg</video:thumbnail_loc><video:title>Worked example: Using the reaction quotient to predict a pressure change</video:title><video:description>We can predict how the total pressure of a reaction mixture will change as the system moves toward equilibrium by first calculating the reaction quotient, Qₚ, and then comparing Qₚ to Kₚ.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pnW1PNJlmWg.mp4/pnW1PNJlmWg.mp4</video:content_loc><video:duration>353</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/le-chateliers-principle-changing-volume</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0f32a0d2f88ed955.jpg</video:thumbnail_loc><video:title>Le Chȃtelier’s principle: Changing volume</video:title><video:description>Le Chȃtelier’s principle can be used to predict the effect that a stress like changing volume has on a system at equilibrium. If the volume of the container is increased (at constant T), the system will shift in the direction that increases the number of moles of gas in the container. If the volume is decreased, the reverse effect will occur. If the system has the same number of moles of gas on both sides of the chemical equation, a change in volume will have no impact on the equilibrium position.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/FmqyKCQo7Tk.mp4/FmqyKCQo7Tk.mp4</video:content_loc><video:duration>669</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/solubility-product-constant-from-the-solubility</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x17fb6c6c.jpg</video:thumbnail_loc><video:title>Introduction to solubility equilibria</video:title><video:description>The solubility product constant, Kₛₚ, is an equilibrium constant that reflects the extent to which an ionic compound dissolves in water. For compounds that dissolve to produce the same number of ions, we can directly compare their Kₛₚ values to determine their relative solubilities. If we know the solubility of a salt, we can use this information to calculate the Kₛₚ value for the compound.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/N9a2r01ToZk.mp4/N9a2r01ToZk.mp4</video:content_loc><video:duration>497</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/solubility-from-the-solubility-product-constant</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9dbdb3a5.jpg</video:thumbnail_loc><video:title>Worked example: Calculating solubility from Kₛₚ</video:title><video:description>A compound&apos;s molar solubility in water can be calculated from its Kₛₚ value at 25°C. To do so, first prepare an ICE (Initial, Change, and Equilibrium) table showing the equilibrium concentrations of the ions in terms of x, the molar solubility of the compound. Then, plug these expressions into the solubility-product expression for the compound and solve for the value of x.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Ywvw32DaxUk.mp4/Ywvw32DaxUk.mp4</video:content_loc><video:duration>292</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/worked-example-predicting-whether-a-precipitate-forms-by-comparing-q-and-k</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xca4bf79a23423862.jpg</video:thumbnail_loc><video:title>Worked example: Predicting whether a precipitate forms by comparing Q and Kₛₚ</video:title><video:description>We can use the reaction quotient to predict whether a precipitate will form when two solutions containing dissolved ionic compounds are mixed. If Q &lt; Kₛₚ, the newly mixed solution is undersaturated and no precipitate will form. If Q &gt; Kₛₚ, the solution is oversaturated and a precipitate will form until Q = Kₛₚ.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vyENVkttVtw.mp4/vyENVkttVtw.mp4</video:content_loc><video:duration>496</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/solubility-and-the-common-ion-effect</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x33617989.jpg</video:thumbnail_loc><video:title>The common-ion effect</video:title><video:description>The solubility of an ionic compound is decreased by the presence of a common ion (an ion that is also present in the compound); this is known as the common-ion effect.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/fI3U9T7LigY.mp4/fI3U9T7LigY.mp4</video:content_loc><video:duration>608</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/solubility-and-the-ph-of-the-solution</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7212c366.jpg</video:thumbnail_loc><video:title>pH and solubility</video:title><video:description>For ionic compounds containing basic anions, solubility increases as the pH of the solution is decreased. For ionic compounds containing anions of negligible basicity (such as the conjugate bases of strong acids), solubility is unaffected by changes in pH.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Z2bDnvDGQHQ.mp4/Z2bDnvDGQHQ.mp4</video:content_loc><video:duration>314</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/autoionization-of-water-ap</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf0385fb1aabd26dd.jpg</video:thumbnail_loc><video:title>Autoionization of water</video:title><video:description>In the autoionization of water, a proton is transferred from one water molecule to another to produce a hydronium ion (H₃O⁺) and a hydroxide ion (OH⁻). The equilibrium expression for this reaction is Kw = [H₃O⁺][OH⁻], where Kw is the autoionization constant for water. At 25°C, the value of Kw is 1.0 x 10⁻¹⁴. In pure water, the concentrations of H₃O⁺ and OH⁻ are equal, and the water is considered to be neutral.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vt6WjF1O_08.mp4/vt6WjF1O_08.mp4</video:content_loc><video:duration>541</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/the-ph-scale</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd2d23bef2d510733.jpg</video:thumbnail_loc><video:title>The pH scale</video:title><video:description>The pH scale is a convenient way to represent the acidity or basicity of a solution. We can calculate the pH of a solution by taking the negative logarithm of the hydronium ion concentration, or pH = -log[H₃O⁺]. At 25°C, a solution with pH &lt; 7 is acidic, a solution with pH &gt; 7 is basic, and a solution with pH = 7 is neutral.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/75j1b1l6PWU.mp4/75j1b1l6PWU.mp4</video:content_loc><video:duration>529</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/worked-examples-calculating-hydronium-ion-concentration-and-ph</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x305408b3c866c70f.jpg</video:thumbnail_loc><video:title>Worked examples: Calculating [H₃O⁺] and pH</video:title><video:description>In this video, we&apos;ll solve for [H₃O⁺] and pH in two different worked examples. First, we&apos;ll walk through the possible approaches for calculating [H₃O⁺] from pOH. Then, we&apos;ll find the pH of pure water at 50°C from the value of the autoionization constant at 50°C.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qK_YVKAat1w.mp4/qK_YVKAat1w.mp4</video:content_loc><video:duration>425</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/strong-acid-solutions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x83c7f6c949baf649.jpg</video:thumbnail_loc><video:title>Strong acid solutions</video:title><video:description>Strong acids (such as HCl, HBr, HI, HNO₃, HClO₄, and H₂SO₄) ionize completely in water to produce hydronium ions. The concentration of H₃O⁺ in a strong acid solution is therefore equal to the initial concentration of the acid. For example, a solution of 0.1 M HNO₃ contains 0.1 M H₃O⁺ and has a pH of 1.0.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pZ43GbTechI.mp4/pZ43GbTechI.mp4</video:content_loc><video:duration>378</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/worked-example-finding-the-percent-ionization-of-a-weak-acid</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x47501ff0ec6cd797.jpg</video:thumbnail_loc><video:title>Worked example: Finding the percent ionization of a weak acid</video:title><video:description>The percent ionization of a weak acid, HA, is defined as the ratio of the equilibrium H₃O⁺ concentration to the initial HA concentration, multiplied by 100%. In this video, we&apos;ll use this relationship to find the percent ionization of acetic acid in a 0.20 M solution.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_jEe0Tkyn3w.mp4/_jEe0Tkyn3w.mp4</video:content_loc><video:duration>410</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/weak-base-equilibria</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xca521b040bbb24b1.jpg</video:thumbnail_loc><video:title>Weak base equilibria</video:title><video:description>Weak bases partially ionize in water to produce hydroxide ions. Because the ionization is not complete, the concentration of OH⁻ in a weak base solution is typically much less than the initial base concentration. The relative strength of a weak base is described by the base ionization constant, Kb, which is the equilibrium constant for the reaction of the weak base with water.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/cvcgH3ohcNg.mp4/cvcgH3ohcNg.mp4</video:content_loc><video:duration>570</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/acid-base-properties-of-salts</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xcb0e59e6.jpg</video:thumbnail_loc><video:title>Acid–base properties of salts</video:title><video:description>We can determine whether a salt solution will be acidic, basic, or neutral by considering the reactivity of both the cation and the anion with water. If neither species reacts with water, the solution will be neutral. If only the cation reacts with water, the solution will be acidic. If only the anion reacts with water, the solution will be basic. If both species react with water, the pH of the solution will depend on the relative strengths of the cation and the anion.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/EDvtwQLJzEg.mp4/EDvtwQLJzEg.mp4</video:content_loc><video:duration>813</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/factors-affecting-acid-strength</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1f18a037178ed995.jpg</video:thumbnail_loc><video:title>Factors affecting acid strength</video:title><video:description>The relative strength of an acid can be predicted based on its chemical structure. In general, an acid is stronger when the H–A bond is more polar. Acidity is also greater when the H–A bond is weaker and when the conjugate base, A⁻, is more stable.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/v_94NsuBwDM.mp4/v_94NsuBwDM.mp4</video:content_loc><video:duration>519</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/weak-acid-strong-base-reactions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xce5c79320ba60574.jpg</video:thumbnail_loc><video:title>Weak acid–strong base reactions</video:title><video:description>When a weak acid and a strong base are mixed, they react according to the following net-ionic equation: HA(aq) + OH⁻(aq) → A⁻(aq) + H₂O(l). If the acid and base are equimolar, the pH of the resulting solution can be determined by considering the equilibrium reaction of A⁻ with water. If the acid is in excess, the pH can be determined from the concentrations of HA and A⁻ after the reaction. If the base is in excess, the pH can be determined from the concentration of excess OH⁻.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/VdAl4QK4-0Q.mp4/VdAl4QK4-0Q.mp4</video:content_loc><video:duration>482</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/worked-example-calculating-the-ph-after-a-weak-acid-strong-base-reaction-excess-</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa623e9dd9076959e.jpg</video:thumbnail_loc><video:title>Worked example: Calculating the pH after a weak acid–strong base reaction (excess acid)</video:title><video:description>When a strong base reacts with excess weak acid, the resulting solution contains both HA and A⁻. We can use reaction stoichiometry to determine the concentration of each species and then solve a common-ion equilibrium problem to find [H₃O⁺] and thus the pH.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9rRlLPx6w7M.mp4/9rRlLPx6w7M.mp4</video:content_loc><video:duration>544</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/weak-base-strong-acid-reactions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x82de9a0fed7a5099.jpg</video:thumbnail_loc><video:title>Weak base–strong acid reactions</video:title><video:description>When a weak base and a strong acid are mixed, they react according to the following net-ionic equation: B(aq) + H₃O⁺(aq) → HB⁺(aq) + H₂O(l). If the acid and base are equimolar, the pH of the resulting solution can be determined by considering the equilibrium reaction of HB⁺ with water. If the base is in excess, the pH can be determined from the concentrations of B and HB⁺ after the reaction. If the acid is in excess, the pH can be determined from the concentration of excess H₃O⁺.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/78Sg3RdEPVk.mp4/78Sg3RdEPVk.mp4</video:content_loc><video:duration>388</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/weak-acid-weak-base-reactions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb06a9cd3343723e0.jpg</video:thumbnail_loc><video:title>Weak acid–weak base reactions</video:title><video:description>When a weak acid and a weak base are mixed, they come to an equilibrium state represented by the following equation: HA(aq) + B(aq) ⇌ A⁻(aq) + HB⁺(aq). The equilibrium position lies on the side of the weaker acid and the weaker base, and we can determine whether the resulting solution is acidic, basic, or neutral by comparing the Ka and Kb values of these species.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/G5FVxAzlmfM.mp4/G5FVxAzlmfM.mp4</video:content_loc><video:duration>431</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/properties-of-buffers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfcfdc1868e2d9dcf.jpg</video:thumbnail_loc><video:title>Properties of buffers</video:title><video:description>Buffer solutions contain high concentrations of both a weak acid and its conjugate base (or a weak base and its conjugate acid). Because these components can neutralize added H⁺ or OH⁻, buffers are highly resistant to changes in pH.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tZH6zvQ8Wl8.mp4/tZH6zvQ8Wl8.mp4</video:content_loc><video:duration>419</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/hendersonhasselbalch-equation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6949bb9400952fe6.jpg</video:thumbnail_loc><video:title>Henderson–Hasselbalch equation</video:title><video:description>One way to determine the pH of a buffer is by using the Henderson–Hasselbalch equation, which is pH = pKₐ + log([A⁻]/[HA]). In this equation, [HA] and [A⁻] refer to the equilibrium concentrations of the conjugate acid–base pair used to create the buffer solution. When [HA] = [A⁻], the solution pH is equal to the pKₐ of the acid.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7QgtdYiWH50.mp4/7QgtdYiWH50.mp4</video:content_loc><video:duration>454</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/methods-for-preparing-buffers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3241eaf69b19a5ec.jpg</video:thumbnail_loc><video:title>Methods for preparing buffers</video:title><video:description>In this video, we&apos;ll explore two common methods for preparing buffer solutions. In the first approach, a certain amount of a weak acid (or weak base) is neutralized with a strong base (or strong acid), forming a conjugate acid–base pair in solution. In the second approach, a weak acid (or weak base) is combined with a salt containing its conjugate base (or conjugate acid).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OCPQaKhVC_0.mp4/OCPQaKhVC_0.mp4</video:content_loc><video:duration>626</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/buffer-range</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x89606686d924813f.jpg</video:thumbnail_loc><video:title>Buffer range</video:title><video:description>A buffer has an effective pH range of one pH unit on either side of the pKₐ value for the weak acid. If the pH of a buffer goes out of this range, the buffer will no longer be effective at resisting large changes in pH.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/yia1GeEEVaM.mp4/yia1GeEEVaM.mp4</video:content_loc><video:duration>317</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/buffer-capacity-ap</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x51def401cab09cf8.jpg</video:thumbnail_loc><video:title>Buffer capacity</video:title><video:description>The capacity of a buffer to neutralize added acid or base depends on the concentrations of HA and A⁻ in solution. For a given ratio of [HA] to [A⁻], the greater the concentrations, the higher the overall buffer capacity. When [HA] is greater than [A⁻], the capacity is higher for added base than acid. When [A⁻] is greater than [HA], the capacity is higher for added acid than base.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/XcSZ5jeG5mA.mp4/XcSZ5jeG5mA.mp4</video:content_loc><video:duration>618</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/strong-acid-strong-base-titrations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x733c3b3326d79057.jpg</video:thumbnail_loc><video:title>Strong acid–strong base titrations</video:title><video:description>The results of an acid–base titration can be summarized using a titration curve, which plots pH vs. volume of titrant added. For the titration of a strong acid with a strong base, the curve begins acidic and then turns basic after the equivalence point, which occurs at pH = 7. For the titration of a strong base with a strong acid, the curve is similar except that it begins basic and turns acidic.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qkh0SMozSBQ.mp4/qkh0SMozSBQ.mp4</video:content_loc><video:duration>540</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/weak-acid-strong-base-titrations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc6bd0d5bfe42207b.jpg</video:thumbnail_loc><video:title>Weak acid–strong base titrations</video:title><video:description>For the titration of a weak acid with a strong base, the pH curve is initially acidic and has a basic equivalence point (pH &gt; 7). The section of curve between the initial point and the equivalence point is known as the buffer region. At the half-equivalence point, the concentrations of the buffer components are equal, resulting in pH = pKₐ.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/sZW1qoQl3ng.mp4/sZW1qoQl3ng.mp4</video:content_loc><video:duration>729</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/weak-base-strong-acid-titrations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0a6a7576a293032e.jpg</video:thumbnail_loc><video:title>Weak base–strong acid titrations</video:title><video:description>For the titration of a weak base with a strong acid, the pH curve is initially basic and has an acidic equivalence point (pH &lt; 7). The section of curve between the initial point and the equivalence point is known as the buffer region. At the half-equivalence point, the concentrations of the buffer components are equal, resulting in pH = pKₐ (where pKₐ refers to the conjugate acid of the weak base).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/IZ7NEYnuovI.mp4/IZ7NEYnuovI.mp4</video:content_loc><video:duration>634</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/titrations-of-polyprotic-acids</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x86414b1cfa2e2bed.jpg</video:thumbnail_loc><video:title>Titrations of polyprotic acids</video:title><video:description>Titrating a polyprotic acid with a strong base produces a pH curve with as many equivalence points as there are acidic protons on the acid. The pKₐ values for these protons can be estimated from the corresponding half-equivalence points on the curve, where pH = pKₐ.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/AXKqh3za1Fg.mp4/AXKqh3za1Fg.mp4</video:content_loc><video:duration>524</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/acid-base-indicators</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7a817f82efe5cb51.jpg</video:thumbnail_loc><video:title>Acid–base indicators</video:title><video:description>Acid–base indicators are compounds that change color when they become protonated or deprotonated. Because this color change occurs over a specific pH range, indicators can be used to approximate the equivalence point of an acid–base titration.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ZDgYWaeuwbw.mp4/ZDgYWaeuwbw.mp4</video:content_loc><video:duration>425</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/introduction-to-entropy-ap</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd817fa423dd049c3.jpg</video:thumbnail_loc><video:title>Introduction to entropy</video:title><video:description>According to the Boltzmann equation, entropy is a measure of the number of microstates available to a system. The number of available microstates increases when matter becomes more dispersed, such as when a liquid changes into a gas or when a gas is expanded at constant temperature. It also increases when energy becomes more dispersed, which occurs with an increase in temperature.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0Z2bIv4DXts.mp4/0Z2bIv4DXts.mp4</video:content_loc><video:duration>714</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/absolute-entropy-and-entropy-change</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x168191bf8a63545c.jpg</video:thumbnail_loc><video:title>Absolute entropy and entropy change</video:title><video:description>The standard molar entropy of a substance is the absolute entropy of 1 mole of the substance in the standard state. For any chemical reaction, the standard entropy change is the sum of the standard molar entropies of the products minus the sum of the standard molar entropies of the reactants.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ObridY7EHyk.mp4/ObridY7EHyk.mp4</video:content_loc><video:duration>688</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/introduction-to-gibbs-free-energy</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb2f2d5ad49bb5347.jpg</video:thumbnail_loc><video:title>Introduction to Gibbs free energy</video:title><video:description>The standard Gibbs free energy change, ΔG°, indicates the thermodynamic favorability of a physical or chemical process. When ΔG° &lt; 0, the process is thermodynamically favored. For a given process, the value of ΔG° can be calculated directly from the values of ΔH° and ΔS° using the following equation: ΔG° = ΔH° - TΔS°.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_ikwCBn8wLE.mp4/_ikwCBn8wLE.mp4</video:content_loc><video:duration>339</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/thermodynamic-favorability-and-temperature</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x335e7a51d00aef50.jpg</video:thumbnail_loc><video:title>Thermodynamic favorability and temperature</video:title><video:description>The temperature conditions under which a process is thermodynamically favored (ΔG° &lt; 0) can be predicted from the signs of ΔH° and ΔS°. When ΔH° &lt; 0 and ΔS° &gt; 0, the process is favored at all temperatures. When ΔH° &gt; 0 and ΔS° &lt; 0, the process is favored at no temperature. When ΔH° &lt; 0 and ΔS° &lt; 0, the process is favored only at low temperatures. When ΔH° &gt; 0 and ΔS° &gt; 0, the process is favored only at high temperatures.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/eejDYxFKGNs.mp4/eejDYxFKGNs.mp4</video:content_loc><video:duration>834</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/worked-example-determining-the-effect-of-temperature-on-thermodynamic-favorabili</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x58c4615bad858602.jpg</video:thumbnail_loc><video:title>Worked example: Determining the effect of temperature on thermodynamic favorability</video:title><video:description>When ΔH° and ΔS° for a reaction have the same sign, the thermodynamic favorability of the reaction depends on temperature. In this video, we&apos;ll determine the thermodynamic favorability of a reaction with ΔH° &lt; 0 and ΔS° &lt; 0 at two different temperatures. We&apos;ll also calculate the temperature at which the reaction changes from being thermodynamically favored to thermodynamically unfavored.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_pRo2jlA-9I.mp4/_pRo2jlA-9I.mp4</video:content_loc><video:duration>407</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/free-energy-of-formation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xeb4447c28cc6fa97.jpg</video:thumbnail_loc><video:title>Free energy of formation</video:title><video:description>The standard free energy of formation of a substance is the free energy change that occurs when 1 mole of the substance is formed from its constituent elements in their standard states. A pure element in its standard state has a standard free energy of formation of zero. For any chemical reaction, the standard free energy change is the sum of the standard free energies of formation of the products minus the sum of the standard free energies of formation of the reactants.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9igPBrHMnCc.mp4/9igPBrHMnCc.mp4</video:content_loc><video:duration>326</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/free-energy-of-dissolution</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0c4baca3ce7eafe5.jpg</video:thumbnail_loc><video:title>Free energy of dissolution</video:title><video:description>The dissolution of a solid can be thought of as occurring in three hypothetical steps: (1) the breaking apart of the solid, (2) the spreading out of the solvent, and (3) the interaction of the dissolved solid with the solvent. As shown in this video, we can predict the signs of the enthalpy and entropy changes for each of these steps and relate this information to the solubility of the solid.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/UJ_etGNuIOg.mp4/UJ_etGNuIOg.mp4</video:content_loc><video:duration>856</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/thermodynamics-vs-kinetics-ap</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3e03784ec6ce4835.jpg</video:thumbnail_loc><video:title>Thermodynamics vs. kinetics</video:title><video:description>Thermodynamics tells us what can occur during a process, while kinetics tell us what actually occurs. Some processes, such as the conversion of diamond to graphite, are thermodynamically favored but kinetically unfavored. In these cases, the processes do not occur to any measurable extent.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ur7GBAQgiB0.mp4/ur7GBAQgiB0.mp4</video:content_loc><video:duration>270</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/nonstandard-free-energy-changes</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7878a267e73e7757.jpg</video:thumbnail_loc><video:title>Nonstandard free energy changes</video:title><video:description>The standard change in free energy, ΔG°, for a reaction applies only when the reactants and products are in their standard states. In all other circumstances, we must consider the nonstandard free energy change, ΔG, which can be calculated from ΔG° using the equation ΔG = ΔG° + RTlnQ. In this equation, R is the appropriate gas constant (8.314 J/mol·K), T is the temperature in kelvin, and Q is the reaction quotient.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/P6dcloxLv2Q.mp4/P6dcloxLv2Q.mp4</video:content_loc><video:duration>615</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/free-energy-and-equilibrium</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8ef554a85bfa3dd6.jpg</video:thumbnail_loc><video:title>Free energy and equilibrium</video:title><video:description>The standard change in free energy, ΔG°, for a reaction is related to its equilibrium constant, K, by the equation ΔG° = -RTlnK. When ΔG° &lt; 0, K &gt; 1, and the reaction is product-favored at equilibrium. When ΔG° &gt; 0, K &lt; 1, and the reaction is reactant-favored at equilibrium. When ΔG° = 0, K = 1, and the reaction is at equilibrium under standard state conditions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4ZcTEiJru84.mp4/4ZcTEiJru84.mp4</video:content_loc><video:duration>521</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/coupled-reactions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x318f183f0f88480b.jpg</video:thumbnail_loc><video:title>Coupled reactions</video:title><video:description>A thermodynamically unfavored reaction can be driven by coupling it to a favored reaction through one or more shared intermediates. The sum of the two reactions yields an overall reaction that has a negative ΔG° value.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/NnSJsYa1IK0.mp4/NnSJsYa1IK0.mp4</video:content_loc><video:duration>434</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/galvanic-voltaic-cells</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7343d24cfad6e4f0.jpg</video:thumbnail_loc><video:title>Galvanic (voltaic) cells</video:title><video:description>Galvanic (or voltaic) cells use a thermodynamically favored redox reaction to generate an electric current. Each half-reaction takes place in a separate compartment, or half-cell, containing an electrode. The electrode where oxidation occurs is the anode, and the electrode where reduction occurs is the cathode. Electrons flow through a wire connecting the two half-cells. To complete the circuit, a salt bridge is used, which allows ions to move between the half-cell solutions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/inXgVjz1BDQ.mp4/inXgVjz1BDQ.mp4</video:content_loc><video:duration>552</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/standard-cell-potential</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc9b387da1e92d475.jpg</video:thumbnail_loc><video:title>Standard cell potential</video:title><video:description>Standard cell potential is the potential of a cell when all reactants and products are in their standard states. The standard potential for any cell can be calculated by subtracting the standard reduction potential of the half-reaction occurring at the anode from the standard reduction potential of the half-reaction occurring at the cathode.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/nBZ4PDBhSrY.mp4/nBZ4PDBhSrY.mp4</video:content_loc><video:duration>419</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/worked-example-calculating-e-using-standard-reduction-potentials</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x416b48408b0d8fea.jpg</video:thumbnail_loc><video:title>Worked example: Calculating E° using standard reduction potentials</video:title><video:description>The standard potential, E°, for a redox reaction is the difference between the standard reduction potentials of the reduction and oxidation half-reactions. In this video, we&apos;ll use this relationship to calculate the E° for the redox reaction between Ag⁺(aq) and Cr(s).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PNolxY6rOKk.mp4/PNolxY6rOKk.mp4</video:content_loc><video:duration>321</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/standard-potential-free-energy-and-the-equilibrium-constant</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x31ef062bfe9caec9.jpg</video:thumbnail_loc><video:title>Standard potential, free energy, and the equilibrium constant</video:title><video:description>The standard potential, E°, for a redox reaction is related to the standard change in free energy, ΔG°, for the reaction by the equation ΔG° = -nFE°. When E° &gt; 0, ΔG° &lt; 0, and the reaction is thermodynamically favored. When E° &lt; 0, ΔG° &gt; 0, and the reaction is thermodynamically unfavored. It is also possible to relate E° to the equilibrium constant, K, for the reaction through the relationship between ΔG° and K (ΔG° = -RTlnK).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/b2YI3AIs6l0.mp4/b2YI3AIs6l0.mp4</video:content_loc><video:duration>548</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/the-nernst-equation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x560b890229e27653.jpg</video:thumbnail_loc><video:title>The Nernst equation</video:title><video:description>The Nernst equation relates the instantaneous potential, E, to the standard potential, E°, and the reaction quotient, Q: E = E° - (0.0592 V/n)logQ at 298 K. When all reactants and products are in their standard states, Q = 1 and E = E°. When the reaction is at equilibrium, Q = K and E = 0.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PemB4mY4Jfk.mp4/PemB4mY4Jfk.mp4</video:content_loc><video:duration>687</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-chemistry-beta/v/quantitative-electrolysis-ap</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5d3b9e1304966117.jpg</video:thumbnail_loc><video:title>Quantitative electrolysis</video:title><video:description>Given the amount of electrical charge that passes through an electrolytic cell, we can calculate the quantity of substances consumed or produced during electrolysis (or vice versa). The total charge is related to the magnitude of the current and the time it runs by the equation I = Q/t, where I is the current in amperes, Q is the charge in coulombs, and t is the time in seconds.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/v5qQusbk-j0.mp4/v5qQusbk-j0.mp4</video:content_loc><video:duration>447</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/ecosystems-and-biomes</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd2ee49ae2ddb5919.jpg</video:thumbnail_loc><video:title>Ecosystems and biomes</video:title><video:description>Ecosystems, made up of living and non-living things, can be as small as a tide pool or as big as a rainforest. Ecosystems can be classified as terrestrial or aquatic, with aquatic further divided into marine and freshwater. Land ecosystems are often categorized into biomes, such as tropical forests or deserts, based on climate and vegetation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/A495e31cDdE.mp4/A495e31cDdE.mp4</video:content_loc><video:duration>453</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-college-environmental-science/v/primary-productivity-in-ecosystems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x97f65e2f807e38f8.jpg</video:thumbnail_loc><video:title>Primary productivity in ecosystems</video:title><video:description>Primary productivity is the rate at which solar energy (sunlight) is converted into organic compounds via photosynthesis over a unit of time. Net primary productivity is the rate of energy storage by photosynthetic organisms in a given area, after subtracting the energy lost to respiration.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8zO0algdgNM.mp4/8zO0algdgNM.mp4</video:content_loc><video:duration>603</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-college-environmental-science/v/energy-flow-in-a-marine-ecosystem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4f11e1ae0cd045f3.jpg</video:thumbnail_loc><video:title>Energy flow in a marine ecosystem</video:title><video:description>All ecosystems depend on a continuous inflow of high-quality energy in order to maintain their structure and function of transferring matter between the environment and organisms via biogeochemical cycles. In terrestrial and near-surface marine communities, energy flows from the sun to producers in the lowest trophic levels and then upward to higher trophic levels. The 10% rule approximates that in the transfer of energy from one trophic level to the next, only about 10% of the energy is passed on.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/fL0W_boPHLs.mp4/fL0W_boPHLs.mp4</video:content_loc><video:duration>398</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-college-environmental-science/v/humans-and-ecosystems-how-do-vultures-provide-ecosystem-services</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x01da1ff235f2c7fb.jpg</video:thumbnail_loc><video:title>Humans and ecosystems: how do vultures provide ecosystem services?</video:title><video:description>The Lammergeier, a bone-eating vulture, exemplifies the importance of biodiversity and ecosystem services. These services, categorized into provisioning, regulating, supporting, and cultural, sustain the environment and human life. However, human disruptions, like harmful chemicals, can endanger species like vultures, leading to ecological and economic consequences.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/bT_2MyIRsas.mp4/bT_2MyIRsas.mp4</video:content_loc><video:duration>299</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/ecological-succession</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3d2d49b0.jpg</video:thumbnail_loc><video:title>Ecological succession</video:title><video:description>Ecological succession, a dynamic process involving gradual changes in biological communities over time, encompasses two main types: primary succession, where life gradually colonizes a new habitat, and secondary succession, triggered by a disaster that disrupts an existing community, instigating shifts in species composition.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/d7xbyNSxxrI.mp4/d7xbyNSxxrI.mp4</video:content_loc><video:duration>280</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-college-environmental-science/v/human-population-dynamics</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x83826b6c4ab54bbc.jpg</video:thumbnail_loc><video:title>Human population dynamics</video:title><video:description>World population growth has surged over the last few centuries due to advancements in healthcare and agriculture. However, as societies develop and family planning is implemented, growth rates are declining. The Earth&apos;s carrying capacity for humans remains an open question, influenced by our ever-evolving technology and resource efficiency.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jKfojKK-8Zk.mp4/jKfojKK-8Zk.mp4</video:content_loc><video:duration>389</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-college-environmental-science/v/rule-of-70-to-approximate-population-doubling-time</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8f8759d9d0ec55dc.jpg</video:thumbnail_loc><video:title>Rule of 70 to approximate population doubling time</video:title><video:description>Doubling time is the period it takes for a population growing at a certain rate to double its size. One way to approximate doubling time is known as the rule of 70. This rule is used in various fields, including finance and environmental science. However, the rule of 70 is an approximation, not a precise calculation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/KBXec1ctCjg.mp4/KBXec1ctCjg.mp4</video:content_loc><video:duration>201</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-college-environmental-science/v/demographic-transition-model</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x74ea28d2639e4347.jpg</video:thumbnail_loc><video:title>Demographic transition model</video:title><video:description>The Demographic Transition Model illustrates how a country&apos;s birth and death rates change as it transitions from pre-industrial to post-industrial. High birth and death rates characterize pre-industrial societies, while industrialization leads to lower death rates and eventually lower birth rates. In post-industrial societies, birth rates may even fall below death rates, leading to population decline.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/kEOgW5Rg0o8.mp4/kEOgW5Rg0o8.mp4</video:content_loc><video:duration>439</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/plate-tectonics-geological-features-of-divergent-plate-boundaries</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179439.jpg</video:thumbnail_loc><video:title>Plate tectonics: Geological features of divergent plate boundaries</video:title><video:description>Divergent plate boundaries, where Earth&apos;s plates move apart, create unique geological features. These boundaries result in seafloor spreading, rift valleys, volcanoes, and earthquakes. The process begins with hot magma rising, causing the lithosphere to crack and form rift valleys. Over time, these valleys can fill with water, forming seas. As the land continues to spread, mid-oceanic ridges form, creating an underwater mountain chain.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/FK1s1-OJ5BE.mp4/FK1s1-OJ5BE.mp4</video:content_loc><video:duration>718</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/plate-tectonics-geological-features-of-convergent-plate-boundaries</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179440.jpg</video:thumbnail_loc><video:title>Plate tectonics: Geological features of convergent plate boundaries</video:title><video:description>Plate tectonics involves the movement and interaction of Earth&apos;s crustal plates, leading to geological changes. Divergent boundaries create new crust, while convergent boundaries, where plates collide, can form mountains, island arcs, earthquakes, and volcanoes. The subduction of one plate under another can result in deep trenches and underwater volcanoes.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Y0eWnOZpSpQ.mp4/Y0eWnOZpSpQ.mp4</video:content_loc><video:duration>364</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-college-environmental-science/v/soil-texture-triangle</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7b074b37bab23ad4.jpg</video:thumbnail_loc><video:title>Soil texture triangle</video:title><video:description>Soil texture, determined by the proportions of sand, silt, and clay, plays a crucial role in plant growth. The soil texture triangle helps categorize soil into 12 types based on these proportions. Understanding soil texture can guide optimal plant selection for different soil types.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Bn9ul9lxIdg.mp4/Bn9ul9lxIdg.mp4</video:content_loc><video:duration>384</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-college-environmental-science/v/global-wind-patterns</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x45a66b603f628d93.jpg</video:thumbnail_loc><video:title>Global wind patterns</video:title><video:description>Global wind patterns, crucial for life on Earth, are primarily driven by the Sun&apos;s intense radiation at the equator, resulting in atmospheric circulation. This process, involving rising hot air and sinking cool air, creates convection cells and prevailing winds that distribute heat and moisture unevenly across the globe, shaping diverse biomes and determining species survival.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xp50_ixPOhY.mp4/xp50_ixPOhY.mp4</video:content_loc><video:duration>383</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-college-environmental-science/v/seasons-ms</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x37fbccdfe032e546.jpg</video:thumbnail_loc><video:title>Seasons</video:title><video:description>Earth&apos;s seasons are not dictated by its distance from the Sun, but rather by its axial tilt. The angle of the Sun&apos;s rays determines the intensity of solar radiation, with the equator receiving the highest intensity. This tilt also causes variations in daylight hours, contributing to the change of seasons.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0r9Lc7oYq5M.mp4/0r9Lc7oYq5M.mp4</video:content_loc><video:duration>306</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-college-environmental-science/v/el-nino-and-la-nina</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x37164ff4a860b19b.jpg</video:thumbnail_loc><video:title>El Niño and La Niña</video:title><video:description>El Niño and La Niña are climate patterns in the Pacific Ocean that can cause global changes in rainfall, wind, and ocean circulation. El Niño characterized by warmer ocean temperatures, can lead to heavy rainfall or severe drought in different regions. La Niña, on the other hand, is its cooler counterpart. These phenomena, influenced by geological and geographic factors, can drastically affect weather patterns worldwide.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/U2-ACg2kbTA.mp4/U2-ACg2kbTA.mp4</video:content_loc><video:duration>416</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-college-environmental-science/v/impacts-of-agricultural-practices</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3903040a49a97dcc.jpg</video:thumbnail_loc><video:title>Impacts of agricultural practices</video:title><video:description>Agricultural practices like tilling, slash-and-burn farming, and the use of fertilizers can cause significant environmental damage. Tilling can lead to soil erosion, while slash-and-burn farming contributes to deforestation and climate change. Overuse of fertilizers can result in water pollution and harmful algal blooms. Sustainable alternatives exist, offering hope for more environmentally friendly agriculture.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/dbEtcjNxGVQ.mp4/dbEtcjNxGVQ.mp4</video:content_loc><video:duration>459</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-college-environmental-science/v/impacts-of-urbanization</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6404e80a65961231.jpg</video:thumbnail_loc><video:title>Impacts of urbanization</video:title><video:description>Urbanization, the growth of cities, offers many advantages but also poses environmental challenges. High population densities can strain resources and increase pollution. However, sustainable urban planning, such as incorporating green spaces and permeable surfaces, can mitigate these effects. Thoughtful city design can reduce runoff, prevent saltwater intrusion, and decrease air pollution, making urban centers more sustainable.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2C7F_2OpRT8.mp4/2C7F_2OpRT8.mp4</video:content_loc><video:duration>379</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-college-environmental-science/v/introduction-to-sustainability</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7d3f2679e9bcc89c.jpg</video:thumbnail_loc><video:title>Introduction to sustainability</video:title><video:description>Sustainability refers to humans living on Earth and their use of resources without depletion of the resources for future generations. Environmental indicators that can guide humans to sustainability include biological diversity, food production, average global surface temperatures and CO2 concentrations, human population, and resource depletion. Sustainable yield is the amount of a renewable resource that can be taken without reducing the available supply.