Lesson video

Welcome back to your year five maths lesson.

My name is Mr. Barton, and over the last week, I've completed a 1500 piece jigsaw puzzle for the first time ever.

We'll be studying the topic of volume for the next five lessons.

Volume can be quite a tricky concept, so make sure you don't miss any of the lessons out.

Before we start, make sure that you're ready to get going.

Have you done the pre-lesson quiz? Have you got your paper and pencil ready? You have? Right then, let's get started.

Now before we start, it's important that we understand some important concepts.

These are things we're going to revisit throughout the rest of these lessons, so don't worry if it doesn't always sink in just yet.

Volume is the amount of space taken up by an object.

Okay, that's really key.

It's the amount of space taken up, not how much there is.

Capacity is the measure of an object's ability to hold a substance, like a solid, liquid or a gas.

Volume is measured in cubic units and we're going to do a whole lesson on that next lesson.

Whereas capacity is measured in almost every other unit.

How many grammes can something hold? How many millilitres can something hold? Really important that we understand the distinction between volume, which is the amount of space taken up, and capacity, which is how much fits in something.

It's quite tricky.

Let's have a look at that idea a bit further.

Here you have a variety of objects which may help us measure volume.

Do each of them have the same scale? Do each of them measure the same thing? Why or why not? Pause your video and write down your answer.

Each of these pieces of equipment have a different scale, and that is because they serve a different purpose.

A 20 litre bucket, like the one in the corner, has a very different purpose to the teaspoon or a pipette.

The 20 litre bucket is holding a lot more.

Because they have different purposes, they need the ability to be precise and they need to be able to be precise in different ways.

If you are mixing millilitres of chemicals, you need to be much more precise than if you are filling up a bucket of water to mix cement.

Their purposes are different.

But how do we read these scales? We touched upon this within our unit two, but we're going to continue to develop the skill.

It's a lifelong skill you're going to need.

So when we are reading the volume, we need to make sure we check which units are being used.

We need to check the value of the intervals and we need to count on from the numbered mark using the correct units.

Now it's normal to round your measurement to the nearest scale or interval.

So here, we can see that whatever's being measured in millilitres, so a liquid, isn't quite touching a full interval.

So what we do is we'll round it to the closest interval, which is this one.

Right then, let's try and read this scale of this image.

The first thing I need to do is check what units are being used, so I'm using millilitres.

So my answer is going to be in millilitres.

Now, I'm going to try and work out the scale.

And this is the trickiest bit.

Normally, scales are one, two, fives, 10s, 20s, 25s, 50s, or 100.

And that's because they go into multiples of 100 and 1000 easily.

Remembering back to our unit on conversions, lots of our metric units are made up of hundreds or thousands.

So, let's have a look here.

We have 500 here, 1000 here.

And one, two, three, four, five units in between.

So what I need to do is I'm going to try counting up.

Now I know it's not going to be ones, so I'm going to try 10s.

500, 510, 520, 530, 540, 550.

Now that's much too little.

Those jumps are nowhere near big enough.

So I'm going to try doing jumps of 100.

500, 600, 700, 800, 900, 1000.

So I have worked out that each of the intervals is 100.

Because if I start at 500, I count up each interval in hundreds, I've reached one thousand.

So, I've check which units are being used, millilitres.

I've checked the intervals, they're 100 millilitres each.

I now count on from the numbered mark using the correct units.

500 millilitres, 600 millilitres, 700 millilitres.

The volume of the liquid inside this container is 700 millilitres.

It takes up 700 millilitres.

Your turn, I'd like you to pause your video here, making sure that you follow the remember tos.

Pause your video.

Well done if you got 375.

In those examples, each interval was 25 millilitres.

Let's have another go.

Now these intervals are a bit smaller, so you might want to start by having a look between 200 and 300, what would be in the middle and working from there.

Again with this one, the liquid isn't quite at an interval so you'll round to the closest and that's this one, here.

I'd like you to pause your video and find the volume of the liquid in this container.

Off you go.

The volume of the liquid in this container is about 230 millilitres.

Each of the intervals was 10 millilitres and we rounded down, or we rounded to the nearest interval there.

We rounded down to the nearest interval.

Let's have another go.

I'm not going to give you any tips this time, but it's quite a tricky one, this one.

Pause your video and have a go at reading the interval.

Now I want to show you my thinking for this one.

This is quite a tricky one.

I start by noting 500, 1000 and millilitres.

The unit I'm dealing with is millilitres.

I now need to check the intervals.

Now there's quite a lot there so I'm going to have a go at doing it in fives.

500, 505, 510, 515, 520, 530, no that's going to be far too small.

So even though there's a lot of intervals, my jump is still going to have to be relatively big.

500, 600, 700, 800, 900, 1000.

So that's too big if they're each 100.

So I'm going to try 50s, 'cause that's half.

500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1000.

Each of my lines is worth 50 millilitres.

Quite a tricky one, that one.

It's not often we have 50 millilitres.

So the volume of the liquid was 650 millilitres.

600 here, 50 there, there were intervals of 50.

It's time for your independent task now.

So you're going to help Syed to read the correct volumes of water for his plants.

It's important that they don't have too much or too little water if they are to remain healthy.

When answering, I'd like you to write down the interval and the volume of each beaker.

There is two pages of questions on this video.

However, if they're still too small, exit the video, move onto the next page, where each of the beakers will take up one whole page, so you can really zoom in.

Don't forget, we're finding the approximate if it's not exact and we normally round to the closest interval.

Normally, our intervals fit easily into multiples of 100 and 1000.

So you're looking at one, two, fives, 10s, 20s, 25s, 50s, or 100s.

However, one of the containers on page two does not have the same scale.

So you're going to have to be really careful there.

I'll repeat, there are two pages of tasks.

If you can't quite see them as clearly as you'd like to, exit the video, go onto the task page, and then come back to find out your answers.

Right then, pause your video there.

And let's look at page two.

Pause your video there.

And now let's go through the answers.

I've written the intervals there for you as well.

And here are your answers for page two.

Question five is a tricky one.

The difference between 500 and 750 is 250, which means the middle marker is 175 millilitres away.

Which makes this middle marker 625 millilitres, halfway.

It seems strange for a middle mark to be not a round number, a multiple of 100.

However, in this case it's not.

I've written again the intervals for you there.

25 millilitres, quite common in real life scales.

And then our interval on number six was four litres.

Well done for completing our first lesson on volume.

Don't forget to complete the end of lesson quiz and come back next time for a slightly trickier lesson.

Well done.