Lesson video

Hello, my name is Mr Whitehead.

What's your name? Well, it's very nice to meet you and you are very welcome to join me for the next 20 minutes in a maths lesson.

Before we can start, though, I need to know that I have your full attention.

So you may need to move away into a quieter space so that you are distraction free, and you are able to focus on your learning for the next 20 minutes.

Press pause take yourself into a quiet space and then press play again when you're ready for your learning.

In this lesson, we are converting between centimetres and metres.

We'll start the lesson off with a bit of conversion between centimetres and millimetres.

Before we spend some time exploring metres and centimetres, then connecting metres and centimetres leaving you ready for the independent task.

Things you're going to need a pen or pencil and some paper to work on and importantly a ruler if you have one.

press pause, go and collect the items and come back and we will start, right.

Let's begin.

I would like you to convert between centimetres and millimetres.

Take a look at the measurements I've given you and look at how you need to convert them from millimetres to centimetres or centimetres to millimetres.

It might be helpful to remind yourself that when we convert from millimetres a smaller unit, to centimetres a bigger unit, we divide by 10.

And when we convert from the bigger centimetre unit to the smaller millimetre unit, we multiply by 10.

Multiplying by 10 we make the number 10 times bigger dividing by 10 we make the number 10 times smaller.

Press pause, complete the task then come back and we'll look at the solutions.

Are you ready to take a look? First one, three centimetres and two millimetres.

What did you get? 3.

2 centimetres, good start.

How about the next one, converting from myth centimetres to millimetres.

So we're multiplying by 10.

How many millimetres is the same as 4.

1 centimetres good, 41.

Eight millimetres becomes how many centimetres? 80 see not super, not 80.

Why not? I'm converting from a small unit to a bigger unit.

So I need to multiply by 10 I need make the number 10 times smaller I needs to divide by 10.

So that's it, good.

Next one I want to record it as centimetres and millimetres.

Tell me what you got, good.

Five centimetres and four millimetres.

Finally multiply by 10, 29 millimetres.

Hold up anything that you had written down there Let me have a look.

Good, good, good, good, good.

Maybe some that you didn't get right the first time, but you've learned from you've spotted where you're thinking perhaps you went wrong and what you would do differently next time and that is learning too so I'm really pleased to see that.

Okay, let's start exploring metres and centimetres.

Before we start, do you have a 30 centimetre ruler handy? Good hold out.

Do You know, how many of these 30 centimetre rulers you would need? If I asked you to make one metre, you probably haven't got a metre stick handy, but if you do know how many of these it would take, you could make one.

It's what I was doing just before the lesson started.

How many how many of this ruler do you think it will take? Just over three 30, 60, 90, three and a third because I want another 10 centimetres three and a third.

So I used that with some scrap paper.

Can I fit it in just about, and I've stuck together three and a bit pieces of paper to make what a metre stick would look like.

So I've gone from one of these 30 centimetres to one of these 100 centimetres a metre stick.

Look at the screen.

That was my 30 centimetre ruler and I said I needed 60, 90, just over three of them to make my metre stick.

And this now represents one metre.

One metre that's divided into equal parts notice that where the decimal numbers are recorded 0.

1, 0.

2.

Those divisions there are 10 of them one metre divided into 10 equal parts, each equal part worth one 10th, worth 10 hundredths.

The smallest lines of which there are so many, how many of them do you think there are? There are 100, a metre divided into 100 equal parts, each equal part represents 100th.

we'll use those fraction connections to help us now.

How long is 100 centimetres? we've been talking about it? 100 centimetres is one metre.

They are equivalent one metre 100 centimetres 100 hundred hundredths is equal to one, one metre, 100 hundred hundredths or 10 tenths.

Next question.

How long is 50 centimetres? Wherever on the number line on the screen.

Wherever on that metre stick on the screen or where on my paper metre stick would 50 centimetres be, tell me, good it would be half way it would be at 50 centimetres, five tenths.

How many hundredths? 50 hundredths, 0.

5 of the metre Stick.

Next one.

How long is 10 centimetres? Hold your finger on the screen to show me where 10 centimetres would be.

Are you ready? Let's see if my arrow is in the same place, good.

10 centimetres, one 10th of the metre stick, 10 hundredths of the metre stick.

They're all equivalent.

What do we know about one centimetre now, show me on the screen with your finger.

Where would one centimetre be? that good.

How many hundredths along the number line is one centimetre? Good, 100th 0.

01, 100th of a metre is one centimetre, one centimetre and 0.

01 metre are equivalent.

Next.

How long is five centimetres? Show me on the screen.

Well done five centimetres.

How do we say that? Yeah, we could say it as five centimetres.

How else? Good, 0.

05 metres.

How is a fraction? Very good, five hundredths of a metre.

Last one.

How long is 15 centimetres? I wonder if you can tell me as a decimal and a fraction and touch on the screen where it would be along the line.

Good, and as a decimal, 0.

15 metre and as a fraction, 15 hundredths really good.

Now let's start to converting from metres to centimetres.

So we know that 0.

1 metre is equal to 10 centimetres, 0.

1, one 10th, 10 hundredths 10 centimetres.

So 0.

2, what would that be in centimetres? I wonder if you'd like to press pause and complete these missing numbers come back and we'll check.

Are you ready to check? Go on then tell me for the first one.