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/k6jUaaQNY28.mp4/k6jUaaQNY28.mp4</video:content_loc><video:duration>381</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-college-environmental-science/v/integrated-pest-management</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdca3e64a3265acb1.jpg</video:thumbnail_loc><video:title>Integrated pest management</video:title><video:description>Integrated pest management (IPM) is a combination of methods used to effectively control pest species while minimizing the disruption to the environment. These methods include biological, physical, and limited chemical methods such as biocontrol, intercropping, crop rotation, and natural predators of the pests. Integrated pest management (IPM) minimizes disruptions to the environment and threats to human health but can be complex and expensive.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/z2AMnP4nn2E.mp4/z2AMnP4nn2E.mp4</video:content_loc><video:duration>403</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-college-environmental-science/v/nuclear-power-generation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7ffc27b764b1bc3d.jpg</video:thumbnail_loc><video:title>Nuclear power generation</video:title><video:description>Nuclear power plants generate electricity by using the heat from nuclear fission to create steam, which spins turbines. This process involves splitting atoms of Uranium-235, a heavy and unstable isotope, in a controlled chain reaction. Nuclear power is considered clean energy because it does not produce air pollutants. The resulting nuclear waste, however, poses significant disposal challenges due to its long-lasting radioactivity.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/E7UIonbL4FU.mp4/E7UIonbL4FU.mp4</video:content_loc><video:duration>439</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-college-environmental-science/v/solar-energy</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2add0be89e793438.jpg</video:thumbnail_loc><video:title>Solar energy</video:title><video:description>Passive solar energy systems absorb heat directly from the sun without the use of mechanical and electric equipment, and energy cannot be collected or stored. Active solar energy systems use solar energy to heat a liquid through mechanical and electric equipment to collect and store the energy captured from the sun. Photovoltaic solar cells capture light energy from the sun and transform it directly into electrical energy. Their use is limited by the availability of sunlight.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OVODBZUJAYE.mp4/OVODBZUJAYE.mp4</video:content_loc><video:duration>408</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-college-environmental-science/v/energy-conservation-methods</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9589d40917e5ed3a.jpg</video:thumbnail_loc><video:title>Energy conservation methods</video:title><video:description>Some of the methods for conserving energy around the home include adjusting the thermostat to reduce the use of heat and air conditioning, conserving water, use of energy efficient appliances, and conservation landscaping. Methods for conserving energy on a large scale include improving fuel economy for vehicles, using BEVs and hybrid vehicles, using public transportation, and implementing green building design features.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/GSc5zo4WjJs.mp4/GSc5zo4WjJs.mp4</video:content_loc><video:duration>357</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-college-environmental-science/v/indoor-air-pollutants</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xda3f60efaf345b1c.jpg</video:thumbnail_loc><video:title>Indoor air pollutants</video:title><video:description>Indoor air pollutants can come from natural sources, human-made sources, and combustion. Common natural pollutants include radon, mold, and dust. Common human-made pollutants include Volatile Organic Compounds (VOCs) and formaldehyde. Common combustion pollutants include carbon monoxide, nitrogen oxides, sulfur dioxide, particulates, and tobacco smoke.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/nqRPRwO79kg.mp4/nqRPRwO79kg.mp4</video:content_loc><video:duration>415</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-college-environmental-science/v/solid-waste-disposal</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfb680d074f409e05.jpg</video:thumbnail_loc><video:title>Solid waste disposal</video:title><video:description>Solid waste is most often disposed of in open dumps and sanitary landfills. A sanitary municipal landfill consists of a bottom liner (plastic or clay), a storm water collection system, a leachate collection system, a cap, and a methane collection system. However, landfills can contaminate groundwater, cause leachate pollution, and release harmful gases. Solid waste can also be disposed of through incineration, where waste is burned at high temperatures.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LOzMugtKmN4.mp4/LOzMugtKmN4.mp4</video:content_loc><video:duration>476</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-college-environmental-science/v/pathogens-and-the-environment</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7087ff0baca6a5a6.jpg</video:thumbnail_loc><video:title>Pathogens and the environment</video:title><video:description>Pathogens, such as the pathogen that causes malaria, adapt to take advantage of new opportunities to infect and spread through human populations. As equatorial-type climate zones spread north and south into what are currently subtropical and temperate climate zones, pathogens, infectious diseases, and any associated vectors are spreading into these areas where the disease has not previously been know to occur.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/wyd0ozxbWkk.mp4/wyd0ozxbWkk.mp4</video:content_loc><video:duration>277</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-college-environmental-science/v/stratospheric-ozone-depletion</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x997edc67965c5b93.jpg</video:thumbnail_loc><video:title>Stratospheric ozone depletion</video:title><video:description>Ozone, a molecule composed of three oxygen atoms, plays a dual role in our atmosphere. In the stratosphere, it forms a protective layer that absorbs harmful UV light, reducing the risk of skin cancer. However, human activities like aerosol sprays and car exhaust can deplete this layer. Conversely, in the troposphere where we live, ozone is harmful, damaging living tissue and respiratory systems.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5CGtESB40Rc.mp4/5CGtESB40Rc.mp4</video:content_loc><video:duration>309</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-college-environmental-science/v/ocean-acidification</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x988f7138251565ec.jpg</video:thumbnail_loc><video:title>Ocean acidification</video:title><video:description>Ocean acidification, a result of increased atmospheric carbon dioxide, is making our oceans more acidic, disrupting the formation of calcium carbonate in sea life and disturbing their homeostasis. This phenomenon is linked to emissions from human activities, such as the combustion of fossil fuels, driving vehicles, and deforestation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8JUEga3MYsM.mp4/8JUEga3MYsM.mp4</video:content_loc><video:duration>325</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-college-environmental-science/v/climate-emergency-feedback-loops-albedo</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x44f701903381efad.jpg</video:thumbnail_loc><video:title>Climate emergency: feedback loops - albedo</video:title><video:description>Climate change is setting off dangerous feedback loops at the Poles. The melting of Arctic ice and snow decreases Earth&apos; ability to reflect the Sun&apos;s rays, leading to further heating and melting of ice and snow. In Antarctica, the warmer climate is melting ice sheets, leading to raised sea levels, which melts ice sheets further in an amplifying loop.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/HNqTxBHgC0Y.mp4/HNqTxBHgC0Y.mp4</video:content_loc><video:duration>636</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-college-environmental-science/v/climate-emergency-feedback-loops-permafrost</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3e5c07edd70ee925.jpg</video:thumbnail_loc><video:title>Climate emergency: feedback loops - permafrost</video:title><video:description>Global warming is causing the thawing of permafrost, the icy expanse of frozen ground covering one-quarter of the Northern Hemisphere. As it melts, previously frozen carbon stored in plant and animal remains is released into the atmosphere as heat-trapping greenhouse gases, warming the climate further, and melting more permafrost in a dangerous feedback loop.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/e44IYZ-gQnE.mp4/e44IYZ-gQnE.mp4</video:content_loc><video:duration>655</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-college-physics-1/v/introduction-to-ap-physics-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xde8838aa7c5bd894.jpg</video:thumbnail_loc><video:title>Introduction to AP Physics 1</video:title><video:description>AP Physics 1 is an algebra-based, introductory college-level mechanics course. In this course you&apos;ll explore the following topics: Kinematics; Forces and translational dynamics; Work, energy, and power; Linear momentum; Torque and rotational dynamics; Energy and momentum of rotating systems; Oscillations; Fluids.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/21p-yiQ9xy4.mp4/21p-yiQ9xy4.mp4</video:content_loc><video:duration>188</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-college-physics-1/v/position-velocity-speed</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf119ffb760f77fa2.jpg</video:thumbnail_loc><video:title>Position, velocity, and speed</video:title><video:description>An object&apos;s position specifies how far the object is from a reference point, and in what direction. The rate that an object&apos;s position changes is called velocity. Average velocity is calculated as change in position divided by change in time. Position and velocity are vector quantities. Average speed is calculated as distance travelled divided by time. Speed and distance are scalar quantities with no direction.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vOipqtdR23s.mp4/vOipqtdR23s.mp4</video:content_loc><video:duration>624</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-college-physics-1/v/intro-to-relative-velocity-class-11-india-physics-khan-academy</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x587cc05eb5ce0e1c.jpg</video:thumbnail_loc><video:title>Relative velocity</video:title><video:description>Velocity depends on the point of view we take. Let&apos;s discuss what relative velocity is and how to visualize it.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/EmOis0kQuxM.mp4/EmOis0kQuxM.mp4</video:content_loc><video:duration>403</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/highschool-physics/v/interpreting-motion-data</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf6edb2e65b2f7003.jpg</video:thumbnail_loc><video:title>Interpreting motion data</video:title><video:description>The same motion data can be presented in various ways, including dot (oil drop) diagrams, position-time tables, and position vs. time graphs. The slope of a position vs. time graph represents the object&apos;s velocity: A straight line (constant slope) means the object moved with constant velocity, and a curved line (changing slope) means the object accelerated.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-1xbgz26ZNs.mp4/-1xbgz26ZNs.mp4</video:content_loc><video:duration>606</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-college-physics-1/v/instantaneous-speed-and-velocity</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc7e30831.jpg</video:thumbnail_loc><video:title>Instantaneous speed and velocity</video:title><video:description>Instantaneous speed is a measurement of how fast an object is moving at that particular moment. Instantaneous velocity is a vector quantity that includes both the speed and the direction in which the object is moving. Learn how to find an object’s instantaneous speed or velocity in three ways - by using calculus, by looking at the slope of a given point on a graph of an object’s rate vs. time, or by using kinematic formulas if the object’s acceleration is constant.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pfTTHx9kCHk.mp4/pfTTHx9kCHk.mp4</video:content_loc><video:duration>278</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-college-physics-1/v/position-vs-time-graphs</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x92717942.jpg</video:thumbnail_loc><video:title>Position vs. time graphs</video:title><video:description>Learn how to interpret a position vs. time graph. Use a position vs. time graph to determine displacement, distance, average velocity, average speed, instantaneous velocity, and instantaneous speed.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/GtoamALPOP0.mp4/GtoamALPOP0.mp4</video:content_loc><video:duration>920</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-college-physics-1/v/intro-to-acceleration</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9430b28c45d8ba63.jpg</video:thumbnail_loc><video:title>Acceleration</video:title><video:description>Acceleration is the rate of change of velocity (a = Δv/Δt). The unit for acceleration is m/s/s, or m/s^2. Acceleration is a vector with magnitude and direction. If velocity and acceleration point the same direction, the object is speeding up. If velocity and acceleration point opposite directions, the object is slowing down. Changing direction is also a form of acceleration.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/JSPwCtIPfQw.mp4/JSPwCtIPfQw.mp4</video:content_loc><video:duration>620</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-c-mechanics/v/developing-kinematic-equations-from-data</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc28c1da86812be33.jpg</video:thumbnail_loc><video:title>Developing kinematic equations from data</video:title><video:description>Experimental data for an object moving with constant acceleration can be used to develop the kinematic equations. See how this can be accomplished using a process called linearization.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/dr39gKnviAc.mp4/dr39gKnviAc.mp4</video:content_loc><video:duration>785</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-c-mechanics/v/proportional-reasoning-with-motion</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x89e97e7d9a53e82f.jpg</video:thumbnail_loc><video:title>Proportional reasoning with motion</video:title><video:description>Different motion scenarios can be compared using proportional reasoning. Even if exact values aren&apos;t known for each value, the factor of change in one variable can be used to predict the factor of change in another.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pJWRXgqn8PA.mp4/pJWRXgqn8PA.mp4</video:content_loc><video:duration>766</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-c-mechanics/v/projectile-motion</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x25aad12b6fe977c1.jpg</video:thumbnail_loc><video:title>Projectile motion</video:title><video:description>Motion in multiple dimensions can be analyzed using one-dimensional kinematic relationships if the motion is separated into components. Projectile motion is a special case of two-dimensional motion that has zero acceleration in the horizontal dimension, and constant acceleration of magnitude g in the vertical dimension.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/txJP95lBv98.mp4/txJP95lBv98.mp4</video:content_loc><video:duration>687</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-c-mechanics/v/forces-and-free-body-diagrams</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb990f782a3eafd50.jpg</video:thumbnail_loc><video:title>Forces and free-body diagrams</video:title><video:description>A force is a vector quantity that describes a push or pull. A variety of contact forces (e.g., normal force, friction) and non-contact forces (e.g., gravity) may act on an object simultaneously. A free-body diagram is a model that shows each of the external forces exerted on an object. Forces are represented as vector arrows originating from the representation of the center of mass, such as a dot. A free-body diagram is useful for determining the net force on an object, which is the vector sum of all the individual forces acting on the object.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/i447NWNpScM.mp4/i447NWNpScM.mp4</video:content_loc><video:duration>734</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/highschool-physics/v/newtons-second-law-calculations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x380fd629c47b0e53.jpg</video:thumbnail_loc><video:title>Newton&apos;s second law calculations</video:title><video:description>Newton&apos;s second law can be used to calculate the acceleration that an object will experience, if the net force acting on the object and its mass are known. The law can also be used to determine the net force required to produce a certain acceleration for a known mass. Remember that the force term in Newton&apos;s second law refers to the net force on the object.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/O5G4uHe-qc4.mp4/O5G4uHe-qc4.mp4</video:content_loc><video:duration>595</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-c-mechanics/v/forces-at-an-angle</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2bcd7bcb1f04bcea.jpg</video:thumbnail_loc><video:title>Forces at an angle</video:title><video:description>Forces may act on an object in more than one dimension. Such scenarios may require one or more the forces to be resolved into components. Learn how to analyze scenarios involving forces acting at different angles by first creating a free-body diagram, and then applying trigonometry and Newton’s second law.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/W6rb-0AghZE.mp4/W6rb-0AghZE.mp4</video:content_loc><video:duration>820</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-c-mechanics/v/two-masses-hanging-from-a-pulley</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x483e06a2.jpg</video:thumbnail_loc><video:title>Analyzing systems</video:title><video:description>Learn how to analyze the motion of one or more masses moving together as a system, using the example of two masses hanging from a pulley.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/BrLbtCnrPaA.mp4/BrLbtCnrPaA.mp4</video:content_loc><video:duration>530</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-c-mechanics/v/gravitational-forces-and-fields</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x41b2aee0d318cf7a.jpg</video:thumbnail_loc><video:title>Gravitational forces and fields</video:title><video:description>Newton’s law of universal gravitation describes the gravitational forces two objects exert on each other. The gravitational force is always attractive and is exerted along the line connecting the two objects’ centers of mass. The gravitational field created by an object at a point in space is the gravitational force exerted on another test object at that location, divided by the mass of the test object. If the gravitational force is the only force exerted on an object, the observed acceleration of the object (in m/s^2) is numerically equal to the magnitude of the gravitational field strength (in N/kg) at that location.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/CJV7RZNCN28.mp4/CJV7RZNCN28.mp4</video:content_loc><video:duration>735</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-c-mechanics/v/weight-apparent-weight-and-weightlessness</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfe1787b7f502fea9.jpg</video:thumbnail_loc><video:title>Weight, apparent weight, and weightlessness</video:title><video:description>The gravitational force exerted by an astronomical body on a relatively small nearby object is called weight. The magnitude of the apparent weight of an object is the magnitude of the normal force exerted on the object. If the system is accelerating vertically, the apparent weight of the object is not equal to the magnitude of the gravitational force exerted on the object. A system appears weightless when there are no forces exerted on the system, or when the force of gravity is the only force exerted on the system.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tVsYgAM8MV4.mp4/tVsYgAM8MV4.mp4</video:content_loc><video:duration>750</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-c-mechanics/v/inertial-mass-vs-gravitational-mass</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4b66995f72c3636e.jpg</video:thumbnail_loc><video:title>Inertial and gravitational mass</video:title><video:description>The inertial and gravitational mass of an object have the same value, but they describe two different things about an object. Learn how to distinguish between inertial and gravitational mass and measure each independently of each other.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Ws3yB3QsKY4.mp4/Ws3yB3QsKY4.mp4</video:content_loc><video:duration>492</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-college-physics-1/v/yo-yo-in-vertical-circle-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd634e085.jpg</video:thumbnail_loc><video:title>Mass swinging in vertical circle example</video:title><video:description>Practice finding the tension in a string that is swinging a mass in a vertical circle.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2lcaBPLLoLo.mp4/2lcaBPLLoLo.mp4</video:content_loc><video:duration>631</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-college-physics-1/v/bowling-ball-in-vertical-loop</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfa6de716.jpg</video:thumbnail_loc><video:title>Ball in vertical loop example</video:title><video:description>Practice finding the normal force on a ball moving through a vertical, circular loop.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Xpgsg-fY4DY.mp4/Xpgsg-fY4DY.mp4</video:content_loc><video:duration>529</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-college-physics-1/v/mass-swinging-in-a-horizontal-circle</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x916bbdd0.jpg</video:thumbnail_loc><video:title>Conical pendulum example</video:title><video:description>Practice solving for the tension and speed of a mass swinging at an angle in a horizontal circle.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0cDmgCcX_nU.mp4/0cDmgCcX_nU.mp4</video:content_loc><video:duration>759</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-college-physics-1/v/work-energy-principle-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x21e9f77d9b2d17da.jpg</video:thumbnail_loc><video:title>Work-energy theorem example</video:title><video:description>The work-energy theorem tells us the amount of work done on an object or system will equal the change in kinetic energy for that object or system. Follow along in this worked example and understand about how to calculate the net work on an object and solve for the change in velocity.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/BYkxKrbETb4.mp4/BYkxKrbETb4.mp4</video:content_loc><video:duration>465</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-college-physics-1/v/work-as-area-under-curve</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4ec43ac2.jpg</video:thumbnail_loc><video:title>Force vs. displacement graphs</video:title><video:description>Explore how the area under a force vs. displacement graph equals the work done by the force.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/z01om-Qk2xM.mp4/z01om-Qk2xM.mp4</video:content_loc><video:duration>751</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-college-physics-1/v/potential-energy</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2d81835ffb8a2805.jpg</video:thumbnail_loc><video:title>Potential energy</video:title><video:description>Potential energy exists in a system of interacting objects. The amount of potential energy depends on the objects&apos; relative positions. If two objects attract gravitationally or electrically, potential energy increases as they get farther apart. If two objects repel electrically, potential energy increases as they get closer. Elastic and chemical potential energy are fundamentally the result of electric potential energy at the particle level.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/aUrms3VFn0I.mp4/aUrms3VFn0I.mp4</video:content_loc><video:duration>840</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-c-mechanics/v/conservation-of-energy-part-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x90c1c34496cc87d8.jpg</video:thumbnail_loc><video:title>Conservation of energy (part 1)</video:title><video:description>Mechanical energy is the sum of a system’s kinetic and potential energies. If the work done on a selected system is zero and there are no nonconservative interactions within the system, the total mechanical energy of the system is constant. If the work done on a selected system is nonzero, energy is transferred between the system and the environment.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/GdDrYgXzBew.mp4/GdDrYgXzBew.mp4</video:content_loc><video:duration>1043</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-c-mechanics/v/conservation-of-energy-part-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x99364af703a675e9.jpg</video:thumbnail_loc><video:title>Conservation of energy (part 2)</video:title><video:description>Energy is conserved in all interactions. Any change to a type of energy within a system must be balanced by an equivalent change of other types of energies within the system, or by a transfer of energy between the system and its surroundings.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/JrVd-czHl_g.mp4/JrVd-czHl_g.mp4</video:content_loc><video:duration>640</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-c-mechanics/v/power</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3e147b11.jpg</video:thumbnail_loc><video:title>Power</video:title><video:description>In physics, power is defined as the rate at which work is done. It measures how quickly energy is being transferred or converted. Learn how to calculate both average and instantaneous power.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/RpbxIG5HTf4.mp4/RpbxIG5HTf4.mp4</video:content_loc><video:duration>346</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-college-physics-1/v/momentum</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6a3d52879f7f19e4.jpg</video:thumbnail_loc><video:title>Momentum</video:title><video:description>Momentum is the product of an object&apos;s mass and its velocity. It is a vector quantity. Newton&apos;s second law can be rearranged to reveal that the net force on an object is equal to the rate of change of the object&apos;s momentum. The larger the net force experienced by an object, the more rapidly the object&apos;s momentum will change.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/UoIIwzHug9M.mp4/UoIIwzHug9M.mp4</video:content_loc><video:duration>601</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-college-physics-1/v/impulse</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd92e4729de316580.jpg</video:thumbnail_loc><video:title>Impulse</video:title><video:description>Impulse is a change in an object&apos;s momentum. The impulse experienced by an object is equal to the net force acting on the object multiplied by the length of time the force acts (Δp = ΣFΔt). The same impulse can be caused by a large force acting for a short time, or a small force acting for a long time.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/JlxJYSFPpQo.mp4/JlxJYSFPpQo.mp4</video:content_loc><video:duration>764</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-college-physics-1/v/impulse-and-momentum-dodgeball-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2680c555.jpg</video:thumbnail_loc><video:title>Impulse and momentum example</video:title><video:description>Practice solving for the impulse and force applied during a dodgeball collision using the impulse-momentum theorem.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/uMYAc04D0ak.mp4/uMYAc04D0ak.mp4</video:content_loc><video:duration>633</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-college-physics-1/v/force-vs-time-graphs</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x33970627.jpg</video:thumbnail_loc><video:title>Force vs. time graphs</video:title><video:description>Learn how to use a force vs. time graph to find the change in momentum. Solve an example problem to find the final velocity of a spaceship.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8bHPj3ll0vs.mp4/8bHPj3ll0vs.mp4</video:content_loc><video:duration>494</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-c-mechanics/v/conservation-of-linear-momentum</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x759ac7a51a8176c0.jpg</video:thumbnail_loc><video:title>Conservation of linear momentum</video:title><video:description>Linear momentum is conserved in all interactions. If the net external force on the selected system is zero, the total momentum of the system is constant. If the net external force on the selected system is nonzero, momentum is transferred between the system and the environment. Conservation of momentum can be used to determine the velocity of objects in a system immediately before or after a collision or explosion.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/zQLxbN8dxJg.mp4/zQLxbN8dxJg.mp4</video:content_loc><video:duration>909</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-college-physics-1/v/bouncing-fruit-collision-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfe43c81b.jpg</video:thumbnail_loc><video:title>Bouncing fruit collision example</video:title><video:description>When an object with known velocity collides with an object at rest, and the velocity of one of the objects after the collision is known, conservation of momentum can be used to determine the velocity of the other object after the collision. It is important to consider the directions of velocity and momentum when interpreting signs in the calculation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1i8VMBvMQ_E.mp4/1i8VMBvMQ_E.mp4</video:content_loc><video:duration>553</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-c-mechanics/v/torque-basics</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x478911d9db4dedc9.jpg</video:thumbnail_loc><video:title>Intro to torque</video:title><video:description>A torque is the rotational equivalent of a force. When a torque is applied to an object it causes the object to rotate. Learn how forces create torques and how to calculate the net torque on a rotating object.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TQQXpFhACSU.mp4/TQQXpFhACSU.mp4</video:content_loc><video:duration>580</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-c-mechanics/v/finding-torque-for-angled-forces</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3956371b.jpg</video:thumbnail_loc><video:title>Finding torque for angled forces</video:title><video:description>David explains how to determine the torque exerted by a non-perpendicular force.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ZQnGh-t25tI.mp4/ZQnGh-t25tI.mp4</video:content_loc><video:duration>714</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-c-mechanics/v/rotational-version-of-newtons-second-law</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x88f76235.jpg</video:thumbnail_loc><video:title>Rotational version of Newton&apos;s second law</video:title><video:description>David explains moment of inertia and the rotational version of Newton&apos;s second law and shows how to solve an example problem.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xusMSv2z77s.mp4/xusMSv2z77s.mp4</video:content_loc><video:duration>836</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-c-mechanics/v/more-on-moment-of-inertia</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfcb88944.jpg</video:thumbnail_loc><video:title>Rotational inertia</video:title><video:description>Learn about rotational inertia, also called &quot;moment of inertia,&quot; for commonly shaped objects.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lwO0V5FitAo.mp4/lwO0V5FitAo.mp4</video:content_loc><video:duration>899</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-c-mechanics/v/rotational-kinetic-energy-of-rigid-systems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0ff40b625f3c3b0f.jpg</video:thumbnail_loc><video:title>Rotational kinetic energy of rigid systems</video:title><video:description>The rotational kinetic energy of a rigid system is related to the rotational inertia and angular velocity of the rigid system. The total kinetic energy of a rigid system is the sum of its rotational kinetic energy due to its rotation about its center of mass, and its translational kinetic energy due to the linear motion of its center of mass. Rotational kinetic energy is a scalar quantity.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pY1rwEsdCRo.mp4/pY1rwEsdCRo.mp4</video:content_loc><video:duration>758</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-c-mechanics/v/rolling-without-slipping-problems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb0e01a66.jpg</video:thumbnail_loc><video:title>Rolling without slipping</video:title><video:description>Learn how to solve problems where an object rolls without slipping.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5eX5WnPDnvs.mp4/5eX5WnPDnvs.mp4</video:content_loc><video:duration>900</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-college-physics-1/v/angular-momentum-of-rigid-systems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5bbe90fc15a802c7.jpg</video:thumbnail_loc><video:title>Angular momentum of rigid systems</video:title><video:description>The magnitude of the angular momentum of a rigid system about a specific axis is related to the rotational inertia and angular velocity of the rigid system. Angular impulse is defined as the product of the torque exerted on an object or rigid system and the time interval during which the torque is exerted. Angular impulse has the same direction as the torque imparting it. A rotational form of the impulse-momentum theorem relates the angular impulse delivered to a rigid system to the change in angular momentum of that rigid system.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/noZr4jX8HIw.mp4/noZr4jX8HIw.mp4</video:content_loc><video:duration>870</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-c-mechanics/v/conservation-of-angular-momentum-ap</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7fb54f2877e8c5fa.jpg</video:thumbnail_loc><video:title>Conservation of angular momentum</video:title><video:description>Angular momentum is conserved in all interactions. The angular impulse exerted by one rigid system on a second is equal and opposite to the angular impulse exerted by the second rigid system on the first. If the net external torque exerted on a selected system is nonzero, angular momentum is transferred between the system and the environment. The angular speed of a nonrigid system may change without the angular momentum of the system changing if the system changes shape by moving mass closer to or farther from the rotational axis.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-7trrETEE7k.mp4/-7trrETEE7k.mp4</video:content_loc><video:duration>859</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-c-mechanics/v/angular-momentum-of-satellites</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x921b86774920501e.jpg</video:thumbnail_loc><video:title>Angular momentum of satellites</video:title><video:description>Point objects have linear momentum. The selection of the axis about which an object is considered to rotate influences the determination of the angular momentum of that object. The measured angular momentum of an object traveling in a straight line depends on the distance between the reference point and the object, the mass of the object, the speed of the object, and the angle between the radial distance and the velocity of the object. Angular momentum is constant for a satellite in a circular or elliptical orbit.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/inus3WE5eTI.mp4/inus3WE5eTI.mp4</video:content_loc><video:duration>931</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-c-mechanics/v/energy-of-satellite-systems</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xec735d999ce9cc24.jpg</video:thumbnail_loc><video:title>Energy of satellite systems</video:title><video:description>In circular and elliptical orbits, the satellite-central-object system’s total mechanical energy is constant. In elliptical orbits, the system’s gravitational potential energy and the satellite’s kinetic energy both change while the total remains constant. The total energy of a system consisting of a satellite orbiting a central object in a circular path can be written in terms of the gravitational potential energy of that system or the kinetic energy of the satellite. The escape velocity of a satellite is the satellite’s velocity such that the mechanical energy of the satellite-central-object system is equal to zero.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/A-YeMNeq55E.mp4/A-YeMNeq55E.mp4</video:content_loc><video:duration>945</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-c-mechanics/v/shm-of-spring-mass-oscillators</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x71aeb67e4e299c68.jpg</video:thumbnail_loc><video:title>SHM of spring-mass oscillators</video:title><video:description>Simple harmonic motion (SHM) is a special case of periodic motion which results when the magnitude of the restoring force exerted on an object is proportional to that object’s displacement from its equilibrium position. SHM is described by sinusoidal position, velocity, and acceleration functions. A spring-mass oscillator is one type of system that undergoes SHM. The period of a spring-mass oscillator is related to its mass and spring constant.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/eRZSzGKDfwU.mp4/eRZSzGKDfwU.mp4</video:content_loc><video:duration>913</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-c-mechanics/v/energy-of-spring-mass-oscillators</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb40960b7284455b1.jpg</video:thumbnail_loc><video:title>Energy of spring-mass oscillators</video:title><video:description>The total energy of a system exhibiting simple harmonic motion (SHM) is the sum of the system’s kinetic and potential energies. The kinetic energy of a horizontal spring-mass system exhibiting SHM is at a maximum when the system’s potential energy is at a minimum, and vice versa. The minimum kinetic energy of a system exhibiting SHM is zero. The mechanical energy of an ideal spring-mass system is proportional to the amplitude of oscillation squared.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8dx1iJTZeGM.mp4/8dx1iJTZeGM.mp4</video:content_loc><video:duration>895</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-c-mechanics/v/shm-simple-pendulums</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe3e68eae0670555a.jpg</video:thumbnail_loc><video:title>SHM of simple pendulums</video:title><video:description>For small amplitudes of motion, the small-angle approximation can be applied to the restoring torque exerted by gravity on a simple pendulum. Therefore, the motion of a pendulum with a small angular displacement can be modeled as simple harmonic motion because the restoring torque is proportional to the angular displacement. The period of a simple pendulum is related to its length and the magnitude of the gravitational field.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Dv5R543h3XM.mp4/Dv5R543h3XM.mp4</video:content_loc><video:duration>734</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-college-physics-1/v/fluids-and-density</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xff493141dae7a7cc.jpg</video:thumbnail_loc><video:title>Fluids and density</video:title><video:description>A fluid is a substance that has no fixed shape. Fluids include liquids and gases. Fluids can be characterized by their density, which is defined as the ratio of mass to volume. The ideal fluid model assumes a fluid is incompressible (same density everywhere) and has no viscosity (no resistance to flow).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/AJxYCosjRH0.mp4/AJxYCosjRH0.mp4</video:content_loc><video:duration>791</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-college-physics-1/v/fluid-pressure</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6a8251710da8a707.jpg</video:thumbnail_loc><video:title>Fluid pressure</video:title><video:description>Pressure is the magnitude of the perpendicular force component exerted per unit area over a given surface area. Pressure is a scalar quantity. The pressure exerted by a fluid is the result of the interactions between the fluid’s particles and the surface with which those particles interact. The absolute pressure of a fluid at a given point is equal to the sum of a reference pressure, such as the atmospheric pressure, and the gauge pressure at that depth in the fluid. Pressure increases with depth in an incompressible fluid.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/p_WLHzF1SdI.mp4/p_WLHzF1SdI.mp4</video:content_loc><video:duration>948</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-college-physics-1/v/buoyant-force</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xec75b8131e0cf089.jpg</video:thumbnail_loc><video:title>Buoyant force</video:title><video:description>The buoyant force is a net upward force exerted on an object by a fluid. The buoyant force results from the increase in fluid pressure with depth. The magnitude of the buoyant force exerted on an object by a fluid is equal to the weight of fluid displaced by the object (ρVg).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/NYWG5eXRBFQ.mp4/NYWG5eXRBFQ.mp4</video:content_loc><video:duration>761</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-college-physics-1/v/fluid-flow</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa0d04651dbce0c98.jpg</video:thumbnail_loc><video:title>Fluid flow</video:title><video:description>A difference in pressure between two locations causes a fluid to flow. Pressure differences can be created in various ways, such as removing air from one region (e.g., drinking through a straw) or maintaining a height of fluid (e.g., water towers). For an incompressible fluid, the rate at which matter enters a fluid-filled tube open at both ends must equal the rate at which fluid exits the tube. This conservation of mass is described by the continuity equation (A1v1 = A2v2).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ZBvQfi3P0l4.mp4/ZBvQfi3P0l4.mp4</video:content_loc><video:duration>622</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-college-physics-1/v/ap-physics-1-review-of-1d-motion</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x98abe201.jpg</video:thumbnail_loc><video:title>Review of 1D motion</video:title><video:description>Review of 1D motion</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/NyPbcdE9v6o.mp4/NyPbcdE9v6o.mp4</video:content_loc><video:duration>963</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-college-physics-1/v/ap-physics-1-review-of-2d-motion-and-vectors</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc28ac6fc.jpg</video:thumbnail_loc><video:title>Review of 2D motion and vectors</video:title><video:description>Review of 2D motion and vectors</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/YJEfSqlSxks.mp4/YJEfSqlSxks.mp4</video:content_loc><video:duration>781</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-college-physics-1/v/ap-physics-1-review-of-forces-and-newtons-laws</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x001423f1.jpg</video:thumbnail_loc><video:title>Review of forces and Newton&apos;s laws</video:title><video:description>Review of forces and Newton&apos;s laws</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Bkl6Mn1Y23Q.mp4/Bkl6Mn1Y23Q.mp4</video:content_loc><video:duration>1036</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-college-physics-1/v/ap-physics-1-review-of-centripetal-forces</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe426ea78.jpg</video:thumbnail_loc><video:title>Review of circular motion and orbits</video:title><video:description>Review of circular motion and orbits</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0r_JWUkXEkY.mp4/0r_JWUkXEkY.mp4</video:content_loc><video:duration>954</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-college-physics-1/v/ap-physics-1-review-of-energy-and-work</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdfe60a80.jpg</video:thumbnail_loc><video:title>Review of energy and work</video:title><video:description>Review of energy and work</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/65uG6v7YY2Q.mp4/65uG6v7YY2Q.mp4</video:content_loc><video:duration>735</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-college-physics-1/v/ap-physics-1-review-of-momentum-and-impulse</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xeab72a31.jpg</video:thumbnail_loc><video:title>Review of momentum and impulse</video:title><video:description>Review of momentum and impulse</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qMc6KOkmjTU.mp4/qMc6KOkmjTU.mp4</video:content_loc><video:duration>801</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-college-physics-1/v/ap-physics-1-review-of-torque-and-angular-momentum</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf5c55bcd.jpg</video:thumbnail_loc><video:title>Review of rotation</video:title><video:description>Review of rotation</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/uRA8vI2Gzvk.mp4/uRA8vI2Gzvk.mp4</video:content_loc><video:duration>1179</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-college-physics-1/v/ap-physics-1-review-of-waves-and-harmonic-motion</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc4addb94.jpg</video:thumbnail_loc><video:title>Review of oscillations and waves</video:title><video:description>Review of oscillations and waves</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/RA7x81NI8C4.mp4/RA7x81NI8C4.mp4</video:content_loc><video:duration>1195</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/boltzmanns-constant</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9135ec72.jpg</video:thumbnail_loc><video:title>Boltzmann&apos;s constant</video:title><video:description>Explore Ludwig Boltzmann&apos;s groundbreaking atomic theory and his constant&apos;s role in thermal physics. Understand the kinetic-molecular explanation of temperature, the ideal gas law, and the concept of entropy. Uncover the microscopic details of gas molecules and their impact on our understanding of heat energy.