Lesson video

Hello, my name is Dr.

Sharik, and I am excited to be learning with you.

You have made a great choice to learn maths with me today, and I'm here to guide you through the learning.

Today's lesson is from the unit Measuring Length and Recording in Tables.

The learning today is called millimetres as a unit of measure.

And we're gonna think about the relationship between millimetres and centimetres.

Sometimes new learning can be tricky, but we're gonna work really hard together, and we will be successful.

And I'm here to guide you through the learning.

And this is the key word that we will be using throughout the course of the lesson.

The word is millimetre.

My turn, millimetre.

Your turn.

Fantastic.

Let's try that one more time.

My turn, millimetre.

Your turn.

Lovely.

So this is the key word that we will be exploring as we move through our learning today.

So our learning today is all about millimetres and using them as a unit of measure, and the relationship between them and centimetres.

We're gonna start off by thinking about small lengths and heights and the fact that they can be measured in millimetres.

It is Laura and Jacob, who will be helping us as we progress through the lesson today.

So a question, how could we measure the width of a small stick? So how wide the stalk of the stick is.

How could we measure that? Well, Jacob's saying we could use a metre ruler.

What do you think? To measure the width of a stick, should we use a metre ruler? Laura is saying the metre ruler is too long, and she's right.

We use metres to measure longer or taller objects.

And today, we just want to measure the width of a small stick.

So this is a 15-centimeter ruler.

You might have a similar ruler near you somewhere.

What do you notice about this ruler? Well, Laura has noticed that the ruler has small intervals marked between the centimetre marks.

Can you see those? Between the zero, one, two, three, they're all centimetres.

But can you see those small intervals marked in between each of those centimetres? And Jacob has noticed the small intervals are called millimetres.

That's our key word, isn't it? Millimetres.

So those are the small intervals.

So when we measure the length or height of small objects, we need to use a standardised unit.

And the millimetre is a standardised unit of length.

It is the standardised unit of length that we all use to measure the length or height of small objects.

Here are some objects that we would measure in millimetres.

So the width of a stick, the width of a fingernail, the length of that point on the pencil, maybe the length of the eraser on the end of a pencil.

I wonder if you can think of any more objects that are small that we could then measure in millimetres.

Laura is saying, "Is this flower too tall to be measured in millimetres?" What do you think? Jacob is saying that anything can be measured in millimetres.

Millimetres are a unit that we use for measure.

They're a standardised unit, so anything can be measured in millimetres.

"However," he expands on his explanation, "it would be more efficient to measure a taller object in centimetres or metres." So we can measure anything in millimetres, but it's more efficient to measure taller objects in centimetres or metres instead.

So reasoning and thinking about the length or height of an object helps us to decide which unit to use to measure it.

So should we use millimetres, centimetres, or metres? So Laura is saying, "The flower petal is small, so its length would be measured in millimetres." And Jacob says, "However, the height of the flower would be measured in centimetres because it is taller." But maybe not tall enough to use metres.

So it's really important that we reason about the length or height of an object because it helps us to decide what we need to use to measure it.

Here we go.

What do you think now? Which of these would you use millimetres to measure? Would you measure the length of a desk in millimetres, the height of a house in millimetres, or the length of a fingernail in millimetres? What do you think? What did you think? Did you think, yes, the length of a fingernail? The length of a desk, that's too long to use millimetres.

The height of a house, that would be even taller than the length of the desk, so we wouldn't use millimetres to measure the height of a house.

But yes, the length of a fingernail, we would use millimetres.

We use millimetres to measure objects that are shorter.

I want you to see if you can find some objects now, three objects that you would measure in millimetres.

So remember, they need to be short objects.

And can you find an object that you would not measure in millimetres? You can draw them here, or you can write their name, whichever you prefer.

So you've got object one, object two.

I'd like to find an interesting object that nobody else will think of for your third object that would be measured in millimetres.

And then you have a box for your fourth object, the one that you would not measure in millimetres.

So something that is longer or taller.

When you have found your objects, press play on the video.

Okay, here are some examples of objects that you might have found.

So I had a look around, and I found, for my first object, I found a toy car.

But then I looked at the wheels, and I think the thickness of the wheels on the toy car, you would measure in millimetres.

And then for object two, I found a dice.

