About this video
This video shows how to read a line plot where some lengths are fractions, using the lengths of caterpillars. Each dot stands for one caterpillar, and fractional lengths like 4 1/2 and 5 1/4 are found by splitting the space between whole numbers into equal parts. The video then uses the plot to answer counting and comparing questions.
You'll be able to
- explain that each dot on a line plot stands for one measurement.
- find fractional lengths like 4 1/2 and 5 1/4 on a line plot.
- use a line plot to count how many data points match, or are more than, a given value.
- compare how many more data points are at one value than another.
Key words
- line plot
- A number line with dots (or Xs) above it, where each dot shows one piece of data.
- data
- Information we collect, like the lengths of caterpillars we measured.
- equal sections
- Parts of the same size; splitting the space between two whole numbers into equal sections lets us find fractions like 1/2 or 1/4.
- centimeter
- A small unit for measuring length; the caterpillars' lengths are in centimeters.
Transcript
- [Instructor] What we're going to do in this video is review what we know about line plots, but apply them in a situation where some of our data involves fractions. So they tell us the lengths of some caterpillars are shown below, and so we can see that here in the line plot, just to refresh our minds how to read a line plot, this tells us that we have two caterpillars that are four centimeters long.
These three show that we have three caterpillars that are seven centimeters long. Each dot represents a caterpillar whose length we are measuring. It allows us to see how those lengths are distributed. For example, we have a lot of caterpillars at this length.
What is that length? Well we can see that is exactly half way between four and five, so that is four and one half centimeters long. We divide the section between four and five into two equal sections, and we're going one of those two equal sections towards five, so this is four and a half centimeters.
I can ask you some questions. How many total caterpillars were measured? Pause this video and think about that. Well each dot represents a caterpillar measurement, and we have one, two, three, four, five, six, seven, eight, nine, 10, 11, 12, 13, 14, 15, 16, 17.
So we have a total of 17 caterpillars. Now another question we could ask ourselves is how many of the caterpillars are five and one fourth centimeters long? Pause the video and think about that. Well five and one fourth is going to be more than five, and what we'd want to do to get to five and one fourth is divide the interval or the length between five and six into four equal sections, they already did that, one, two, three, four, and then we want to go one of those four equal sections.
So five and one fourth is right over here and we can see that there's one caterpillar that is five and one fourth centimeters long. We can ask ourselves other questions. How many caterpillars, let me write it over here, how many have length more than six and one half centimeters?
Pause the video and try to answer that. Where is six and a half centimeters? Well, we can divide the section between six and seven into two equal sections, and if you go one of those two equal sections, that is six and a half, so that is six and a half right over there.
How many have a length more than or greater than six and a half centimeters? Well we can see it right over here. One, two, three, four, five, six. Six of them do. And we can even try to answer questions like how many more have a length of nine and a half centimeters than five and one fourth centimeters?
Try to answer that question. Well nine and a half centimeters, that's half way between nine and 10, right over there. We can see two of them have a length of nine and a half centimeters. And we already know that one of them has a length of five and one fourth, so how many more have nine and a half centimeters versus five and one fourth?
Well that would be two minus one, or one more. We have one more caterpillar with a length of nine and a half centimeters than we do with five and one fourth. I'll leave you there. We have plenty of examples on Khan Academy for you to practice this.
Video © Khan Academy, used under CC BY-NC-SA. Watch on Khan Academy. Puzzicle is not affiliated with Khan Academy.