Lesson video

Hi there, my name is Miss Darwish and for our maths lesson today, we are going to be solving some problems, some word problems, when it comes to converting units of mass.

So before we get started, if I could just ask you to take yourself away from any distractions to a nice quiet place, ready for the lesson.

Okay, so for today's agenda, we are going to, first of all, just be talking about metric mass, and then having a go reading some scales.

And then we'll be having a look at some word problems. At the end of the session, there will be of course, a quiz for you to complete on today's learning.

So before we start, if you could just grab yourself a pencil, a notepad, or a sheet of paper and a ruler so we can start.

Okay, just to recap now.

One kilogramme, there are 1000 grammes, right? What about in three kilogrammes? 3000 grammes, good.

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

So in front of you are two scales.

What do you notice about the scales? What do you notice? What's the same and what's different between both? Okay, first of all, of course, the shapes a bit different.

Have you noticed that? Might be the first thing you noticed.

Okay, one of them reads in grammes and the other one reads in kilogrammes.

So now I've got a cat and we've got a pigeon.

Assuming they would stay still if we put them on the scale, which one would go where? Where would the cat go and where might the pigeon go? Have a think.

What'd you think the scales read? And how much do you think the cat might weigh roughly? And what about the pigeon? Okay, should we have a look together? Okay, let's see what you said.

So the cat would weigh a bit more than the pigeon.

So I've put the cat on the scale that red in kilogrammes and the pigeon on the one with grammes.

And the reading is 1,650 grammes, the pigeon.

Can you see that? Can you see? Can you point to where 1000 grammes are on the scale with the pigeon? And then point to 2000 grammes for me.

And then point to a 1,500 grammes.

That would be in the middle between the 1000 and the 2000.

And then we're going to count in fifties.

So 1,500, 1,550, 1,600, 1,650.

Okay and then if we have a look at the cat, there's our four kilogrammes.

There's our five kilogrammes.

Halfway between four and five would be 4.

5 kilogrammes or four and a half kilogrammes, well done.

So then we'll go 4, 4.

1, 4.

2, 4.

3 or 4.

4, 4.

5.

So that cat is reading 4.

1 kilogrammes.

Okay, now how much do you think these three things weigh? A toddler, a heavy suitcase and a piano.

Just an estimate.

I want you to write something down for me.

So three different weights, roughly.

Okay, I'm going to give you 10 seconds.

Just a quick estimate.

How much do you think a toddler might weigh? How much do you think heavy suitcase might weigh? And how much do you think a piano might weigh? And five more seconds.

Okay and pens down or pencils down.

Okay, let's have a look.

So a toddler, roughly, my estimate is about 14 kilogrammes might be a three year old, four year old.

A heavy suitcase, so if you go on holiday, what's the minimum.

What's the limit on a suitcase? Maybe about 20 kilogrammes, maybe a bit more.

But usually when we go on holiday, 20 kilogrammes, you're usually not allowed any more than that.

That's the limit.

Okay and what about piano? Would it be heavier or lighter than a heavy suitcase and a toddler? It would be heavier, won't it? So about 250 kilogrammes.

It would be a lot heavier than a heavy suitcase and definitely a lot heavier than a toddler.

Okay, so how much does an elephant weigh? I hope you like my drawing of an elephant by the way.

Okay, how much do you think an elephant might weigh? Again, get that pencil, get that pen and quickly.

I'm going to give you six seconds just to write an estimate down.

And pencils down or pens down, okay.

A lot of kilogrammes, let's just say.

An elephant is very, very heavy.

Now, an adult elephant could weigh about six or seven tonnes, okay.

So we're not talking about kilogrammes anymore because it would weight a lot of kilogrammes.

So instead of talking about a very big number of kilogrammes, we're going to use tonnes, okay.

'Cause grammes is just if we're weighing pigeons, but when we want to come and weigh an elephant we're even going to skip grammes, we're skipping kilogrammes.

We are talking tonnes.

That's how heavy an elephant is.

Okay, so let's talk about tonnes then.

One tonne is equivalent or the same as 1000 kilogrammes.

Can you say that for me? One tonne is equivalent or the same as 1000 kilogrammes.

It's easy to remember because we know 1000 grammes, one kilogramme, one tonne, 1000 kilogrammes.

So now we know if we go back to the elephant, if an elephant weigh six tonnes, how much does an elephant weight in kilogrammes? So we go back to my lovely picture of an elephant.

If an elephant weighs six tonnes, how much is this in kilogrammes? 6,000 kilogrammes, that is a lot.

Okay, what about if we had 5,200 kilogrammes, how many tonnes would that be? 5,200 kilogrammes would be the same as 5.

2 tonnes, well done if you said that.

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

So, a school bus weighs 12,400 kilogrammes.

How much does a school bus weigh? 12,400 kilogrammes, very heavy.

Now, the shortest route to school means it can go over a bridge which has a maximum of nine tonnes.

Have you seen those bridges before? Where you can only go over the bridge and there's usually a sign about how much, how heavy the lorry or the school bus or whatever the vehicle can go over it.

So on this bridge, you're only allowed nine tonnes.

How much? Nine tonnes.

Okay, or in kilogrammes? 9,000 kilogrammes.

So, can the school bus take the short route? How much does the school bus weigh? 12,400 kilogrammes.

And what about the bridge, what's the maximum? That means the highest ever weight.

The most weight.

Nine tonnes.

So 12,400 kilogrammes, we're looking at the school bus now, is the same as 12.

4 tonnes.

Can you see the problem? It can't take the short shortcut over the bridge, its got to take the other long route, unfortunately.

It can't go over the bridge because it weighs too much.

Okay, right.

Now it's time for you to pause the video and have a go at completing the independent task that I've left for you to do.

Once you've had a go on that you've checked over your answer, bring a marking pen and carry on with the rest of the video and we'll go through the answer together, good luck.

Okay, should we go through the word problem together? Let's have a look.

So let me just move myself out of the way there.

Okay, that seems better.

That's better.

Right, so a school bus weighs 12,500 kilogrammes.

How much does the school bus weigh? 12,500 kilogrammes.

Now the less congested route, do you know what congestion means? There's a lot of traffic.

So the route or the way that doesn't have a lot of traffic means it can cross a bridge with a limit though, of 12.

5 tonnes.

Can it take this route when picking up children and taking them back? So how much does a school bus weigh? 12,500 Kilogrammes.

What's that in tonnes? 12 and a half tonnes or 12.

5 tonnes.

Now, that is the same as the limit of the bridge, because it says 12.

5 tonnes maximum.

Can you see that? 12.

5 tonnes maximum.

And that's how much the school bus weighs.

Now I take this route when picking up children and taking them back? What did you say? Let's have a look.

The school bus weighs 12,500 kilogrammes, which is the equivalent to 12.

5 tonnes.

The bridge, like we said, has a limit of 12 and a half tonnes.

And so the bus can only go over the bridge when it's empty and not carrying children.

Did you think about that? Because it's a school bus and it's got to pick up the children.

But it will go over its limit.

So it won't actually be able to take this route when there are children inside.

Oh dear.

Okay, now if you would like to share your work with, oh.

Let's start again.

If you would like to share your work with us here at Oak National, then please ask your parent or your carer to share your work for you on Twitter, tagging @oaknational and to use the hashtag learn with Oak.

Now, I just want to say, well done on today's learning.

You have worked extremely hard converting between tonnes kilogrammes and grammes and solving those word problems. And I'm just going to leave you there and say good luck with the quiz.