Lesson Video: Comparing Groups by Counting up to 20 Mathematics • Kindergarten

Video Transcript

Comparing Groups by Counting Up to 20.

In this video, we’re going to learn how to compare groups of up to 20 objects. We’re going to do this in lots of different ways, including splitting a number up into a group of 10 and some more ones. Do you have a sticker chart at school or maybe home for good work or good behavior? Here’s a reward chart for two children.

Now let’s imagine that each time these children get a star for good behavior or good work, they don’t really worry about where to put it. They just stick it somewhere in the box, next to their face. So can you see? We’ve got two groups of stars here: one green and one blue. Which group contains more stickers?

We need to compare these two groups to find out. One way we could compare the stickers is by lining them up. This is why sometimes on a reward chart, you see little boxes where you have to stick the next star in. It makes things a lot easier to count and compare. Now, if we’re going to do this, we need to make sure that each sticker is level with each other. Can you see how the first green star is level with the first blue star and the second green star is lined up with the second blue star? And because we’ve lined up all of the stickers like this, it makes it much easier to compare them. Which group contains most stickers? And how do we know?

Well, because all of the stickers are the same size and we’ve made sure to line them all up, we can say that the group that has the most stickers is going to be the one that makes the longest line, isn’t it? We don’t even need to count them, do we? We can answer this question just by comparing the lines that we’ve made. The blue stickers make the longest line, don’t they? And so we can say there are more blue stickers than green stickers.

We can even say how many more. We’ve matched up all of the green stars with a blue star. But we can count one, two blue stars left over. There are two more blue stars than green stars.

This is an interesting reward chart, isn’t it? Instead of stickers, every time the children have received a reward, they’ve drawn a smiley face. But this means we can’t peel them off and put them in a line this time to compare them. How could we find out which group is largest this time? Perhaps what we could do is count them. And so that we remember which smiley faces we’ve counted, let’s cross them off as we say each number.

How many rewards has the girl received? We can see one, two, three, four, five, six, seven, eight, nine, 10, 11, 12, 13. Let’s make a note of that number because we might forget it. Do you remember how to write the number 13? It’s a one followed by a three. The girl has 13 rewards. Now let’s count the boy’s rewards. How many smiley faces has he got? One, two, three, four, five, six, seven, eight, nine, 10, 11, 12, 13.

Now we can see we’ve already got to the same number as the girl, and the boy still has one more smiley face to count. So we know that the boy has one more reward, doesn’t he? And one more than 13 is 14. We found out who has more rewards by counting them. The boy has one more reward.

Let’s try one more way of comparing groups. This time, we’ve got a group of pink stickers and a group of orange stickers. We could put them all in a line and match them and see which line is longest. Oh, we’ve already done that. Or we could count both groups and see which group is the larger number. But we’ve already done that too. Let’s try using some ten frames. We could arrange our stickers so that they fit in ten frames, just like we’d use counters, first the pink stars and then the orange.

Now it’s become a little bit easier to see which group is larger. To begin with, can you see that both groups of stickers have filled up one ten frame completely? And we know that a ten frame holds 10. That’s why it’s called a ten frame and not an eight frame or a nine frame. So both groups are the same so far. They’ve got one full ten frame. But both groups show some more ones.

Now, because both the ten frames are exactly the same, should we just look at the ones and compare those? That might be quicker, mightn’t it? So with the pink stickers, we have a group of 10 and then one, two, three, four, five, six, seven, eight more ones. The orange stars also have a group of 10, but they have one, two, three, four, five more ones. Now, which is larger, eight more ones or five more ones? We know that eight is larger than five, don’t we? So we can say that the group of pink stars is greater than the group of orange stars.

Now, we can say this another way if we start by thinking about our orange stars first. There are fewer orange stars than pink stars. We could even say how many fewer. So that our two lots of ten frames look exactly the same, we would need to show another one, two, three more orange stars, five, six, seven, eight. So let’s put a number into that last sentence. There are three fewer orange stars than pink stars.

Let’s try answering some questions now where we have to compare groups of objects. And perhaps we’ll try some of these different ways we’ve looked at.

Who has fewer stamps, Mason Or Madison?

