Lesson video

Hi there, my name is Miss Darwish and for today's maths lesson we are going to be doing some problem solving activities involving metric units of length.

So, before we get started, if I could just ask you to take yourself to a nice, quiet, cosy, comfortable environment away from any distractions.

Okay.

So for this lesson, first of all, we're just going to recap our metric units of length, and then we're going to move onto some word problems. And then have you get doing some problem solving activities? And then at the end of the session, there will be a quiz for you to complete on today's learning.

So, what you will need for today is a ruler, something to write on and something to write with.

If you want to grab those three things and then come back and we can start the lesson.

Okay.

So we're ready to start? So, converting between metric units of length.

So when converting between millimetres and centimetres, it's important that we remember that there are 10 millimetres in one centimetre, and that there are 100 centimetres in one metre.

And that they're all 1000 metres in one kilometre.

Okay.

So, quickly I'm just going to give you a do-now task to do.

If you want to write these down and then we can check through together.

So how many metres in nine kilometres? How many kilometres in 4,500 metres? How many metres in 750 centimetres? And how many centimetres in 9.

8 metres? I'm just going to give you a few more seconds.

So just write down the conversions and then we can check them together.

Okay, I will give you 15 more seconds.

Okay, five seconds left.

Okay.

Hopefully you've checked over those.

Let's have a look.

So in nine kilometres, there are 9,000 metres.

Remember what Kilo means? Kilo means 1000.

So in nine kilometres there are 9,000 metres.

4,500 metres is the same as saying four and a half kilometres.

750 centimetres is the equivalent to 7.

5 metres, seven and a half metres we can say.

And then 9.

8 metres is like saying 980 centimetres.

So, give them a tick if you got them right.

Okay, let's have a look at some word problems now.

So I've got two boys, Antoni and Xavier, and they compete in the long jump.

Antoni jumped 2.

2 metres.

How long did Antoni jump? 2.

2 metres were jumped.

And Xavier's jump was 13 centimetres shorter than Antoni's jump.

So who jumped longer, Antoni or Xavier? Antoni, because we know that Xavier's jump was shorter than Antoni's by 13 centimetres.

So you can see where this word problems going.

Can't you? How far did Xavier jump is what we want to know, because we know how far Antoni jumped, but we don't know how far Xavier jumped.

But what we do know is that we can work it out because it was 13 centimetres shorter than Antoni's jump.

Okay.

So Antoni jumped 220 centimetres because we know Antoni jumped 2.

2 metres.

And because we know how to convert between centimetres and metres, like you just showed me you can do, 2.

2 metres is the same as 220 centimetres.

So Xavier jumped 13 centimetres less than 220 centimetres.

So how far did Xavier jump? Before I reveal the answer? Okay.

Xavier jumped 207 centimetres, or we can say 2.

07 metres.

So Xavier jumped 207 centimetres.

Okay.

Let's have a look at some problem solving activities.

Now, we have got some measurements over here and we've got a mixture of measurements.

How many different measurements can you see? I can see three different measurements.

Can you? What are they? We've got to start with the smallest.

Millimetres, centimetres and metres.

That's a bit awkward because usually we stick to everything being in centimetres or everything being in metres or everything being in millimetres.

'Cause the difference between millimetres and metres, it's quite a big difference.

Okay.

So we've got the first, second and third for gold, silver and bronze.

And they've all got different measurements.

Now, which units should we convert this all to? Does it seem sensible to have them all in millimetres? All in metres? Or all in centimetres? What do you need to sort the ones that are in millimetres? They're quite big aren't they? 600 millimetres, 1,800 millimetres.

When you notice you're using very big numbers, you know that actually, maybe the units that I've got that I'm using, there's probably a better unit for it.

Okay.

So we've got 600 millimetres.

What can we convert that to? Tell me.

It could be 60 centimetres if we convert it to 60 centimetres? Yeah.

60 centimetres doesn't sound bad.

Metres, it will be less than one metre, right? 60 centimetres would be less than one metre.

So actually going from 600 millimetres to 60 centimetres, that seems right to keep that in centimetres and to use centimetres as our units.

Okay.