And I know that the spot on the dice is really quite small.

So I would measure the length of the spot on the dice in millimetres.

And my interesting object that I don't think anybody else would've found is the width of the stud on a Lego block.

So on that Lego block, that little bubbly bit is called a stud.

And the width of that stud, I would measure in millimetres because it is short.

And the object that I would not measure in millimetres would be the height of a bicycle.

That's too large to measure in millimetres.

I would probably use centimetres or metres for that.

I wonder how you got on and what objects you found.

Let's move on now to the second part of our learning.

Describe the relationship between centimetres and millimetres.

So we've learned that the small interval marks are called millimetres.

And millimetres are used to measure short objects.

What do you notice though about these millimetres? Maybe you could pause the video and tell somebody near you, what do you notice about millimetres? Laura has noticed that millimetres make up centimetres.

Because they are smaller than the centimetres, they make up centimetres.

Jacob has noticed, actually, he's been a bit more accurate.

There are 10 millimetres, are equal to one centimetre.

So he is counted 10 of those marks, and they are equal to one centimetre.

So 10 one-millimeter lengths are the same as one centimetre.

There are 10 one-millimeter lengths in one centimetre.

If we look really closely at just one centimetre, we can see that there are 10 one-millimeter lengths in that one centimetre.

My turn.

There are 10 one-millimeter lengths in one centimetre.

Your turn.

Fantastic.

That's a really important piece of learning.

So I think we need to do that again.

So my turn.

There are 10 one-millimeter lengths in one centimetre.

Your turn.

Fantastic.

It's a really important fact there to see if you can remember.

It will really help us with our learning.

So Jake is saying one millimetre must then be smaller than one centimetre.

Why do you think he's saying that? How do you think he knows that? Well, that's right.

One millimetre must be smaller than one centimetre because 10 millimetres make up one centimetre.

So each millimetre must be smaller than one centimetre because you need 10 of them to make one centimetre.

So what do you think? True or false? One centimetre is bigger than one millimetre.

Is that true, or is that false? And then once you've decided if it's true or false, I would like you to pick a reason as to why.

So is it reason A? There are 10 millimetres in one centimetre.

So one millimetre must be larger.

Or is it B? There are 10 millimetres in one centimetre.

So one centimetre must be larger.

Pause the video, maybe find someone, tell them what you think.

Is one centimetre bigger than one millimetre? Press play when you have decided.

Okay, how did you get on? So yes, one centimetre is bigger than one millimetre.

And why? Well, because there are 10 millimetres in one centimetre.

So one centimetre must be larger.

One centimetre is made up of 10 millimetres.

So they must, the centimetre must be larger.

We can use the relationship between centimetres and millimetres to compare length and height.

So there's a leaf here.

The length of the leaf is seven millimetres, and Jacob's wondering if the leaf is longer than one centimetre.

Well, let's use the relationship.

One centimetre is equal to 10 millimetres.

So if one centimetre is equal to 10 millimetres, do you think this seven millimetre leaf is longer or shorter than one centimetre? So Laura is explaining, "One centimetre is equal to 10 millimetres." So if an object is shorter than 10 millimetres, it will also be shorter than one centimetre.

So our leaf is seven millimetres.

The object is shorter than 10 millimetres, so it will be shorter than one centimetre.

The leaf is shorter than one centimetre.

The leaf is shorter than one centimetre because its length is less than 10 millimetres.

Ooh, let's have a look at this leaf here.

This leaf is 15 millimetres.

One centimetre is equal to 10 millimetres.

So an object that is longer than 10 millimetres will be longer than one centimetre.

So our leaf here is longer than one centimetre because it is 15 millimetres, and we know 10 millimetres is one centimetre.

15 millimetres must be more than one centimetre.

So the leaf is longer than one centimetre because it's length is more than 10 millimetres.

Do your turn now.

Is the length of the pebble shorter or longer than one centimetre? A is shorter, B is longer, or C is I'm not sure.

So the pebble is 19 millimetres.

Do you think it's longer or shorter than one centimetre? Pause the video and press play when you think you know.

Okay, should we have a look? What did you think? Is the pebble shorter or longer than one centimetre? That's right, it's longer.

Why is it longer? Well, it is 19 millimetres long, and we know that 10 millimetres is one centimetre.

