# Lesson video

In progress...

Hi, my name is Mrs. Behan.

And today I'm going to teach you how to divide by 10 looking carefully at place value.

You might already think that you can do this but we are going to be paying special attention to what happens to the digits as we divide by 10 and seeing if we can find the secrets of the lesson.

We're going to start off with a game.

We've got some activities and then you can have a go at testing out your new learning in one of the activities I have planned.

Are you ready to begin? Let's go then.

Let's check out our lesson agenda.

Our ultimate goal of this lesson is to be able to divide multiples of 10 by 10.

We'll use our understanding of place value, something you will be very good at if you've made it to this lesson.

We're going to play a game to begin with.

I'm going to show you some examples to help you find the secrets of this lesson.

Then we will complete a practise activity together and after that you will be ready to do an independent task.

I know you will be keen to know how you got on so I will make sure I go through the answers with you.

For this lesson you will just need two things, something to write with, a pen or a pencil and something to write on.

If you haven't got those things handy, pause the video whilst you go and get them.

Try to work in a quiet place where you won't be disturbed.

The game we're going to play at the start of our lesson is called the "ladder game".

This is a game that you'll be able to play with some of your family members once I've shown you how to do it.

If you're playing at home then you will need to have a dice as well.

But to join in for today, I've already got a dice so we're good to go.

The first thing that you need to do is draw a ladder like the one I'm about to show you.

You should have around seven spaces.

Don't worry if you have more but the game could take you slightly longer.

The aim of the game is to fill the ladder with two digit numbers.

Now we're going to roll the dice twice.

The largest number that we could get with two rolls of the dice would be 66.

So I would like you to write the number 66 at the top of your ladder.

The smallest number we could make would be 11 because we could roll two ones.

Here's an example of the onscreen dice.

This dice could show four tens and this one could show three ones which would make the number 43.

Now, we can choose for the dice to represent the opposite.

So we could have three tens and four ones giving us the number 34.

We should not say the blue die shows four and the green die shows three if we've decided that the blue dice is tens, it would show 40.

So once you've decided on your number, we put it in the ladder.

The aim is to fill all the spaces on the ladder before I do.

If you can't use a number, you should write it next to the ladder.

Remember the largest number is 66.

The smallest number is 11.

So you'll have to make decisions on where to put the numbers on your ladder.

Let's have a go.

Here is an example of what to do if you are unsure.

As the dice changed, that's when I decided which numbers to put in.

So when I wrote in 43, I could have written 34 but I decided to keep it as 43 and put it where I did on the ladder.

Okay, we are ready to make a start.

You will see the dice change.

If you think it's going too quickly, just pause the video each time you see the dice spots changed.

It will give you more time to make your decisions.

Remember the blue dice can represent either the tens or ones and your aim is to fill the ladder.

Are you ready? I'll roll the dice.

Did you manage to fill the ladder? Well, I've shown you how I got on and then you can see if you managed to get more numbers on the ladder than I did.

As you can see, I didn't manage to fill the ladder.

What decisions did you make? If you could have played again what might you have done differently? A quick warm-up game helps us get into the right frame of mind for today's lesson.

We're going to be able to divide quickly by 10 once we found the secret.

Here is a place value chart.

Now is a reminder when we multiply by 10, we move all of the digits one place to the left.

The ones become 10 times greater, so they become tens.

The tens become 10 times greater so they become one hundreds.

In this example, we can see that 23 multiplied by 10 is equal to 230.

Follow what I do on the next couple of slides to see if you can work out the secrets to dividing by 10.

Let's be really clear on two words we will need to use correctly.

Multiply and divide.

Why do you think multiply shows up larger on your screen? Well, I've done this as a reminder that when we multiply a whole number by another whole number, the product is a larger whole.

Two multiplied by three is equal to six.

The product is six.

Divide is showing smaller on your screen because when we divide a whole number by another whole number, the quotient is a smaller whole number.

Six divided by three is equal to two.

The quotient is two.

We're now I'm going to look at two characters, Zara and Michael.

They've been comparing the number of pencils they've had and they've noticed something.

Let's take a look.

Michael has 10 pencils.

He has 10 times as many as Zara.

How many pencils does Zara have? can you tell me? Good.

The picture really helps us here too.

We can see that Zara has just one pencil.

One multiplied by 10 is equal to 10.

10 divided by 10 is equal to one.

Say this sentence with me.

10 is 10 times the size of one.

Zara has one pencil.

Michael and Zara have disappeared now but remember that these pencil pictures represent Zara's pencils and these pencil pictures represent Michael's pencils.

Michael has 20 pencils.

He has 10 times as many as Zara.

How many pencils does Zara have? We know that 2 multiplied by 10 is equal to 20.

We know that 20 divided by 10 is equal to two.

Together, we can say 20 is 10 times the size of two.

Zara has two pencils.

Michael has 30 pencils.

He has 10 times as many as Zara.

How many pencils does Zara have? Three multiplied by 10 is equal to 30.

30 divided by 10 is equal to three.

So together we can say 30 is 10 times the size of three.

Zara has three pencils.