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/rVD7HKafnnE.mp4/rVD7HKafnnE.mp4</video:content_loc><video:duration>586</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/hs-chemistry/v/thermal-energy-temperature-and-heat</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x842d6d2d2ab7398c.jpg</video:thumbnail_loc><video:title>Thermal energy, temperature, and heat</video:title><video:description>Thermal energy refers to the kinetic energy of randomly moving particles in a substance. Particles can have translational, rotational, and/or vibrational kinetic energy, depending on the state of matter. Temperature is a measure of the average kinetic energy of the particles in a substance. Heat is thermal energy that transfers into or out of a system. Heat can transfer by conduction, convection, or radiation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-7Gl-yKF6Y4.mp4/-7Gl-yKF6Y4.mp4</video:content_loc><video:duration>692</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/hs-chemistry/v/first-and-second-laws-of-thermodynamics</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfff5b5c700229413.jpg</video:thumbnail_loc><video:title>First and second laws of thermodynamics</video:title><video:description>The first law of thermodynamics states that if a system gains/loses some amount of energy, the surroundings must lose/gain the same amount of energy. The second law of thermodynamics states that entropy does not spontaneously decrease. Entropy is a measure of how spread out energy is. As an example, if two systems at different temperatures are in contact, heat will flow from the warmer system to the cooler system until they reach thermal equilibrium (equal temperatures).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/f1OokOgtcqg.mp4/f1OokOgtcqg.mp4</video:content_loc><video:duration>740</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/hs-chemistry/v/specific-heat-capacity</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x42ab0ebb72ccdf09.jpg</video:thumbnail_loc><video:title>Specific heat capacity</video:title><video:description>If the same amount of heat flows into (or out of) equal masses of different substances, their temperatures may not change by the same amount. Specific heat capacity (c) tells us how much heat energy is required to change one unit mass of a substance by one unit of temperature. Specific heat is related to heat (q), the mass of the sample (m), and the change in temperature (∆T) by the equation q=cm∆T.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/GNelfJ6IAJw.mp4/GNelfJ6IAJw.mp4</video:content_loc><video:duration>828</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/first-law-of-thermodynamics</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xcae8d5fc.jpg</video:thumbnail_loc><video:title>First law of thermodynamics equation</video:title><video:description>Equation for the first law of thermodynamics.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/u4-HYwo0Gsc.mp4/u4-HYwo0Gsc.mp4</video:content_loc><video:duration>683</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/first-law-of-thermodynamics-problem-solving</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9552a749.jpg</video:thumbnail_loc><video:title>First law of thermodynamics problem solving</video:title><video:description>First law of thermodynamics problem solving</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6sP3kV-zgZk.mp4/6sP3kV-zgZk.mp4</video:content_loc><video:duration>454</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/pv-diagrams-part-1-work-and-isobaric-processes</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa78c7d17.jpg</video:thumbnail_loc><video:title>PV diagrams - part 1: Work and isobaric processes</video:title><video:description>PV diagrams - part 1: Work and isobaric processes</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Xcrco59p40o.mp4/Xcrco59p40o.mp4</video:content_loc><video:duration>714</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/pv-diagrams-part-2-isothermal-isometric-adiabatic-processes</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3fea420f.jpg</video:thumbnail_loc><video:title>PV diagrams - part 2: Isothermal, isometric, adiabatic processes</video:title><video:description>There are three types of thermodynamic processes you should know: isothermal, isometric, and adiabatic. An isothermal process is all about keeping the temperature constant, while an isometric process maintains a constant volume. The trickiest of the three is the adiabatic process, where no heat is exchanged and changes in volume can alter both pressure and temperature.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/nkOtOMNS5bQ.mp4/nkOtOMNS5bQ.mp4</video:content_loc><video:duration>780</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/electric-charge-and-electric-force</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0904666c9ca2fdbf.jpg</video:thumbnail_loc><video:title>Electric charge and electric force</video:title><video:description>Electric charge is a scalar quantity and is described as positive or negative. Coulomb’s law describes the electrostatic force between two charged objects as directly proportional to the magnitude of each of the charges and inversely proportional to the square of the distance between the objects. The direction of the electrostatic force depends on the signs of the charges of the interacting objects and is along the line of separation between the objects. Free space has a constant value of electric permittivity that appears in physical relationships.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lU8qZ0UyZUk.mp4/lU8qZ0UyZUk.mp4</video:content_loc><video:duration>720</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/conservation-of-electric-charge</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbfd65529fc7ca75a.jpg</video:thumbnail_loc><video:title>Conservation of electric charge</video:title><video:description>The net charge or charge distribution of a system can change in response to the presence of, or changes in, the net charge or charge distribution of other systems. Any change to a system’s net charge is due to a transfer of charge between the system and its surroundings. Grounding involves electrically connecting a charged object to a much larger and approximately neutral system (e.g., Earth).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1IXsgu44pMs.mp4/1IXsgu44pMs.mp4</video:content_loc><video:duration>797</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/electric-fields-part-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xae2924f3faae10ab.jpg</video:thumbnail_loc><video:title>Electric fields (part 1)</video:title><video:description>The electric field at a given point is the ratio of the electric force exerted on a test charge at the point to the charge of the test charge. An electric field points away from isolated positive charges and toward isolated negative charges. By superposition, the net electric field at a given location is the vector sum of individual electric fields created by nearby charged objects. The electric field is a vector quantity and can be represented in space using vector field maps.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/D2Lh7Dlqn1o.mp4/D2Lh7Dlqn1o.mp4</video:content_loc><video:duration>726</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/electric-fields-part-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6535ea7a2300cda4.jpg</video:thumbnail_loc><video:title>Electric fields (part 2)</video:title><video:description>While in electrostatic equilibrium, the excess charge of a conductor is distributed on the surface of the conductor, and the electric field within the conductor is zero. At the surface of a charged conductor, the electric field is perpendicular to the surface. While in electrostatic equilibrium, the excess charge of an insulator may be distributed throughout the interior of the insulator as well as at the surface, and the electric field within the insulator may have a nonzero value.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/UypFZ2GNoKg.mp4/UypFZ2GNoKg.mp4</video:content_loc><video:duration>593</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/electric-potential-energy-ap</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xec63afba68616423.jpg</video:thumbnail_loc><video:title>Electric potential energy</video:title><video:description>The electric potential energy of a system of two point charges equals the amount of work required for an external force to bring the point charges to their current positions from infinitely far away. The total electric potential energy of a system can be determined by finding the sum of the electric potential energies of the individual interactions between each pair of charged objects in the system.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/CNNLv7COpyY.mp4/CNNLv7COpyY.mp4</video:content_loc><video:duration>671</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/electric-potential</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xecdacbdec8ddd5c9.jpg</video:thumbnail_loc><video:title>Electric potential</video:title><video:description>Electric potential describes the electric potential energy per unit charge at a point in space. The electric potential due to multiple point charges can be determined by the principle of scalar superposition of the electric potential due to each of the point charges. The electric potential difference between two points is the change in electric potential energy per unit charge when a test charge is moved between the two points.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Fj_G5tN84Eg.mp4/Fj_G5tN84Eg.mp4</video:content_loc><video:duration>740</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/electric-potential-and-electric-field</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0744dcb081b12527.jpg</video:thumbnail_loc><video:title>Electric potential and electric field</video:title><video:description>Equipotential lines represent lines of equal electric potential. These lines are also referred to as isolines of electric potential. Isolines are perpendicular to electric field vectors. An isoline map of electric potential can be constructed from an electric field vector map, and an electric field map may be constructed from an isoline map. An electric field vector points in the direction of decreasing potential. There is no component of an electric field along an isoline.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PrykTpvJDOM.mp4/PrykTpvJDOM.mp4</video:content_loc><video:duration>878</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/conservation-of-electric-energy</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5a0d89cd2eeacc9c.jpg</video:thumbnail_loc><video:title>Conservation of electric energy</video:title><video:description>When a charged particle moves between two locations with different electric potentials, the resulting change in the electric potential energy of the particle-field system can be found by multiplying the charge by the electric potential difference between the locations. Assuming no resistive forces, the movement of a charged particle between two points with different electric potentials results in a change in kinetic energy of the particle consistent with the conservation of energy. An electron volt (eV) is a unit of energy equal to the kinetic energy gained by an electron or proton when it accelerates through a potential difference of one volt under the electric force alone.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/cPxnWRp4oPo.mp4/cPxnWRp4oPo.mp4</video:content_loc><video:duration>825</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/what-is-voltage</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x294dfcab2adcb6fb.jpg</video:thumbnail_loc><video:title>Voltage (electric potential difference)</video:title><video:description>The electric potential at a point represents the electric potential energy per unit charge that a particle would have at that location. The difference in electric potential between two points is called voltage. It&apos;s measured in volts (V), equivalent to joules per coulomb (J/C). When comparing two points, the point with the higher electric potential is labelled positive (+), and the point with the lower electric potential is negative (-). If two points are at the same electric potential, the voltage between them is zero.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/NT6LYNq3jRE.mp4/NT6LYNq3jRE.mp4</video:content_loc><video:duration>767</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/electric-current</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x14a4196184e1f05d.jpg</video:thumbnail_loc><video:title>Electric current</video:title><video:description>Electric current is the net rate that charge flows through a cross-sectional area. Current is measured in amperes (A), equivalent to coulombs per second (C/s). Current flows when there is an electric potential difference (voltage) between two points, and there are charge carriers that are free to move between those points. Electrical conductors (metals) contain electrons that are free to move. Electrons are the drifting particles in a current-carrying wire, but conventional current is defined as the direction that positive charge would flow.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6K1Bl0cqecE.mp4/6K1Bl0cqecE.mp4</video:content_loc><video:duration>809</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/electric-circuits-part-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1f725db40c87ea1f.jpg</video:thumbnail_loc><video:title>Intro to electric circuits</video:title><video:description>Electric circuits are paths through which electric current can flow. Circuits are composed of specific building blocks known as circuit elements. Circuit elements include batteries and other voltage sources, wires, resistors, light bulbs and LEDs, and switches. Ammeters and voltmeters can be used to measure current and voltage in a circuit, respectively. An open circuit contains a broken path, preventing current flow. A short circuit contains a path with negligible resistance, resulting in very high current.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Nbb5Lw14wvo.mp4/Nbb5Lw14wvo.mp4</video:content_loc><video:duration>718</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/electric-circuits-part-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfca4d22d4f21f414.jpg</video:thumbnail_loc><video:title>Series and parallel circuits</video:title><video:description>Circuit elements can be connected in series or in parallel. A series connection exists when elements are joined along a single chain. The same current flows through every element in the chain. A parallel connection exists when elements are connected across the same two points in a circuit, with no other components between them. The same voltage exists across each element in a parallel connection. Real-world circuits often utilize a combination of both series and parallel connections.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1ASc6piVKhQ.mp4/1ASc6piVKhQ.mp4</video:content_loc><video:duration>852</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/ohms-law</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x40f69842b7189e6e.jpg</video:thumbnail_loc><video:title>Ohm&apos;s law</video:title><video:description>Through experiment, we can uncover the relationship between the current through a circuit element and the voltage across it. Measurements show that the current is equal to the voltage divided by the element’s resistance (I=ΔV/R). This relationship is called Ohm’s law. Since the current is proportional to the voltage, a graph of current through an element versus the voltage across it is a straight line. The slope of the line is the element’s conductance, which is the reciprocal of resistance. Though many circuit elements obey Ohm’s law, some do not. Such components are called non-ohmic.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/FuIn1L3qeqI.mp4/FuIn1L3qeqI.mp4</video:content_loc><video:duration>738</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/resistivity-and-conductivity</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2d278559.jpg</video:thumbnail_loc><video:title>Resistivity and conductivity</video:title><video:description>Let&apos;s look at the properties of materials that cause a resistor to resist the flow of current. Explore the principles of Ohm&apos;s law, resistance, and resistivity in electrical circuits. Understand how resistance is defined by voltage and current, and how it remains constant in Ohmic materials. Discover the factors that influence resistance, including the length, cross-sectional area, and material of a resistor.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4rsswT_Rv1M.mp4/4rsswT_Rv1M.mp4</video:content_loc><video:duration>722</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/ee-kirchhoffs-current-law</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5d40a1b6.jpg</video:thumbnail_loc><video:title>Kirchhoff&apos;s current law</video:title><video:description>Kirchhoff&apos;s Current Law says the currents flowing into a node must add up to zero.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OYerdzZPSI0.mp4/OYerdzZPSI0.mp4</video:content_loc><video:duration>363</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/ee-kirchhoffs-voltage-law</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2eab8586.jpg</video:thumbnail_loc><video:title>Kirchhoff&apos;s voltage law</video:title><video:description>Kirchhoff&apos;s Voltage Law says if you travel around any loop in a circuit, the voltages across the elements add up to zero.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Bt6V7D5av9A.mp4/Bt6V7D5av9A.mp4</video:content_loc><video:duration>410</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/electric-power</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x93fcbc34.jpg</video:thumbnail_loc><video:title>Electric power</video:title><video:description>In this video David derives the formula to find the power used by a resistor.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3zt7DWUiaDE.mp4/3zt7DWUiaDE.mp4</video:content_loc><video:duration>643</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/ee-series-resistors</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa405e84f.jpg</video:thumbnail_loc><video:title>Series resistors</video:title><video:description>Resistors connected head-to-tail are in series. The equivalent overall resistance is the sum of the individual resistance values.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/P_SELh0dPW0.mp4/P_SELh0dPW0.mp4</video:content_loc><video:duration>717</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/ee-parallel-resistors-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa85f5f14.jpg</video:thumbnail_loc><video:title>Parallel resistors</video:title><video:description>Practice calculating equivalent resistance for resistors in parallel. In the special case where two equal resistors are in parallel, the equivalent resistance is half their value. Parallel resistance is always smaller than the smallest resistor, as it provides multiple current paths, effectively reducing the overall resistance in the circuit.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/S0AJZjt0sEg.mp4/S0AJZjt0sEg.mp4</video:content_loc><video:duration>561</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/ee-simplifying-resistor-networks</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x618abc88.jpg</video:thumbnail_loc><video:title>Simplifying resistor networks</video:title><video:description>Learn strategies for combining resistors in series and parallel to simplify resistor networks.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tnYQ_tQmYrM.mp4/tnYQ_tQmYrM.mp4</video:content_loc><video:duration>486</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/solved-example-finding-current-voltage-in-a-circuit</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x29f42217e680a0a0.jpg</video:thumbnail_loc><video:title>Solved example: Finding current and voltage in a circuit</video:title><video:description>Let&apos;s learn how to calculate current and voltage across each resistor in a circuit.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/rkiBof2pvbE.mp4/rkiBof2pvbE.mp4</video:content_loc><video:duration>805</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/voltmeters-and-ammeters</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa8591b23.jpg</video:thumbnail_loc><video:title>Voltmeters and ammeters</video:title><video:description>Learn how to measure voltage and current in electrical circuits using voltmeters and ammeters. Discover why voltmeters are connected in parallel and ammeters in series. Understand the importance of resistance in these devices to ensure accurate readings and prevent damage.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/yE3eQ6q39f4.mp4/yE3eQ6q39f4.mp4</video:content_loc><video:duration>498</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/ap-physics-1-review-of-charge-and-circuits</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x83413413.jpg</video:thumbnail_loc><video:title>Review of electric charge and circuits</video:title><video:description>Review of electric charge and circuits</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qdmYAXjhWiw.mp4/qdmYAXjhWiw.mp4</video:content_loc><video:duration>1152</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/capacitors-and-capacitance</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc64de00d.jpg</video:thumbnail_loc><video:title>Capacitors and capacitance</video:title><video:description>Capacitors, essential components in electronics, store charge between two pieces of metal separated by an insulator. This video explains how capacitors work, the concept of capacitance, and how varying physical characteristics can alter a capacitor&apos;s ability to store chargeBy David Santo Pietro.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/u-jigaMJT10.mp4/u-jigaMJT10.mp4</video:content_loc><video:duration>343</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/dielectrics-capacitors</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb0101987.jpg</video:thumbnail_loc><video:title>Dielectrics in capacitors</video:title><video:description>Capacitors use non-conducting materials, or dielectrics, to store charge and increase capacitance. Dielectrics, when placed between charged capacitor plates, become polarized, reducing the voltage across the plates and increasing capacitance. The degree of capacitance increase depends on the dielectric constant of the material used. By David Santo Pietro.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/rkntp3_cZl4.mp4/rkntp3_cZl4.mp4</video:content_loc><video:duration>387</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/energy-capacitor</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x28f1d646.jpg</video:thumbnail_loc><video:title>Energy of a capacitor</video:title><video:description>Capacitors store energy as electrical potential. When charged, a capacitor&apos;s energy is 1/2 Q times V, not Q times V, because charges drop through less voltage over time. The energy can also be expressed as 1/2 times capacitance times voltage squared. Remember, the voltage refers to the voltage across the capacitor, not necessarily the battery voltage. By David Santo Pietro.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/SIU_9SMd5q0.mp4/SIU_9SMd5q0.mp4</video:content_loc><video:duration>383</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/capacitors-series</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x276a1169.jpg</video:thumbnail_loc><video:title>Capacitors in series</video:title><video:description>When capacitors are connected one after another, they are said to be in series. For capacitors in series, the total capacitance can be found by adding the reciprocals of the individual capacitances, and taking the reciprocal of the sum. Therefore, the total capacitance will be lower than the capacitance of any single capacitor in the circuit.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-MaD9Ycy3a4.mp4/-MaD9Ycy3a4.mp4</video:content_loc><video:duration>575</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/capacitors-parallel</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9e833752.jpg</video:thumbnail_loc><video:title>Capacitors in parallel</video:title><video:description>A capacitator is a device that stores electrical energy in an electrical field. This video discusses the behavior of two capacitors connected in parallel. It compares two capacitators, and shows how to calculate the amount of charge each will receive. Finally, it discusses how to find the equivalent capacitance of the two capacitors combined.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/P-1mWGeJjmg.mp4/P-1mWGeJjmg.mp4</video:content_loc><video:duration>601</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/magnetic-field-lines-their-properties</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x55e0ac08db74e462.jpg</video:thumbnail_loc><video:title>Magnetic field lines</video:title><video:description>Let&apos;s explore what magnetic field lines are, why we draw them, and what their properties are. Here is the link to the simulation https://www.khanacademy.org/science/physics/discoveries/magnetic-fields/pi/tracing-a-magnetic-field</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/GgRCkduKCLE.mp4/GgRCkduKCLE.mp4</video:content_loc><video:duration>656</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/comparing-properties-of-magnetic-lorentz-electric-forces</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3b5be1f27ab788be.jpg</video:thumbnail_loc><video:title>Comparing magnetic and electric forces</video:title><video:description>Let&apos;s compare and contrast properties of the magnetic force and the electric force acting on a charged particle.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9C8mRW43X0Q.mp4/9C8mRW43X0Q.mp4</video:content_loc><video:duration>757</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/oersteds-experiment-magnetic-field-due-to-current</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x741a474aea85f590.jpg</video:thumbnail_loc><video:title>Magnetic field due to current</video:title><video:description>Electric current produces a magnetic field around a wire, demonstrating that electricity and magnetism are fundamentally connected. The magnetic field becomes stronger with greater current and weaker with increasing distance from the wire. Around a straight current-carrying wire, magnetic field lines form concentric circles, and reversing the current reverses the field&apos;s direction.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/V-irinjvhmc.mp4/V-irinjvhmc.mp4</video:content_loc><video:duration>546</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/right-hand-thumb-rule-solved-numerical</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe2ed3365612da2be.jpg</video:thumbnail_loc><video:title>Right hand thumb rule</video:title><video:description>Learn how to use the right-hand thumb rule to find the direction of the magnetic field around a current-carrying wire.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/NLieiomI4sA.mp4/NLieiomI4sA.mp4</video:content_loc><video:duration>652</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/force-on-a-current-carrying-conductor-ni-a-magnetic-field</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1136bc2bae900274.jpg</video:thumbnail_loc><video:title>Force on a current-carrying conductor in a magnetic field</video:title><video:description>Current carrying wires can push magnets. Can magnets push current carrying wires too? Let&apos;s find out.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/uW8scRjaam8.mp4/uW8scRjaam8.mp4</video:content_loc><video:duration>560</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/electromagnetic-induction-faradays-experiments</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc34c4d81ecbdb697.jpg</video:thumbnail_loc><video:title>Electromagnetic induction</video:title><video:description>Electromagnetic induction is the production of an induced voltage or current by a changing magnetic field through a coil. A stationary magnetic field produces no current; only changes in magnetic field induce electricity. Relative motion between a magnet and coil or changing current in a nearby coil creates induction, forming the operating principle of electric generators.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/yU--8Zk57-Y.mp4/yU--8Zk57-Y.mp4</video:content_loc><video:duration>612</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/faraday-s-law-n-t</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9363bd5a00eb89d7.jpg</video:thumbnail_loc><video:title>Faraday&apos;s Law</video:title><video:description>We know that changing magnetic flux induces emf. In this video, let&apos;s figure out the magnitude of that induced emf.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/MHRBjGCgb4U.mp4/MHRBjGCgb4U.mp4</video:content_loc><video:duration>815</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/lenzs-law</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xcc21a8f2.jpg</video:thumbnail_loc><video:title>Lenz&apos;s law</video:title><video:description>When the magnetic flux through a conducting loop changes, current is induced in the loop. This current produces it&apos;s own magnetic field. Lenz&apos;s law tells us that the current flows in the direction that produces a magnetic field in the loop that opposes the change in magnetic flux.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xxZenoBs2Pg.mp4/xxZenoBs2Pg.mp4</video:content_loc><video:duration>346</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/emf-induced-in-rod-traveling-through-magnetic-field</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa173a477.jpg</video:thumbnail_loc><video:title>Emf induced in rod traveling through magnetic field</video:title><video:description>An emf induced by motion relative to a magnetic field is called a motional emf. This is represented by the equation emf = LvB, where L is length of the object moving at speed v relative to the strength of the magnetic field B.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/rqq11Id_x5E.mp4/rqq11Id_x5E.mp4</video:content_loc><video:duration>482</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/paramagnetism-diamagnetism</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa8ebae998095d899.jpg</video:thumbnail_loc><video:title>Paramagnetism &amp; diamagnetism</video:title><video:description>Most materials are either weakly attracted (paramagnets) or weakly repelled (diamagnets) by magnets. Diamagnetism is an inherent property of all materials, and it arises from Lenz&apos;s laws. Paramagnetism is seen in materials whose atoms have at least one unpaired electron.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/wK7Jr1g4_ws.mp4/wK7Jr1g4_ws.mp4</video:content_loc><video:duration>771</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/ferromagnetism-curie-temperature</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4bfc5beab8041c86.jpg</video:thumbnail_loc><video:title>Ferromagnetism &amp; curie temperature</video:title><video:description>Ferromagnets are strongly attracted to magnets due to their magnetic domains. Magnetic domains are groups of atoms whose dipole moments are spontaneously aligned in the same direction. Above the Curie temperature, these magnetic domains break down and the material becomes a paramagnet.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8a2IZZdIeXw.mp4/8a2IZZdIeXw.mp4</video:content_loc><video:duration>563</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/specular-and-diffuse-reflection</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187516.jpg</video:thumbnail_loc><video:title>Specular and diffuse reflection</video:title><video:description>Specular reflection, which occurs with smooth surfaces like mirrors, causes light rays to reflect at the same angle as they hit the surface. Diffuse reflection, which occurs with rougher surfaces, scatters light rays in different directions. The video also introduces double reflection, which occurs when light reflects off of one surface and then reflects off of another surface before reaching your eye.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/sd0BOnN6aNY.mp4/sd0BOnN6aNY.mp4</video:content_loc><video:duration>660</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/virtual-image</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187523.jpg</video:thumbnail_loc><video:title>Virtual image</video:title><video:description>Let&apos;s explore the concept of a virtual image.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/nrOg85VPQgw.mp4/nrOg85VPQgw.mp4</video:content_loc><video:duration>473</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/concave-mirrors</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9c7bc095abef3bef.jpg</video:thumbnail_loc><video:title>Concave mirrors</video:title><video:description>In this video, we will see how concave mirrors focus a parallel beam of light to a single point.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7p0_YK7hQ04.mp4/7p0_YK7hQ04.mp4</video:content_loc><video:duration>756</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/concave-mirror-applications</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbd7e72589050a2d7.jpg</video:thumbnail_loc><video:title>Concave mirror applications</video:title><video:description>In this video, we will look at some applications of concave mirrors.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xhfKsl1WcO4.mp4/xhfKsl1WcO4.mp4</video:content_loc><video:duration>517</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/convex-mirror-applications</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbef05574b73d9b97.jpg</video:thumbnail_loc><video:title>Convex mirror &amp; applications</video:title><video:description>When curved mirrors have a reflecting surface on the outside, they are called convex mirrors. (vex stands for bulging out). Let&apos;s learn what they do and their applications in our day to day life.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4sZZYkIwgqg.mp4/4sZZYkIwgqg.mp4</video:content_loc><video:duration>774</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/spherical-parabolic-mirrors</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe17bbcf06d5b73b7.jpg</video:thumbnail_loc><video:title>Spherical &amp; parabolic mirrors</video:title><video:description>In this video, we will explore two kinds of curved mirrors, parabolic and spherical mirrors.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/djkBahaEHG4.mp4/djkBahaEHG4.mp4</video:content_loc><video:duration>331</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/spherical-mirrors-radius-of-curvature-focal-length</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x26476658aa67c606.jpg</video:thumbnail_loc><video:title>Spherical mirrors, radius of curvature &amp; focal length</video:title><video:description>In this video, we will introduce the terms radius of curvature, and see its connection with focal length. We will also introduce the term principal axis and see the need for it.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/H1eRmNbTkm0.mp4/H1eRmNbTkm0.mp4</video:content_loc><video:duration>536</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/convex-concave-mirror-ray-diagrams-class-12-india-physics-khan-academy</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2ba94ea0892e0960.jpg</video:thumbnail_loc><video:title>Convex &amp; concave mirror ray diagrams</video:title><video:description>Let&apos;s explore the ray tracing technique to figure out the properties of images when things are kept in front of a concave or a convex mirror.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OHXOwz1NLh0.mp4/OHXOwz1NLh0.mp4</video:content_loc><video:duration>803</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/sign-conventions-for-mirror-lenses</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc1fbec526643e2ca.jpg</video:thumbnail_loc><video:title>Sign convention for mirrors (&amp; lenses)</video:title><video:description>Let&apos;s explore the sign conventions (rules to assign +ve and -ve values) we use for mirrors and lenses. These rules are called Cartesian sign conventions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Mc--Yz_YrsU.mp4/Mc--Yz_YrsU.mp4</video:content_loc><video:duration>610</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/mirror-formula</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4c269e893fe2032c.jpg</video:thumbnail_loc><video:title>Mirror formula</video:title><video:description>Let&apos;s explore the mirror formula (1/f = 1/v+1/u) and see how to locate images without drawing any ray diagrams.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/EPlr16b4XnQ.mp4/EPlr16b4XnQ.mp4</video:content_loc><video:duration>533</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/magnification-formula-for-mirrors</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2e50ac540380247c.jpg</video:thumbnail_loc><video:title>Magnification formula for mirrors</video:title><video:description>Let&apos;s explore how to calculate image height and it&apos;s nature (real or virtual) using magnification formula.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/FfvuY8xsO1Y.mp4/FfvuY8xsO1Y.mp4</video:content_loc><video:duration>613</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/refraction-and-snell-s-law</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187518.jpg</video:thumbnail_loc><video:title>Refraction and Snell&apos;s law</video:title><video:description>Refraction and Snell&apos;s Law</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/y55tzg_jW9I.mp4/y55tzg_jW9I.mp4</video:content_loc><video:duration>864</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/refraction-through-glass-slab</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3ff4ed3d372136d3.jpg</video:thumbnail_loc><video:title>Refraction through glass slab</video:title><video:description>Let&apos;s explore refraction of light through any parallel sided medium. Will also see why things appear to shift (lateral shift) when looked through such a medium.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/YIYnSAb9Q9Y.mp4/YIYnSAb9Q9Y.mp4</video:content_loc><video:duration>666</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/snell-s-law-examples-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187520.jpg</video:thumbnail_loc><video:title>Snell&apos;s law example</video:title><video:description>Example calculation using Snell&apos;s law</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/HahjsBApxLE.mp4/HahjsBApxLE.mp4</video:content_loc><video:duration>644</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/total-internal-reflection</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187522.jpg</video:thumbnail_loc><video:title>Total internal reflection</video:title><video:description>Critical incident angle and total internal reflection</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/WRuatAcd2WY.mp4/WRuatAcd2WY.mp4</video:content_loc><video:duration>475</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/convex-lenses</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187527.jpg</video:thumbnail_loc><video:title>Convex lenses</video:title><video:description>Explore convex lenses, including how they refract and transmit light. Learn about a lens&apos;s focal point and the thin lens assumption.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/K0sjZ5nqQ7g.mp4/K0sjZ5nqQ7g.mp4</video:content_loc><video:duration>563</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/convex-lens-examples</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187528.jpg</video:thumbnail_loc><video:title>Convex lens examples</video:title><video:description>Explore how convex lenses form images, including different scenarios where an object is placed at various distances from the lens. Learn how light rays refract through a convex lens, forming real, inverted, or virtual images. This video emphasizes understanding the process rather than memorizing outcomes.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xxF_mdoZom0.mp4/xxF_mdoZom0.mp4</video:content_loc><video:duration>576</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/concave-lenses</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187529.jpg</video:thumbnail_loc><video:title>Concave lenses</video:title><video:description>Concave lenses, with their inward curve, create divergent light rays. When a ray parallel to the principal axis hits the lens, it refracts outward as if coming from the focal point. Another ray, passing through the lens center, doesn&apos;t refract. These rays form a virtual, upright, and smaller image, appearing closer to the lens than the actual object.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Vh70PyitQzo.mp4/Vh70PyitQzo.mp4</video:content_loc><video:duration>186</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/lens-formula</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x33600821156ee2df.jpg</video:thumbnail_loc><video:title>Lens formula</video:title><video:description>Let&apos;s see how to use lens formula (1/v-1/u= 1/f) to locate images without having to draw ray diagrams.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/NQ8OLvIcffg.mp4/NQ8OLvIcffg.mp4</video:content_loc><video:duration>511</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/solved-example-on-lens-formula</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe3e86662d3ba7542.jpg</video:thumbnail_loc><video:title>Solved example on lens formula</video:title><video:description>Using the lens formula can be tricky because we need to substitute using signs. In this video, we will take one example and discuss how to use the lens formula.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/HOaI6_F4ht8.mp4/HOaI6_F4ht8.mp4</video:content_loc><video:duration>786</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/magnification-formula-for-lenses</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x56b2ca797ceaf438.jpg</video:thumbnail_loc><video:title>Magnification formula for lenses</video:title><video:description>Let&apos;s explore the magnification formula (M= v/u) for lenses and see how to find the image height and its nature (whether it&apos;s real or virtual).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/if-X8MCltso.mp4/if-X8MCltso.mp4</video:content_loc><video:duration>596</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/physics/v/introduction-to-waves</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25743.jpg</video:thumbnail_loc><video:title>Introduction to waves</video:title><video:description>Transverse and longitudinal waves are two types of mechanical waves, which involve the transfer of energy through a medium (e.g. water, air, a solid). Learn about transverse and longitudinal waves through the examples of a rope and a sound wave. Explore the difference between a single wave pulse and periodic waves.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/c38H6UKt3_I.mp4/c38H6UKt3_I.mp4</video:content_loc><video:duration>783</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/physics/v/amplitude-period-frequency-and-wavelength-of-periodic-waves</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25745.jpg</video:thumbnail_loc><video:title>Properties of periodic waves</video:title><video:description>Learn about different properties of waves, including amplitude, period, frequency, and wavelength. Explore how these properties are related to one another.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tJW_a6JeXD8.mp4/tJW_a6JeXD8.mp4</video:content_loc><video:duration>866</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/physics/v/wave-equation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbb44b237.jpg</video:thumbnail_loc><video:title>The equation of a wave</video:title><video:description>In this video David shows how to determine the equation of a wave, how that equation works, and what the equation represents.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9WZM68aVnGk.mp4/9WZM68aVnGk.mp4</video:content_loc><video:duration>884</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/physics/v/standing-waves-on-strings</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7e8ce62f.jpg</video:thumbnail_loc><video:title>Standing waves on strings</video:title><video:description>A standing wave occurs when two waves of the same frequency and amplitude are moving in opposite directions and interfere with each other. It has certain points (called nodes) where the amplitude is always zero, and other points (called antinodes) where the amplitude fluctuates with maximum intensity. Use the distance between two consecutive nodes or two consecutive antinodes to calculate the length of a standing wave.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gT0IqL1dyyk.mp4/gT0IqL1dyyk.mp4</video:content_loc><video:duration>805</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/physics/v/production-of-sound</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa4f83089.jpg</video:thumbnail_loc><video:title>Production of sound</video:title><video:description>Sound is vibrating air. But how does the air start vibrating? Explore the intriguing science of sound waves and how they travel. Learn how speakers use oscillation to create sound, and discover why sound waves can transport energy without moving the medium itself. Uncover the mystery behind the difference in our voices in person and on recordings.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/nGKffdaI4Pg.mp4/nGKffdaI4Pg.mp4</video:content_loc><video:duration>226</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/physics/v/sound-properties-amplitude-period-frequency-wavelength</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3dd64aec.jpg</video:thumbnail_loc><video:title>Sound properties: amplitude, period, frequency, wavelength</video:title><video:description>How to find the amplitude, period, frequency, and wavelength for a sound wave</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-_xZZt99MzY.mp4/-_xZZt99MzY.mp4</video:content_loc><video:duration>316</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/physics/v/speed-of-sound</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x089b4e4b.jpg</video:thumbnail_loc><video:title>Speed of sound</video:title><video:description>How fast does sound travel? Explore the nature of sound waves and how they travel. Discover why sound is a longitudinal wave and how its speed is influenced by the medium it travels through. Learn about the relationship between wavelength, frequency, and speed, and how changing the medium affects the speed of sound.