How many centimetres? 20 centimetres, 20 hundredths.

The next one.

Good, 25 centimetres 25 hundredths.

So also one quarter because we know 0.

25 is equal to one quarter is equal to 25 hundredths.

Next one, good 45 centimetres.

How many hundredths? 45 hundredths of a metre and the last one 83 centimetres, 83 hundredths.

Well done for joining in with the fractions as well.

Let's take a look at what we have found.

Have a look and see what you notice look how the metres converted to centimetres and the centimetres converted to metres.

Do you spot any patterns? Can you explain or describe the patterns to me? What have you noticed numbers getting bigger and numbers getting smaller.

How much bigger are the numbers getting from metres to centimetres? 100 times bigger, one multiplied by 100 is 100, one 10th multiplied by 100 is 10.

100th multiplied by 100 is one.

So when we convert from metres centimetres, numbers get 100 times bigger.

What about from centimetres to metres, 100 times smaller, 100 to one, 10 to one 10th, one to 100th.

How do we make numbers 100 times smaller? We divide by 100.

So when we convert from metres to centimetres from a bigger unit to a smaller unit, we multiply by 100, and when we convert from a smaller unit centimetres to a bigger unit metres, we divide by 100.

Keep those in mind.

Maybe copy them down onto a piece of paper it might be helpful with the next activity.

Copy them down quickly.

Just the the metres multiply by 100 and centimetres and centimetres divided by 100 metres.

Copy that down I'll give you 10 seconds.

Five, four, three, two, one, moving on.

Order these measurements from shortest to largest.

Helpful hint, write each measurement in centimetres and metres, press pause, have a go at ordering them use the helpful hint then come back and we'll have a look.

Let's check who used the helpful hints give me a wave if you did, good to hear I hope it helped you.

I'm going to use the helpful hint first.

So I'm going to make sure that anything in metres is converted to centimetres as well, here we go and there, good.

And anything in centimetres is converted to metres as well by dividing by 100.

Now we can order them by just looking at the values as centimetres or as metres, which is the smallest.

Say it again, good.

Two centimetres, two hundredths of a metre, which is next, good next well done.

28 hundredths of a metre is bigger than three hundredths of a metre, but it's not the largest because it's smaller than which one's next.

Yes, it's smaller than 30 hundredths of a metre only two hundredths difference though.

Next good and well done.

As the largest three metres as the largest 300 centimetres compared to the smallest of only two centimetres.

Well done, everyone let's move our learning on.

I would like you to represent an amount that's in metres and centimetres as just metres or just centimetres.

So for example, two metres 73 centimetres, two metres in centimetres, I would multiply by 100, 200 centimetres, 73 centimetres as metres, I would divide by 100, 0.

73 metres.

Can I now find how many can I now find, sorry, the amount in just metres or the amount in just centimetres? Yes, metres, two metres and 0.

73 metres.

What would that be? 2.

73 metres, centimetres 273, 273 centimetres.

And you could see the connection look from metres to centimetres 2.

73 multiplied by 100 is 273 centimetres.

Next one, four metre and five centimetres just in metres or just in centimetres.

Pause, have a go, come back and we'll check.

Shall we look for me? Four metres in centimetres multiplied by 100 400 centimetres, five centimetres in metres, five hundredths of a metre 0.

05.

So the metres four and 0.

05, 4.

05 metres centimetres 405 405 centimetres.

One more pause again if you want to come back and we'll look ready to check.

So tell me what would one metre become in centimetres and 40 centimetres in metres? Good it would be four tenths of a metre, 40 hundredths of a metre.

So in metre, our value is 1.

4 and then centimetres 140 really good.

I think you're ready for your independent task.

I've got some values that are filled in and some that are missing your job is to fill in the missing values.

So use for example, 311 centimetres use that and tell me what it would be in metres.

tell me what two would be in metres and centimetres, press pause, go and complete the task then come back and we'll share the solutions.

Are you ready to take a look? First of all, hold up your paper Let me see how you got on.

Keep it still when it's waving I can't read it properly.

Keep it still good, good, good, fantastic.

I can see the same value represented in different ways.

Really good, let's have a look.

three metres and 11 centimetres, 3.

11 metres.

Next one, zero metres, but 15 centimetres.

It's 15 hundredths of a metre.

Next one, good, I wonder if anyone put 1.

5 metres, why would 1.

5 metres be wrong? Because five centimetres is five hundredths of a metre.

If you had 1.

5, you're saying five tenths, 50 hundredths, you're saying one metre 50 centimetres, bottom one.

Well done, Pardon? Which one? The bottom, seven metres and nine centimetres, 7.

9 multiply by that certainly been multiplied by, by 10.

It needs to be multiplied by 100.

So the answer should be 790 centimetres really good spots well done.

If you would like to share any of your learning from this session, please ask your parents or care to share your work on Twitter, tagging @OakNational and hashtag LearnwithOak.

What a fantastic lesson.

Thank you so much for joining me for the last 20 minutes.

You have all done so well, really thinking deeply about the maths that we've covered, and I've really enjoyed all of your participation and taking part in the activities too.

If you got any more learning lined up for the day, perhaps take a bit of a break before you start it and I hope that you enjoy it, whatever it is.

I look forward to seeing you again soon for some more maths learning.

Bye.