Lesson video

Hello, everyone, my name is Miss Sabzvari and I'm really excited that you decided to join me today for our math lesson.

The unit we're studying is multiplication and division.

In the previous lesson, we identified multiplication as commutative.

In this lesson, we will focus on using the division symbol when sharing.

So when you're ready, let's begin.

So let's have a look at today's lesson agenda.

First, we're going to begin by looking at division as sharing.

Next, we're going to move onto a talk task where you will have more opportunities to see some word problems, which involves division as sharing.

Then we will look at whether division is commutative, and finally, you will complete your independent task.

But before we begin, you will need the following items. You will need something to write with and something to write on, and you will need some counters or cubes.

Alternatively, you can ask your parents or carer to cut out some small pieces of paper that you can use instead.

So pause the video now to get the things that you need.

Division as sharing.

So let's have a look at the word problem on our screen.

Follow with me.

There are 18 children altogether.

There are two rows on the carpet.

How many children will be in each row? What I would like you to do is to pause the video and tell me what is known and what is unknown.

Great work.

What we know is we know the whole, we know that there are 18 children altogether.

And what we know is how many parts there are.

There are two rows on the carpet, so two rows, I know that I know how many parts or how many groups there are.

What I don't know is how many children will be in each group.

Okay, what I have done is I have created this part whole model to show you the difference between when we are multiplying and when you're dividing by sharing.

So let's read it together.

When we multiply, we know how many parts there are and the value of each part but we don't know is the whole, how many there are altogether.

So we know that there are, for example here, we know that there are two parts.

And we know how many parts there are.

So for instance, I know here I've got two parts and in each part, let's say that I have three dots, or three people, okay? So three multiplied by two, because there are two parts, is equal to six, okay? So I didn't know my whole, I worked it out.

Now like our problem now, what we need to do is we know that we're dividing by sharing because we know the value of the whole, we know how many children there are altogether.

How many? Good job, 18.

And we know how many parts there are.

So we know how many groups or how many rows we want to place our children in but what we don't know is the value of each part.

What we don't know is how many children are going to be in each row, okay? So we know our whole, which is 18.

And what we're trying to work out is how many children will be in each row.

So what I would like you to do now is to pause the video here and try and work out, using your counters, how many children are going to be in each row.

Try and write down the division equation as well.

Great work.

I know that there are 18 children altogether.

Therefore, I have chosen 18 counters to represent the 18 children.

Now there are two rows on the carpet and I want to work out how many children will be in each row.

Therefore, I'm going to add a counter for each row.

And then I'm going to carry on adding a counter to each row one at a time.

What I'm not going to do is add all of my counters to one row and then add all of my counters to other.

If we're sharing, I'm going to give one row a counter and I'm going to give my second row a counter as well.

Okay? And I keep going until I run out of all of my 18 counters.

Now what I need to remember is that teach group needs to be of an equal size.

So whatever I add to one group, I need to add to the other group.

They need to be equal.

Okay? And I will make sure that they're all aligned and they're all straight and here, I can see that one, two, three, four, five, six, seven, eight, nine.

So I know that 18 divided by two or shared into two equal groups is nine.

As I just modelled, when we are sharing, we need to place each counter in each group, okay? Until we run out of the counters that we have.

And if I wanted to draw or to show my representation pictorially, so if I wanted to draw my arrays, I would add a counter to each group, okay? Until I run out of counters.

And here, I know that 18 is my whole, 18 shared or divided into two equal groups is equal to nine, okay? So nine children will be in each row.

Great job if you've got that correct.

So let's have a look at another question.

Follow with me, there are 15 children altogether.

There are five rows on the carpet.

How many children will be in each row? I would like you to pause the video to represent the question using your arrays and then I would like you to draw your arrays and finally, to write down your division equation.

Great.

I know that there are 15 children altogether.

So I'm going to choose my 15 counters to represent 15 children.

And there are five rows on the carpet so I know that I'm sharing my 15 counters into five equal groups.

So I'm going to add a counter to represent each row, so I know that there are five of them, so four, five.

And I'm going to now give a counter to each group until I run out of counters.

Okay.

So making sure that we share or we add a counter to each group as we are going along.

Okay? So one, two, three, four, five, five groups, and I have shared my counters between five equal groups because there are one, two, three in each group.

As I just modelled, each time, we are going to add our counter to each group until we run out of counters.

So we will select 15 because we know there are 15 children altogether.

And then I will add a counter to each group until I run out.

And that's when I know that in each group there are three children, or three counters.

So 15 divided by, or shared into, five equal groups, one, two, three, four, five, is going to equal to three.

Our quick check question.

So very quickly, you're going to point to true or point to false if you think that the statement is true or if the statement is false.

When we are dividing by sharing, we know the value of the whole.

Is this statement true or false? In three, two, one, point.

That's right, it's true.

When we're dividing by sharing, we know the value of whole.

We know the total that we're beginning with and we're going to share it into equal groups.

Now, moving onto your independent task.

There are 18 children altogether.

What is a sensible number of rows for 18 children? And I would like you to answer this question and I would like you to represent your rows using arrays and division equations, okay? And remember that the rows should be of equal size.

That means an equal number of children in each row.

So I would like you to represent them using your arrays, then to draw your arrays on your piece of paper, and finally to write down your equations.

So come up with as many sensible number of rows for 18 children as you can.

And once you're finished, we will go over the answers together.

Great, so let's have a look at your answers.

So we know that there were 18 children and we knew that if we divided by two groups, we will have nine in each row.

And alternatively, if we divided 18 by nine, we would have by nine, would have two in each group.

Okay? Now, can I, instead of writing 18 divided by nine, is it possible for me to divide nine by 18? Is that possible? Can I do that? Is division commutative? Does it matter which way I write these two numbers? Share your answer with the screen.

That's right, division is not commutative.

It is not like multiplication.

We cannot write the numbers in the opposite way, okay? The whole is always has to, our equation always has to start with the whole, okay? And now, another way that we could divide our 18 children would be in groups of three.

And that means that if we divide 18, divide it by three, that would equal to six, and if we divide 18 by six, that would equal to three.

So these are all the possible ways that you could have divided your children into sensible groups.

And depending on the size of your room, of course you would choose which one you think is the most sensible, okay? Great work, well done, everyone.

You have done so well this lesson.

Today, we've learnt how to divide when it's sharing.

So if you would like to, please ask your parents or carer to share your work on Twitter, tagging @OakNational and LearningWithOak.

And don't forget, it's now time for you to complete your end of lesson quiz.

I hope you've enjoyed today's lesson.

Next lesson, we will look at using the division symbol when grouping.

See you then.