Lesson video

Hello, everybody.

My name is Mrs. Johnson.

I am so happy to be here today to help you with some of your maths learning.

I hope you are ready to work hard and have lots of fun as we learn new things.

Let's have a look at what we're going to be learning about today.

This lesson is called, length can be measured in metres and centimetres.

It comes from the unit sense of measure.

By the end of this lesson, you will be able to describe the size of a metre and a centimetre and you'll be able to choose which unit might be best to measure different lengths.

There are some key words that you need to practise that are going to really help in this lesson.

We're going to practise saying them.

It will be my turn first and then your turn.

Ready? My turn, centimetre.

Your turn.

My turn, metre.

Your turn.

Well done.

Listen out for those words.

They are going to be really important for your learning today.

There are going to be two parts to this lesson.

To begin with, you are going to think about this question, what is a metre? And then in a little while, you're going to think about choosing a unit of measure.

Let's get started by thinking about what is a metre.

There are two friends who are going to help in this lesson today.

Their names are Sam and Alex.

Listen carefully to the things that Sam and Alex have to tell you because they're going to be really helpful for what you are learning about today.

Alex and Sam are thinking about how they could measure the length of this game card.

I wonder if you've got any ideas for how you might measure the length of this card.

Alex says, "I could use objects such as building blocks to measure its length like this." We could say the game card is five blocks long.

Sam says, "I could use a standard unit such as centimetres to measure its length." Sam could use a ruler and measure it in centimetres.

And Sam would say that the game card is 9 centimetres long.

Alex says, "I remember learning about centimetres before." Sam says, "We learned that these lengths are all about the same as 1 centimetre." Can you think of anything that's about the same as 1 centimetre? Let's have a look at some of these ideas.

The width of a thumbnail, the width of a paperclip, the length of a Ladybird, all of these things are about the same length as 1 centimetre.

Alex says, "Do you think there might be any other standard units for measuring length?" Sam says, "Yes, there are lots more.

I've been learning more about metres.

Let's find out about metres.

A metre is a standard unit.

People in different countries all over the world could measure the length of the same object in metres and they would all get the same result because the size of a metre never changes.

That's what makes it a standard unit.

So how big is a metre? I wonder if you know how big a metre is.

Here are some lengths that are about the same as 1 metre.

Let's have a look at some, the width of my staircase at home, how tall I was when I was five years old, the height of a door handle, all of these lengths are about the same as 1 metre.

Alex says, "I asked my dad, 'What else is about the same length as 1 metre?'" "What did he say?" Let's have a look.

The length of a large dog like this German Shepherd police dog is about 1 metre.

The length of a guitar is about 1 metre.

Let's check if you understand how long 1 metre is.

Which of these lengths could be about 1 metre, the length of a child's foot, the length of a 10 pound note or the height of a chair.

Pause the video and have a think Good thinking.

Let's have a look.

The length that could be about 1 metre is the height of a chair.

Well done if that's what you said.

Now you are going to do some practise where you really have to think about how long 1 metre is.

You are going to look around to see what you can see around you.

You are going to look for different lengths that you could write in each column of this table.

You've got to look for things that might be shorter than 1 metre, things that are about 1 metre and things that are longer than 1 metre.

Try and remember that the height of a door handle is about 1 metre.

Pause the video and have a go at that now.

Well done.

You are looking around really carefully to try and find all those different lengths.

Here are some of the things that Alex found when he was completing this table.

I wonder if you found anything the same or if you found different lengths to these.

Alex found all of these things that he thinks are shorter than 1 metre.

The length of a pencil case, a pen, a pencil, a book, a ruler, and a water bottle.

In the middle, the things that are about 1 metre, Alex found the height of the bookshelves, the length of his desk, the width of the door, the height of his little brother, the distance he could jump and the length of a cricket bat.

And the things that were longer than 1 metre, Alex found the length of a skipping rope, the height of the ceiling, the length of his classroom, the distance he can throw a ball, his height and the height of the door.

Well done for thinking really carefully about how long 1 metre is and then trying to find lots of different lengths to write in your table.

Now it's time for the second part of our lesson, and now you are going to be thinking about choosing a unit of measure.

Alex says, "Now we know that there are at least two different units of measure for length.

We know centimetres and metres." but Sam is wondering, "Why do you think there is more than one unit of measure? Why can't we just always use centimetres?" I wonder if you've got any ideas about that.

Hmm? Let's have a look at it together.

Alex says, "Let's have a look again at how long 1 centimetre and 1 metre are." These lengths are all about the same as 1 centimetre, a length of a lady bird, the width of a thumbnail and the width of a paperclip.

