About this video
Sal looks at shapes cut into parts and picks the ones divided into halves or fourths. Halves means two equal sections, thirds means three equal sections, and fourths (or quarters) means four equal sections. Pieces that are not the same size don't count.
You'll be able to
- tell if a shape is divided into halves.
- tell if a shape is divided into fourths, also called quarters.
- explain why parts must be equal to be halves or fourths.
Key words
- halves
- Two equal sections of a whole shape.
- thirds
- Three equal sections of a whole shape.
- fourths
- Four equal sections of a whole shape.
- quarters
- Another word for fourths.
- equal
- The same size.
Transcript
- [Voiceover] Which picture divides a rectangle in half? So to divide something in half we need to divide it into two equal sections. Over here we're divided into two sections but these aren't equal. These don't have the same area. This part has a much larger area than this one.
So this isn't divided in half. This one's also divided into two sections but they're not equal. This one is much bigger than this one. This is divided into equal sections, but it's not two equal sections. This is divided into three equal sections, so this isn't divided in half.
Here we're divided into two equal sections. One, two sections, and they are the same size, the same area. So I'd pick that one. Let's keep going. This is a lot of fun. Which picture divides a circle into halves? Once again, two equal sections. This one, this one, and this one divide into three sections, and actually these two right over here, the three sections aren't even equal.
Then here, this is three equal sections but that would be thirds not halves. Halves would be two equal sections, so it'll be that, right over there. Which picture divides a square into fourths or sometimes people might say divides a square into quarters. Well fourths or quarters would be four equal sections.
Well this is two equal sections. This is one section, this is just one whole. This is two equal sections, right over here. Or I guess you could say this one actually is just not divided at all. This right over here is two equal sections. This is four equal sections, so this is fourths, or you could say this is divided into quarters.
Let's keep going. Let's do a few more of these. Which picture divides a circle in half? So this circle isn't divided. This is a circle divided into thirds, three equal sections. This is a circle divided into two pieces, but they're not equal, so this isn't divided into halves.
This is two equal sections, right over here, so that one is halves. Let's do one more. Which picture divides a rectangle into halves? Well, it has to be two equal sections. This is three equal sections. This is three not even equal sections. This is three equal sections, so this would be thirds, just as this one would be thirds.
This one over here is two equal sections, so that is halves.
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