Lesson video

Hi, my name's Mr. Peters.

In this lesson today, we are gonna be thinking about the word volume and what this means in a range of contexts.

Now, you may be most familiar with the word volume from things like, watching the television, where you have to turn the sound up and down.

Don't you have to turn the volume up or down? We're gonna be looking at it from a slightly different perspective today, from a mathematical perspective.

If you're ready, let's get started.

By the end of this lesson today, you should be able to say that "I can explain what volume is in a range of different contexts." In this lesson, we've got a couple of keywords we're gonna be referring to throughout.

I'll have a go at saying them first, and then you repeat them after me.

Are you ready? Volume.

Your turn.

Space.

Your turn.

Mass.

Your turn.

Great.

Let's think about what these mean, then.

Well, the amount of three dimensional space that something takes up is known as its volume.

Space refers to the place in which an object exists and the measure of how much matter is in an object is known as its mass.

Look out for these words throughout our lesson as we go.

This lesson today will be broken down to two cycles.

In the first cycle, we're gonna be exploring what volume is, and in the second cycle we're gonna be comparing volume and mass.

Let's get started.

Throughout this lesson today, you'll meet Jacob and Alex.

They'll be helping us along the way, sharing their thinking as we go.

Okay, so here, we've got a picture.

This is Jacob's bedroom, and in Jacob's bedroom you'll see a whole host of different items. Now, each one of those items takes up a certain amount of space in his bedroom.

That space that it takes up is known as its volume, the object's volume.

We can compare the different volumes of the objects within Jacob's bedroom.

Let's have a look at some of them.

Here, for example, we've got Jacob's bed and we've got a cushion.

Both of these have their own volume.

Which one do you think has the largest volume? Let's use our stem sentence to help us say this.

The something has a larger volume than the something.

That's right.

The bed has a larger volume than the pillow or the cushion.

We could also say that the something has a smaller volume than the something.

Have a think.

That's right.

We could say that the pillow has a smaller volume than the bed.

So finally we could say that the something has a larger volume because it occupies more space.

What would that be? That's right, it would be the bed, wouldn't it? The bed has a larger volume as it occupies more space.

Let's have a look at a different example.

We've got Jacob's door to his bedroom here, and we've got a tiny toy brick here, haven't we? Let's use our sentence stem to help articulate the difference between these volumes.

Maybe you could have a go at saying it along with me.

The door has a larger volume than the brick, therefore, the brick has a smaller volume than the door.

The door has a larger volume because it occupies more space.

Well done, if you managed to say that along with me.

Now, here's a slightly different example.

We're no longer in Jacob's bedroom, we're now in the city.

Here you can see a block of flats and a tree.

Let's use our stem sentence again, shall we? The block of flats has a larger volume than the tree.

Therefore the tree has a smaller volume than the block of flats.

The block of flats has a larger volume as it occupies more space.

Well done, if you managed to get that.

Have a look at these two items now, then, what do you notice? Well, that's right.

One of 'em is a pen and one of them is a pencil, isn't it? And you may have also noticed that they're the same length, aren't they? But they do have a different width, don't they? One of them is thicker than the other one.

Hmm, I wonder what you think, which one has the largest volume? That's right.

The pen has a larger volume than the pencil.

Therefore, the pencil has a smaller volume than the pen, and the pen has a larger volume as it occupies more space.

Well done if you managed to get that.

Hmm, here's an interesting example.

Here's a block of cheese.

Watch carefully.

Ah, we've chopped off a slice from the block of cheese, haven't we? What's the same about these items and what's different about these items? That's right.

They're both the same length, aren't they? Because the slice of cheese has been chopped from the top of the block.

However, the thickness is significantly different, isn't it? The slice of cheese is a lot thinner than the block of cheese.

Let's use our stem sentence again.

The block of cheese has a larger volume than the slice of cheese.

Therefore, the slice of cheese has a smaller volume than the block of cheese and the block of cheese has a larger volume because it occupies more space.

Well done, if you got that.

Okay, time for you to check your understanding now.

Which item has the largest volume, a, b, or c? Take a moment to have a think.

That's right, it was b, wasn't it? Now, can we explain why B has a larger volume? That's right.

It's significantly longer than the other items, isn't it? But it also is a lot wider, it's a lot thicker than the other items. Therefore, the pineapple has a larger volume than both the cherry and the pear.

Here's another quick check.

True or false? If two shapes have the same length, they have the same volume.

Take a moment to think.

That's right, it's false, isn't it? Have a look at these justifications, which justification here helps you to reason why? That's right.

If they have a different thickness, then the thicker the item, the more space it would take up, therefore, it would have a greater volume.

Well done, if you got that as well.

Okay, onto your first task for today then.

What I'd like you to do is use a malleable object.

It might be some plasticine, it might be a bit of Blu Tack, or it might be some salt dough.

Take your shape and remould your shape into lots of different shapes.