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/UgE2GIQwUCw.mp4/UgE2GIQwUCw.mp4</video:content_loc><video:duration>225</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/physics/v/relative-speed-of-sound-in-solids-liquids-and-gases</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x96f7dd45.jpg</video:thumbnail_loc><video:title>Relative speed of sound in solids, liquids, and gases</video:title><video:description>Sounds travels at different speeds in different media</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/yF4cvbAYjwI.mp4/yF4cvbAYjwI.mp4</video:content_loc><video:duration>199</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/physics/v/standing-waves-in-tubes-part-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1cd52325.jpg</video:thumbnail_loc><video:title>Standing waves in open tubes</video:title><video:description>Find out how ​standing waves and resonance cause a flute makes such specific notes. Discover why blowing over a soda bottle creates a tone, how air molecules oscillate in an open-ended tube, and the mathematical representation of these phenomena.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/BhQUW9s-R8M.mp4/BhQUW9s-R8M.mp4</video:content_loc><video:duration>859</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/physics/v/standing-waves-in-tubes-part-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x255e2941.jpg</video:thumbnail_loc><video:title>Standing waves in closed tubes</video:title><video:description>Explore the intriguing world of sound waves in open and closed tubes! This lesson breaks down how the length of a tube influences the wavelength and frequency of sound, revealing why you hear different notes as you sip your soda. Discover the unique patterns of harmonics in open-closed tubes, and how they differ from open-open tubes.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1S4DtuMY88I.mp4/1S4DtuMY88I.mp4</video:content_loc><video:duration>597</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/physics/v/beat-frequency</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xca74c9ea.jpg</video:thumbnail_loc><video:title>Beat frequency</video:title><video:description>Beat frequency occurs when two waves with different frequencies overlap, causing a cycle of alternating constructive and destructive interference between waves. Learn how this results in a fluctuation in sound loudness, and how the beat frequency can be calculated by finding the difference between the two original frequencies.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Ca91iOVGd9A.mp4/Ca91iOVGd9A.mp4</video:content_loc><video:duration>708</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/electromagnetic-waves-and-the-electromagnetic-spectrum</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x93657b33.jpg</video:thumbnail_loc><video:title>Electromagnetic waves and the electromagnetic spectrum</video:title><video:description>Learn how electromagnetic waves are formed from changing electric and magnetic fields. Understand the electromagnetic spectrum, including different regions from visible light to gamma rays and their uses.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7eutept5h0Q.mp4/7eutept5h0Q.mp4</video:content_loc><video:duration>662</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/polarization-of-light-linear-and-circular</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x38701d13.jpg</video:thumbnail_loc><video:title>Polarization of light</video:title><video:description>Light, as electromagnetic waves, can oscillate in specific directions. This phenomenon is called polarization. Explore into the difference between polarized and non-polarized light, and see how polarization is important for everyday applications like sunglasses and 3D movies.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/HH58VmUbOKM.mp4/HH58VmUbOKM.mp4</video:content_loc><video:duration>870</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/physics/v/constructive-and-destructive-interference</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x00cc1549.jpg</video:thumbnail_loc><video:title>Constructive and destructive interference</video:title><video:description>Constructive interference happens when two waves overlap in such a way that they combine to create a larger wave. Destructive interference happens when two waves overlap in such a way that they cancel each other out. Wave interference also depends on the relative phase of the two waves, as this video shows through the examples of path length differences and pi shifts.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/oTjTXS40pqs.mp4/oTjTXS40pqs.mp4</video:content_loc><video:duration>824</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/youngs-double-split-part-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7aa60791.jpg</video:thumbnail_loc><video:title>Young&apos;s double slit introduction</video:title><video:description>We can see interference in action if we shine laser light through two slits onto a screen. Explore Young&apos;s Double Slit experiment, a cornerstone in understanding light as a wave. Discover how light waves spread out, overlap, and create patterns of constructive and destructive interference. Uncover the rules of wave interference in two dimensions, and how path length differences lead to these intriguing patterns.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Pk6s2OlKzKQ.mp4/Pk6s2OlKzKQ.mp4</video:content_loc><video:duration>573</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/youngs-double-slit-part-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd2a6554e.jpg</video:thumbnail_loc><video:title>Young&apos;s double slit equation</video:title><video:description>Let&apos;s derive a formula that relates all the variables in Young&apos;s double slit experiment as we explore Young&apos;s Double Slit Equation. Uncover how light&apos;s path length difference relates to the angle of incidence, and how this leads to constructive and destructive interference. Apply this knowledge to the world of wave patterns, trigonometry, and the wonders of diffraction!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1abpdO27KTo.mp4/1abpdO27KTo.mp4</video:content_loc><video:duration>401</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/youngs-double-slit-problem-solving</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb810086a.jpg</video:thumbnail_loc><video:title>Young&apos;s double slit problem solving</video:title><video:description>Continue to explore Young&apos;s double slit equation through a sample problem involving a double slit experiment. See how light waves of specific wavelengths interact when they pass through two slits, creating a pattern of bright spots on a screen. Get insights into the math behind calculating these distances and understand the impact of changing slit spacing.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5-2RZsU8e3U.mp4/5-2RZsU8e3U.mp4</video:content_loc><video:duration>429</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/diffraction-grating</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x917c7a7b.jpg</video:thumbnail_loc><video:title>Diffraction grating</video:title><video:description>What happens when there&apos;s way more than two holes? Uncover the power of diffraction gratings. Learn how adding more slits to a double slit experiment results in sharper, brighter interference patterns. Understand why this occurs and its significance in measuring light waves.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/F6dZjuw1KUo.mp4/F6dZjuw1KUo.mp4</video:content_loc><video:duration>861</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/single-slit-interference</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdc1d3db2.jpg</video:thumbnail_loc><video:title>Single slit interference</video:title><video:description>What happens when there&apos;s only one hole? Explore the concept of Single Slit Interference in light waves. Uncover how waves spread out at a hole due to Huygen&apos;s Principle, leading to diffraction. Understand how each point on a wavefront acts as a source of another wave, creating an interference pattern, and examine the math behind destructive points and the role of slit width in wave interference.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7CmbItRjM-Y.mp4/7CmbItRjM-Y.mp4</video:content_loc><video:duration>900</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/more-on-single-slit-interference</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1a496461.jpg</video:thumbnail_loc><video:title>More on single slit interference</video:title><video:description>Continue to explore the phenomenon of single slit interference. See how there&apos;s actually constructive (rather than just destructive) interference at some points on the screen. single slit interference, a complex phenomenon in light physics. Learn about the mathematical reasoning behind destructive points and why it doesn&apos;t apply to constructive points, and relate this to diffraction gratings, phase differences, and the challenge of finding exact locations of constructive points.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/T-kgoxhFSmU.mp4/T-kgoxhFSmU.mp4</video:content_loc><video:duration>786</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/thin-film-interference-part-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1408ebe1.jpg</video:thumbnail_loc><video:title>Thin film interference (part 1)</video:title><video:description>Thin film interference occurs when light waves reflecting off the top and bottom surfaces of a thin film interfere with one another. This type of interference is the reason that thin films, such as oil or soap bubbles, form colorful patterns.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/oXowkdgJPO4.mp4/oXowkdgJPO4.mp4</video:content_loc><video:duration>723</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/thin-film-interference-part-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6ddace9a.jpg</video:thumbnail_loc><video:title>Thin film interference (part 2)</video:title><video:description>Let&apos;s work out a few details on how thin film interference works as we explore the concept of thin film interference as it relates to light waves. Understand how light&apos;s wavelength changes as it moves through different mediums, like air and oil. Learn how to calculate the wavelength in a new medium using either the speeds of light or the indices of refraction. Master the conditions for constructive and destructive interference.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/yWkga94iBzU.mp4/yWkga94iBzU.mp4</video:content_loc><video:duration>723</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/photon-energy</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x160e6164.jpg</video:thumbnail_loc><video:title>Photon energy</video:title><video:description>Learn what a photon is and how to determine the energy of a photon as you explore the dual nature of light as both a wave and a particle, known as wave-particle duality. Uncover the concept of quantum mechanics, where light deposits energy in discrete amounts called photons. Investigate Planck&apos;s constant and how it relates to the energy of a photon.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Zqt3btS1FwE.mp4/Zqt3btS1FwE.mp4</video:content_loc><video:duration>558</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/photon-momentum</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8d9d935e.jpg</video:thumbnail_loc><video:title>Photon momentum</video:title><video:description>Learn how to determine the momentum of a photon.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Qwtz-QSDyOM.mp4/Qwtz-QSDyOM.mp4</video:content_loc><video:duration>175</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/de-broglie-wavelength</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe3fa6319.jpg</video:thumbnail_loc><video:title>de Broglie wavelength</video:title><video:description>Is it a particle or a wave? This is the question that physicists of the 1920s were asking about light. In 1924, Louis de Broglie took this question to another level as he explored how electrons - which are matter, and were thought to be simply particles - can behave like waves.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/iTRxuBxttj8.mp4/iTRxuBxttj8.mp4</video:content_loc><video:duration>680</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/bohr-model-energy-levels-derivation-using-physics</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdb4337d3.jpg</video:thumbnail_loc><video:title>Bohr model energy levels (derivation using physics)</video:title><video:description>Using classical physics to calculate the energy of electrons in Bohr model. Solving for energy of ground state and more generally for level n.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7Zin8hG9Nhw.mp4/7Zin8hG9Nhw.mp4</video:content_loc><video:duration>728</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/hs-chemistry/v/atomic-spectra</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc8123f835ad11b76.jpg</video:thumbnail_loc><video:title>Atomic spectra</video:title><video:description>Electrons only exist at specific, discrete energy levels in an atom. If an electron absorbs a photon with energy equal to the difference between two energy levels, the electron will transition to the higher energy level. The atom is then in an excited state. When an electron transitions to a lower energy level, it emits a photon with energy equal to the difference. Every element has a unique emission/absorption spectrum, making atomic spectral lines a valuable tool for identifying elements in distant astronomical objects.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/N0lBsW3ZzN8.mp4/N0lBsW3ZzN8.mp4</video:content_loc><video:duration>883</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/the-photoelectric-and-photovoltaic-effects</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc0bd6659e907c854.jpg</video:thumbnail_loc><video:title>The photoelectric and photovoltaic effects</video:title><video:description>When light at or above a threshold frequency shines on a metal surface, electrons are emitted from the surface. This phenomenon is called the photoelectric effect. The photoelectric effect is evidence that light is quantized—light exists as discrete packets of energy called photons. The greater the frequency of the light, the greater the energy of its photons. A closely related phenomenon is the photovoltaic effect, which is the underlying mechanism of solar cells.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/HCCm0lFwqNw.mp4/HCCm0lFwqNw.mp4</video:content_loc><video:duration>861</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/einsteins-photoelectric-equation-work-function</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf0aad8681f369332.jpg</video:thumbnail_loc><video:title>Einstein&apos;s photoelectric equation &amp; work function</video:title><video:description>Let&apos;s explore what work function is, and why, in photoelectric effect, electrons come out with different kinetic energies. While exploring this, we will rediscover Einstein&apos;s photoelectric equation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ARa6MWdmg2Y.mp4/ARa6MWdmg2Y.mp4</video:content_loc><video:duration>589</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/calculate-threshold-frequency</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x63421143a9eac300.jpg</video:thumbnail_loc><video:title>Calculate threshold frequency</video:title><video:description>When light of frequency 2.42 X 10^15 Hz is incident on a metal surface, the fastest photoelectrons are found to have a kinetic energy of 1.7eV. Find the threshold frequency of the metal. Let&apos;s explore how to use Einstein&apos;s photoelectric equation to solve such numerical on photoelectric effect.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/IqmDELIaDKQ.mp4/IqmDELIaDKQ.mp4</video:content_loc><video:duration>529</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/which-metals-will-show-photoelectric-emission</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9397f06593024a2f.jpg</video:thumbnail_loc><video:title>Which metals will show photoelectric emission</video:title><video:description>Light of wavelength 430 nm is incident on each of the metals given in the table. We will explore how to predict which of the metals will show photoelectric emission.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/rVLhBl6J4Qg.mp4/rVLhBl6J4Qg.mp4</video:content_loc><video:duration>551</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/blackbody-radiation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2b3483cb8e21f684.jpg</video:thumbnail_loc><video:title>Blackbody radiation</video:title><video:description>A blackbody is an idealized object that absorbs all electromagnetic radiation (light) that shines on it. Blackbodies do not perpetually warm up as they absorb light because the accelerating charged particles inside them radiate their own light. The spectrum radiated by a blackbody depends only on its temperature. The hotter a blackbody is, the more intense its radiation is, and the shorter its peak wavelength is. The relationship between temperature and spectrum is used to estimate a star&apos;s surface temperature based on its color.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DHG61XPuWyk.mp4/DHG61XPuWyk.mp4</video:content_loc><video:duration>858</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/hs-chemistry/v/intro-to-radioactive-decay</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5b2a641f29fd36b2.jpg</video:thumbnail_loc><video:title>Intro to radioactive decay</video:title><video:description>During radioactive decay, an unstable nucleus (the &quot;parent&quot;) spontaneously changes to become a different nucleus (the &quot;daughter&quot;), emitting radiation in the process. The nuclear radiation emitted during radioactive decay is high energy, ionizing radiation. Nuclear radiation is potentially dangerous to living things but also has many beneficial applications. Types of radioactive decay include alpha, beta, and gamma.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/P_SD5Rt6XMk.mp4/P_SD5Rt6XMk.mp4</video:content_loc><video:duration>482</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/hs-chemistry/v/alpha-decay</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x873157d4a30d924c.jpg</video:thumbnail_loc><video:title>Alpha decay</video:title><video:description>During alpha decay, a large, unstable parent nucleus becomes a smaller daughter nucleus. It does this by emitting an alpha particle, a clump of two protons and two neutrons (a He-4 nucleus). The nucleus&apos;s atomic number decreases by two, and its mass number decreases by four. The alpha particle is high-energy ionizing radiation—it travels at high speed because it carries away the majority of the energy lost by the nucleus during the decay.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/QCZQCi_uKpM.mp4/QCZQCi_uKpM.mp4</video:content_loc><video:duration>666</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/hs-chemistry/v/beta-decay</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe2c5e28638221f92.jpg</video:thumbnail_loc><video:title>Beta decay</video:title><video:description>During beta minus decay, a neutron in an unstable nucleus transforms into a proton, releasing a high energy electron and antineutrino in the process. During beta plus decay, a proton in an unstable nucleus transforms into a neutron, releasing a high energy positron and neutrino in the process. Beta particles carry away energy lost by the nucleus and are ionizing radiation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/iGr6atucsBw.mp4/iGr6atucsBw.mp4</video:content_loc><video:duration>708</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/hs-chemistry/v/gamma-decay</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfee7add64448283a.jpg</video:thumbnail_loc><video:title>Gamma decay</video:title><video:description>During gamma decay, an excited nucleus releases energy in the form of a gamma photon. Gamma radiation is high-energy electromagnetic radiation (light) which has a shorter wavelength and higher frequency than visible light. Gamma rays are ionizing radiation. The number of protons and neutrons in the parent nucleus does not change, so the identity of the daughter nucleus is the same as the parent, but in a lower energy state.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ksLNmLQbNT4.mp4/ksLNmLQbNT4.mp4</video:content_loc><video:duration>709</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/hs-chemistry/v/half-life-radiometric-dating</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa4a3f55553bb9fba.jpg</video:thumbnail_loc><video:title>Half-life</video:title><video:description>Half-life is the time required for half of a radioactive sample to decay. Half-life cannot be changed—nuclei cannot be forced to decay faster or slower. Additionally, we cannot predict when an individual nucleus will decay. However, when analyzing a large sample containing many nuclei, half-life allows us to predict how much of the sample will remain after a given amount of time. This is useful for radiometric dating.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gDpyBifg6-s.mp4/gDpyBifg6-s.mp4</video:content_loc><video:duration>656</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-2/v/half-life-of-radioactive-isotopes</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb514d30c.jpg</video:thumbnail_loc><video:title>Half-life plot</video:title><video:description>Definition of half-life and graphing the decay of phosphorus-32. Calculating how much phosphorus-32 remains after 57.2 days.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/dnYyMHSSb8M.mp4/dnYyMHSSb8M.mp4</video:content_loc><video:duration>407</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/hs-chemistry/v/nuclear-fusion</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbc30d5d0a48df1a1.jpg</video:thumbnail_loc><video:title>Nuclear fusion</video:title><video:description>During nuclear fusion, two or more nuclei combine to form a different nucleus. When light nuclei fuse to produce a nucleus lighter than iron, energy is released (exothermic). When heavy nuclei fuse to produce a nucleus heavier than iron, energy is absorbed (endothermic). The release or absorption of energy relates to the difference in total mass of the reactants and products by E=mc^2. Nuclear fusion powers the Sun and other stars.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/b9qxAFLpz9U.mp4/b9qxAFLpz9U.mp4</video:content_loc><video:duration>825</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/hs-chemistry/v/nuclear-fission</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfb5c32e6455a15bd.jpg</video:thumbnail_loc><video:title>Nuclear fission</video:title><video:description>During a nuclear fission reaction, a fissile nucleus absorbs a neutron and splits into two smaller nuclei. One or more free neutrons are also released. If enough fissile nuclei are located close enough together, the neutrons released from one fission can induce further fissions, resulting in a chain reaction. Nuclear weapons utilize fast, uncontrolled chain reactions to produce an explosion. Nuclear reactors utilize slower, controlled chain reactions to generate electricity. The release of energy during fission relates to the difference in total mass of the reactants and products by E=mc^2.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5jDFqpoTgDo.mp4/5jDFqpoTgDo.mp4</video:content_loc><video:duration>627</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-c-mechanics/v/introduction-to-ap-physics-c-mechanics</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6359629ff75e7e8e.jpg</video:thumbnail_loc><video:title>Introduction to AP Physics C: Mechanics</video:title><video:description>AP Physics C: Mechanics is a calculus-based, introductory college-level physics course. In this course you&apos;ll explore the following topics: Kinematics; Forces and translational dynamics; Work, energy, and power; Linear momentum; Torque and rotational dynamics; Energy and momentum of rotating systems; Oscillations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_pH22LAM7Ek.mp4/_pH22LAM7Ek.mp4</video:content_loc><video:duration>189</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-c-mechanics/v/kinematic-quantities-rates-of-change</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x154ba44082ddfeaf.jpg</video:thumbnail_loc><video:title>Kinematic quantities: Rates of change</video:title><video:description>An object’s average velocity over some interval is the object’s change in position (displacement) divided by the time interval over which that displacement occurs. Taking the limit of this quotient as the time interval goes to zero gives the object’s instantaneous velocity at some time, which is the derivative of position with respect to time. An object’s average acceleration over some interval is the object’s change in velocity divided by the time interval over which that change in velocity occurs. Taking the limit of this quotient as the time interval goes to zero gives the object’s instantaneous acceleration at some time, which is the derivative of velocity with respect to time.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8bHhZ66tvfo.mp4/8bHhZ66tvfo.mp4</video:content_loc><video:duration>924</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-c-mechanics/v/kinematic-quantities-accumulations-of-change</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x183e3a44832007d0.jpg</video:thumbnail_loc><video:title>Kinematic quantities: Accumulations of change</video:title><video:description>An object’s change in velocity during a time interval is equal to the integral of the object’s acceleration with respect to time over that interval. On a graph of acceleration as a function of time, the change in velocity is represented by the signed area between the curve and the time axis. An object’s change in position (displacement) during a time interval is equal to the integral of the object’s velocity with respect to time over that interval. On a graph of velocity as a function of time, the displacement is represented by the signed area between the curve and the time axis.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ClCSbLcKDyE.mp4/ClCSbLcKDyE.mp4</video:content_loc><video:duration>1030</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-c-mechanics/v/motion-as-a-function-of-time-friction-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xae7468a1b94969f8.jpg</video:thumbnail_loc><video:title>Motion as a function of time: Friction example</video:title><video:description>Applying Newton’s second law to a moving object experiencing kinetic friction results in a differential equation for velocity. The differential equation can be solved to find the object’s velocity as a function of time. The velocity function can then be used to find the object’s acceleration and position as functions of time through differentiation and integration, respectively. The force is constant while the object moves, so we find the velocity function is linear and the position function is quadratic.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/T3UBiY4sHKA.mp4/T3UBiY4sHKA.mp4</video:content_loc><video:duration>769</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-c-mechanics/v/motion-as-a-function-of-time-resistive-force-example-part-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x16b8196bff3106d4.jpg</video:thumbnail_loc><video:title>Motion as a function of time: Resistive force example (part 1)</video:title><video:description>A resistive (drag) force is a velocity-dependent force which acts opposite the direction of an object’s velocity. Applying Newton’s second law to an object experiencing a resistive force results in a differential equation for velocity. Using the method of separation of variables, the velocity can be determined by integrating over the proper limits of integration. Terminal velocity is the maximum speed achieved by an object moving under the influence of a constant force and a resistive force that are exerted on the object in opposite directions. Terminal velocity is reached when the net force exerted on the object is zero.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/d5BNFRylOZE.mp4/d5BNFRylOZE.mp4</video:content_loc><video:duration>900</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-c-mechanics/v/motion-as-a-function-of-time-resistive-force-example-part-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9b7b2e063d6f5dd3.jpg</video:thumbnail_loc><video:title>Motion as a function of time: Resistive force example (part 2)</video:title><video:description>A resistive (drag) force is a velocity-dependent force which acts opposite the direction of an object’s velocity. Applying Newton’s second law to an object experiencing a resistive force results in a differential equation for velocity. The differential equation can be solved to find the object’s velocity as a function of time. The velocity function can then be used to find the object’s acceleration and position as functions of time through differentiation and integration, respectively. The functions are exponential and have asymptotes that are determined by the initial conditions and the forces exerted on the object.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/F5Tg46DVWzo.mp4/F5Tg46DVWzo.mp4</video:content_loc><video:duration>730</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-c-mechanics/v/work-done-by-forces-part-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe7a8a84e31a79199.jpg</video:thumbnail_loc><video:title>Work done by forces (part 1)</video:title><video:description>Work is the amount of energy transferred into or out of a system by a force exerted on that system over a distance. Work is a scalar quantity that may be positive, negative, or zero. Only the component of the force exerted on a system that is parallel to the displacement of the point of application of the force will change the system’s total energy. The work-energy theorem states that the change in an object’s kinetic energy is equal to the sum of the work (net work) being done by all forces exerted on the object.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Qf8hIBrsWZI.mp4/Qf8hIBrsWZI.mp4</video:content_loc><video:duration>752</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-c-mechanics/v/work-done-by-forces-part-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2376bbbf7994e559.jpg</video:thumbnail_loc><video:title>Work done by forces (part 2)</video:title><video:description>If a force varies with position, the work done by that force cannot generally be calculated as a simple product. Instead, an integral is required to sum the infinitesimal work contributions along the object’s path. The work done by such a force is given by a line integral, evaluated along the path from the object’s initial to final position. For one-dimensional motion, work is equal to the area under the curve of the parallel component of force versus position.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gS2yei7d0_E.mp4/gS2yei7d0_E.mp4</video:content_loc><video:duration>1151</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-c-mechanics/v/potential-energy-and-conservative-forces-part-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8dfc8a50b62104b0.jpg</video:thumbnail_loc><video:title>Potential energy and conservative forces (part 1)</video:title><video:description>Potential energies are only associated with conservative forces. The change in potential energy between two configurations of a system is the negative of the work done by the conservative force during the change. Because the gravitational field near the surface of a planet is nearly constant, the change in gravitational potential energy of a system containing an object and a planet when the object is near the surface of the planet can be approximated by ΔU_g = mgΔy.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1eooA5q9GCs.mp4/1eooA5q9GCs.mp4</video:content_loc><video:duration>1026</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-c-mechanics/v/potential-energy-and-conservative-forces-part-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfcf5dfe92985dc62.jpg</video:thumbnail_loc><video:title>Potential energy and conservative forces (part 2)</video:title><video:description>The general form for the gravitational potential energy of a system consisting of two approximately spherical distributions of mass is given by the equation U_g = -GMm/r. The gravitational energy is negative because the zero reference configuration is chosen as the two masses being infinitely far away from each other (r = infinity). Therefore, the gravitational potential energy for any closer configuration is less than zero.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9o1WbcK7_-g.mp4/9o1WbcK7_-g.mp4</video:content_loc><video:duration>853</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-c-mechanics/v/potential-energy-and-conservative-forces-part-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x018b777e5fd9c554.jpg</video:thumbnail_loc><video:title>Potential energy and conservative forces (part 3)</video:title><video:description>The force exerted by an ideal spring is a conservative and obeys Hooke’s law. Applying the general equation for change in potential energy reveals that the elastic potential energy of a system containing an ideal spring is given by the following equation, where Δx is the distance the spring has been stretched or compressed from its equilibrium length: ΔU_s = ½k(Δx)^2. The elastic potential energy is zero when the spring is at its relaxed length.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Q6EgiGx7EUQ.mp4/Q6EgiGx7EUQ.mp4</video:content_loc><video:duration>693</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-c-mechanics/v/potential-energy-and-conservative-forces-part-4</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xee5b6a72f7def80f.jpg</video:thumbnail_loc><video:title>Potential energy and conservative forces (part 4)</video:title><video:description>A conservative force exerted on a system in a single dimension is equal to the negative derivative of the system’s potential energy with respect to position in that dimension. The force points in the direction of decreasing potential energy. The relationship is represented by the following equation: F_x = -dU(x)/dx</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qKTBVL5jBIA.mp4/qKTBVL5jBIA.mp4</video:content_loc><video:duration>760</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-c-mechanics/v/potential-energy-and-conservative-forces-part-5</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0d74acb9c86b99fb.jpg</video:thumbnail_loc><video:title>Potential energy and conservative forces (part 5)</video:title><video:description>Graphs of a system’s potential energy as a function of position can be useful in determining properties of that system. Stable equilibrium is a location at which a small displacement results in a force opposite the direction of the displacement, accelerating the object back toward the equilibrium position. Stable equilibrium positions exist where the potential energy as a function of position has a local minimum. Unstable equilibrium is a location at which a small displacement results in a force in the same direction as the displacement, accelerating the object away from the equilibrium position. Unstable equilibrium positions exist where the potential energy as a function of position has a local maximum.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gY8sqnmju-0.mp4/gY8sqnmju-0.mp4</video:content_loc><video:duration>816</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-c-mechanics/v/linear-momentum-and-impulse</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8c9df72bf62ec7b6.jpg</video:thumbnail_loc><video:title>Linear momentum and impulse</video:title><video:description>An object’s linear momentum is the product of its mass and velocity. Momentum is a vector quantity and has the same direction as the velocity. The rate of change of a system’s momentum is equal to the net external force exerted on that system. Impulse is defined as the integral of the net force exerted on an object or system over a time interval. The impulse-momentum theorem relates the impulse delivered to an object and the object’s change in momentum.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/u1SOrLcHtVA.mp4/u1SOrLcHtVA.mp4</video:content_loc><video:duration>1002</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-c-mechanics/v/time-dependent-forces</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc025371fd7bb309b.jpg</video:thumbnail_loc><video:title>Time-dependent forces</video:title><video:description>Impulse is defined as the integral of the net force exerted on an object or system over a time interval. The impulse-momentum theorem relates the impulse delivered to an object and the object’s change in momentum. If the force on an object is constant over an interval, the impulse delivered during that interval is simply the product of the constant force and the amount of time it acts. But if a force varies with time, the force as a function of time must be integrated with respect to time to find the impulse.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/p8d72VuAjP8.mp4/p8d72VuAjP8.mp4</video:content_loc><video:duration>544</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-c-mechanics/v/angular-momentum-of-rigid-systems-with-calculus</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb6947f193ef7fcb4.jpg</video:thumbnail_loc><video:title>Angular momentum of rigid systems (with calculus)</video:title><video:description>The magnitude of the angular momentum of a rigid system about a specific axis is related to the rotational inertia and angular velocity of the rigid system. Angular impulse is defined as the product of the torque exerted on an object or rigid system and the time interval during which the torque is exerted. Angular impulse has the same direction as the torque imparting it. A rotational form of the impulse-momentum theorem relates the angular impulse delivered to a rigid system to the change in angular momentum of that rigid system.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/UCREaEXFiIA.mp4/UCREaEXFiIA.mp4</video:content_loc><video:duration>837</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-c-mechanics/v/modeling-spring-mass-oscillators</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa5d559731a61de1e.jpg</video:thumbnail_loc><video:title>Modeling spring-mass oscillators</video:title><video:description>Simple harmonic motion (SHM) can be modeled mathematically as a second-order differential equation derived using Newton’s second law. The solution to this differential equation is the object’s position as a function of time, which is sinusoidal. The position function can be differentiated with respect to time to find the object’s velocity and acceleration functions, which are also sinusoidal.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-inpCcFh9qk.mp4/-inpCcFh9qk.mp4</video:content_loc><video:duration>812</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-c-mechanics/v/modeling-pendulums</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0e23c64b3916ca29.jpg</video:thumbnail_loc><video:title>Modeling pendulums</video:title><video:description>A physical pendulum is a rigid system that undergoes oscillation about a fixed axis. For small amplitudes of motion, the period of a physical pendulum is derived from the application of Newton’s second law in rotational form. A simple pendulum is a special case of physical pendulums in which the object can be modeled as a point mass hanging from the pivot point. A torsion pendulum involves a twisted wire or other material that behaves analogously to a spring. If the wire exerts a restoring torque proportional to its angle of twist, simple harmonic motion can result.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0NjBjpGQpUQ.mp4/0NjBjpGQpUQ.mp4</video:content_loc><video:duration>746</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/ap-physics-c-mechanics/v/resonance-and-damped-oscillations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1f92e8f7f6a4ba9c.jpg</video:thumbnail_loc><video:title>Resonance</video:title><video:description>The natural frequency of a system is the frequency at which the system will oscillate when it is displaced from its equilibrium position. In the presence of a sinusoidal external force, a system may exhibit resonance. Resonance occurs when an external force is exerted at the natural frequency of the oscillating system. Resonance increases the amplitude of oscillating motion.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ubFGdZM1ziM.mp4/ubFGdZM1ziM.mp4</video:content_loc><video:duration>897</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/overview-of-biology</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7be07a3b.jpg</video:thumbnail_loc><video:title>Biology overview</video:title><video:description>Biology at Khan Academy explores life in all its forms, from humans to bacteria and how living things convert energy, grow, and reproduce. The course covers key biological molecules, the role of DNA, and the complexity of cells. It also touches on the intriguing world of viruses and how life continues to change and adapt through evolution and natural selection.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/dQCsA2cCdvA.mp4/dQCsA2cCdvA.mp4</video:content_loc><video:duration>274</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/lebron-asks-why-does-sweating-cool-you-down</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1022193589.jpg</video:thumbnail_loc><video:title>LeBron Asks: Why does sweating cool you down?</video:title><video:description>LeBron asks Sal why sweating helps cool the body down. Explore the molecular level of sweat and skin, understanding how temperature is related to molecular motion. Learn about evaporation and how high-energy water molecules escaping the skin&apos;s surface leads to cooling.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jgnNhL2jSXY.mp4/jgnNhL2jSXY.mp4</video:content_loc><video:duration>341</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/evaporative-cooling</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x57ce9014.jpg</video:thumbnail_loc><video:title>Evaporative cooling</video:title><video:description>Evaporative cooling. Why sweating cools you down.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_eEONOJHnEs.mp4/_eEONOJHnEs.mp4</video:content_loc><video:duration>314</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/heat-of-vaporization-of-water-and-ethanol</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xac337cc2.jpg</video:thumbnail_loc><video:title>Heat of vaporization of water and ethanol</video:title><video:description>Heat of vaporization of water and ethanol.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/bVHuI_QpYIM.mp4/bVHuI_QpYIM.mp4</video:content_loc><video:duration>436</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/specific-heat-of-water</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd0570e1e.jpg</video:thumbnail_loc><video:title>Specific heat of water</video:title><video:description>Specific heat of water. A calorie as the specific heat of water. How water moderates temperature.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/h-31O7CaF2o.mp4/h-31O7CaF2o.mp4</video:content_loc><video:duration>650</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/liquid-water-denser-than-solid-water-ice</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x79241b59.jpg</video:thumbnail_loc><video:title>Liquid water denser than solid water (ice)</video:title><video:description>Water less dense as ice. Why lakes don&apos;t freeze solid.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Y3ATc9he254.mp4/Y3ATc9he254.mp4</video:content_loc><video:duration>343</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/autoionization-water</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x389f5189.jpg</video:thumbnail_loc><video:title>Autoionization of water</video:title><video:description>Autoionization of water into hydronium and hydroxide ions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/NUyYlRxMtcs.mp4/NUyYlRxMtcs.mp4</video:content_loc><video:duration>654</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/introduction-to-definition-of-ph</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xff203ebc.jpg</video:thumbnail_loc><video:title>Definition of pH</video:title><video:description>Introduction to pH and the pH scale. Examples of calculating pH of pure water, bleach, and orange juice.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/J7-GewgqWUQ.mp4/J7-GewgqWUQ.mp4</video:content_loc><video:duration>697</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/buffer-system</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x39758a10.jpg</video:thumbnail_loc><video:title>Introduction to buffers</video:title><video:description>Introduction to buffer systems, which regulate pH in blood.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gjKmQ501sAg.mp4/gjKmQ501sAg.mp4</video:content_loc><video:duration>380</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/molecular-structure-of-glucose</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x66379952.jpg</video:thumbnail_loc><video:title>Molecular structure of glucose</video:title><video:description>Molecular structure of glucose. Monosaccharide structure. Linear and ring forms.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-Aj5BTnz-v0.mp4/-Aj5BTnz-v0.mp4</video:content_loc><video:duration>559</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/molecular-structure-of-fructose</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6fc25ec1.jpg</video:thumbnail_loc><video:title>Molecular structure of fructose</video:title><video:description>Fructose in comparison with glucose. Pyranose and furanose rings. Sucrose made from glucose and fructose.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/662koqcIXSk.mp4/662koqcIXSk.mp4</video:content_loc><video:duration>579</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/lipid-overview</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3bc71445.jpg</video:thumbnail_loc><video:title>Lipid overview</video:title><video:description>Types of lipids including fats, waxes, steroids and phospholipids.