19 is more than 10, so the pebble must be longer than one centimetre because it's longer than 10 millimetres.

Another one for you to have a go at now.

Which pebble is longer? Pebble A or pebble B? Pebble A is one centimetre, and pebble B is 10 millimetres.

Pause the video, maybe go and find someone to talk to and tell them which pebble you think is longer.

Press play when you've had a discussion.

Okay, what did you think? Which pebble is longer? That's right.

Did you get that both pebbles are the same length? And that is because 10 millimetres are equal to one centimetre.

My turn.

10 millimetres are equal to one centimetre.

Your turn.

Fantastic.

And that is that key fact that we'll try and remember.

10 millimetres are equal to one centimetre.

So the pebbles must be exactly the same length.

One is one centimetre.

The other was 10 millimetres, and they are the same length, just different ways of describing using different units.

Using millimetres, it's 10 millimetres.

If we choose to use centimetres, it's one centimetre.

So now it's your turn to have a go.

For your first task, I want you to look at these four ribbons of different lengths.

We've got one that's 14 millimetres, one that's one centimetre, a length of ribbon that's one millimetre, and a length of ribbon that is eight millimetres.

I'd like you to put those ribbons in order of length, shortest to longest, and explain how you know.

And for your second task today, I'd like you to tick the three lines that have a total length of one centimetre.

I'd like to write an equation to show the sum of the length of the ones that you have ticked.

You have a one centimetre line, a five millimetre line, a two millimetre line, a 10 millimetre line, and a three millimetre line.

So tick the three lines that have a total length of one centimetre and write the equation.

For your third task today, there's a problem for you to have a go at solving.

A pile of 10 sheets of card is one centimetre tall.

What would be the height of one sheet? And explain how you know.

So let's read that through again.

A pile of 10 sheets of card is one centimetre tall.

What would be the height of one sheet? And explain how you know.

You might like to draw something to help you, maybe a bar model or maybe some other representation of this problem to help you solve it.

So pause the video, and when you have finished all three tasks, press play.

Let's see how you got on.

For the first question, you were asked to put the ribbons in order of length, shortest to longest.

So we have one millimetre, eight millimetres, one centimetre, and 14 millimetres.

Then I ask you to explain how you knew, how you put them in that order.

And maybe you wrote something like this.

You may have said that 14 millimetres is larger than 10 millimetres, which is the same as one centimetre.

So therefore, 14 millimetres is the largest.

Eight millimetres and one millimetre are smaller than 10 millimetres.

So they are smaller than one centimetre.

And one millimetre is smaller than eight millimetres, so that one millimetre must be the smallest.

So for your second task, you were asked to tick the three lines that have a total length of one centimetre.

I wonder if you've got the same lines as me.

Five centi, five millimetres, sorry, two millimetres and three millimetres.

If I added those together, they gave me a total of 10 millimetres, which is the same as one centimetre.

And my equation was two millimetres, add three millimetres, add five millimetres.

That equaled 10 millimetres, which is the same as one centimetre.

I couldn't use the one centimetre line because it's already at one centimetre, and I needed to tick three lines.

The same with the 10 millimetre line.

I couldn't tick that because it's already the same as one centimetre.

I wonder if you notice that.

And for the third task, the problem, you asked to find the height of one sheet in a pile of 10 sheets of cards, which was one centimetre, and explain how you know.

This is what I was thinking.

You might have written something similar.

10 sheets of card are one centimetre thick.

One centimetre is the same as 10 millimetres.

So if 10 sheets of paper are 10 millimetres, then each sheet must be one millimetre.

Maybe you wrote something like that.

So fantastic learning, everybody, today.

I am really impressed with the progress that we have made on understanding millimetres as a unit of measure and the relationship between them and centimetres.

We now know that small objects are measured in millimetres.

So small objects like the width of a fingernail or the length of a flower petal, not things like the height of a house.

They are too big to be measured in millimetres.

We've also learned that there is a relationship between millimetres and centimetres.

We have learned that there are 10 millimetres in one centimetre, and that's a key fact for us to remember.

So let's do it one more time.

My turn.

There are 10 millimetres in one centimetre.

Your turn.

Fantastic.

Really key fact to remember there.

So really well done on the learning today, everybody.