Video: Dividing into Equal Groups

In this video, we will learn how to divide a number of objects into equal groups.

12:16

Video Transcript

Dividing into Equal Groups

In this video, we’re going to learn how to divide a number of objects into equal groups. Now, what do we mean when we say equal groups? We mean groups that are the same size or groups that have the same amount. Here are three polar bears and a pile of 12 fresh fish. Now, let’s imagine that they want to share or divide these fish out between them. What if they split up the fish like this? Is it fair? No, it’s not, is it? One bear has more fish than the others. The groups of fish are not equal. They don’t contain the same amount.

One way that we can make sure that we divide a number of objects into equal groups is to add the objects into groups one at a time. Maybe you’ve divided some sweets this way in the past: one for you, one for me, one for you, and so on. Let’s try dividing our 12 fish this way. We’ll begin by adding one fish to each polar-bears group. Now, they all have one fish. Now, let’s add another fish: one for the first bear, one for the second bear, and one for the third bear. And we can keep splitting up the fish like this until there are no fish left. Can you see? Now, each bear has the same amount of fish. The groups are equal. We had 12 fish, and we divided them into three equal groups. There are four fish in each group. So our polar bears are finally happy.

But what about the fish? Now, let’s imagine that underneath the ice there are 12 fish swimming around. But they don’t much want to be caught by a polar bear. And at the moment, they’re in one big group. So they decide to split themselves into groups of two to stay safe. How many groups of two will there be?

We could draw rings around them. Here’s one group of two, and another, one more. Can you see that each of these groups are the same size? They’re all equal. We have divided 12 fish into equal groups of two. There are one, two, three, four, five, six groups altogether.

Shall we put into practice what we’ve learned now? Let’s try answering some questions where we have to divide an amount into equal groups.

16 cookies are divided into groups of what. There are what groups.

This question is about something that happens in cookie factories all over the world every day, because we have an amount of cookies that’s been divided into packets. We could call these packets groups really. And they look like they’re equal groups, don’t they? Equal groups are groups of the same size. And when we’re talking about packets of cookies, what we mean by equal groups is that you’re going to buy a packet from the shop and it’s going to contain the same number of cookies as your friend. Nobody is going to be disappointed.

In the first sentence, we’re told that we start off with 16 cookies. It tells us 16 cookies are divided or split up or shared out. We could use 16 counters to represent our 16 cookies. Now, in our first sentence, we’re told that the 16 cookies are divided into groups of what. Let’s get cookie counting.

In the first packet or group, we can see one, two, three, four, five, six, seven, eight. Now, for our two packets to be equal, we’d expect to see eight cookies in the second group too. And we can count one, two, three, four, five, six, seven, eight. Just like we thought, our groups are the same size. Let’s split up our counters in the same way. So if we split up 16 cookies into groups of eight, how many groups will there be?

Our second sentence says there are what groups. We split our counters into one, two groups of eight. And we know that from the top picture, don’t we? Because the cookies have been divided into two packets or two groups. 16 cookies are divided into groups of eight. There are two groups.

Look at the picture, and then answer the questions. 15 books are divided into what equal groups. There are what books in each group.

This question starts off by telling us to look at the picture. So, do you think we better do that? What can you see? We can see some piles of books, can’t we? There are one, two, three piles. What else can we tell? How many books are there altogether? Let’s count them. There are one, two, three, four, five, six, seven, eight, nine, 10, 11, 12, 13, 14, 15 books altogether. Can you see the number 15 in our first sentence? We are told that 15 books are divided into equal groups.

We’ll talk about the equal groups in a moment. But to begin with, we need to find out how many equal groups there are. Well, each group is a different pile, isn’t it? As we’ve said already, there are three piles of books. Our 15 books have been divided or split up into three equal groups. What do we mean when we say that some groups are equal? They’re groups of the same size. So our 15 books have been split up into three groups of the same size.

Can you imagine three children going to the library and coming out with the same number of books each? Now, some of these books are thicker than others, aren’t they? So maybe these piles don’t look the same size. But in our final sentence, this is what we need to find out. There are what books in each group.

Let’s count them. In the first group, there are one, two, three, four, five books in the first group. Now, if our groups are the same size, we’d expect to see five books in the other two groups too. Well, we can see five books in the second pile and five books in the third group. If we split 15 objects into three equal groups, there will be five objects in each group. We know this because in the picture 15 books are divided into three equal groups. And there are five books in each group.

How many groups of three apples are there?

In this question, we’re shown an amount of apples and we need to split it up or divide it into equal groups. And we know that it needs to be split up into equal groups because we need to find out how many groups of three apples are there. All of the groups we make need to have three apples in them.

Now, if we look at the way that the apples have been arranged, we can’t see any rows of three, can we? There aren’t really any groups of three that jump out at us, which makes it quick to answer the question. So how are we going to count our groups of three then? What if we circle them?

We can see one, two, three, four. Can you see what we’re doing here? We’re circling three apples every time. We’re making equal groups. Five, six, seven, eight. We’ve divided this amount of apples into equal groups with three apples in each group. There are eight groups altogether.

David has 36 balls. He wants to divide them into groups of 12. How many groups will he make?

In this question, we are told that David has 36 balls. And we can see them in the picture, can’t we? Here are David’s 36 balls. Now, we’re told that David wants to divide these balls into groups of 12. Now, if each of the groups he makes has got 12 balls in it, we can say that they’re going to be equal. They’re going to be the same size. But how many groups is he going to make?

Let’s use cubes to help us see how many groups of 12 we can make. Our first group needs to have one, two, three, four, five, six, seven, eight, nine, 10, 11, 12. That’s one group of 12 we’ve made. But this is interesting; we’ve used all the blue balls in the first section. Can you see how there’s a group of blue, then a group of green, then another group of blue? It’s almost as if the groups are being shown to us before we start.

But maybe they’re not equal groups of 12. We can’t just look at the colors of these balls. We’re going to have to carry on counting to find the answer. On to the green balls, and we need to make another group of 12. Let’s skip count in twos this time to get there more quickly. Two, four, six, eight, 10, 12. They were 12 green balls. So do you think this last group of blue balls might have 12 in it too? Should we try some even more speedy counting? Let’s skip count in threes this time. Three, six, nine, 12. We didn’t know for sure, but the colors of the balls were giving us a clue all along.

David has 36 balls. And in the picture, we’ve counted 12 blue balls, then 12 green balls, then another 12 blue balls. So when David divides or splits up his 36 balls into equal groups of 12, how many groups is he going to make? We know he’s going to make three equal groups.

What have we learned in this video? We’ve learned how to divide a number of objects into equal groups.

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