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Ezp8F7XJHWE.mp4/Ezp8F7XJHWE.mp4</video:content_loc><video:duration>691</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/tertiary-structure-of-proteins</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1cc9afc4.jpg</video:thumbnail_loc><video:title>Tertiary structure of proteins</video:title><video:description>How side chain interactions can impact the tertiary structure of proteins.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7udSVZ7bDb8.mp4/7udSVZ7bDb8.mp4</video:content_loc><video:duration>448</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/introduction-to-energy</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xad7ec6d2.jpg</video:thumbnail_loc><video:title>Introduction to energy</video:title><video:description>Energy is defined as the ability to do work. Energy can be found in many things and can take different forms. For example, kinetic energy is the energy of motion, and potential energy is energy due to an object&apos;s position or structure. Energy is never lost, but it can be converted from one form to another.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qzvatDIDXwo.mp4/qzvatDIDXwo.mp4</video:content_loc><video:duration>657</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/introduction-to-entropy</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x84002b90.jpg</video:thumbnail_loc><video:title>Introduction to entropy</video:title><video:description>Introduction to entropy, and how entropy relates to the number of possible states for a system.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Svvr5uF_FZ8.mp4/Svvr5uF_FZ8.mp4</video:content_loc><video:duration>447</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/the-second-law-of-thermodynamics</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x932d408d.jpg</video:thumbnail_loc><video:title>Second Law of Thermodynamics</video:title><video:description>The Second Law of Thermodynamics: there can be no spontaneous transfer of heat from cold to hot.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Vc8mmZTrNtI.mp4/Vc8mmZTrNtI.mp4</video:content_loc><video:duration>622</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/why-heat-increases-entropy</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x78208c62.jpg</video:thumbnail_loc><video:title>Why heat increases entropy</video:title><video:description>Why heat increases entropy—even though some of it can do work!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/cKAF1v5hJoE.mp4/cKAF1v5hJoE.mp4</video:content_loc><video:duration>421</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/gibbs-free-energy-and-spontaneous-reactions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xca9e7640.jpg</video:thumbnail_loc><video:title>Gibbs free energy and spontaneous reactions</video:title><video:description>Gibbs free energy and spontaneous reactions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/CHHu-iTwHjg.mp4/CHHu-iTwHjg.mp4</video:content_loc><video:duration>558</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/endergonic-exergonic-exothermic-and-endothermic-reactions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb760620c.jpg</video:thumbnail_loc><video:title>Endergonic, exergonic, exothermic, and endothermic</video:title><video:description>Endergonic, exergonic, exothermic, and endothermic reactions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/J2L-X2sUigs.mp4/J2L-X2sUigs.mp4</video:content_loc><video:duration>712</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/adenosine-triphosphate</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb7f05d8d.jpg</video:thumbnail_loc><video:title>ATP: Adenosine triphosphate</video:title><video:description>ATP, or Adenosine Triphosphate, is the energy currency in biological systems. It&apos;s made up of adenosine and three phosphate groups. Energy is stored when ATP is formed and released when it&apos;s broken down into ADP (Adenosine Diphosphate) and a phosphate group. This energy release powers various biological processes.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PK6HmIe2EAg.mp4/PK6HmIe2EAg.mp4</video:content_loc><video:duration>379</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/atp-hydrolysis-mechanism</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x20655c75.jpg</video:thumbnail_loc><video:title>ATP hydrolysis mechanism</video:title><video:description>ATP hydrolysis mechanism. How energy is released when ATP is converted to ADP and phosphate.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-KE7jTXwNYs.mp4/-KE7jTXwNYs.mp4</video:content_loc><video:duration>267</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/enzyme-cofactors-and-coenzymes</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf9e84d4d.jpg</video:thumbnail_loc><video:title>Enzyme cofactors and coenzymes</video:title><video:description>The cofactors and coenzymes (organic cofactors) that help enzymes catalyze reactions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jYR0RlMft8Y.mp4/jYR0RlMft8Y.mp4</video:content_loc><video:duration>599</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/cell-theory</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7771d81a.jpg</video:thumbnail_loc><video:title>Cell theory</video:title><video:description>Hooke and Leeuwenhoek were two of the first scientists to use microscopes to study the microscopic world of cells. Hooke coined the term &quot;cell&quot; after observing the tiny compartments in cork, while Leeuwenhoek discovered a variety of living creatures in pond water, blood, and other samples. They contributed to cell theory, which states that 1) all living things are made of one or more cells, 2) cells are the basic unit of life, and 3) all cells come from other cells.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/zk3vlhz1b6k.mp4/zk3vlhz1b6k.mp4</video:content_loc><video:duration>483</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/cytoskeletons</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd96ae2b8.jpg</video:thumbnail_loc><video:title>The cytoskeleton</video:title><video:description>Exploring the cell cytoskeleton, including microfilaments and microtubules (with a brief mention of intermediate filaments).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4BAGI6LbHeo.mp4/4BAGI6LbHeo.mp4</video:content_loc><video:duration>413</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/extracellular-matrix</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5c4ff82c.jpg</video:thumbnail_loc><video:title>Extracellular matrix</video:title><video:description>Overview of how cells interact with the extracellular matrix.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/cMNx17H3dRU.mp4/cMNx17H3dRU.mp4</video:content_loc><video:duration>414</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/overview-of-animal-and-plant-cells</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0e8b1264.jpg</video:thumbnail_loc><video:title>Overview of animal and plant cells</video:title><video:description>Animal and plant cells share common elements like plasma membranes, cytoskeletons, and mitochondria. However, they differ in certain aspects. For example, plant cells have a cell wall and a central vacuole, while animal cells contain centrosomes. The understanding of these cellular structures continues to evolve through ongoing research.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/24YMQ9GvLss.mp4/24YMQ9GvLss.mp4</video:content_loc><video:duration>522</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/concentration-gradients</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x094bd875.jpg</video:thumbnail_loc><video:title>Concentration gradients</video:title><video:description>Particles move from high to low concentration areas, a process called diffusion. Each particle type has its own unique concentration gradient. This movement isn&apos;t planned, but happens randomly. Over time, particles spread evenly, balancing the probability of movement in all directions. This is a key concept in biology and chemistry.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/CNP-dCQ-Cmg.mp4/CNP-dCQ-Cmg.mp4</video:content_loc><video:duration>184</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/oxidation-and-reduction-from-biological-view</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23956.jpg</video:thumbnail_loc><video:title>Oxidation and reduction review from biological point-of-view</video:title><video:description>Taking a look at oxidation and reduction in a biological context. Discover how these processes, involving the loss and gain of electrons, are the same in both fields. Uncover why biologists often refer to oxidation as losing hydrogen atoms and reduction as gaining them.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/orI2m6IarJg.mp4/orI2m6IarJg.mp4</video:content_loc><video:duration>809</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/oxidation-and-reduction-in-cellular-respiration</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23958.jpg</video:thumbnail_loc><video:title>Oxidation and reduction in cellular respiration</video:title><video:description>Oxidation and reduction in cellular respiration. Reconciling the biology and chemistry definitions of oxidation and reduction.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_KyyVhlUDNU.mp4/_KyyVhlUDNU.mp4</video:content_loc><video:duration>1028</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/glycolysis</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23960.jpg</video:thumbnail_loc><video:title>Overview of glycolysis</video:title><video:description>Let&apos;s explore the process of glycolysis, the first phase of cellular respiration. Learn how this process breaks down glucose into two 3-carbon compounds, using two ATPs in the investment phase and generating a net of two ATPs in the payoff phase.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/FE2jfTXAJHg.mp4/FE2jfTXAJHg.mp4</video:content_loc><video:duration>810</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/glycolysis-overview</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x66a00a38.jpg</video:thumbnail_loc><video:title>Steps of glycolysis</video:title><video:description>Introduction to glycolysis. Role of glycolysis in producing ATPs and NADHs and converting glucose to pyruvates.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ArmlWtDnuys.mp4/ArmlWtDnuys.mp4</video:content_loc><video:duration>722</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/krebs-citric-acid-cycle</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23962.jpg</video:thumbnail_loc><video:title>Krebs / citric acid cycle</video:title><video:description>Overview of the Krebs or citric acid cycle, which is a series of reactions that takes in acetyl CoA and produces carbon dioxide, NADH, FADH2, and ATP or GTP.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/juM2ROSLWfw.mp4/juM2ROSLWfw.mp4</video:content_loc><video:duration>1067</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/lactic-acid-fermentation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5a5ece83.jpg</video:thumbnail_loc><video:title>Lactic acid fermentation</video:title><video:description>Glycolysis breaks down glucose into two pyruvate molecules, producing ATP and reducing NAD to NADH. If oxygen is unavailable, lactic acid fermentation occurs, recycling pyruvate and NADH to produce more NAD+ for glycolysis. This process is common in organisms like lactobacillus, which is used in making yogurt, kimchi, and sauerkraut.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lfeXuK8pbFw.mp4/lfeXuK8pbFw.mp4</video:content_loc><video:duration>682</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/alcohol-or-ethanol-fermentation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xcc1b90e8.jpg</video:thumbnail_loc><video:title>Alcohol or ethanol fermentation</video:title><video:description>Glycolysis breaks down glucose into two pyruvate molecules, producing ATP and reducing NAD+ to NADH. When oxygen isn&apos;t available, organisms can use lactic acid fermentation or alcohol fermentation to recycle NADH back to NAD+. In alcohol fermentation, pyruvate loses a carboxyl group, becoming acetaldehyde, which is then reduced to ethanol. This process, performed by yeast, is used in bread and alcohol production.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/D6mRPgvAEOc.mp4/D6mRPgvAEOc.mp4</video:content_loc><video:duration>383</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/light-dependent-reactions-actors</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x614c1624.jpg</video:thumbnail_loc><video:title>Light dependent reactions actors</video:title><video:description>More detailed description of the various molecular actors in the light dependent reactions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/KzpRivhr6HI.mp4/KzpRivhr6HI.mp4</video:content_loc><video:duration>398</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/photosynthesis-light-reactions-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23970.jpg</video:thumbnail_loc><video:title>Photosynthesis: Overview of the light-dependent reactions</video:title><video:description>Overview of the light-dependent reactions, including the structure of the chloroplast, the photosystems, and how ATP is synthesized.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/GR2GA7chA_c.mp4/GR2GA7chA_c.mp4</video:content_loc><video:duration>1216</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/photosynthesis-calvin-cycle</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23974.jpg</video:thumbnail_loc><video:title>Photosynthesis: Calvin cycle</video:title><video:description>The Calvin cycle, or the light-independent (dark) reactions of photosythesis.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/slm6D2VEXYs.mp4/slm6D2VEXYs.mp4</video:content_loc><video:duration>808</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/photorespiration</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23976.jpg</video:thumbnail_loc><video:title>Photorespiration</video:title><video:description>The Calvin cycle and a competing pathway called photorespiration (also initiated by Rubisco).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DnNqe8o0ehc.mp4/DnNqe8o0ehc.mp4</video:content_loc><video:duration>665</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/c-4-photosynthesis</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23978.jpg</video:thumbnail_loc><video:title>C4 photosynthesis</video:title><video:description>C4 photosynthesis: how some plants avoid photorespiration.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7ynX_F-SwNY.mp4/7ynX_F-SwNY.mp4</video:content_loc><video:duration>1018</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/cam-plants</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23980.jpg</video:thumbnail_loc><video:title>CAM plants</video:title><video:description>How CAM Plants are able to fix carbon at night so they don&apos;t have to keep their stomata open during the day.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xp6Zj24h8uA.mp4/xp6Zj24h8uA.mp4</video:content_loc><video:duration>517</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/somatic-germ-cells</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x754b170b.jpg</video:thumbnail_loc><video:title>Zygote differentiating into somatic and germ cells</video:title><video:description>Learn how a zygote, the single cell produced by fertilization, divides by mitosis to produce all the tissues of the human body (including germ cells, which can undergo meiosis to make sperm and eggs).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PvoigrzODdE.mp4/PvoigrzODdE.mp4</video:content_loc><video:duration>575</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/chromosomes-chromatids-chromatin-etc</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23928.jpg</video:thumbnail_loc><video:title>Chromosomes, chromatids and chromatin</video:title><video:description>DNA replication, transcription, and translation are key biological processes. Replication involves DNA duplicating itself. Transcription involves DNA creating mRNA, and translation converts mRNA into proteins.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/s9HPNwXd9fk.mp4/s9HPNwXd9fk.mp4</video:content_loc><video:duration>1103</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/cancer</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23938.jpg</video:thumbnail_loc><video:title>Cancer</video:title><video:description>Cells replicate through a process called mitosis, making perfect copies of themselves. Sometimes, a cell&apos;s DNA can mutate during replication. Most mutations are harmless, but some can cause cells to grow uncontrollably, leading to cancer.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/RZhL7LDPk8w.mp4/RZhL7LDPk8w.mp4</video:content_loc><video:duration>756</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/apoptosis</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7b82c8ab.jpg</video:thumbnail_loc><video:title>Apoptosis</video:title><video:description>Apoptosis, or programmed cell death, is a natural and healthy process occurring in our bodies. It&apos;s like a cell&apos;s self-destruct button, activated when a cell is damaged beyond repair. This process prevents the spread of potential diseases like cancer. Apoptosis is also crucial during development, shaping our fingers from a block of tissue, for example. Unlike necrosis, where a cell explodes and can harm neighboring cells, apoptosis is a tidy process where cells are broken down and their components reused.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/gNFDONSjB7Q.mp4/gNFDONSjB7Q.mp4</video:content_loc><video:duration>648</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/establishing-dna-as-transformation-principle</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x53fe520f.jpg</video:thumbnail_loc><video:title>DNA as the &quot;transforming principle&quot;</video:title><video:description>How Griffith and later Avery, McCarty and MacLeod found strong evidence that DNA is the &quot;transforming principle&quot; that encodes genetic information.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9X12OVvOznU.mp4/9X12OVvOznU.mp4</video:content_loc><video:duration>619</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/hershey-and-chase-conclusively-show-dna-genetic-material</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc7b4e9cb.jpg</video:thumbnail_loc><video:title>Hershey and Chase: DNA is the genetic material</video:title><video:description>How Alfred Hershey and Martha Chase showed conclusively that DNA is the genetic material.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/bNsSaxCsIIg.mp4/bNsSaxCsIIg.mp4</video:content_loc><video:duration>529</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/the-discovery-of-the-double-helix-structure-of-dna</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x658eb73b.jpg</video:thumbnail_loc><video:title>The discovery of the double helix structure of DNA</video:title><video:description>How the double helix structure of DNA was discovered. Work of Watson, Crick, Franklin, Wilkins, and Chargaff.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hCUce36Ganc.mp4/hCUce36Ganc.mp4</video:content_loc><video:duration>537</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/bacteria</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23948.jpg</video:thumbnail_loc><video:title>Bacteria</video:title><video:description>Introduction to bacteria.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TDoGrbpJJ14.mp4/TDoGrbpJJ14.mp4</video:content_loc><video:duration>1106</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/viruses</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23950.jpg</video:thumbnail_loc><video:title>Viruses</video:title><video:description>Introduction to viruses.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0h5Jd7sgQWY.mp4/0h5Jd7sgQWY.mp4</video:content_loc><video:duration>1397</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/ape-clarification</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/42120192.jpg</video:thumbnail_loc><video:title>Ape clarification</video:title><video:description>Apes, tailless primates, are divided into two families: lesser apes like gibbons, and great apes, which include chimpanzees, gorillas, and humans. The absence of a tail is a key characteristic distinguishing apes. This clarification corrects a previous error where an ape was incorrectly depicted with a tail.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/oFGkYA_diDA.mp4/oFGkYA_diDA.mp4</video:content_loc><video:duration>64</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/genetic-variation-gene-flow-and-new-species</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x92bc392c.jpg</video:thumbnail_loc><video:title>Genetic variation, gene flow, and new species</video:title><video:description>Natural selection, DNA, and gene flow are key to understanding evolution. DNA, or Deoxyribonucleic acid, is the genetic code that determines traits in organisms. Variations in this code, called mutations, lead to unique traits. Gene flow, the mixing of genetic information, maintains consistency within a species. When gene flow is restricted, species can diverge, leading to new species. This process, called speciation, contributes to biodiversity.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/11iYk0Yrx3g.mp4/11iYk0Yrx3g.mp4</video:content_loc><video:duration>712</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/ozone-layer-and-eukaryotes-show-up-in-the-proterozoic-eon</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179299.jpg</video:thumbnail_loc><video:title>Ozone layer and eukaryotes show up in the Proterozoic eon</video:title><video:description>Ozone layer and eukaryotes show up in the Proterozoic eon. Great oxygenation event (oxygen catastrophe).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/E1P79uFLCMc.mp4/E1P79uFLCMc.mp4</video:content_loc><video:duration>596</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/first-living-things-on-land-clarification</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179435.jpg</video:thumbnail_loc><video:title>First living things on land clarification</video:title><video:description>First living things on land clarification (This video copyrighted under Create Commons Attribution and Share-Alike CC-BY-SA license)</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3gUE_P9T-Wk.mp4/3gUE_P9T-Wk.mp4</video:content_loc><video:duration>335</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/biodiversity-flourishes-in-phanerozoic-eon</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179300.jpg</video:thumbnail_loc><video:title>Biodiversity flourishes in Phanerozoic eon</video:title><video:description>Cambrian explosion and biodiversity in the Phanerozoic Eon</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/MS7x2hDEhrw.mp4/MS7x2hDEhrw.mp4</video:content_loc><video:duration>628</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/human-evolution-overview</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/99682014.jpg</video:thumbnail_loc><video:title>Human evolution overview</video:title><video:description>The extinction of dinosaurs 65 million years ago paved the way for a rodent-like creature to evolve into various species. This creature survived the mass extinction event and gradually evolved into primates, monkeys, apes, and us—Homo sapiens.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/frE1rjhH77Y.mp4/frE1rjhH77Y.mp4</video:content_loc><video:duration>746</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/chronometric-revolution</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/334540860.jpg</video:thumbnail_loc><video:title>Chronometric revolution</video:title><video:description>Discussion of the relatively recent changes in our ability as a species to shine light on our deep past</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5mNTvtjDnP8.mp4/5mNTvtjDnP8.mp4</video:content_loc><video:duration>593</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/carbon-14-dating-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187417.jpg</video:thumbnail_loc><video:title>Carbon 14 dating 2</video:title><video:description>Carbon 14 Dating 2</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4YUtnod-YuE.mp4/4YUtnod-YuE.mp4</video:content_loc><video:duration>255</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/potassium-argon-k-ar-dating</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/328018950.jpg</video:thumbnail_loc><video:title>Potassium-argon (K-Ar) dating</video:title><video:description>How K-Ar dating can be used to date very old volcanic rock and the things that might be buried in between</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/NMZ5kJEviD0.mp4/NMZ5kJEviD0.mp4</video:content_loc><video:duration>635</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/k-ar-dating-calculation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/328024200.jpg</video:thumbnail_loc><video:title>K-Ar dating calculation</video:title><video:description>Working through a calculation for K-Ar dating (good to have some prior experience with e and logarithms)</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/iLFcSfzrlMk.mp4/iLFcSfzrlMk.mp4</video:content_loc><video:duration>667</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/ecology-introduction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x598ab453.jpg</video:thumbnail_loc><video:title>Ecology introduction</video:title><video:description>Ecology studies how life interacts with other life and their environment, focusing on both living (biotic) and non-living (abiotic) factors. It explores different scales, from individual organisms to populations, communities, ecosystems, and the biosphere. Each level offers unique insights into the complex, often balanced systems that form our world. Ecology also considers potential biospheres beyond Earth.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OfV3VNgjpvw.mp4/OfV3VNgjpvw.mp4</video:content_loc><video:duration>589</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/thomas-malthus-and-population-growth</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/467947556.jpg</video:thumbnail_loc><video:title>Thomas Malthus and population growth</video:title><video:description>Thomas Malthus&apos;s views on population. Malthusian limits.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/r1ywppAJ1xs.mp4/r1ywppAJ1xs.mp4</video:content_loc><video:duration>493</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/biogeochemical-cycles</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1f5392abf0304d17.jpg</video:thumbnail_loc><video:title>Biogeochemical cycles overview</video:title><video:description>Biogeochemical cycles are nature&apos;s way of recycling essential elements for life, like water, carbon, nitrogen, and phosphorus. These cycles circulate these molecules through ecosystems and the entire biosphere. From the water cycle to the carbon cycle, these processes ensure the constant reuse of matter, while energy flows through the ecosystem.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ccWUDlKC3dE.mp4/ccWUDlKC3dE.mp4</video:content_loc><video:duration>475</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/distribution-how</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x427d430d.jpg</video:thumbnail_loc><video:title>How biodiversity is distributed globally</video:title><video:description>How biodiversity is distributed globally. Video by California Academy of Sciences.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/BTOHSRVqN20.mp4/BTOHSRVqN20.mp4</video:content_loc><video:duration>438</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/distributionwhy</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb482835e.jpg</video:thumbnail_loc><video:title>Why biodiversity is distributed unevenly</video:title><video:description>Factors that influence the global distribution of biodiversity. Video by California Academy of Sciences.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3OAfLjxQUg4.mp4/3OAfLjxQUg4.mp4</video:content_loc><video:duration>649</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/ecosystem-services</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1be8fe42.jpg</video:thumbnail_loc><video:title>Ecosystem services</video:title><video:description>Describing and quantifying the benefits that healthy ecosystems provide to humans. Video by California Academy of Sciences.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/BCH1Gre3Mg0.mp4/BCH1Gre3Mg0.mp4</video:content_loc><video:duration>543</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/biodiversity-hotspot</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe98900f2.jpg</video:thumbnail_loc><video:title>What is a biodiversity hotspot?</video:title><video:description>Biodiversity hotspots, unique areas on Earth with a high number of endemic species and significant habitat loss, are crucial for conservation efforts. These hotspots, representing less than three percent of the Earth&apos;s land surface, serve as a scientific tool to measure human impact on biodiversity and guide resource allocation for protection efforts.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/RaQBaVeEbW8.mp4/RaQBaVeEbW8.mp4</video:content_loc><video:duration>354</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/ocean-acidification-and-biodiversity-impacts</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa74094f2.jpg</video:thumbnail_loc><video:title>Demystifying ocean acidification and biodiversity impacts</video:title><video:description>Why rising carbon dioxide levels in the atmosphere affect the acidity of the ocean, and what the consequences are for marine life. Video by California Academy of Sciences.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/GL7qJYKzcsk.mp4/GL7qJYKzcsk.mp4</video:content_loc><video:duration>733</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/conservation-and-the-race-to-save-biodiversity</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x34bb666c.jpg</video:thumbnail_loc><video:title>Conservation and the race to save biodiversity</video:title><video:description>Conservation, a study focused on preventing loss of Earth&apos;s biological diversity, uses two key approaches: protecting species and safeguarding their habitats. Laws, international treaties, and species survival plans help shield endangered species. Meanwhile, conserving places, like biodiversity hotspots and protected parks, ensures the survival of entire ecosystems. Emerging fields like conservation genetics offer new perspectives, emphasizing the importance of protecting genetic diversity within ecosystems.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-u8xi7KFHY4.mp4/-u8xi7KFHY4.mp4</video:content_loc><video:duration>724</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/protecting-biodiversity-the-power-of-the-individual</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa0b8415e.jpg</video:thumbnail_loc><video:title>Protecting biodiversity: the power of the individual</video:title><video:description>Individuals hold significant power and responsibility in safeguarding biodiversity. This involves gaining knowledge about biodiversity, understanding our actions&apos; effects on ecosystems, and making eco-friendly consumer choices. It&apos;s also crucial to reuse and recycle, engage in citizen science projects, and spread the passion for biodiversity.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PxAHbuyBvBY.mp4/PxAHbuyBvBY.mp4</video:content_loc><video:duration>608</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/protecting-biodiversity-local-and-global-policies</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x46fd888f.jpg</video:thumbnail_loc><video:title>Protecting biodiversity: local and global policies</video:title><video:description>Policy making plays a crucial role in protecting biodiversity. Since organisms do not adhere to human-made borders, conservation efforts need to be local, regional, national, and international. While economic factors often overshadow conservation, long-term environmental effects are starting to impact short-term views. Scientific data is vital in shaping effective policies.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/mXsFQONwIic.mp4/mXsFQONwIic.mp4</video:content_loc><video:duration>640</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/genes-and-biodiversity</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x79f3cdca.jpg</video:thumbnail_loc><video:title>Genes and biodiversity</video:title><video:description>How does the gene pool contribute to biodiversity? Learn how genetic diversity within populations contributes to species survival. Video by California Academy of Sciences.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/XOxsjdB4-ZQ.mp4/XOxsjdB4-ZQ.mp4</video:content_loc><video:duration>401</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/ecosystem-biodiversity</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x11780233.jpg</video:thumbnail_loc><video:title>Ecosystem biodiversity</video:title><video:description>Ecosystem diversity is a critical aspect of Earth&apos;s biodiversity. Ecosystems, defined by habitat and climate, are unique and diverse. Species within ecosystems are specialized and vary globally. Protecting ecosystem diversity is vital, focusing not just on the most biodiverse but on the interconnectedness of all ecosystems. Preserving these complex webs of interactions is essential for the stability of Earth&apos;s ecosystems.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ixf33dQDlXc.mp4/ixf33dQDlXc.mp4</video:content_loc><video:duration>254</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/the-lungs-and-pulmonary-system</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23986.jpg</video:thumbnail_loc><video:title>The lungs and pulmonary system</video:title><video:description>Breathing is a vital process that allows our bodies to take in necessary oxygen and expel waste carbon dioxide. Air enters through the nose or mouth, journeys down the throat, and reaches the lungs via tubes called bronchi. These bronchi split into smaller tubes, bronchioles, ending in tiny air sacs known as alveoli. Oxygen crosses the alveoli membrane into our bloodstream, while carbon dioxide moves from the blood into the alveoli, ready to be exhaled.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/SPGRkexI_cs.mp4/SPGRkexI_cs.mp4</video:content_loc><video:duration>1233</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/red-blood-cells</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23988.jpg</video:thumbnail_loc><video:title>Red blood cells</video:title><video:description>Oxygen uptake by hemoglobin in red blood cells.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/fLKOBQ6cZHA.mp4/fLKOBQ6cZHA.mp4</video:content_loc><video:duration>990</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/circulatory-system-and-the-heart</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23990.jpg</video:thumbnail_loc><video:title>Circulatory system and the heart</video:title><video:description>Hemoglobin, found in red blood cells, absorbs oxygen, increasing the diffusion gradient. This process encourages oxygen to cross the membrane. Hemoglobin is contained within red blood cells to prevent blood from becoming too thick. The blood flows from the heart to the lungs via the pulmonary artery, gets oxygenated, and returns to the heart via the pulmonary vein. The oxygenated blood is then pumped to the rest of the body.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/QhiVnFvshZg.mp4/QhiVnFvshZg.mp4</video:content_loc><video:duration>897</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/hemoglobin</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23992.jpg</video:thumbnail_loc><video:title>Hemoglobin</video:title><video:description>Hemoglobin and its role in the circulatory system.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LWtXthfG9_M.mp4/LWtXthfG9_M.mp4</video:content_loc><video:duration>874</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/anatomy-of-a-neuron</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/23994.jpg</video:thumbnail_loc><video:title>Anatomy of a neuron</video:title><video:description>Neurons (or nerve cells) are specialized cells that transmit and receive electrical signals in the body. Neurons are composed of three main parts: dendrites, a cell body, and an axon. Signals are received through the dendrites, travel to the cell body, and continue down the axon until they reach the synapse (the communication point between two neurons).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ob5U8zPbAX4.mp4/ob5U8zPbAX4.mp4</video:content_loc><video:duration>373</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/electrotonic-action-potential</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbfcf48e2.jpg</video:thumbnail_loc><video:title>Electrotonic and action potentials</video:title><video:description>Two different types of changes in the membrane potential of a neuron.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/kY8FEq0teOs.mp4/kY8FEq0teOs.mp4</video:content_loc><video:duration>618</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/saltatory-conduction-neurons</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x45263500.jpg</video:thumbnail_loc><video:title>Saltatory conduction in neurons</video:title><video:description>Myelin sheaths, nodes of Ranvier, and saltatory conduction in neurons.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ikFUv-gdNLQ.mp4/ikFUv-gdNLQ.mp4</video:content_loc><video:duration>668</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/neuronal-synapses-chemical</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24002.jpg</video:thumbnail_loc><video:title>Neuronal synapses (chemical)</video:title><video:description>How one neuron can stimulate (or inhibit) another neuron at a chemical synapse.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Tbq-KZaXiL4.mp4/Tbq-KZaXiL4.mp4</video:content_loc><video:duration>953</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/overview-of-the-functions-of-the-cerebral-cortex</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xda7ddf7a.jpg</video:thumbnail_loc><video:title>Overview of the functions of the cerebral cortex</video:title><video:description>The human brain, with its wrinkly cerebral cortex, is split into four lobes: frontal, parietal, occipital, and temporal. The frontal lobe controls body movements and executive functions, including thinking and problem-solving. The parietal lobe processes touch, pressure, temperature, and spatial orientation. The occipital lobe handles vision, while the temporal lobe manages auditory processing and language comprehension.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/X-m0JDCw6TE.mp4/X-m0JDCw6TE.mp4</video:content_loc><video:duration>344</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/the-kidney-and-nephron</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24028.jpg</video:thumbnail_loc><video:title>The kidney and nephron</video:title><video:description>The video provides a detailed overview of the kidney&apos;s smallest functional unit, the nephron. It explains how the nephron filters blood, excretes waste, and maintains water levels. The video also highlights the role of the renal cortex and renal medulla in this process. The loop of Henle&apos;s function in reabsorbing water and making the renal medulla salty is also discussed.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/cc8sUv2SuaY.mp4/cc8sUv2SuaY.mp4</video:content_loc><video:duration>1118</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/secondary-active-transport-in-the-nephron</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24030.jpg</video:thumbnail_loc><video:title>Secondary active transport in the nephron</video:title><video:description>This video provides an in-depth look at how the nephron, the functional unit of the kidney, actively pumps molecules against their concentration gradients. It details the process of secondary active transport, focusing on the roles of sodium-potassium pumps and cotransporters in reabsorbing essential molecules like glucose, salts, and calcium from the filtrate.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/czY5nyvZ7cU.mp4/czY5nyvZ7cU.mp4</video:content_loc><video:duration>853</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/myosin-and-actin</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24004.jpg</video:thumbnail_loc><video:title>Myosin and actin</video:title><video:description>Learn how proteins, specifically myosin and actin, use ATP to produce movement in muscles. Understand the role of ATP hydrolysis in this process. This is a key part of how muscles function, converting chemical energy into mechanical energy.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/zopoN2i7ALQ.mp4/zopoN2i7ALQ.mp4</video:content_loc><video:duration>578</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/tropomyosin-and-troponin-and-their-role-in-regulating-muscle-contraction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24006.jpg</video:thumbnail_loc><video:title>How tropomyosin and troponin regulate muscle contraction</video:title><video:description>Lean how calcium ion concentration dictates whether a muscle contracts or not. Explore how myosin II, using ATP, interacts with actin filaments to enable muscle contraction. Learn about the regulatory roles of proteins tropomyosin and troponin, and the crucial part calcium ions play in muscle contraction and relaxation. This is a deep look into muscle cell anatomy and function.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LiOfeSsjrB8.mp4/LiOfeSsjrB8.mp4</video:content_loc><video:duration>562</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/role-of-the-sarcoplasmic-reticulum-in-muscle-cells</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24008.jpg</video:thumbnail_loc><video:title>Role of the sarcoplasmic reticulum in muscle cells</video:title><video:description>Explore the role of the sarcoplasmic reticulum in muscle cells, crucial for muscle contraction and relaxation. Learn how calcium ions are regulated, triggering muscle contraction when released into the cell&apos;s cytoplasm. Understand the interaction between troponin, tropomyosin, myosin, and actin, and how the nervous system controls these processes.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/SauhB2fYQkM.mp4/SauhB2fYQkM.mp4</video:content_loc><video:duration>882</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/anatomy-of-a-muscle-cell</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24010.jpg</video:thumbnail_loc><video:title>Anatomy of a skeletal muscle fiber</video:title><video:description>Understanding the structure of a muscle fiber.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/uY2ZOsCnXIA.mp4/uY2ZOsCnXIA.mp4</video:content_loc><video:duration>992</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/role-of-phagocytes-in-innate-or-nonspecific-immunity</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24012.jpg</video:thumbnail_loc><video:title>Role of phagocytes in innate or nonspecific immunity</video:title><video:description>The immune system&apos;s primary role is to protect the body from harmful pathogens. It employs two lines of defense for non-specific immunity: the first line, which includes skin and mucus membranes, aims to keep pathogens out. The second line, featuring phagocytes, targets pathogens that have entered the body. This non-specific or innate immune system does not distinguish between types of pathogens, but effectively eliminates them.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/O1N2rENXq_Y.mp4/O1N2rENXq_Y.mp4</video:content_loc><video:duration>980</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/types-of-immune-responses-innate-and-adaptive-humoral-vs-cell-mediated</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24014.jpg</video:thumbnail_loc><video:title>Types of immune responses: Innate and adaptive, humoral vs. cell-mediated</video:title><video:description>The immune system is divided into nonspecific (innate) and specific (adaptive) responses. Nonspecific defenses, like skin and stomach acid, block pathogens indiscriminately. Specific defenses, such as B and T lymphocytes, adapt to specific pathogens after exposure. B lymphocytes are part of the humoral response, dealing with pathogens in body fluids.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/rp7T4IItbtM.mp4/rp7T4IItbtM.mp4</video:content_loc><video:duration>487</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/b-lymphocytes-b-cells</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24016.jpg</video:thumbnail_loc><video:title>B lymphocytes (B cells)</video:title><video:description>Learn about the role of B cells (B lymphocytes) in the humoral immune response. See how they are activated and produce antibodies that can recognize and bind to pathogens, leading to their destruction. The video also highlights the process of clonal selection and the importance of memory cells in immunity.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Z36dUduOk1Y.mp4/Z36dUduOk1Y.mp4</video:content_loc><video:duration>853</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/professional-antigen-presenting-cells-apc-and-mhc-ii-complexes</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24018.jpg</video:thumbnail_loc><video:title>Professional antigen presenting cells (APC) and MHC II complexes</video:title><video:description>Professional antigen presenting cells (APCs) are immune cells that specialize in presenting an antigen to a T-cell. The main types of professional APCs are dendritic cells (DC), macrophages, and B cells. A professional APC takes up an antigen, processes it, and returns part of it to its surface, along with a class II major histocompatibility complex (MHC). The T-cell is activated when it interacts with the formed complex.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/j_kSmmEpvQk.mp4/j_kSmmEpvQk.mp4</video:content_loc><video:duration>693</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/helper-t-cells</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24020.jpg</video:thumbnail_loc><video:title>Helper T cells</video:title><video:description>Explore the adaptive immune system&apos;s key players: B cells, T cells, and helper T cells. Learn how B cells generate antibodies to disable pathogens, while helper T cells raise the alarm. Discover the double-check system that prevents autoimmune diseases and the role of cytotoxic T cells in attacking infiltrated cells.