And then secondly, take your shape and break it down into smaller parts, and then recombine those parts to make your shape again.

Jacob's asking, "I wonder if you could create a generalisation for yourself to show what you've learned." Good luck and I'll see you back here shortly.

Okay, welcome back, here's an example that Jacob did.

You can see here that Jacob made a starting shape of a ball with some Play-Doh.

He then made all of these different shapes with the Play-Doh.

He used exactly the same amount of Play-Doh, he didn't add anymore or he didn't take any away.

Therefore, we can say that each one of these shapes has the same volume as the original starting shape that Jacob created.

And hopefully, you came up with a little generalisation for yourself.

Jacob certainly did.

He said that "Shapes can look different, but they can also have the same volume." Well done, if you managed to come up with something like that.

Okay, onto cycle two of our lesson now.

Comparing volume and mass.

Here you go, I've got two boxes here.

One of them is a box full of cuddly toys, and one of them is also a box full of books.

What's the same and what's different about these? Take a moment to have a think.

That's right.

As Alex has pointed out, "The boxes have the same shape and therefore, they have the same volume." But as Jake is pointing out, "Their masses are different," aren't they? The box of books would be heavier than the box of cuddly toys, wouldn't it? So we could say that the box of cuddly toys has a lesser mass than the box of books or the box of books has a greater mass than the box of cuddly toys.

Here's another example, what do you notice this time? Well, again, both the balls are the same size, aren't they? So they share the same volume.

However, the cricket ball is heavier than the tennis ball, so that cricket ball has a greater mass than the tennis ball, and the tennis ball has a lesser mass than the cricket ball.

Here's one more example, what do you notice this time? That's right, the weighing scales are equal, aren't they? But the two objects at either end of the scale are completely different.

One of them's a lot taller, isn't it, than the other one? And the other one's a lot shorter.

We've got two objects here that look completely different, but they share the same mass, don't they? The spaceman model is the same mass as the weight, the 50 gramme weight on the right-hand side of the scale.

So Jacob's saying that "Items could have the same mass and different volumes, but they could also have the same volume with different masses." Alex is now asking, "Well, can we have something with the same mass and the same volume?" Can you think of any examples? Jacob says, "Of course we can! Here's an example." And there you go.

He's got two eggs here.

He's got a light brown egg and a darker brown egg, and both of these eggs have the same volume and they also have the same mass.

So it's possible to have the same mass, the same volume, a different mass, and the same volume or the same mass, and a different volume.

Okay, time to check your understanding.

Have a go at ordering these from the greatest volume to the smallest volume.

Okay, as Jacob's saying, "The rugby ball has the greatest volume," doesn't it? The tennis ball would then have the second greatest volume, and then finally the golf ball would have the smallest volume, wouldn't it? I think the golf ball might actually be heavier than the tennis ball, although, it still has a smaller volume, doesn't it because of its size? Okay, and our next check then, does the toy car or the cardboard box have the smallest volume? Take a moment to have a think.

That's right.

The toy car has the smallest volume, doesn't it? Because the toy car is significantly smaller than the cardboard box, even though they weigh the same amount.

Okay, what I'd like you to do is choose the correct phrase, either greater than, less than or equal to, to compare each of the items, and you can write that in on the blank line.

And then for task two, Alex says, "The tin cans that have fallen over will have the greater volume because they're more spread out on the floor and they cover more space." Do you agree or do you disagree with Alex? Good luck with that and I'll see you back here shortly.

Okay, let's go through these together.

The volume of the bowling ball is equal to the volume of the football.

They're the same size, aren't they? Even though the bowling ball weighs a lot more than the football.

The volume of the not pumped up balloon is less than the volume of the pumped up balloon, even though they're the same type of object.

Obviously, once the balloon's been pumped up, it takes up more space and therefore has a greater volume.

And finally, the volume of the sponge is equal to the volume of the brick.

Again, the sponge and the brick are exactly the same size here.

However, even though the brick is a lot heavier, they are equal to in their volume.

Okay, and onto task two.

Thinking about Alex and his reasoning with regards to the space of the tin cans.

Well, Jacob's saying that he actually disagrees.

He says that each can would take up the same space regardless of whether it was stacked up or whether it was lying down.

If you think back to the first task when we were using the malleable dough and you are breaking it into parts and then recombining it, that's exactly the same principle here.

So both of these would have the same volume.

Okay, that's the end of our learning for today.

Well done for keeping up, and hopefully, you enjoy thinking about the word volume in different contexts.

To summarise what we've learned today, the amount of space that an item takes up is its volume.

Different shapes can have the same volume, the same shapes can have different volumes, and the same shapes can also have the same volumes.

Finally, shapes with the same volume can have a different mass.

Thanks for learning with me today.

Hopefully, you've enjoyed yourself.

I know I really have.

I look forward to seeing you again soon.

Take care.