Looks like both these children have been collecting stamps, doesn’t it? Because we can see two groups. Mason has been collecting blue stamps, and Madison has a collection of purple stamps. And our question asks us, who has fewer stamps? In other words, which group is smaller, Mason’s group or Madison’s group?

Now, there are some things the same about these groups of stamps. Can you spot what they are? Firstly, we can see that all the stamps are the same size. This might help us compare the groups. And there’s also something interesting about the way these stamps have been arranged. We can see a longer line of stamps and then a shorter one in both groups. We can also see that the stamps in the groups have been lined up.

Let’s just count how many stamps there are in the first long line. One, two, three, four. Can you see how all these stamps are lined up with each other? Makes it a lot easier to compare them, doesn’t it? Five, six, seven, eight, nine, 10. Did you guess that each group had a row of 10 on the top? So we can see a row of 10 but then some more. How many more blue stamps are there? There are one, two more than 10. And how many more purple stamps? One, two. This is now the same as the blue stamps, isn’t it? But look, we’ve got some more to count. Three, four, five, six more than 10. I think we know who has fewer stamps, don’t we?

Both groups of stamps show a row of 10 and then some more. Mason has two more than 10, but Madison has six more than 10. So we can see there are less blue stamps than purple stamps. The person who has fewer stamps is Mason.

Olivia is counting beads on a string. Complete using more than, less than, or equal to. The number of blue beads is what the number of red beads.

This question is all about comparing two groups together. Can you see the two groups of objects that we’re looking at? It’s the beads that are on this string. There are a group of blue beads and a group of red beads. And we need to compare the group of blue beads with the group of red beads because we’re given a sentence to complete: the number of blue beads is what the number of red beads. Is it more than the number of red beads? Is it less than the number of red beads? Or are the two groups the same? Is the number of blue beads equal to the number of red beads?

Perhaps if these were objects in real life, maybe beads or counters, we could compare them by matching them up. But in this question, this is just a picture of the objects. So how can we compare these groups? Let’s count them. How many blue beads can we see? One, two, three, four, five, six, seven, eight, nine, 10, 11, 12. The group of blue beads contains 12 beads. And the group of red beads contains one, two, three, four, five, six, seven, eight, nine, 10, 11, 12. This is interesting. We counted 12 blue beads but also 12 red beads. These groups are exactly the same size.

So are we going to use more than, less than, or equal to to compare our groups? Well, we know that the word “equal” means the “same as.” Both groups contain 12 beads. And so we can say the number of blue beads is equal to the number of red beads. Our missing words are “equal to.”

Use greater than, less than, or equal to to complete the sentence.

This is an interesting sentence because it’s made up of pictures, a word, and a gap. Let’s try and read it. This group of smiley stickers is what this group of smiley stickers. Can you see what we need to do here? We need to compare these two groups. And we’re given some ways to complete this sentence.

Perhaps there are more stickers in the first group, in which case we need to use the words greater than and use this symbol. Or maybe the first group is the smaller group, and we need to say that it’s less than the second group. Or maybe both groups are exactly the same, in which case we need to use the words “equal to.”

Now, just by looking at these two groups without doing anything else, can you have a guess? Do you think the first group is larger, smaller, or do you think they’re both the same? The only way we’re going to find out really is by counting these groups. Let’s try counting them at the same time. As we count each sticker, we can cross them off. One, two, three, four, five, six, seven, eight, nine, 10, 11, 12, 13, 14, 15.

We could stop here, couldn’t we? Because we’ve run out of stickers in the second group. There must be 15 stickers in this group. Do you remember how to write the number 15? It’s a one followed by a five. There are 15 stickers in the second group. But we can see some more stickers in the first group that we haven’t counted yet. We can see now that the first group is bigger. There are two more stickers in the first group than the second group, aren’t there? Should we count on from 15? 15, 16, 17.

We found that the first group is larger than the second group. And so we know which words to complete this sentence with. 17 is greater than 15. The first group is greater than the second group. The words that we need to complete this sentence with are “greater than.”

So what have we learned in this video? We’ve learned how to compare two groups of objects. We’ve used counting. We’ve lined the objects up to compare them. And we’ve also split the objects up into a group of 10 and some more ones.