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/uwMYpTYsNZM.mp4/uwMYpTYsNZM.mp4</video:content_loc><video:duration>1233</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/cytotoxic-t-cell-mhc-i-complexes</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb1e2a45d.jpg</video:thumbnail_loc><video:title>Cytotoxic T cells and MHC I complexes</video:title><video:description>How damaged cells present antigens from inside the cell on MHC I and are recognized by cytotoxic T cells.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/YdBXHm3edL8.mp4/YdBXHm3edL8.mp4</video:content_loc><video:duration>556</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/review-of-b-cells-cd4-t-cells-and-cd8-t-cells</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24024.jpg</video:thumbnail_loc><video:title>Review of B cells, CD4+ T cells and CD8+ T cells</video:title><video:description>Review the roles of B cells, T cells, and plasma cells in the immune system. Understand how these cells respond to pathogens, differentiate into effector and memory cells, and produce antibodies. Learn the distinction between CD4 and CD8 T cells and their functions in fighting infections and diseases.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xaz5ftvZCyI.mp4/xaz5ftvZCyI.mp4</video:content_loc><video:duration>667</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/inflammatory-response</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/24026.jpg</video:thumbnail_loc><video:title>Inflammatory response</video:title><video:description>Overview of the inflammatory response.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/FXSuEIMrPQk.mp4/FXSuEIMrPQk.mp4</video:content_loc><video:duration>875</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/phototropism</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5bd7eab9044a6e96.jpg</video:thumbnail_loc><video:title>Phototropism</video:title><video:description>Phototropism and the role that auxin plays.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2A_LKrLlhxE.mp4/2A_LKrLlhxE.mp4</video:content_loc><video:duration>415</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/photoperiodism</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x56f1b2c995788144.jpg</video:thumbnail_loc><video:title>Photoperiodism</video:title><video:description>How plants can regulate processes like flowering based on day length (photoperiod).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/AQf3gKTCffs.mp4/AQf3gKTCffs.mp4</video:content_loc><video:duration>476</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/2015-ap-biology-free-response-1-a-c</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc288bd09.jpg</video:thumbnail_loc><video:title>1a-c, Responses to the environment</video:title><video:description>Genetic and environmental influences on mouse activity cycles.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Tbpj-dNGrhc.mp4/Tbpj-dNGrhc.mp4</video:content_loc><video:duration>672</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/2015-ap-biology-free-response-1-d-e</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9754acf0.jpg</video:thumbnail_loc><video:title>1d-e, Responses to the environment &amp; natural selection</video:title><video:description>Light-dark activity cycle of mutant mice and evolutionary implications.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LpryknYN2xg.mp4/LpryknYN2xg.mp4</video:content_loc><video:duration>424</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/2015-ap-biology-free-response-2-a-b</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb2b6f0c6.jpg</video:thumbnail_loc><video:title>2a-b, Cellular respiration &amp; common ancestry</video:title><video:description>Questions on cellular respiration and common ancestry.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/UNT8uh9io2o.mp4/UNT8uh9io2o.mp4</video:content_loc><video:duration>704</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/2015-ap-biology-free-response-2-c-d</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x85d1a41b.jpg</video:thumbnail_loc><video:title>2c-d, Cellular respiration &amp; cell compartmentalization and its origins</video:title><video:description>Questions on cellular respiration and the origins of cell compartmentalization.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/dktGVfUWIv8.mp4/dktGVfUWIv8.mp4</video:content_loc><video:duration>572</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/2015-ap-biology-free-response-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x721ed261.jpg</video:thumbnail_loc><video:title>3a-b, Phylogeny</video:title><video:description>Thinking about evolutionary distance between species. Constructing phylogenetic trees (cladograms).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/yjU49bK1gkA.mp4/yjU49bK1gkA.mp4</video:content_loc><video:duration>511</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/2015-ap-biology-free-response-4</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x32d512c5.jpg</video:thumbnail_loc><video:title>4a-b, Meiosis and genetic diversity</video:title><video:description>Commonalities and differences between mitosis and meiosis.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/nfqYCmt6RAc.mp4/nfqYCmt6RAc.mp4</video:content_loc><video:duration>324</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/2015-ap-biology-free-response-5</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x41f7e698.jpg</video:thumbnail_loc><video:title>5a-b, Responses to the environment</video:title><video:description>Phototropism investigation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/JVbdSwK5i1c.mp4/JVbdSwK5i1c.mp4</video:content_loc><video:duration>414</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/biology/v/2015-ap-biology-free-response-6</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1b47e25f.jpg</video:thumbnail_loc><video:title>6a-c, Population ecology</video:title><video:description>Fixing a declining snake population.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/NEm1AupTkto.mp4/NEm1AupTkto.mp4</video:content_loc><video:duration>356</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/chem37-history-of-atomic-chemistry</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x56806d67.jpg</video:thumbnail_loc><video:title>The history of atomic chemistry</video:title><video:description>How did we get here? Well, in terms of Atomic Chemistry, Hank takes us on a tour of the folks that were part of the long chain of other folks who helped us get to these deeper understandings of the world. From Leucippus to Heisenberg to you - yes, YOU - the story of Atomic Chemistry is all wibbly-wobbly... and amazing. Writers: Edi Gonzalez Chief Editor: Blake de Pastino Consultant: Dr. Heiko Langner Director/Editor: Nicholas Jenkins Sound Designer: Michael Aranda Graphics: Thought Cafe</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/agjG7kgixJs.mp4/agjG7kgixJs.mp4</video:content_loc><video:duration>527</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/rutherfords-gold-foil-experiment</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x72ec884f.jpg</video:thumbnail_loc><video:title>Rutherford’s gold foil experiment</video:title><video:description>Learn about Rutherford&apos;s discovery of the nucleus and the development of the nuclear model of the atom.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/bVlwH1kfDeg.mp4/bVlwH1kfDeg.mp4</video:content_loc><video:duration>684</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/heisenberg-uncertainty-principle</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5a9c24f5.jpg</video:thumbnail_loc><video:title>Heisenberg uncertainty principle</video:title><video:description>The Heisenberg uncertainty principle states that there is a limit to how precisely certain pairs of physical properties of a particle can be known simultaneously. Explore the Heisenberg uncertainty principle by calculating uncertainty in position given the uncertainty in momentum for Bohr model of hydrogen.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PZIoFD_Z73M.mp4/PZIoFD_Z73M.mp4</video:content_loc><video:duration>618</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/quantum-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7448f8b7.jpg</video:thumbnail_loc><video:title>Quantum numbers</video:title><video:description>An orbital is a region around an atom&apos;s nucleus where electrons are likely to be found. Different types of orbitals (s, p, d, f) have different shapes and can hold different numbers of electrons. Learn how quantum numbers are used to describe the orbitals, and compare Bohr model orbits with the quantum mechanical model of atom.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/KrXE_SzRoqw.mp4/KrXE_SzRoqw.mp4</video:content_loc><video:duration>720</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/quantum-numbers-for-the-first-four-shells</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfe7eabb6.jpg</video:thumbnail_loc><video:title>Quantum numbers for the first four shells</video:title><video:description>Calculates number of orbitals and number of electrons in different kinds of orbitals for n = 1 to 4. Explains that only two electrons are allowed per orbital, and gives shortcuts for calculating number of orbitals and total number of electrons for a given n.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qLU0X154wlE.mp4/qLU0X154wlE.mp4</video:content_loc><video:duration>757</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/noble-gas-configuration-electronic-structure-of-atoms-chemistry-khan-academy</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1faeaecd.jpg</video:thumbnail_loc><video:title>Noble gas configuration</video:title><video:description>How to write electron configurations for atoms and monatomic ions using noble gas configuration</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tlSJCG5DqzI.mp4/tlSJCG5DqzI.mp4</video:content_loc><video:duration>407</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/electron-configurations-for-the-first-period</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf39357d2.jpg</video:thumbnail_loc><video:title>Electron configurations for the first period</video:title><video:description>Introduces aufbau principle, Pauli exclusion principle, and orbital notation. Writes out the quantum numbers for the electrons in H and He.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0MKsFD03Ukc.mp4/0MKsFD03Ukc.mp4</video:content_loc><video:duration>382</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/electron-configurations-for-the-second-period</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x50988bfb.jpg</video:thumbnail_loc><video:title>Electron configurations for the second period</video:title><video:description>Writes out quantum numbers for all elements of the second period. Introduces Hund&apos;s rule, and connects blocks in periodic table with electron configuration.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/UEPs-GA2s40.mp4/UEPs-GA2s40.mp4</video:content_loc><video:duration>732</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/electron-configurations-for-the-third-and-fourth-periods</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf22e57ff.jpg</video:thumbnail_loc><video:title>Electron configurations for the third and fourth periods</video:title><video:description>How to write the electron configurations for elements in the third and fourth periods of the periodic table. includes using noble gas notation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3tyrkxruz88.mp4/3tyrkxruz88.mp4</video:content_loc><video:duration>788</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/paramagnetism-and-diamagnetism</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb73055ce.jpg</video:thumbnail_loc><video:title>Paramagnetism and diamagnetism</video:title><video:description>Paramagnetism and diamagnetism from Chemistry archive</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-lIc5z3XjXQ.mp4/-lIc5z3XjXQ.mp4</video:content_loc><video:duration>485</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/periodic-table-groups</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x68205349.jpg</video:thumbnail_loc><video:title>Groups of the periodic table</video:title><video:description>The s-, p-, and d-block elements of the periodic table are arranged into 18 numbered columns, or groups. The elements in each group have the same number of valence electrons. As a result, elements in the same group often display similar properties and reactivity.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jQGUkJc7_04.mp4/jQGUkJc7_04.mp4</video:content_loc><video:duration>461</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/periodic-table-valence-electrons</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf654ebd5.jpg</video:thumbnail_loc><video:title>Counting valence electrons for main group elements</video:title><video:description>How to determine the number of valence electrons and draw Lewis structures for main group elements starting from the electron configuration.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/akm5H2JsccI.mp4/akm5H2JsccI.mp4</video:content_loc><video:duration>499</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/periodic-table-transition-metals</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x545922ca.jpg</video:thumbnail_loc><video:title>The periodic table - transition metals</video:title><video:description>The definition of a transition metal, and how to write the electron configuration including examples for Fe and Zn.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/kCM2mSb4qIU.mp4/kCM2mSb4qIU.mp4</video:content_loc><video:duration>334</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/atomic-radius-trend</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2875bdf8.jpg</video:thumbnail_loc><video:title>Atomic radius trends on periodic table</video:title><video:description>How atomic radius is defined, and trends across a period and down a group.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/q--2WP8wXtk.mp4/q--2WP8wXtk.mp4</video:content_loc><video:duration>580</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/mini-video-on-ion-size</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/426005.jpg</video:thumbnail_loc><video:title>Mini-video on ion size</video:title><video:description>Correcting a mistake and learning a bit about ion size</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/HBi8xjMchZc.mp4/HBi8xjMchZc.mp4</video:content_loc><video:duration>184</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/ionization-energy-trends</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xaed272e3.jpg</video:thumbnail_loc><video:title>Ionization energy trends</video:title><video:description>Definition of ion and ionization energy, and trends in ionization energy across a period and down a group.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5CBs36jtZxY.mp4/5CBs36jtZxY.mp4</video:content_loc><video:duration>602</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/electronegativity-and-chemical-bonds</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x57ecb61f.jpg</video:thumbnail_loc><video:title>Electronegativity and bonding</video:title><video:description>Electronegativity differences in bonding using the Pauling scale. Classifying bonds as covalent, polar covalent, or ionic.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/126N4hox9YA.mp4/126N4hox9YA.mp4</video:content_loc><video:duration>699</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/ionic-bonds-and-coulombs-law</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x88a88398.jpg</video:thumbnail_loc><video:title>Ionic bonds and Coulomb&apos;s law</video:title><video:description>Introduction to how the strength of ionic bonds is related to Coulomb&apos;s law. Example of using Coulomb&apos;s law to explain differences in melting points of ionic compounds.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TwqMtO2FLYk.mp4/TwqMtO2FLYk.mp4</video:content_loc><video:duration>452</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/drawing-dot-structures</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4b64d771.jpg</video:thumbnail_loc><video:title>Drawing dot structures</video:title><video:description>Guidelines for drawing Lewis dot structures.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/p7Fsb21B2Xg.mp4/p7Fsb21B2Xg.mp4</video:content_loc><video:duration>882</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/resonance-and-dot-structures</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc17639e8.jpg</video:thumbnail_loc><video:title>Resonance and dot structures</video:title><video:description>Drawing resonance structures and resonance hybrid using example of nitrate anion.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/bUCu7bPkZeI.mp4/bUCu7bPkZeI.mp4</video:content_loc><video:duration>375</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/formal-charge-and-dot-structures</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x999bc93d.jpg</video:thumbnail_loc><video:title>Formal charge and dot structures</video:title><video:description>Definition of formal charge, and how minimization of formal charge can help choose the more stable dot structure.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/dNPs-cr_6Bk.mp4/dNPs-cr_6Bk.mp4</video:content_loc><video:duration>690</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/more-on-the-dot-structure-for-sulfur-dioxide</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdc597ee2.jpg</video:thumbnail_loc><video:title>More on the dot structure for sulfur dioxide</video:title><video:description>How to analyze different ways to draw the dot structure for sulfur dioxide</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Fr_La6MrAfM.mp4/Fr_La6MrAfM.mp4</video:content_loc><video:duration>268</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/2015-ap-chemistry-free-response-2-d-e</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1dae2933.jpg</video:thumbnail_loc><video:title>2015 AP Chemistry free response 2d and e</video:title><video:description>Lewis electron-dot diagram and bond angles for ethanol. From 2015 AP Chemistry free response 2d and 2e.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ImTwySWxA4U.mp4/ImTwySWxA4U.mp4</video:content_loc><video:duration>380</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/hs-chemistry/v/balancing-chemical-equations-introduction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc8ecefc8.jpg</video:thumbnail_loc><video:title>Balancing chemical equations</video:title><video:description>A balanced chemical equation shows the same number of each type of atom on both sides of the arrow.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TUuABq95BBM.mp4/TUuABq95BBM.mp4</video:content_loc><video:duration>304</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/hs-chemistry/v/balancing-more-complex-chemical-equation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x068874ad.jpg</video:thumbnail_loc><video:title>Balancing more complex chemical equations</video:title><video:description>A balanced chemical equation shows the same number of each type of atom on both sides of the arrow. In this example, we balance the combustion reaction of ethylene, C₂H₄, and provide tips on how to balance more complex chemical equations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xqpYeiefZl8.mp4/xqpYeiefZl8.mp4</video:content_loc><video:duration>277</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/hs-chemistry/v/visually-understanding-balancing-chemical-equations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x58fe4869.jpg</video:thumbnail_loc><video:title>Visually understanding balancing chemical equations</video:title><video:description>A balanced chemical equation shows the same number of each type of atom on both sides of the arrow. We can relate a balanced chemical equation to the structural formulas of its reactants and products.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/HbIdp5DURJA.mp4/HbIdp5DURJA.mp4</video:content_loc><video:duration>277</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/hs-chemistry/v/balancing-another-combustion-reaction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf98cead0.jpg</video:thumbnail_loc><video:title>Balancing another combustion reaction</video:title><video:description>A balanced chemical equation shows the same number of each type of atom on both sides of the arrow. In this example, we balance the combustion reaction of ethane, C₂H₆.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/cmi8EnJQA84.mp4/cmi8EnJQA84.mp4</video:content_loc><video:duration>298</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/balancing-chemical-equation-with-substitution</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf8a51a8a.jpg</video:thumbnail_loc><video:title>Balancing chemical equation with substitution</video:title><video:description>Using the substitution method to balance a reaction where a reactant and product have a polyatomic ion in common.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/8KXWJCmshEE.mp4/8KXWJCmshEE.mp4</video:content_loc><video:duration>252</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/chem09-precipitation-reactions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb7a71439.jpg</video:thumbnail_loc><video:title>Precipitation reactions</video:title><video:description>A lot of ionic compounds dissolve in water, dissociating into individual ions. But when two ions find each other that form an insoluble compound, they suddenly fall out of solution in what&apos;s called a precipitation reaction. In this episode of Crash Course Chemistry, we learn about precipitation, precipitates, anions, cations, and how to describe and discuss ionic reactions. Writer: Kim Krieger Chief Editor: Blake de Pastino Consultant: Dr. Heiko Langner Director/Editor: Nicholas Jenkins Sound Designer: Michael Aranda Graphics: Thought Cafe</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/cdvV8O90HJM.mp4/cdvV8O90HJM.mp4</video:content_loc><video:duration>634</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/vapor-pressure-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/6022729.jpg</video:thumbnail_loc><video:title>Worked example: Vapor pressure and the ideal gas law</video:title><video:description>Vapor pressure example using the ideal gas law.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-QpkmwIoMaY.mp4/-QpkmwIoMaY.mp4</video:content_loc><video:duration>962</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/van-der-waals-equation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc0a2763a9023469c.jpg</video:thumbnail_loc><video:title>The van der Waals equation</video:title><video:description>By adding corrections for interparticle attractions and particle volumes to the ideal gas law, we can derive a new equation that more accurately describes real gas behavior. This equation, known as the van der Waals equation, can be used to calculate the properties of a gas under non-ideal conditions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9_epJ4vUsNI.mp4/9_epJ4vUsNI.mp4</video:content_loc><video:duration>317</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/specific-heat-and-latent-leat-of-fusion-and-vaporization-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf8a20837.jpg</video:thumbnail_loc><video:title>Specific heat and latent heat of fusion and vaporization</video:title><video:description>Defining specific heat, heat of fusion, and heat of vaporization. How to calculate the amount of heat to change the temperature of water and the energy required to change for a phase change.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/WU7TfO-iaK8.mp4/WU7TfO-iaK8.mp4</video:content_loc><video:duration>897</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/specific-heat-heat-of-fusion-and-vaporization</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/418012.jpg</video:thumbnail_loc><video:title>Specific heat, heat of fusion and vaporization example</video:title><video:description>Specific heat and phase changes: Calculating how much heat is needed to convert 200 g of ice at -10 degrees C to 110 degree steam.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/zz4KbvF_X-0.mp4/zz4KbvF_X-0.mp4</video:content_loc><video:duration>889</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/chilling-water-problem</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/432003.jpg</video:thumbnail_loc><video:title>Chilling water problem</video:title><video:description>How much ice at -10 degrees C is necessary to get 500 g of water down to 0 degrees C?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lsXcKgjg8Hs.mp4/lsXcKgjg8Hs.mp4</video:content_loc><video:duration>683</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/change-of-state-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/6022730.jpg</video:thumbnail_loc><video:title>Change of state example</video:title><video:description>Specific heat capacity and enthalpy of vaporization example: calculating how much energy it takes to vaporize 1.00 kg of ethanol starting from 20 degrees C.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tvO0358YUYM.mp4/tvO0358YUYM.mp4</video:content_loc><video:duration>458</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/vapor-pressure</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/417006.jpg</video:thumbnail_loc><video:title>Vapor pressure</video:title><video:description>Vapor pressure, volatility, and evaporation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hA5jddDYcyg.mp4/hA5jddDYcyg.mp4</video:content_loc><video:duration>1084</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/phase-diagrams</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/373049.jpg</video:thumbnail_loc><video:title>Phase diagrams</video:title><video:description>Understanding and interpreting phase diagrams</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Qp87Z4m8R-w.mp4/Qp87Z4m8R-w.mp4</video:content_loc><video:duration>756</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/boiling-points-of-organic-compounds</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe50d545d.jpg</video:thumbnail_loc><video:title>Boiling points of organic compounds</video:title><video:description>How to analyze the different boiling points of organic compounds using intermolecular forces</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pILGRZ0nT4o.mp4/pILGRZ0nT4o.mp4</video:content_loc><video:duration>667</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/boiling-points-ap-chemistry-multiple-choice-sample</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x92f9f310.jpg</video:thumbnail_loc><video:title>Boiling point comparison: AP Chemistry multiple choice</video:title><video:description>Comparing the boiling point of nonane and 2,3,4-trifluoropentane. A sample multiple choice problem from the 2014 AP course description.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/JRxFsmvsmHY.mp4/JRxFsmvsmHY.mp4</video:content_loc><video:duration>379</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/solubility-of-organic-compounds-redo</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd9a60692.jpg</video:thumbnail_loc><video:title>Solubility of organic compounds</video:title><video:description>Organic compounds tend to dissolve well in solvents that have similar properties to themselves. This principle is often referred to as &quot;like dissolves like,&quot; which means that polar molecules will generally dissolve well in polar solvents and non-polar molecules will generally dissolve in non-polar solvents.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_mWHWJiMKXU.mp4/_mWHWJiMKXU.mp4</video:content_loc><video:duration>741</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/le-chateliers-principle-worked-example-chemical-equilibrium-chemistry-khan-acade</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xee318355.jpg</video:thumbnail_loc><video:title>Le Chatelier&apos;s principle: Worked example</video:title><video:description>A worked example using Le Chatelier&apos;s principle to predict how concentrations will shift for different perturbations. Example includes changing reaction vessel volume, changing amount of solid product, adding inert gas, and adding a catalyst.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5gujU2QcGcY.mp4/5gujU2QcGcY.mp4</video:content_loc><video:duration>477</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/intro-to-reaction-quotient-q</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x353b5962.jpg</video:thumbnail_loc><video:title>Introduction to reaction quotient Qc</video:title><video:description>Introduction to the reaction quotient Qc, and comparing the reaction quotient with the equilibrium constant to predict how concentrations will change.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2PM1yc_z4Bk.mp4/2PM1yc_z4Bk.mp4</video:content_loc><video:duration>456</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/acid-strength-anion-size-and-bond-energy</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x13d9aabd.jpg</video:thumbnail_loc><video:title>Acid strength, anion size, and bond energy</video:title><video:description>How anion size and bond dissociation energies affect acid strength</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Ce4BGV1DVVg.mp4/Ce4BGV1DVVg.mp4</video:content_loc><video:duration>347</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/relationship-between-ka-and-kb</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe0b51228.jpg</video:thumbnail_loc><video:title>Relationship between Ka and Kb</video:title><video:description>The relationship between Ka and Kb, and pKa and pKb. Examples of finding Ka of a weak acid given Kb of the conjugate base.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DGMs81-Rp1o.mp4/DGMs81-Rp1o.mp4</video:content_loc><video:duration>680</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/ka-and-acid-strength</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4c27d237.jpg</video:thumbnail_loc><video:title>Ka and acid strength</video:title><video:description>How to write an equilibrium expression for an acid-base reaction and how to evaluate the strength of an acid using Ka</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/BeHOvYchtBg.mp4/BeHOvYchtBg.mp4</video:content_loc><video:duration>558</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/weak-acid-equilibrium</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe962fbd5.jpg</video:thumbnail_loc><video:title>Weak acid equilibrium</video:title><video:description>Quick overview of Ka and pKa. Example of calculating the pH of a weak acid solution.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/icNOBmKjDLo.mp4/icNOBmKjDLo.mp4</video:content_loc><video:duration>571</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/weak-base-equilibrium</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1676f258.jpg</video:thumbnail_loc><video:title>Weak base equilibrium</video:title><video:description>Quick overview of Kb and pKb. Examples of calculating the pH of a weak base solution.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xGE3sEz6U9Y.mp4/xGE3sEz6U9Y.mp4</video:content_loc><video:duration>682</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/ph-of-salt-solutions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3029a604.jpg</video:thumbnail_loc><video:title>pH of salt solutions</video:title><video:description>The pH of a salt solution is determined by the relative strength of its ​conjugated acid-base pair. Salts can be acidic, neutral, or basic. Salts that form from a strong acid and a weak base are acid salts, like ammonium chloride (NH4Cl). Salts that form from a weak acid and a strong base are basic salts, like sodium bicarbonate (NaHCO3).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/XZWoMXVANww.mp4/XZWoMXVANww.mp4</video:content_loc><video:duration>855</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/common-ion-effect</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x177cf25c.jpg</video:thumbnail_loc><video:title>Common ion effect and buffers</video:title><video:description>The common ion effect describes the effect on ​equilibrium that occurs when a common ion (an ion that is already contained in the solution) is added to a solution. The common ion effect generally decreases ​solubility of a solute. It also can have an effect on buffering solutions, as adding more conjugate ions may shift the pH of the solution.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/223KLPnJCBI.mp4/223KLPnJCBI.mp4</video:content_loc><video:duration>799</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/buffer-solution-calculations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x81deb5b6.jpg</video:thumbnail_loc><video:title>Buffer solution pH calculations</video:title><video:description>Example of calculating the pH of a buffer solution using the Henderson-Hasselbalch equation, including the pH of the buffer solution after adding some NaOH.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lsHq5aqz4uQ.mp4/lsHq5aqz4uQ.mp4</video:content_loc><video:duration>699</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/ph-and-pka-relationship-for-buffers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe0d3b723.jpg</video:thumbnail_loc><video:title>pH and pKa relationship for buffers</video:title><video:description>How the Henderson-Hasselbalch equation can be used to look at the ratio of conjugate acid and base using relationship between buffer pH and pKa.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7ZLjzp7thNI.mp4/7ZLjzp7thNI.mp4</video:content_loc><video:duration>470</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/buffer-capacity</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8be0d8f0.jpg</video:thumbnail_loc><video:title>Buffer capacity</video:title><video:description>The definition of buffer capacity, and an example showing why it depends on the absolute concentrations of the conjugate acid and base.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pnPWdDOR9XE.mp4/pnPWdDOR9XE.mp4</video:content_loc><video:duration>644</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/titration-of-a-strong-acid-with-a-strong-base</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x884a1838.jpg</video:thumbnail_loc><video:title>Titration of a strong acid with a strong base</video:title><video:description>In a strong acid-strong base titration, the acid and base will react to form a neutral solution. At the equivalence point of the reaction, hydronium (H+) and hydroxide (OH-) ions will react to form water, leading to a pH of 7. This is true of all strong acid-strong base titrations. An example of this would be the titration of hydrochloric acid (strong acid) and sodium hydroxide (strong base) to form sodium chloride and water.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/JoGQYSTlOKo.mp4/JoGQYSTlOKo.mp4</video:content_loc><video:duration>612</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/titration-of-a-strong-acid-with-a-strong-base-continued</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0f5bb35f.jpg</video:thumbnail_loc><video:title>Titration of a strong acid with a strong base (continued)</video:title><video:description>Calculating the pH at and after the equivalence point for titration of strong acid, hydrochloric acid, with strong base, NaOH.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/HO1dsNrzE58.mp4/HO1dsNrzE58.mp4</video:content_loc><video:duration>617</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/titration-of-a-weak-acid-with-a-strong-base</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe3933619.jpg</video:thumbnail_loc><video:title>Titration of a weak acid with a strong base</video:title><video:description>Calculating the pH for titration of acetic acid with strong base NaOH before adding any base and at half-equivalence point.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/x3CbfUr449Y.mp4/x3CbfUr449Y.mp4</video:content_loc><video:duration>867</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/titration-of-a-weak-acid-with-a-strong-base-continued</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xcf6e8167.jpg</video:thumbnail_loc><video:title>Titration of a weak acid with a strong base (continued)</video:title><video:description>Calculating the pH for titration of acetic acid with strong base NaOH at equivalence point and past the equivalence point.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/WbDL7xN-Pn0.mp4/WbDL7xN-Pn0.mp4</video:content_loc><video:duration>913</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/titration-of-a-weak-base-with-a-strong-acid</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa23021eb.jpg</video:thumbnail_loc><video:title>Titration of a weak base with a strong acid</video:title><video:description>In a weak base-strong acid titration, the acid and base will react to form an acidic solution. A conjugate acid will be produced during the titration, which then reacts with water to form hydronium ions. This results in a solution with a pH lower than 7. An example of this is the titration of hydrochloric acid (strong acid) into ammonia (weak base), which forms the conjugate acid ammonium and produces an acidic solution.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pmHlKhv7C0E.mp4/pmHlKhv7C0E.mp4</video:content_loc><video:duration>898</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/titration-of-a-weak-base-with-a-strong-acid-continued</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf9342364.jpg</video:thumbnail_loc><video:title>Titration of a weak base with a strong acid (continued)</video:title><video:description>Calculating the pH for titration of weak base, ammonia, with strong acid, HCl, at the equivalence point and past the equivalence point.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/kWucfgOkCIQ.mp4/kWucfgOkCIQ.mp4</video:content_loc><video:duration>888</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/titration-curves-and-acid-base-indicators</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x394a1fa6.jpg</video:thumbnail_loc><video:title>Titration curves and acid-base indicators</video:title><video:description>Choosing the best indicator for different titrations depending on the pH at the equivalence point.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1YlXtpF-19A.mp4/1YlXtpF-19A.mp4</video:content_loc><video:duration>430</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/2015-ap-chemistry-free-response-4</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x252359c2.jpg</video:thumbnail_loc><video:title>2015 AP Chemistry free response 4</video:title><video:description>Calculating the molar solubility of calcium hydroxide in a 0.10 M calcium nitrate solution. From 2015 AP Chemistry free response 4.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/JbLRFt_Z8nI.mp4/JbLRFt_Z8nI.mp4</video:content_loc><video:duration>560</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/solubility-and-complex-ion-formation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd322f5e7.jpg</video:thumbnail_loc><video:title>Solubility and complex ion formation</video:title><video:description>Calculating the solubility of silver chloride in pure water and 3.0 M ammonia. Calculating new equilibrium constant to account for formation of complex ion.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/r7gTH_5XfOI.mp4/r7gTH_5XfOI.mp4</video:content_loc><video:duration>890</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/disproportionation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x528f68ef.jpg</video:thumbnail_loc><video:title>Disproportionation</video:title><video:description>Assigning oxidation states for the decomposition of hydrogen peroxide, a disproportionation reaction.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PXlvKtpvUEk.mp4/PXlvKtpvUEk.mp4</video:content_loc><video:duration>303</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/redox-reaction-from-dissolving-zinc-in-copper-sulfate</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfc2d5f2d.jpg</video:thumbnail_loc><video:title>Redox reaction from dissolving zinc in copper sulfate</video:title><video:description>What happens when you add zinc to a solution of copper sulfate? Identifying the half reactions to see what got oxidized and reduced.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/wVMe8ZmCZo0.mp4/wVMe8ZmCZo0.mp4</video:content_loc><video:duration>301</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/galvanic-cell-voltaic-cell</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe7416dc9.jpg</video:thumbnail_loc><video:title>Introduction to galvanic/voltaic cells</video:title><video:description>How to use a redox reaction to construct a galvanic/voltaic cell to produce a flow of current.. Shows the flow of electrons and ions, and explains the role of the salt bridge.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/9Xncz_mMc5g.mp4/9Xncz_mMc5g.mp4</video:content_loc><video:duration>360</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/electrodes-and-voltage-of-galvanic-cell</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1773beb6.jpg</video:thumbnail_loc><video:title>Electrodes and voltage of Galvanic cell</video:title><video:description>Identifying the anode and cathode in a galvanic cell, and calculating the voltage using standard electrode potentials.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/m0SFJt_0v28.mp4/m0SFJt_0v28.mp4</video:content_loc><video:duration>273</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/shorthand-notation-for-galvanicvoltaic-cells</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x13a28207.jpg</video:thumbnail_loc><video:title>Shorthand notation for galvanic/voltaic cells</video:title><video:description>Get a grip on Galvanic cells in this electrochemistry tutorial! You&apos;ll see how redox reactions generate electric currents, understand the functions of anodes and cathodes, and learn the shorthand notation for these cells.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xHuLZHasldg.mp4/xHuLZHasldg.mp4</video:content_loc><video:duration>437</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/lead-storage-battery</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x51f5d849.jpg</video:thumbnail_loc><video:title>Lead storage battery</video:title><video:description>Explore the process of balancing redox reactions in acidic solutions using a lead storage battery as an example. Understand the assignment of oxidation states, the creation of oxidation and reduction half-reactions, and how to balance atoms and charge. Discover how this reaction powers car batteries and can be reversed for recharging.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PQ48N5jaG2w.mp4/PQ48N5jaG2w.mp4</video:content_loc><video:duration>546</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/nickel-cadmium-battery</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc191ac11.jpg</video:thumbnail_loc><video:title>Nickel-cadmium battery</video:title><video:description>Get charged up about the nickel-cadmium battery! This tutorial breaks down the redox reaction that powers these rechargeable batteries. Learn how solid cadmium and nickel oxide hydroxide transform into cadmium hydroxide and nickel hydroxide, and how this process is easily reversed, making recharging a breeze.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/tUvpwdqdLlI.mp4/tUvpwdqdLlI.mp4</video:content_loc><video:duration>667</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/standard-reduction-potentials</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9f0707ce.jpg</video:thumbnail_loc><video:title>Standard reduction potentials</video:title><video:description>How to use a table of standard reduction potentials to calculate standard cell potential. Identifying trends in oxidizing and reducing agent strength.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/oAOq55MPJpM.mp4/oAOq55MPJpM.mp4</video:content_loc><video:duration>550</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/voltage-as-an-intensive-property</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xda15e076.jpg</video:thumbnail_loc><video:title>Voltage as an intensive property</video:title><video:description>Demonstrating that voltage is an intensive property by calculating the voltage and change in Gibbs free energy for a half reaction.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xsSLvlonxs4.mp4/xsSLvlonxs4.mp4</video:content_loc><video:duration>322</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/using-reduction-potentials</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa118949b.jpg</video:thumbnail_loc><video:title>Using reduction potentials</video:title><video:description>Learn how to calculate the standard cell potential using standard reduction potentials. This video explains the process of oxidation and reduction, how to identify half-reactions, and the role of moles in these reactions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/79OmpES_9OE.mp4/79OmpES_9OE.mp4</video:content_loc><video:duration>364</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/spontaneity-and-redox-reactions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1c447583.jpg</video:thumbnail_loc><video:title>Spontaneity and redox reactions</video:title><video:description>Learn how lead can oxidize aluminum but not copper in standard conditions. Using reduction potential tables and the diagonal rule, we confirm predictions by calculating standard cell potentials. Understand the spontaneity of reactions and the activity series in chemistry.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/sorB6XFJ8Jc.mp4/sorB6XFJ8Jc.mp4</video:content_loc><video:duration>742</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/free-energy-and-cell-potential</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf918ece2.jpg</video:thumbnail_loc><video:title>Free energy and cell potential</video:title><video:description>Relationship between Gibbs free energy and standard cell potential.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4tcLzVJdxZs.mp4/4tcLzVJdxZs.mp4</video:content_loc><video:duration>494</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/standard-cell-potential-and-the-equilibrium-constant</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4f2f97b8.jpg</video:thumbnail_loc><video:title>Standard cell potential and the equilibrium constant</video:title><video:description>Finding the relationship between standard cell potential and equilibrium constant K.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/CdE1Sa18gIo.mp4/CdE1Sa18gIo.mp4</video:content_loc><video:duration>322</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/calculating-the-equilibrium-constant-from-the-standard-cell-potential</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0a77eceb.jpg</video:thumbnail_loc><video:title>Calculating the equilibrium constant from the standard cell potential</video:title><video:description>Example problem for calculating the equilibrium constant K using the standard cell potential.