What about 1,800 millimetres? Again, it's a bit too big to be using millimetres.

What could we convert that to? What do you think? 1.

8 metres.

Good.

Again, because it's, it's overwhelmed metre, so actually we could be using metres rather than centimetres.

Okay.

And then we've got 0.

2 metre.

It's less than a metre.

So it wouldn't make sense to use metres for that.

20 centimetres and then 60 centimetres.

60 Centimetres seems fair enough because we've already got 60 centimetres there.

And then we've got, so we've got 60 centimetres, 60 centimetres, 20 centimetres, 180 centimetres.

Now we've converted everything to centimetres just so it all stays the same.

Okay? Okay.

So, here is somebody's bedroom.

This is the design to somebody's bedroom.

And again, how many different units of measurements can you see? Three again? Millimetres, centimetres and metres Millimetres, centimetres and metres, a bit all over the place.

Okay.

So, what we need to do is we've got 1,900 millimetres and 1,500 millimetres in pink.

And these are the millimetres that actually, maybe we need to convert.

And then we've got the dark ones, 2.

4 metres and 3.

9 metres in bold are the metres and then 245 centimetres and 435 centimetres at the bottom.

So we've got three different measurements.

Ideally, for a living room plan, a kitchen plan, a bedroom plan.

We would want all the measurements for you to be of the same unit.

Okay.

So, if we have a look at 1,900 millimetres and 1,500 millimetres, we can convert it to centimetres and then convert it to metres, which would give us 1.

9 metres and 1.

5 metres.

So, ideally when you have a problem like this, where you're looking at a plan and you want to know.

Oh, let's keep this stick to the same measurements here in our plan.

Compare and take the measurements at a time.

So first of all, I'm just looking at the metres first.

Then I can just look at the centimetres and then I can just look at the millimetres.

Okay? So we're just sticking to one unit at a time.

Okay.

So next we have got 245 centimetres and 435 centimetres.

What would those be converted to in metres? What do you think? Okay.

2.

45 metres wide if you said that and 4.

35 metres.

Now, what do you notice about our design for the room? And they are all using the same units of measure now? Yeah.

3.

9 metres, 1.

9 metres, 2.

4 metres, 2.

45 metres, 1.

5 metres, 4.

35 metres.

They are all in metres.

It feels better to look at now rather than having millimetres and centimetres and metres.

Now we've all just got the dimensions in metres.

And actually, because this is a large room, it's best to have it all in metres.

If it was for a doll's house, however, would we be using metres? No, we'll probably be using millimetres or centimetres for a doll's house.

Okay.

Now I would like you to pause the video right now and have a go at completing the independent tasks.

Once you've done that and checked over your work, then come back and we will go through the answers together.

Good luck.

Okay.

Welcome back.

How did you find that? Okay.

Let's go through the answers together.

So, I left you with some measurements, some dimensions for a room.

What did you notice? Did you spot the mistake? There was one mistake that was made.

Did you spot it? 5.

1 centimetres for a room? Where's my ruler.

5.

1 centimetres, I would not be able to fit in that.

If it was a doll's house then yes, maybe, but definitely not 5.

1 centimetres.

Okay.

So hopefully you corrected that.

What should it have been then? 5.

1 metres.

That was what it should have been.

So you're not 5.

1 centimetres, but 5.

1 metres.

That makes sense.

So this is a nice big, large room.

Okay.

What else did we change? So we've got our metres there.

I've got 5.

1 metres, 2.

2 metres, 3 metres.

And then the other three measurements are in centimetres and we'd like to ideally convert them to metres.

So 2.

1 metres, 2.

1 metres and 4.

3 metres.

So if you just want to check that over and give yourself a nice big tick if you got them correct.

So, 5.

1 Metres, 4.

3 metres, 2.

1 metres, 2.

1 metres, 3 metres, and 2.

2 metres.

Okay, well done.

So if you would like to share your work with us here at Oak National, then please do ask your parent or carer to share your work for you on Twitter, tagging @OakNational and to use the hashtag #LearnwithOak.

Now, I just want to say before I leave you to complete the quiz, well done on all of the brilliant learning that you have done today.

Good luck with the quiz.