We're going to stop here for a quick pause.

Now, I love a "spot the difference" game.

Have you ever played one? It's where you have to compare two pictures and try and find the very, very tiny differences between them.

So I've come up with something fairly similar.

On the screen you are going to see two options.

And you're going to see if you can spot the difference.

The difference is actually a mistake.

So pause the video, have a look through, when you've spotted it, come back to me.

Here is option one.

Here is option to two.

Pause first you have a think.

Did you find the mistake? The mistake was actually in the statements at the bottom of the options.

Four is 10 times the size of forty.

Is that right? Four is 10 times the size of 40.

No, that's not right at all.

Option two is correct.

Everything makes sense here.

40 is 10 times the size of four.

That makes sense With four multiplied by 10 is equal to 40 and 40 divided by 10 is equal to four.

Well done if you've got that right.

This chart is called a chart and it helps us to see the relationships between numbers.

Each level multiplies the number by 10 as you work up the way.

It also means that each level divides the number by 10 as you work down the way.

Let's see how it works with the calculation.

One multiplied by 10 is equal to 10.

You can see the sentence I've used at the top.

10 divided by 10 is equal to one.

You can use the sentences at the top of the screen to say what you see out loud with me.

Two multiplied by 10 is equal to 20.

20 divided by 10 is equal to two.

Three multiply by 10 is equal to 30.

30 divided by 10 is equal to three.

Four multiplied by 10 is equal 40.

40 divided by 10 is equal to four.

I'm sure you're getting the hang of this now.

Five multiplied by 10 is equal to 50.

And 50 divided by 10 is equal to five.

Six multiplied by 10 is equal to 60.

60 divided by 10 is equal to six.

Seven multiplied by 10 is equal to 70.

70 divided by 10 is equal to seven.

Eight multiplied by 10 is equal to eight 80.

80 divided by 10 is equal to eight.

Nine multiplied by 10 is equal to 90.

90 divided by 10 is equal to nine.

So we've worked our way along the chart.

Can you see any connections between the two rows and the calculations? You might've noticed that all of the numbers in the tens row are multiples of 10.

You will also have noticed that all of the dividends in the division calculation are multiples of ten too.

We're going to have another look at the calculation 90 divided by 10.

If we were to multiply by 10, our digits would move one place to the left.

But if we divide by 10, which direction would our digits move? That's right, they would move one place to the right.

Now, it's important that we keep our digits together.

Here we have moved them ground ready to divide and we're going to move from one place to the right.

You'll see that the zero has fallen off our place value chart.

And that's fine because our nine tens have become nine ones.

I'm going to stay quiet now as you follow what happens to number 50 when it gets divided by 10.

Our zero has fallen off.

Our five tens has become five ones.

So, have we worked out the secrets of the lesson? Here it is onscreen, you can say it with me.

To divide a multiple of 10 by 10, remove the zero from the ones place.

Let's say that again.

To divide a multiple of 10 by 10, remove the zero from the ones place.

Before I set you off on your independent task, let's just make sure we are really clear on how we see dividing multiples of 10 by 10.

I have 40, this is four tens.

How much will I have if I divide by 10? We had four tens, now we have four ones.

Four tens divided by 10 is equal to four ones.

So 40 divided by 10 is equal to four.

Does the same apply when dividing a three digit multiple of 10 by 10? I have 130, this is 100 and three tens.

How much will I have if I divide by 10? That's right.

I will have one 10 and three ones, which is 13.

I'd like you to find the missing numbers to the calculations that you can see on your screen.

When you're finished, come back to me and we will go through the answers together.

Harry has 10 times as many toy cars as Joseph.

Harry has 90 cars.

How many cars does Joseph have? Jake has 10 times as many beads as Jessica.

How many beads does Jake have? What else do you know if you know that three multiplied by 10 is equal to 30? Pause the video to complete your task.

Once you've finished, come back to me.

Let's review the answers and see how you got on.

20 divided by 10 is equal to two.

200 divided by 10 is equal to 20.

220 divided by 10 is equal to 22.

40 is equal to 400 divided by 10.

40 divided by 10 is equal to four.

440 divided by 10 is equal to 44.

300 divided by 10 is equal to 30.

30 divided by 10 is equal to three.

33 is equal to 330 divided by 10.

Harry has 10 times as many toy cars as Joseph.

Harry has 90 cars.

How many cars does Joseph have? Well, 90 divided by 10 is equal to nine.

So Joseph has nine cars.

Jake has 10 times as many beads as Jessica.

How many beads does Jake have? On this question we have to multiply by 10.

There is a special relationship between multiplication and division.

What are the facts did you come up with if you know that three multiplied by 10 is equal to 30? These are just some of the possibilities you could have had.

30 divided by 10 is equal to three.

We've moved to three, one place to the right which now gives us three ones instead of three tens.

300 divided by 10 is equal to 30.

We've moved the digits in 300, one place to the right, which now shows us 30.

You also know that 10 multiplied by three is equal to 30 because if you change the order of the factors, the product will still remain the same.

3000 divided by 10 is equal to 300.

That's a bit of a challenge but maybe you manage that one.