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/kxNaVzQ07yc.mp4/kxNaVzQ07yc.mp4</video:content_loc><video:duration>583</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/galvanic-cells-and-changes-in-free-energy</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0c9df053.jpg</video:thumbnail_loc><video:title>Galvanic cells and changes in free energy</video:title><video:description>Relationship between Gibbs free energy, reaction quotient Q, and cell voltage.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TYFAJHx5LFA.mp4/TYFAJHx5LFA.mp4</video:content_loc><video:duration>758</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/nernst-equation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xac7a2c03.jpg</video:thumbnail_loc><video:title>Nernst equation</video:title><video:description>Deriving a few different forms of the Nernst equation, the relationship between Gibbs free energy and reaction quotient Q.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/QaOtsYouet0.mp4/QaOtsYouet0.mp4</video:content_loc><video:duration>393</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/using-the-nernst-equation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0442f790.jpg</video:thumbnail_loc><video:title>Using the Nernst equation</video:title><video:description>Using the Nernst equation to calculate the cell potential when concentrations are not standard conditions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/WqsJNtBEKtg.mp4/WqsJNtBEKtg.mp4</video:content_loc><video:duration>690</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/concentration-cell</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2c135e90.jpg</video:thumbnail_loc><video:title>Concentration cell</video:title><video:description>Concentration cells are galvanic (or voltaic) cells made of two half-cells, each of which containing the same electrodes, but different concentrations. Concentration cells work to establish equilibrium by transferring electrons from the cell with the lower concentration to the cell with the higher concentration. The electrode potential difference between the two half-cells can be calculated using the Nernst equation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/mMzbr5rm4j8.mp4/mMzbr5rm4j8.mp4</video:content_loc><video:duration>578</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/quantitative-electrolysis</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x37e22dab.jpg</video:thumbnail_loc><video:title>Quantitative electrolysis</video:title><video:description>Calculating how much zinc deposits on the zinc electrode after 1.0 h when a current of 5.0 A is applied to the battery.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/QEUsZeKYsgo.mp4/QEUsZeKYsgo.mp4</video:content_loc><video:duration>420</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/electrolysis-of-molten-sodium-chloride</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdf4ac844.jpg</video:thumbnail_loc><video:title>Electrolysis of molten sodium chloride</video:title><video:description>Example quantitative electrolysis problem using molten sodium chloride.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Q9BtOLDr0vg.mp4/Q9BtOLDr0vg.mp4</video:content_loc><video:duration>744</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/first-order-reaction-with-calculus</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6e4aa8e2.jpg</video:thumbnail_loc><video:title>First-order reaction (with calculus)</video:title><video:description>Deriving the integrated rate law for first-order reactions using calculus. How you can graph first-order rate data to see a linear relationship.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Bt0mz4mGddk.mp4/Bt0mz4mGddk.mp4</video:content_loc><video:duration>434</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/plotting-data-for-a-first-order-reaction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2fe55283.jpg</video:thumbnail_loc><video:title>Plotting data for a first-order reaction</video:title><video:description>Example of graphing first-order rate data to see a linear relationship, and calculating rate constant k from the slope.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vN7O7zsRKb8.mp4/vN7O7zsRKb8.mp4</video:content_loc><video:duration>561</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/second-order-reaction-with-calculus</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xde3bccae.jpg</video:thumbnail_loc><video:title>Second-order reaction (with calculus)</video:title><video:description>Deriving the integrated rate law for second order reactions using calculus. How you can graph second order rate data to see a linear relationship.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/BRVPlDCMgMg.mp4/BRVPlDCMgMg.mp4</video:content_loc><video:duration>434</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/half-life-of-a-second-order-reaction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1d7ae02d.jpg</video:thumbnail_loc><video:title>Half-life of a second-order reaction</video:title><video:description>Deriving half-life equation of a second-order reaction starting from the integrated rate law.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/XUmB0reCB-U.mp4/XUmB0reCB-U.mp4</video:content_loc><video:duration>429</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/zero-order-reaction-with-calculus</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa0344f0e.jpg</video:thumbnail_loc><video:title>Zero-order reaction (with calculus)</video:title><video:description>Deriving the integrated rate law for zeroth order reactions using calculus. How you can graph zero order rate data to see a linear relationship.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/49LcF9Zf9TI.mp4/49LcF9Zf9TI.mp4</video:content_loc><video:duration>593</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/forms-of-the-arrhenius-equation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x71322e6f.jpg</video:thumbnail_loc><video:title>Forms of the Arrhenius equation</video:title><video:description>How to write different forms of the Arrhenius equation. Using the Arrhenius equation to look at how changing temperature and activation energy affects collisions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/J0ndBMMQW20.mp4/J0ndBMMQW20.mp4</video:content_loc><video:duration>401</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/chemistry/v/using-the-arrhenius-equation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x260a2638.jpg</video:thumbnail_loc><video:title>Using the Arrhenius equation</video:title><video:description>How to use the Arrhenius equation to calculate the activation energy.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/aIvYdSzLGoI.mp4/aIvYdSzLGoI.mp4</video:content_loc><video:duration>666</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/scale-of-the-large</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/89868304.jpg</video:thumbnail_loc><video:title>Scale of the large</video:title><video:description>Attempting to comprehend the scale of the large</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5FEjrStgcF8.mp4/5FEjrStgcF8.mp4</video:content_loc><video:duration>662</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/scale-of-the-small</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/91063693.jpg</video:thumbnail_loc><video:title>Scale of the small</video:title><video:description>From honey bees to cells, viruses, and atoms -- understanding the scale of the very small</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ERKx3Oa2omo.mp4/ERKx3Oa2omo.mp4</video:content_loc><video:duration>794</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/scale-of-earth-and-sun</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187268.jpg</video:thumbnail_loc><video:title>Scale of earth and sun</video:title><video:description>Scale of Earth and Sun</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/GZx3U0dbASg.mp4/GZx3U0dbASg.mp4</video:content_loc><video:duration>571</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/scale-of-solar-system</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187269.jpg</video:thumbnail_loc><video:title>Scale of solar system</video:title><video:description>Sal Khan describes the scale of our Solar System.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/GP53b__h4ew.mp4/GP53b__h4ew.mp4</video:content_loc><video:duration>751</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/scale-of-distance-to-closest-stars</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187270.jpg</video:thumbnail_loc><video:title>Scale of distance to closest stars</video:title><video:description>The nearest stars to our solar system, are located in the Alpha Centauri system. The two main stars are Alpha Centauri A and Alpha Centauri B, which are approximately 4.3 light years away from Earth. The third star in the Alpha Centauri system, Proxima Centauri, is actually the closest star to our solar system at approximately 4.2 ​lightyears away from Earth.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jEeJkkMXt6c.mp4/jEeJkkMXt6c.mp4</video:content_loc><video:duration>498</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/scale-of-the-galaxy</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187271.jpg</video:thumbnail_loc><video:title>Scale of the galaxy</video:title><video:description>Scale of the Galaxy</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/rcLnMe1ELPA.mp4/rcLnMe1ELPA.mp4</video:content_loc><video:duration>775</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/intergalactic-scale</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187272.jpg</video:thumbnail_loc><video:title>Intergalactic scale</video:title><video:description>Intergalactic Scale</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/JiE_kNk3ucI.mp4/JiE_kNk3ucI.mp4</video:content_loc><video:duration>650</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/hubble-image-of-galaxies</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187273.jpg</video:thumbnail_loc><video:title>Hubble image of galaxies</video:title><video:description>Hubble Image of Galaxies</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Wl4re38deh0.mp4/Wl4re38deh0.mp4</video:content_loc><video:duration>252</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/cosmological-time-scale-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187354.jpg</video:thumbnail_loc><video:title>Cosmological time scale 1</video:title><video:description>Cosmological Time Scale 1</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DRtLXagrMHw.mp4/DRtLXagrMHw.mp4</video:content_loc><video:duration>427</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/cosmological-time-scale-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187355.jpg</video:thumbnail_loc><video:title>Cosmological time scale 2</video:title><video:description>Cosmological Time Scale 2</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LO7-3MpWijU.mp4/LO7-3MpWijU.mp4</video:content_loc><video:duration>378</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/introduction-to-light</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/148049940.jpg</video:thumbnail_loc><video:title>Introduction to light</video:title><video:description>Light and the electromagnetic radiation spectrum. Wave and particle-like behavior, and how to calculate the wavelength or frequency of a light wave.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/rLNM8zI4Q_M.mp4/rLNM8zI4Q_M.mp4</video:content_loc><video:duration>577</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/four-fundamental-forces</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187356.jpg</video:thumbnail_loc><video:title>Four fundamental forces</video:title><video:description>Gravity, Weak, Electromagnetic and Strong</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/FEF6PxWOvsk.mp4/FEF6PxWOvsk.mp4</video:content_loc><video:duration>629</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/light-and-the-luminiferous-ether</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x761aba17.jpg</video:thumbnail_loc><video:title>Light and the luminiferous ether</video:title><video:description>If waves are disruptions traveling through a medium and light is a wave, what medium does it travel through? A luminiferous ether?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/iAPYsOaq-VY.mp4/iAPYsOaq-VY.mp4</video:content_loc><video:duration>478</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/potential-ways-to-detect-an-ether-wind</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3a23ded7.jpg</video:thumbnail_loc><video:title>Potential ways to detect an ether wind</video:title><video:description>Thinking about how Earth&apos;s relative velocity to hypothetical luminiferous ether can be used to detect ether.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/88hs5LcCoX4.mp4/88hs5LcCoX4.mp4</video:content_loc><video:duration>444</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/michelson-morley-experiment-introduction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x926ab958.jpg</video:thumbnail_loc><video:title>Michelson–Morley Experiment introduction</video:title><video:description>Simple idea behind the Michelson‒Morley experiment to detect ether wind.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/3G_Q6AggQF8.mp4/3G_Q6AggQF8.mp4</video:content_loc><video:duration>492</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/starting-to-set-up-a-newtonian-space-time-diagram</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe37b647e.jpg</video:thumbnail_loc><video:title>Starting to set up a Newtonian path–time diagram</video:title><video:description>We introduce a graph that&apos;s a lot like your good old position-vs-time graph—but with a twist!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PRx_R9iIWk4.mp4/PRx_R9iIWk4.mp4</video:content_loc><video:duration>475</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/visualizing-multiple-newtonian-space-time-diagrams</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd3080b6e.jpg</video:thumbnail_loc><video:title>Visualizing multiple Newtonian path–time diagrams</video:title><video:description>Now that we know what path–time diagrams are, let&apos;s see what happens when we bring along a friend!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/F7BU1sXtul4.mp4/F7BU1sXtul4.mp4</video:content_loc><video:duration>578</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/galilean-transformation-and-contradictions-with-light</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x134b3407.jpg</video:thumbnail_loc><video:title>Galilean transformation and contradictions with light</video:title><video:description>Here we&apos;ll see how classical physics predicts scenarios that disagree with what we observe in nature. Something&apos;s got to give…</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/OIwp8m3S30c.mp4/OIwp8m3S30c.mp4</video:content_loc><video:duration>484</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/introduction-to-special-relativity-and-minkowski-spacetime-diagrams</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb19d0f64.jpg</video:thumbnail_loc><video:title>Introduction to special relativity and Minkowski spacetime diagrams</video:title><video:description>Including multiple observers in the &quot;most obvious&quot; way led to some problems. Let&apos;s see how we can start to solve those problems by introducing (what we&apos;ll later call) Minkowski spacetime diagrams.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ii-KBKSODek.mp4/ii-KBKSODek.mp4</video:content_loc><video:duration>824</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/measuring-time-in-meters-in-minkowski-spacetime</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0c31cbce.jpg</video:thumbnail_loc><video:title>Measuring time in meters in Minkowski spacetime</video:title><video:description>As counterintuitive as it might sound, it will become extremely convenient to use the same units for space and time. Happily, we can do that just by multiplying the time axis by c, the speed of light. Here&apos;s how.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/nEqexIckVCM.mp4/nEqexIckVCM.mp4</video:content_loc><video:duration>298</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/angle-of-x-axis-in-minkowski-spacetime</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0b9d5690.jpg</video:thumbnail_loc><video:title>Angle of x&apos; axis in Minkowski spacetime</video:title><video:description>It looks like there might be some relationship between the relative angles of the axes in the two references frames we&apos;ve considered. Let&apos;s take a closer look.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qzNokxFaAAg.mp4/qzNokxFaAAg.mp4</video:content_loc><video:duration>442</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/introduction-to-the-lorentz-transformation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd92fd692.jpg</video:thumbnail_loc><video:title>Introduction to the Lorentz transformation</video:title><video:description>So we&apos;ve got two coordinate systems from the perspectives of two observers. How can we convert spacetime coordinates between these? Enter the Lorentz transformation!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/HIQ5hnm61LQ.mp4/HIQ5hnm61LQ.mp4</video:content_loc><video:duration>501</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/evaluating-a-lorentz-transformation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x817d8cc7.jpg</video:thumbnail_loc><video:title>Evaluating a Lorentz transformation</video:title><video:description>We&apos;ll consider an example of the Lorentz transformation with actual numbers, and analyze the results we get.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/G-aTU0RXJww.mp4/G-aTU0RXJww.mp4</video:content_loc><video:duration>521</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/algebraically-manipulating-lorentz-transformation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x02c6977d.jpg</video:thumbnail_loc><video:title>Algebraically manipulating Lorentz transformation</video:title><video:description>The forms in which we&apos;ve introduced the Lorentz transformations are really nice in that they reveal the symmetry of the two axes of spacetime. But there are other representations: some are just more common in practical use, while others reveal other interesting similarities with classical mechanics!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Z9DuKef9jkw.mp4/Z9DuKef9jkw.mp4</video:content_loc><video:duration>481</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/lorentz-transformation-derivation-part-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8cac90b6.jpg</video:thumbnail_loc><video:title>Lorentz transformation derivation part 1</video:title><video:description>Using symmetry of frames of reference and the absolute velocity of the speed of light (regardless of frame of reference) to begin to solve for the Lorentz factor.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_qiFIMviIeM.mp4/_qiFIMviIeM.mp4</video:content_loc><video:duration>655</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/deriving-lorentz-transformation-part-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd60dd018.jpg</video:thumbnail_loc><video:title>Deriving Lorentz transformation part 2</video:title><video:description>Continuing the algebra to solve for the Lorentz factor.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Lm_Yn_MZU6k.mp4/Lm_Yn_MZU6k.mp4</video:content_loc><video:duration>368</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/lorentz-transformation-derivation-part-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2a444ed5.jpg</video:thumbnail_loc><video:title>Lorentz transformation derivation part 3</video:title><video:description>Finishing our Lorentz transformation derivation for t&apos;.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xb8nBY4MDC8.mp4/xb8nBY4MDC8.mp4</video:content_loc><video:duration>682</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/lorentz-transformation-for-change-in-coordinates</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbfc52e3d.jpg</video:thumbnail_loc><video:title>Lorentz transformation for change in coordinates</video:title><video:description>Lorentz transformation for change in coordinates</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1F1tFouUGTU.mp4/1F1tFouUGTU.mp4</video:content_loc><video:duration>306</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/einstein-velocity-addition-formula-derivation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd39ef880.jpg</video:thumbnail_loc><video:title>Einstein velocity addition formula derivation</video:title><video:description>Einstein velocity addition formula derivation</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/F9BW57exRn8.mp4/F9BW57exRn8.mp4</video:content_loc><video:duration>456</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/applying-einstein-velocity-addition</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdb3d50bd.jpg</video:thumbnail_loc><video:title>Applying Einstein velocity addition</video:title><video:description>Applying Einstein velocity addition</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0XkyAPXq55k.mp4/0XkyAPXq55k.mp4</video:content_loc><video:duration>382</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/finding-an-in-between-frame-of-reference</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1e47fcb4.jpg</video:thumbnail_loc><video:title>Finding an in-between frame of reference</video:title><video:description>Let&apos;s use Einstein velocity addition to find a frame of reference where A and B are traveling in opposite directions at the same speed.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/Biua3BgRf54.mp4/Biua3BgRf54.mp4</video:content_loc><video:duration>492</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/calculating-neutral-velocity</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xcbc0b377.jpg</video:thumbnail_loc><video:title>Calculating neutral velocity</video:title><video:description>Let&apos;s now do the math to calculate the equal speed at which both A and B could be traveling away from a &quot;neutral&quot; observer.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/iTyBlnTK2ac.mp4/iTyBlnTK2ac.mp4</video:content_loc><video:duration>405</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/time-dilation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xfbd3b322.jpg</video:thumbnail_loc><video:title>Time dilation</video:title><video:description>We&apos;ll start thinking about time dilation in special relativity and how a Loedel diagram can help up appreciate symmetry between inertial frames.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2BVGig1LXLs.mp4/2BVGig1LXLs.mp4</video:content_loc><video:duration>554</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/big-bang-introduction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187274.jpg</video:thumbnail_loc><video:title>Big bang introduction</video:title><video:description>Big bang introduction from Cosmology and astronomy</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/eUF59jCFcyQ.mp4/eUF59jCFcyQ.mp4</video:content_loc><video:duration>663</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/radius-of-observable-universe</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187275.jpg</video:thumbnail_loc><video:title>Radius of observable universe</video:title><video:description>Radius of Observable Universe</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6nVysrZQnOQ.mp4/6nVysrZQnOQ.mp4</video:content_loc><video:duration>999</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/correction-radius-of-observable-universe</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187276.jpg</video:thumbnail_loc><video:title>Radius of observable universe (correction)</video:title><video:description>(Correction) Radius of Observable Universe</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/b6VQv76BQDs.mp4/b6VQv76BQDs.mp4</video:content_loc><video:duration>134</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/red-shift</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187351.jpg</video:thumbnail_loc><video:title>Red shift</video:title><video:description>Red shift from Cosmology and astronomy</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/mx2M_ZKXM_c.mp4/mx2M_ZKXM_c.mp4</video:content_loc><video:duration>604</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/cosmic-background-radiation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187352.jpg</video:thumbnail_loc><video:title>Cosmic background radiation</video:title><video:description>Cosmic Background Radiation</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/sxbPwl_KRuA.mp4/sxbPwl_KRuA.mp4</video:content_loc><video:duration>696</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/cosmic-background-radiation-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187353.jpg</video:thumbnail_loc><video:title>Cosmic background radiation 2</video:title><video:description>Cosmic Background Radiation 2 - Redshift of the Cosmic Background Radiation</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/06z7Q8TWPyU.mp4/06z7Q8TWPyU.mp4</video:content_loc><video:duration>615</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/hubble-s-law</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187365.jpg</video:thumbnail_loc><video:title>Hubble&apos;s law</video:title><video:description>Hubble&apos;s Law</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1V9wVmO0Tfg.mp4/1V9wVmO0Tfg.mp4</video:content_loc><video:duration>672</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/a-universe-smaller-than-the-observable</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187279.jpg</video:thumbnail_loc><video:title>A universe smaller than the observable</video:title><video:description>A Universe Smaller than the Observable</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0w9R_foNLrg.mp4/0w9R_foNLrg.mp4</video:content_loc><video:duration>538</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/birth-of-stars</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187357.jpg</video:thumbnail_loc><video:title>Birth of stars</video:title><video:description>Stars are formed from massive clouds of hydrogen atoms in space. Under intense pressure and temperature, these atoms undergo fusion, combining to form helium and releasing energy. This energy provides an outward pressure, preventing the star from collapsing, thus creating a star.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/i-NNWI8Ccas.mp4/i-NNWI8Ccas.mp4</video:content_loc><video:duration>478</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/accreting-mass-due-to-gravity-simulation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/1272530969.jpg</video:thumbnail_loc><video:title>Accreting mass due to gravity simulation</video:title><video:description>The simulation Sal mentions in the video can be found directly following this video in the lesson.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hD4ySbQYYyA.mp4/hD4ySbQYYyA.mp4</video:content_loc><video:duration>214</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/becoming-a-red-giant</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187358.jpg</video:thumbnail_loc><video:title>Becoming a red giant</video:title><video:description>Becoming a Red Giant</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/kJSOqlcFpJw.mp4/kJSOqlcFpJw.mp4</video:content_loc><video:duration>690</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/white-and-black-dwarfs</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187359.jpg</video:thumbnail_loc><video:title>White and black dwarfs</video:title><video:description>White and Black Dwarfs</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/EdYyuUUY-nc.mp4/EdYyuUUY-nc.mp4</video:content_loc><video:duration>774</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/star-field-and-nebula-images</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187360.jpg</video:thumbnail_loc><video:title>Star field and nebula images</video:title><video:description>Star Field and Nebula Images</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/w3IKEa_GOYs.mp4/w3IKEa_GOYs.mp4</video:content_loc><video:duration>424</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/lifecycle-of-massive-stars</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187386.jpg</video:thumbnail_loc><video:title>Lifecycle of massive stars</video:title><video:description>Massive stars begin as large hydrogen clouds that condense under gravity. They burn hotter and faster than smaller stars, undergoing fusion to create heavier elements. This fusion process continues until iron is formed. Beyond iron, fusion requires energy, leading to a supernova.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/UhIwMAhZpCo.mp4/UhIwMAhZpCo.mp4</video:content_loc><video:duration>401</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/supernova-supernovae</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187387.jpg</video:thumbnail_loc><video:title>Supernova (supernovae)</video:title><video:description>A supernova is a powerful explosion of a massive star at the end of its life cycle. This event releases an enormous amount of energy, temporarily outshining an entire galaxy. It also disperses heavier elements formed during the star&apos;s life and the explosion itself into the universe.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qOwCpnQsDLM.mp4/qOwCpnQsDLM.mp4</video:content_loc><video:duration>718</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/supernova-clarification</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187388.jpg</video:thumbnail_loc><video:title>Supernova clarification</video:title><video:description>Supernova clarification</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/QMv4kxATfzs.mp4/QMv4kxATfzs.mp4</video:content_loc><video:duration>92</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/black-holes</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187389.jpg</video:thumbnail_loc><video:title>Black holes</video:title><video:description>Black Holes</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/JoL2pO3O0rg.mp4/JoL2pO3O0rg.mp4</video:content_loc><video:duration>609</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/supermassive-black-holes</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187393.jpg</video:thumbnail_loc><video:title>Supermassive black holes</video:title><video:description>Supermassive Black Holes</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DxkkAHnqlpY.mp4/DxkkAHnqlpY.mp4</video:content_loc><video:duration>568</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/quasars</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187394.jpg</video:thumbnail_loc><video:title>Quasars</video:title><video:description>Quasars</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4LmIyMyAuN0.mp4/4LmIyMyAuN0.mp4</video:content_loc><video:duration>555</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/quasar-correction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187395.jpg</video:thumbnail_loc><video:title>Quasar correction</video:title><video:description>Quasar Correction</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PX_XSnVWlNc.mp4/PX_XSnVWlNc.mp4</video:content_loc><video:duration>106</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/galactic-collisions</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187396.jpg</video:thumbnail_loc><video:title>Galactic collisions</video:title><video:description>Collision of the Milky Way Galaxy with Andromeda (forming &quot;Milkomeda&quot;)</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/QXYbGZ3T3_k.mp4/QXYbGZ3T3_k.mp4</video:content_loc><video:duration>214</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/parallax-in-observing-stars</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187361.jpg</video:thumbnail_loc><video:title>Parallax in observing stars</video:title><video:description>Parallax in Observing Stars</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ETzUpoqZIHY.mp4/ETzUpoqZIHY.mp4</video:content_loc><video:duration>441</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/stellar-parallax</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/145846956.jpg</video:thumbnail_loc><video:title>Stellar parallax</video:title><video:description>Another version of the stellar parallax introduction</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/omvNINaRdxg.mp4/omvNINaRdxg.mp4</video:content_loc><video:duration>566</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/stellar-distance-using-parallax</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187362.jpg</video:thumbnail_loc><video:title>Stellar distance using parallax</video:title><video:description>Stellar Distance Using Parallax</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lVadjWOjvV8.mp4/lVadjWOjvV8.mp4</video:content_loc><video:duration>700</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/stellar-parallax-clarification</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187363.jpg</video:thumbnail_loc><video:title>Stellar parallax clarification</video:title><video:description>Stellar Parallax Clarification</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6FP-hLuAlr4.mp4/6FP-hLuAlr4.mp4</video:content_loc><video:duration>142</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/parsec-definition</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187364.jpg</video:thumbnail_loc><video:title>Parsec definition</video:title><video:description>Parsec Definition</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6zV3JEjLoyE.mp4/6zV3JEjLoyE.mp4</video:content_loc><video:duration>453</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/cepheid-variables-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187390.jpg</video:thumbnail_loc><video:title>Cepheid variables 1</video:title><video:description>Cepheid Variables 1</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/BWs-ONRDDG4.mp4/BWs-ONRDDG4.mp4</video:content_loc><video:duration>563</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/why-cepheids-pulsate</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187391.jpg</video:thumbnail_loc><video:title>Why cepheids pulsate</video:title><video:description>Why Cepheids Pulsate</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/X_3QAB3o4Vw.mp4/X_3QAB3o4Vw.mp4</video:content_loc><video:duration>430</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/why-gravity-gets-so-strong-near-dense-objects</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/8187392.jpg</video:thumbnail_loc><video:title>Why gravity gets so strong near dense objects</video:title><video:description>Why Gravity Gets So Strong Near Dense Objects</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/RpOHZc6cDIw.mp4/RpOHZc6cDIw.mp4</video:content_loc><video:duration>493</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/plate-tectonics-difference-between-crust-and-lithosphere</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179436.jpg</video:thumbnail_loc><video:title>Plate tectonics: Difference between crust and lithosphere</video:title><video:description>Plate Tectonics Introduction and Difference between crust and lithosphere</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/f2BWsPVN7c4.mp4/f2BWsPVN7c4.mp4</video:content_loc><video:duration>479</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/structure-of-the-earth</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179437.jpg</video:thumbnail_loc><video:title>Structure of the earth</video:title><video:description>Structure of the Earth - crust, mantle, core</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4AxZ-6MOznY.mp4/4AxZ-6MOznY.mp4</video:content_loc><video:duration>573</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/plate-tectonics-evidence-of-plate-movement</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179438.jpg</video:thumbnail_loc><video:title>Plate tectonics: Evidence of plate movement</video:title><video:description>Plate Tectonics -- Evidence of plate movement</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6EdsBabSZ4g.mp4/6EdsBabSZ4g.mp4</video:content_loc><video:duration>798</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/plates-moving-due-to-convection-in-mantle</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179441.jpg</video:thumbnail_loc><video:title>Plates moving due to convection in mantle</video:title><video:description>Plates Moving Due to Convection in Mantle</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/f8GK2oEN-uI.mp4/f8GK2oEN-uI.mp4</video:content_loc><video:duration>362</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/hawaiian-islands-formation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179442.jpg</video:thumbnail_loc><video:title>Hawaiian islands formation</video:title><video:description>The Hawaiian Islands formed primarily as a result of volcanic activity. While most islands ​form near tectonic plate boundaries, the Hawaiian Islands are nearly 2000 miles away from the nearest plate margin. Therefore, scientists believe that the islands formed due to the presence of the Hawaiian &quot;hot spot,&quot; a region deep in the Earth&apos;s mantle from which heat rises. This heat produces melted rock (magma), which then pushes through the crust and solidifies.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/D1eibbfAEVk.mp4/D1eibbfAEVk.mp4</video:content_loc><video:duration>481</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/pangaea</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179459.jpg</video:thumbnail_loc><video:title>Pangaea</video:title><video:description>Pangaea - the idea of Pangaea and some of the evidence behind it</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/axB6uhEx628.mp4/axB6uhEx628.mp4</video:content_loc><video:duration>358</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/compositional-and-mechanical-layers-of-the-earth</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179443.jpg</video:thumbnail_loc><video:title>Compositional and mechanical layers of the earth</video:title><video:description>The crust is the outermost layer of Earth and is composed of solid rock. The lithosphere contains the crust and upper mantle. The mantle is the thickest layer and is made up of hot, mostly solid rock. The core is divided into two parts: the inner core and outer core. The inner core is solid and the outer core is liquid.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/hHteUIS0OFY.mp4/hHteUIS0OFY.mp4</video:content_loc><video:duration>710</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/how-we-know-about-the-earth-s-core</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179458.jpg</video:thumbnail_loc><video:title>How we know about the earth&apos;s core</video:title><video:description>S-wave shadow and P-wave detection patterns give us information about the core</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/KL0i1RSnpfI.mp4/KL0i1RSnpfI.mp4</video:content_loc><video:duration>349</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/seismic-waves</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179444.jpg</video:thumbnail_loc><video:title>Seismic waves</video:title><video:description>S-waves and P-waves</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/NhioAAdYDJM.mp4/NhioAAdYDJM.mp4</video:content_loc><video:duration>518</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/why-s-waves-only-travel-in-solids</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179455.jpg</video:thumbnail_loc><video:title>Why S-waves only travel in solids</video:title><video:description>Why S-Waves Only Travel in Solids</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/BTWLwoaNeBA.mp4/BTWLwoaNeBA.mp4</video:content_loc><video:duration>255</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/refraction-of-seismic-waves</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179456.jpg</video:thumbnail_loc><video:title>Refraction of seismic waves</video:title><video:description>Refraction of Seismic Waves</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/UNZ171fDja4.mp4/UNZ171fDja4.mp4</video:content_loc><video:duration>562</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/the-mohorovicic-seismic-discontinuity</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/13179457.jpg</video:thumbnail_loc><video:title>The mohorovicic seismic discontinuity</video:title><video:description>The Mohorovicic Seismic Discontinuity- boundary between crust and mantle (or Moho)</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/yAQSucmHrAk.mp4/yAQSucmHrAk.mp4</video:content_loc><video:duration>373</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/seasons-aren-t-dictated-by-closeness-to-sun</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/150055884.jpg</video:thumbnail_loc><video:title>Seasons aren&apos;t dictated by closeness to sun</video:title><video:description>Why our closeness to the sun does not dictate the seasons</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/SJUd5du0T08.mp4/SJUd5du0T08.mp4</video:content_loc><video:duration>279</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/how-earth-s-tilt-causes-seasons</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/150055883.jpg</video:thumbnail_loc><video:title>How Earth&apos;s tilt causes seasons</video:title><video:description>How Earth&apos;s tilt causes seasons</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/05qDIjKevJo.mp4/05qDIjKevJo.mp4</video:content_loc><video:duration>1247</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/are-southern-hemisphere-seasons-more-severe</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/152085900.jpg</video:thumbnail_loc><video:title>Are southern hemisphere seasons more severe?</video:title><video:description>Are Southern Hemisphere seasons more severe because of the eccentricity in Earth&apos;s orbit?</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/umvNQj-zmq4.mp4/umvNQj-zmq4.mp4</video:content_loc><video:duration>437</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/milankovitch-cycles-precession-and-obliquity</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/150055882.jpg</video:thumbnail_loc><video:title>Milankovitch cycles precession and obliquity</video:title><video:description>How changes in Earth&apos;s rotation can effect Earth&apos;s seasons and climate</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ZD8THEz18gc.mp4/ZD8THEz18gc.mp4</video:content_loc><video:duration>777</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/precession-causing-perihelion-to-happen-later</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/152085903.jpg</video:thumbnail_loc><video:title>Precession causing perihelion to happen later</video:title><video:description>Clarifying the effect of axial precession on the calendar and the date of perihelion and aphelion</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2o-Sef6wllg.mp4/2o-Sef6wllg.mp4</video:content_loc><video:duration>724</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/what-causes-precession-and-other-orbital-changes</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/152085901.jpg</video:thumbnail_loc><video:title>What causes precession and other orbital changes</video:title><video:description>What causes precession and other orbital changes</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/nL6LMX8-bPY.mp4/nL6LMX8-bPY.mp4</video:content_loc><video:duration>126</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/apsidal-precession-perihelion-precession-and-milankovitch-cycles</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/152085902.jpg</video:thumbnail_loc><video:title>Apsidal precession (perihelion precession) and Milankovitch cycles</video:title><video:description>Apsidal Precession (Perihelion Precession)</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/m6lMGoZTJnc.mp4/m6lMGoZTJnc.mp4</video:content_loc><video:duration>427</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/intro-to-moon-phases</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x71004a2e3a9c632b.jpg</video:thumbnail_loc><video:title>Intro to Moon phases</video:title><video:description>The Moon and the sun look roughly the same size in the sky because although the sun’s diameter is ~400 times greater than the Moon’s, the sun is ~400 times farther away from the Earth as the Moon is! The Moon goes through phases because as it rotates around the Earth, different parts of the Moon are made visible to us from the sun’s light.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ZQcf9xLABa0.mp4/ZQcf9xLABa0.mp4</video:content_loc><video:duration>334</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/solar-and-lunar-eclipses</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x65c91ab6fe86292e.jpg</video:thumbnail_loc><video:title>Solar and lunar eclipses</video:title><video:description>Understanding solar eclipses and lunar eclipses. Why don&apos;t we have a solar eclipse every new moon (every time the Moon is between the Earth and Sun)? Why don&apos;t we have a lunar eclipse every time the Earth is between the Sun and Moon.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/qJqGg3Xe4iE.mp4/qJqGg3Xe4iE.mp4</video:content_loc><video:duration>332</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/understanding-calendar-notation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/101104459.jpg</video:thumbnail_loc><video:title>Understanding calendar notation</video:title><video:description>Difference between BC, BCE, AD and CE. A little bit about the birth of Jesus as well.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/EKKe7DBZVhI.mp4/EKKe7DBZVhI.mp4</video:content_loc><video:duration>581</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/correction-calendar-notation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/105033394.jpg</video:thumbnail_loc><video:title>Correction calendar notation</video:title><video:description>Correcting the time difference calculation by taking into account that there is no year 0</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/N06Jy-gQog8.mp4/N06Jy-gQog8.mp4</video:content_loc><video:duration>252</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/energy-inputs-for-tilling-a-hectare-of-land</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/465986949.jpg</video:thumbnail_loc><video:title>Energy inputs for tilling a hectare of land</video:title><video:description>Thinking about energy consumption for tilling land</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/5I9dH5im24U.mp4/5I9dH5im24U.mp4</video:content_loc><video:duration>821</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/random-predictions-for-2060</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/466052144.jpg</video:thumbnail_loc><video:title>Random predictions for 2060</video:title><video:description>Sal&apos;s random predictions for the year 2060</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/E4rbS0oxg30.mp4/E4rbS0oxg30.mp4</video:content_loc><video:duration>667</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/detectable-civilizations-in-our-galaxy-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/91824745.jpg</video:thumbnail_loc><video:title>Detectable civilizations in our galaxy 1</video:title><video:description>A framework for thinking about how many detectable civilizations are out there.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/YYEgq1bweN4.mp4/YYEgq1bweN4.mp4</video:content_loc><video:duration>783</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/detectable-civilizations-in-our-galaxy-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/92633418.jpg</video:thumbnail_loc><video:title>Detectable civilizations in our galaxy 2</video:title><video:description>Why do we even care about the Drake Equation. Thinking about the fraction of a planet&apos;s life when a civilization might be detectable.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jN03g05TSWM.mp4/jN03g05TSWM.mp4</video:content_loc><video:duration>533</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/detectable-civilizations-in-our-galaxy-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/92633419.jpg</video:thumbnail_loc><video:title>Detectable civilizations in our galaxy 3</video:title><video:description>Reconciling with the traditional Drake Equation</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LRmwUsxNSL0.mp4/LRmwUsxNSL0.mp4</video:content_loc><video:duration>438</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/detectable-civilizations-in-our-galaxy-4</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/92633420.jpg</video:thumbnail_loc><video:title>Detectable civilizations in our galaxy 4</video:title><video:description>Taking a shot at estimating the number of detectable civilizations</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/T5DGZIsfK-0.mp4/T5DGZIsfK-0.mp4</video:content_loc><video:duration>375</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/cosmology-and-astronomy/v/detectable-civilizations-in-our-galaxy-5</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/94896541.jpg</video:thumbnail_loc><video:title>Detectable civilizations in our galaxy 5</video:title><video:description>More reasons why we haven&apos;t detected anything yet.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xL9ejqb53ms.mp4/xL9ejqb53ms.mp4</video:content_loc><video:duration>309</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-current</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x91cda9c9.jpg</video:thumbnail_loc><video:title>Electric current</video:title><video:description>Current is the flow of charge. Copper and silver atoms have loose electrons, making them good conductors. Current is measured by counting charges passing through a boundary per second. It also shows how saltwater conducts current with positive and negative ions moving in opposite directions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ZRLXDiiUv8Q.mp4/ZRLXDiiUv8Q.mp4</video:content_loc><video:duration>558</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/current-direction</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6c7f6193.jpg</video:thumbnail_loc><video:title>Current direction</video:title><video:description>The positive sign for current corresponds to the direction a positive charge would move. In metal wires, current is carried by negatively charged electrons, so the positive current arrow points in the opposite direction the electrons move. This has been the sign convention for 270 years, ever since Ben Franklin named electric charges with + and - signs. This convention came about 150 years before the discovery of the electron.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4frpZ4Q0q58.mp4/4frpZ4Q0q58.mp4</video:content_loc><video:duration>328</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-voltage-intuition</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd11f8925.jpg</video:thumbnail_loc><video:title>Voltage</video:title><video:description>Voltage is a cornerstone concept in electricity. We create an intuitive mental image by comparing voltage to gravity.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/k9SwNST1eW0.mp4/k9SwNST1eW0.mp4</video:content_loc><video:duration>179</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-conventional-current</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x267eb7e6.jpg</video:thumbnail_loc><video:title>Conventional current direction</video:title><video:description>By convention, we define positive direction of current to be in the direction a positive charge would move. Electrons (with their negative charge) move in the opposite direction of the positive current arrow.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/17EhKw2tsu4.mp4/17EhKw2tsu4.mp4</video:content_loc><video:duration>237</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ideal-circuit-elements</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x0085d2b0.jpg</video:thumbnail_loc><video:title>Ideal circuit elements</video:title><video:description>Explore the world of circuit analysis with the three fundamental circuit elements: resistors, capacitors, and inductors. Understand their unique symbols, properties, and the key equations that connect voltage and current for each component. Master Ohm&apos;s law for resistors, the capacitor equation, and the inductor equation to build a strong foundation in circuit design and analysis. These ideal component equations will unlock the door to creating and understanding a wide variety of electrical circuits.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/l-h72j2-X0o.mp4/l-h72j2-X0o.mp4</video:content_loc><video:duration>391</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-ideal-sources</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x99d7332b.jpg</video:thumbnail_loc><video:title>Ideal sources</video:title><video:description>The ideal voltage source has a constant voltage. The ideal current source has a constant current. Both sources can be plotted on an IV curve. These sources are crucial for providing power and signals within electrical circuits.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/CBlfcuUXzUY.mp4/CBlfcuUXzUY.mp4</video:content_loc><video:duration>175</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/circuit-terminology</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x05b9c9e6.jpg</video:thumbnail_loc><video:title>Circuit terminology</video:title><video:description>The key terms for circuits are components (resistors, capacitors, inductors), elements, nodes (junctions), branches, meshes (loops), and loops. In our analysis of circuits, we will learn how to identify nodes, branches, and meshes.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/-82UNytyrCQ.mp4/-82UNytyrCQ.mp4</video:content_loc><video:duration>483</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-passive-sign-convention</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb4f026f4.jpg</video:thumbnail_loc><video:title>Sign convention for passive components</video:title><video:description>The sign convention for passive components defines what we mean by positive and negative voltage and current.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1Oopq5U0b08.mp4/1Oopq5U0b08.mp4</video:content_loc><video:duration>269</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-parallel-resistors-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf40ba5f6.jpg</video:thumbnail_loc><video:title>Parallel resistors (derivation)</video:title><video:description>Discover the fascinating world of parallel resistors in electrical circuits! Learn how to identify parallel resistors, understand the concept of shared nodes and voltage, and apply Ohm&apos;s law to calculate equivalent resistance. Master the formula for parallel resistors and enhance your circuit analysis skills with real-life examples.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/MHADYILlW1E.mp4/MHADYILlW1E.mp4</video:content_loc><video:duration>668</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-parallel-resistors-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd00091cc.jpg</video:thumbnail_loc><video:title>Parallel resistors (derivation continued)</video:title><video:description>Learn how to calculate the equivalent resistance for multiple parallel resistors. This method simplifies complex resistor networks by replacing them with a single equivalent parallel resistor, streamlining circuit analysis and improving efficiency. Grasp the concept of current splitting among resistors and understand that all parallel resistors share the same voltage, making this technique applicable to various electrical engineering scenarios.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0IeWoAiHbAY.mp4/0IeWoAiHbAY.mp4</video:content_loc><video:duration>255</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-voltage-divider</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa22475c5.jpg</video:thumbnail_loc><video:title>Voltage divider</video:title><video:description>Explore the voltage divider, a fundamental circuit pattern in electrical engineering, consisting of two series resistors that control output voltage. Master the voltage divider expression, which calculates output voltage based on input voltage and resistor values. Dive into practical examples, learn when to apply this versatile circuit, and understand the importance of considering current flow for accurate voltage division in real-world applications.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/t_hPrz7rs34.mp4/t_hPrz7rs34.mp4</video:content_loc><video:duration>399</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/analyzing-a-resistor-circuit-with-two-batteries</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x159d4673.jpg</video:thumbnail_loc><video:title>Analyzing a resistor circuit with two batteries</video:title><video:description>Discover how to solve complex circuit problems in physics by simplifying schematics, combining parallel resistors, and applying Ohm&apos;s law. Master the art of analyzing circuits with multiple batteries and resistors to find the current flowing through each component. Boost your electrical engineering skills and conquer challenging circuit questions.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/j-iR7puLj6M.mp4/j-iR7puLj6M.mp4</video:content_loc><video:duration>584</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-labeling-voltages</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbbbe6a4d.jpg</video:thumbnail_loc><video:title>Labeling voltages</video:title><video:description>Labeling voltages on a schematic is not a matter of &quot;right&quot; and &quot;wrong&quot;. It simply establishes how the voltage appears in the analysis equations.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ZjPs0V6tiR0.mp4/ZjPs0V6tiR0.mp4</video:content_loc><video:duration>667</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-application-of-the-fundamental-laws-setup</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x501e0a36.jpg</video:thumbnail_loc><video:title>Application of the fundamental laws (setup)</video:title><video:description>We can solve circuits by the direct application of the fundamental laws: Ohm&apos;s Law and Kirchhoff&apos;s Laws. (Part 1 of 2)</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1VaKLjvbWZ0.mp4/1VaKLjvbWZ0.mp4</video:content_loc><video:duration>482</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-application-of-the-fundamental-laws-solve</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x889b22a3.jpg</video:thumbnail_loc><video:title>Application of the fundamental laws (solve)</video:title><video:description>We solve the equations created by direct application of the fundamental laws: Ohm&apos;s Law and Kirchhoff&apos;s Laws. (Part 2 of 2)</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ShxyPUl7asE.mp4/ShxyPUl7asE.mp4</video:content_loc><video:duration>520</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-node-voltage-method-steps-1-to-4</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x86bd1a36.jpg</video:thumbnail_loc><video:title>Node voltage method (steps 1 to 4)</video:title><video:description>The Node Voltage Method solves circuits with the minimum number of KCL equations. Steps 1 to 4 out of 5.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2lY757QaaKs.mp4/2lY757QaaKs.mp4</video:content_loc><video:duration>597</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-node-voltage-method-step-5</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7c70cce8.jpg</video:thumbnail_loc><video:title>Node voltage method (step 5)</video:title><video:description>Last step of the Node voltage method for analyzing circuits: Solve the system of simultaneous equations</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LMC3jcNomNc.mp4/LMC3jcNomNc.mp4</video:content_loc><video:duration>385</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-mesh-current-steps-1-to-3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x8d04abc2.jpg</video:thumbnail_loc><video:title>Mesh current method (steps 1 to 3)</video:title><video:description>We solve a circuit by writing Kirchhoff&apos;s Voltage Law in terms of &quot;mesh currents.&quot; This video covers the first three steps out of four.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/j8LHrm3_brk.mp4/j8LHrm3_brk.mp4</video:content_loc><video:duration>556</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-mesh-current-method-step-4-solve</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7c56cf3c.jpg</video:thumbnail_loc><video:title>Mesh current method (step 4)</video:title><video:description>We complete the solution of a circuit using the mesh current method. Fourth step (solve) out of four.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7I3-HAW8rmM.mp4/7I3-HAW8rmM.mp4</video:content_loc><video:duration>732</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-capacitor-i-v-equations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb62c6631.jpg</video:thumbnail_loc><video:title>Capacitor i-v equations</video:title><video:description>The capacitor current-voltage equation in derivative form and integral form</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/EqlsSqET1kk.mp4/EqlsSqET1kk.mp4</video:content_loc><video:duration>521</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-capacitor-integrates-current</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf4894782.jpg</video:thumbnail_loc><video:title>A capacitor integrates current</video:title><video:description>A current flowing into a capacitor causes charge to accumulate. The voltage rises according to q = Cv and we say the capacitor integrates current.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/JxOMm24lSR4.mp4/JxOMm24lSR4.mp4</video:content_loc><video:duration>561</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-inductor-equations</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x192b1d27.jpg</video:thumbnail_loc><video:title>Inductor equations</video:title><video:description>We look at the inductor i-v equations in derivative and integral form.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/w1NR5sjsChI.mp4/w1NR5sjsChI.mp4</video:content_loc><video:duration>767</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-inductor-kickback-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3d6518e7.jpg</video:thumbnail_loc><video:title>Inductor kickback (1 of 2)</video:title><video:description>We notice how important it is to give inductor current a place to flow</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/YKKd5p4a5Lo.mp4/YKKd5p4a5Lo.mp4</video:content_loc><video:duration>769</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-inductor-kickback-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x5c5c4af3.jpg</video:thumbnail_loc><video:title>Inductor kickback (2 of 2)</video:title><video:description>We give the inductor&apos;s kickback current a path to flow by adding a diode</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/xOoMotHFOKk.mp4/xOoMotHFOKk.mp4</video:content_loc><video:duration>446</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-rc-natural-response-intuition</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xed38ea01.jpg</video:thumbnail_loc><video:title>RC natural response - intuition</video:title><video:description>We put some charge on a capacitor in an RC circuit and observe what happens to the voltage and current. This is called the natural response.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PZM6acXvsoQ.mp4/PZM6acXvsoQ.mp4</video:content_loc><video:duration>446</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-rc-natural-response-derivation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9e7f9050.jpg</video:thumbnail_loc><video:title>RC natural response - derivation</video:title><video:description>We derive the natural response of an RC circuit and discover it has an exponential form.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4qgLz0TF8-M.mp4/4qgLz0TF8-M.mp4</video:content_loc><video:duration>659</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/rc-natural-response-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6879a53e.jpg</video:thumbnail_loc><video:title>RC natural response - example</video:title><video:description>An example of the exponential natural response of an RC circuit, with real component values</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2NRBn6ZLmDc.mp4/2NRBn6ZLmDc.mp4</video:content_loc><video:duration>173</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-rc-step-response-intuition</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3d9229e2.jpg</video:thumbnail_loc><video:title>RC step response - intuition</video:title><video:description>An RC circuit responds to a step of voltage with a smooth transition between the starting and ending voltage. The RC step response is a fundamental behavior of all digital circuits.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/zfqJRZyeGRE.mp4/zfqJRZyeGRE.mp4</video:content_loc><video:duration>609</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-rc-step-response-1-of-3-setup</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd7e40b7e.jpg</video:thumbnail_loc><video:title>RC step response setup (1 of 3)</video:title><video:description>The RC step response is an exponential curve. We set up the circuit and create the differential equation we need to solve. We introduce the technique of Natural response + Forced response.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/k6KH4WmcgaU.mp4/k6KH4WmcgaU.mp4</video:content_loc><video:duration>548</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-rc-step-response-2-of-3-solve</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa7268fa5.jpg</video:thumbnail_loc><video:title>RC step response solve (2 of 3)</video:title><video:description>We find the RC step response using the method of Natural + Forced response = Total response.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/A_1N561qdSw.mp4/A_1N561qdSw.mp4</video:content_loc><video:duration>567</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-rc-step-response-3-of-3-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7270efde.jpg</video:thumbnail_loc><video:title>RC step response example (3 of 3)</video:title><video:description>An example solution of an RC step response, with real component values.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/A4aoLMC1-5Y.mp4/A4aoLMC1-5Y.mp4</video:content_loc><video:duration>220</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-sketching-exponentials</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x74c74eda.jpg</video:thumbnail_loc><video:title>Sketching exponentials</video:title><video:description>Voltages and currents often have an exponential shape. We look at some properties of exponential curves and learn how to rapidly sketch accurate waveforms.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4XHMqvVByFQ.mp4/4XHMqvVByFQ.mp4</video:content_loc><video:duration>470</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-sketching-exponentials-examples</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa7d45c96.jpg</video:thumbnail_loc><video:title>Sketching exponentials - examples</video:title><video:description>Sketch exponentials with different time constants</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/kxE7wipiMps.mp4/kxE7wipiMps.mp4</video:content_loc><video:duration>441</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-lc-natural-response-intuition1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6a27615d.jpg</video:thumbnail_loc><video:title>LC natural response intuition 1</video:title><video:description>The inductor-capacitor (LC) circuit is the place where sinewaves are born. We talk about how this circuit works by tracking the movement of an initial charge we placed on the capacitor.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/FuuR_SqwXm4.mp4/FuuR_SqwXm4.mp4</video:content_loc><video:duration>313</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-lc-natural-response-intuition2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xadf4d02b.jpg</video:thumbnail_loc><video:title>LC natural response intuition 2</video:title><video:description>We can predict the shape of voltage and current in an LC circuit by tracking the motion of charge as it flows back and forth.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/DIxU2l204HU.mp4/DIxU2l204HU.mp4</video:content_loc><video:duration>573</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-lc-natural-response-derivation1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1a672ae3.jpg</video:thumbnail_loc><video:title>LC natural response derivation 1</video:title><video:description>We begin the derivation of the natural response of the LC circuit, by modeling it with a 2nd-order differential equation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vvf-qiN9SWA.mp4/vvf-qiN9SWA.mp4</video:content_loc><video:duration>399</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-lc-natural-response-derivation2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x77ef60da.jpg</video:thumbnail_loc><video:title>LC natural response derivation 2</video:title><video:description>Starting from the differential equation, we come up with a proposed exponential solution and plug it into the equation. This gives us a characteristic equation. A &quot;natural frequency&quot; emerges.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/aSTvToHuG3I.mp4/aSTvToHuG3I.mp4</video:content_loc><video:duration>570</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-lc-natural-response-derivation3</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x57ae5231.jpg</video:thumbnail_loc><video:title>LC natural response derivation 3</video:title><video:description>We use Euler&apos;s Formula to change our complex exponential solution into a solution expressed in terms of sines and cosines.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/p-b6k9jyIkE.mp4/p-b6k9jyIkE.mp4</video:content_loc><video:duration>431</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-lc-natural-response-derivation4</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xccd5c0d0.jpg</video:thumbnail_loc><video:title>LC natural response derivation 4</video:title><video:description>In this final step of the derivation, we find two initial conditions and use them to come up with a sinusoidal solution for the LC natural response.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/51UHJnjUOSs.mp4/51UHJnjUOSs.mp4</video:content_loc><video:duration>452</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-lc-natural-response-example</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb469f4a4.jpg</video:thumbnail_loc><video:title>LC natural response example</video:title><video:description>We solve the voltage and current of an example LC circuit with given values for L and C, and an initial charge on the capacitor</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/vkIBypq8MTE.mp4/vkIBypq8MTE.mp4</video:content_loc><video:duration>444</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-ac-analysis-intro1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd05ad841.jpg</video:thumbnail_loc><video:title>AC analysis intro 1</video:title><video:description>Solving circuits with differential equations is hard. If we limit ourselves to sinusoidal input signals, a whole new method of AC analysis emerges.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/7UJi2GQCi00.mp4/7UJi2GQCi00.mp4</video:content_loc><video:duration>403</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-ac-analysis-intro2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbf82f3c6.jpg</video:thumbnail_loc><video:title>AC analysis intro 2</video:title><video:description>Here&apos;s a preview of how AC analysis is going to work. To get ready we need to review some of the ideas from trig and complex numbers.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/NuAgmNaX58M.mp4/NuAgmNaX58M.mp4</video:content_loc><video:duration>538</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-ac-trig-review</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xeca5168a.jpg</video:thumbnail_loc><video:title>Trigonometry review</video:title><video:description>A quick review of some ideas from trigonometry that will help us with AC analysis. The definitions of sine, cosine, and tangent, circles, degrees, radians.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6hjr4n4MCPA.mp4/6hjr4n4MCPA.mp4</video:content_loc><video:duration>450</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-sine-cosine-circles</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x2c67c16e.jpg</video:thumbnail_loc><video:title>Sine and cosine come from circles</video:title><video:description>Sine and cosine can be generated by projecting the tip of a vector onto the y-axis and x-axis as the vector rotates about the origin.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LmxGmUOiP2A.mp4/LmxGmUOiP2A.mp4</video:content_loc><video:duration>280</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-sine-of-time</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb88ed089.jpg</video:thumbnail_loc><video:title>Sine of time</video:title><video:description>If we introduce time as the argument to the sine function, we get a sine wave. Animated.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/R3en76G8_W0.mp4/R3en76G8_W0.mp4</video:content_loc><video:duration>638</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-sine-cosine-from-rotating-vector</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xdde03158.jpg</video:thumbnail_loc><video:title>Sine and cosine from rotating vector</video:title><video:description>One way to generate sine and cosine is to track the motion of a rotating vector. Animated.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/a_zReGTxdlQ.mp4/a_zReGTxdlQ.mp4</video:content_loc><video:duration>237</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-lead-lag</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x6d4df74e.jpg</video:thumbnail_loc><video:title>Lead Lag</video:title><video:description>Sine and cosine look similar, except they are out of phase. When we talk about sine and cosine as a function of time, the difference is called &quot;lead&quot; or &quot;lag&quot;.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/G0h9Sa_s18A.mp4/G0h9Sa_s18A.mp4</video:content_loc><video:duration>446</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-complex-numbers</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x53c95fe4.jpg</video:thumbnail_loc><video:title>Complex numbers</video:title><video:description>Complex numbers can be represented three ways on the complex plane: cartesian coordinates, radius and angle, and exponential form.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/wbEEWmJFDVg.mp4/wbEEWmJFDVg.mp4</video:content_loc><video:duration>516</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-multiplying-j-rotation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x99f14726.jpg</video:thumbnail_loc><video:title>Multiplying by j is rotation</video:title><video:description>Successive powers of the imaginary unit j correspond to a rotation.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/giO5ACdU2LA.mp4/giO5ACdU2LA.mp4</video:content_loc><video:duration>373</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-complex-rotation</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7079f83a.jpg</video:thumbnail_loc><video:title>Complex rotation</video:title><video:description>Multiplying a real or complex number by the imaginary unit j corresponds to a rotation by +90 degrees. This is the key feature of j that makes it such a useful number.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/CIQmq1wOjnc.mp4/CIQmq1wOjnc.mp4</video:content_loc><video:duration>380</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-eulers-formula</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9bea2f03.jpg</video:thumbnail_loc><video:title>Euler&apos;s formula</video:title><video:description>Euler&apos;s formula relates the complex exponential to the cosine and sine functions. This formula is the most important tool in AC analysis. It is why electrical engineers need to understand complex numbers.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/LE2uwd9V5vw.mp4/LE2uwd9V5vw.mp4</video:content_loc><video:duration>522</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-complex-exponential-magnitude</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7d155a8b.jpg</video:thumbnail_loc><video:title>Complex exponential magnitude</video:title><video:description>A closer look at the complex exponential term in Euler&apos;s Formula. We see that it represents a complex number, a distance of 1 from the origin of the complex plane.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/XxP6auFa44M.mp4/XxP6auFa44M.mp4</video:content_loc><video:duration>370</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-complex-exponentials-spin</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb095c462.jpg</video:thumbnail_loc><video:title>Complex exponentials spin</video:title><video:description>When we put time in the exponent of a complex exponential, the complex number it represent rotates in a circle on the complex plane. You can think of it as a spinning number!</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/4-gVIRgZi2U.mp4/4-gVIRgZi2U.mp4</video:content_loc><video:duration>400</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-eulers-sine-wave</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x1ecb1090.jpg</video:thumbnail_loc><video:title>Euler&apos;s sine wave</video:title><video:description>A sine wave emerges from Euler&apos;s Formula. Music, no narration. Animated with d3.js.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/1tSrRYU6LKM.mp4/1tSrRYU6LKM.mp4</video:content_loc><video:duration>203</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-euler-cosine</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xf6747f03.jpg</video:thumbnail_loc><video:title>Euler&apos;s cosine wave</video:title><video:description>A cosine wave emerges from Euler&apos;s Formula. Music, no narration. Animated with d3.js.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/zGTzWgSDFR0.mp4/zGTzWgSDFR0.mp4</video:content_loc><video:duration>184</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-negative-frequency</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbb83765d.jpg</video:thumbnail_loc><video:title>Negative frequency</video:title><video:description>The concept of negative frequency is perplexing, but it makes sense when you think about rotating complex exponentials</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/SvFfVtRT1UI.mp4/SvFfVtRT1UI.mp4</video:content_loc><video:duration>401</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-ac-analysis-superposition</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xafc6252e.jpg</video:thumbnail_loc><video:title>AC analysis superposition</video:title><video:description>We break a sinusoidal input voltage into two complex exponentials. Using superposition, we can recover the complex output signals and reassemble them into a real sinusoidal output voltage.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/UjiLH7RE8_Y.mp4/UjiLH7RE8_Y.mp4</video:content_loc><video:duration>439</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-impedance</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7ea223b6.jpg</video:thumbnail_loc><video:title>Impedance</video:title><video:description>The ratio of a sinusoidal voltage to a sinusoidal current is called &quot;impedance&quot;. This is a generalization of Ohm&apos;s Law for resistors. We derive the impedance of a resistor, inductor, and capacitor. The inductor and capacitor impedance includes a term for frequency, so the impedance of these components depends on frequency.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/WmTlioVfS78.mp4/WmTlioVfS78.mp4</video:content_loc><video:duration>701</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-impedance-vs-frequency</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x9dbef6a8.jpg</video:thumbnail_loc><video:title>Impedance vs frequency</video:title><video:description>The impedance of capacitors and inductors in a circuit depend on the frequency of the electric signal. The impedance of an inductor is directly proportional to frequency, while the impedance of a capacitor is inversely proportional to frequency.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/I21hginkKk0.mp4/I21hginkKk0.mp4</video:content_loc><video:duration>536</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-eli-the-ice-man</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xbb84e633.jpg</video:thumbnail_loc><video:title>ELI the ICE man</video:title><video:description>Remember the relationship between current and voltage in an inductor and capacitor with the help of ELI the ICE man.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/2yqjMiFUMlA.mp4/2yqjMiFUMlA.mp4</video:content_loc><video:duration>629</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-impedance-of-simple-networks</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x022a2cf2.jpg</video:thumbnail_loc><video:title>Impedance of simple networks</video:title><video:description>Impedance of 2 elements in series is a complex number. Impedance terminology: reactance, susceptance, admittance.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/smLN8WKJjas.mp4/smLN8WKJjas.mp4</video:content_loc><video:duration>703</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-kvl-frequency-domain</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x04d23e29.jpg</video:thumbnail_loc><video:title>KVL in the frequency domain</video:title><video:description>Demonstration that Kirchhoff&apos;s voltage law applies in the frequency domain. The voltage phase offsets around a loop sum to zero.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/779k4-oFjuc.mp4/779k4-oFjuc.mp4</video:content_loc><video:duration>771</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-opamp-intro</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xaf155f88.jpg</video:thumbnail_loc><video:title>What is an operational amplifier?</video:title><video:description>The &quot;operational amplifier&quot; has two differential inputs and very high gain. Willy describes the symbol and properties of an op-amp. Op-amps are the backbone of analog circuit design.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/lJDjWZqhpVc.mp4/lJDjWZqhpVc.mp4</video:content_loc><video:duration>694</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-noninverting-opamp</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb80be02c.jpg</video:thumbnail_loc><video:title>Non-inverting op-amp</video:title><video:description>An op-amp can be used to amplify a voltage. The gain is determined by the ratio of two resistors.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/_Ut-nQ535iE.mp4/_Ut-nQ535iE.mp4</video:content_loc><video:duration>752</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-feedback</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb159b105.jpg</video:thumbnail_loc><video:title>Feedback</video:title><video:description>Feedback is the design technique where a part of the amplifier output &quot;feeds back&quot; to the input of the amplifier. The overall effect creates a very stable gain determined by resistor ratios.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ua4eMZTxpQ0.mp4/ua4eMZTxpQ0.mp4</video:content_loc><video:duration>356</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-inverting-opamp</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xd6dd3ffd.jpg</video:thumbnail_loc><video:title>Inverting op-amp</video:title><video:description>We analyze the inverting op-amp configuration, doing all the algebra from first principles.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/U1KbM4ffiLg.mp4/U1KbM4ffiLg.mp4</video:content_loc><video:duration>770</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-virtual-ground</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xa9088670.jpg</video:thumbnail_loc><video:title>Virtual ground</video:title><video:description>The idea of a &quot;virtual ground&quot; makes some simplifying assumptions, giving us an elegant and simple way to look at op-amp circuits.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/pxKLeIjzxAk.mp4/pxKLeIjzxAk.mp4</video:content_loc><video:duration>358</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-virtual-ground-examples</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x83b79b90.jpg</video:thumbnail_loc><video:title>Virtual ground - examples</video:title><video:description>Using the &quot;virtual ground&quot; idea, we reexamine the inverting op-amp and find a solution much quicker. We apply the virtual ground method to a unity-gain buffer (amplifier with gain = 1).</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/aD6l5bNnJgE.mp4/aD6l5bNnJgE.mp4</video:content_loc><video:duration>387</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-summing-opamp</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x78eefffe.jpg</video:thumbnail_loc><video:title>Summing op-amp</video:title><video:description>This op-amp circuit outputs the sum of two input voltages. You can do analog arithmetic on signals.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/jlwcIRKCqek.mp4/jlwcIRKCqek.mp4</video:content_loc><video:duration>548</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-diode</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x4ce88ac1.jpg</video:thumbnail_loc><video:title>Diode</video:title><video:description>Introducing the diode as a circuit element. A diode conducts current in one direction but not the other.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/0FbeUMPZFjU.mp4/0FbeUMPZFjU.mp4</video:content_loc><video:duration>660</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-diode-graphical-solution</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x3c002e02.jpg</video:thumbnail_loc><video:title>Diode graphical solution</video:title><video:description>We solve a diode circuit graphically by plotting a diode i-v curve and resistor to find the intersection. Graphical solution methods are a common way to work with non-linear components like diodes.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/IMZ2D8Nz6sA.mp4/IMZ2D8Nz6sA.mp4</video:content_loc><video:duration>487</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/proof-advanced-field-from-infinite-plate-part-1</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25687.jpg</video:thumbnail_loc><video:title>Proof: Field from infinite plate (part 1)</video:title><video:description>Advanced proof of the formula for the electric field generated by a uniformly charged, infinite plate</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/prLfVucoxpw.mp4/prLfVucoxpw.mp4</video:content_loc><video:duration>807</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/proof-advanced-field-from-infinite-plate-part-2</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25689.jpg</video:thumbnail_loc><video:title>Proof: Field from infinite plate (part 2)</video:title><video:description>We see that the infinite, uniformly charged plate generates a constant electric field (independent of the height above the plate)</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/TxwE4_dXo8s.mp4/TxwE4_dXo8s.mp4</video:content_loc><video:duration>688</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/electric-potential-energy</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/25691.jpg</video:thumbnail_loc><video:title>Electric potential energy</video:title><video:description>Explore the concept of electrical potential energy and its similarities to gravitational potential energy. Understand how work is required to move an object within a gravitational or electric field, and how this work translates into potential energy. Discover how potential energy changes can impact kinetic energy and velocity.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/elJUghWSVh4.mp4/elJUghWSVh4.mp4</video:content_loc><video:duration>757</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-fourier-series-intro</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x05009cb1.jpg</video:thumbnail_loc><video:title>Fourier Series introduction</video:title><video:description>Fourier series are a powerful tool that can help us break down complex signals into their constituent parts. By using some basic mathematics, we can deconstruct signals into simple sine waves, making them much easier to understand and analyze.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/UKHBWzoOKsY.mp4/UKHBWzoOKsY.mp4</video:content_loc><video:duration>313</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-integral-of-sinmt-and-cosmt</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xb8db33db.jpg</video:thumbnail_loc><video:title>Integral of sin(mt) and cos(mt)</video:title><video:description>Integrating sin(mt) and cos(mt) over a full period equals zero.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/6AWZT8owvO8.mp4/6AWZT8owvO8.mp4</video:content_loc><video:duration>385</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-integral-of-sine-times-cosine</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xee75f2fb.jpg</video:thumbnail_loc><video:title>Integral of sine times cosine</video:title><video:description>Definite integral of the product of sine and cosine. Integrating sin(mt) * cos(nt) over a full period equals zero for any integer m and n.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/EDhYig0bEpA.mp4/EDhYig0bEpA.mp4</video:content_loc><video:duration>267</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-integral-sine-times-sine</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x90a87d13.jpg</video:thumbnail_loc><video:title>Integral of product of sines</video:title><video:description>Definite integral of product of sines. The integral of sin(mt) * sin(nt) = 0, except for the special case when m = n. When m = n, the integral evaluates to pi.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/PLxHkjrVBgE.mp4/PLxHkjrVBgE.mp4</video:content_loc><video:duration>495</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-integral-cosine-times-cosine</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x7e684a10.jpg</video:thumbnail_loc><video:title>Integral of product of cosines</video:title><video:description>Definite integral of the product of cosines. The integral of cos(mt) * cos(nt) = 0, except for the special case when m = n. When m = n, the integral evaluates to pi.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/ki4VK_dQlPs.mp4/ki4VK_dQlPs.mp4</video:content_loc><video:duration>435</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-first-term-fourier-series</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x19e42e4e.jpg</video:thumbnail_loc><video:title>First term in a Fourier series</video:title><video:description>The first term in a Fourier series is the average value (DC value) of the function being approximated.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/59RIABaGTcs.mp4/59RIABaGTcs.mp4</video:content_loc><video:duration>409</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-fourier-coefficients-cosine</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x24abab90.jpg</video:thumbnail_loc><video:title>Fourier coefficients for cosine terms</video:title><video:description>Fourier coefficients for cosine terms</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/kwqNDIacqt0.mp4/kwqNDIacqt0.mp4</video:content_loc><video:duration>368</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-fourier-coefficients-sine</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/x91ce05b4.jpg</video:thumbnail_loc><video:title>Fourier coefficients for sine terms</video:title><video:description>Fourier coefficients for sine terms</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/khDD_9g5YTM.mp4/khDD_9g5YTM.mp4</video:content_loc><video:duration>393</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-fourier-coefficients-for-square-wave</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xc0806f77.jpg</video:thumbnail_loc><video:title>Finding Fourier coefficients for square wave</video:title><video:description>Finding Fourier coefficients for a square wave</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/WTD8jg8fXoE.mp4/WTD8jg8fXoE.mp4</video:content_loc><video:duration>640</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
<url><loc>https://puzzicle.org/science/electrical-engineering/v/ee-visualize-fourier-series-square-wave</loc><video:video><video:thumbnail_loc>https://puzzicle.org/thumbs/xe5597c6d.jpg</video:thumbnail_loc><video:title>Visualizing the Fourier expansion of a square wave</video:title><video:description>Visualize the Fourier expansion of a square wave. A square wave can be approximated by adding odd harmonics of a sine wave.</video:description><video:content_loc>https://cdn.kastatic.org/ka-youtube-converted/aalANrz7bi8.mp4/aalANrz7bi8.mp4</video:content_loc><video:duration>210</video:duration><video:family_friendly>yes</video:family_friendly></video:video></url>
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