And these lengths are all about 1 metre, the height of a 5-year-old, the length of a guitar and the width of a staircase.

You can see that a centimetre is much shorter than a metre.

Alex thinks that maybe there are different units of measure so that you can choose the most helpful unit for the length that you are measuring.

So Sam thinks if I wanted to measure something shorter, maybe I could choose centimetres, but if I wanted to measure something longer, I could choose metres.

Metres are really helpful when you want to measure a longer length, something like the height of the ceiling or the length of the room.

Whilst it would be possible to measure longer lengths in centimetres, it could be more difficult and not as efficient as measuring in metres.

Let's have a look at that a little bit more.

Let's think about 1 centimetre, which is about the width of a paperclip.

Imagine if we wanted to use centimetres to measure the height of the ceiling.

When you compare the width of a paperclip with the height of the ceiling, you can see that it would be quite difficult to measure the height of the ceiling In centimetres.

You would need to count a lot of them, wouldn't you, to be able to measure the height of the ceiling? Now let's look at a guitar, which is about 1 metre long and compare that to the height of the ceiling.

Alex thinks that metres might be a more helpful unit for measuring the height of the ceiling because he wouldn't need to count so many.

If you used paperclips or centimetres, you would need a lot of them.

That would be a lot of counting, whereas if you used guitars or metres, you wouldn't need to count as many, so perhaps it might be more efficient to choose metres if you wanted to measure the height of the ceiling.

Let's check if you understand when it might be helpful to choose metres or centimetres.

Have a think about this one.

True or false, if you wanted to measure the distance from one side of the playground to the other, it is sensible to choose to measure in metres.

Do you think it's true or false? And can you explain why? Pause the video and have a go now.

Good thinking This is true.

It would be sensible to choose metres if you wanted to measure the distance from one side of the playground to the other.

Here is the reason why.

Remember that 1 metre is about the height of the door handle.

The distance from one side of the playground to the other is likely to be several metres long, so it would be more helpful to measure in metres rather than centimetres because you would need many, many centimetres and it would be a lot of counting.

If you chose to measure in centimetres.

When it's a longer length that you want to measure, it can be more helpful to choose metres.

Well done if that's what you were thinking too.

Now Alex and Sam are going to play a game.

Alex is going to show Sam two measurements and Sam has to say which one she thinks is correct.

Sam is going to use what she's learned so far to help her.

She can remember that 1 metre is about the height of a door handle and 1 centimetre is about the width of a thumbnail.

Let's watch them play this game.

Alex says, "Do you think the length of my classroom is about six metres or 6 centimetres?" Hmm? I wonder what Sam's going to say.

Let's have a look.

Sam says, "I choose six metres.

6 centimetres is far too short for a classroom.

You are correct.

Well done.

Well done if you were thinking that too.

Let's look at Alex's next question.

Do you think the height of my chair is about 80 metres or 80 centimetres? Hmm? What's Sam going to say this time? Sam says, "I choose 80 centimetres.

80 metres is far too tall for a chair." "Correct again.

You really understand metres and centimetres now." Well done, Sam.

Let's check if you know whether it would be metres or centimetres.

How could you complete this sentence? My desk is about mm, wide.

Would it be 1 centimetre or 1 metre? Pause the video and have a think.

Well done if you said 1 metre, remember that 1 centimetre is only about the width of your thumbnail.

It's unlikely that your desk is going to be the same width of your nail, isn't it? So it's much more likely that your desk would be about 1 metre, which is about the same length as a guitar.

Well done if that's what you were thinking too.

Now it's time for you to practise choosing a unit of measure.

First, you're going to choose the most sensible measurement for each length.

For example, the first one says, my bedroom is about mm, long.

Would it be three metres or 3 centimetres? You need to tick the most sensible measurement for each length.

Next, we're going to have a look around you and see how any different lengths you can find to write in each column of this table.

The first column is something that you would choose to measure in metres, and the second column is something that you would choose to measure in centimetres.

Sam says, "Remember that 1 metre is about the height of a door handle and 1 centimetre is about the width of your thumbnail." Try and keep those known lengths in your mind to help you decide whether you should choose to measure in metres or in centimetres.

Pause the video and go and have a go at that now.

Good work, everybody.

<v ->Let's have a look at the first question</v> and see which would be the most sensible measurement for each length.

My bedroom is about three metres long.

My skipping rope is about 2 metres long.

My water bottle is about 30 centimetres tall.

And my chair is about 70 centimetres wide.

Well done if you've got those correct.

Good job.

The second question, there are lots of different objects and lengths that you might have found to write into your table.

Here are some ideas of the kinds of things that you might have written down.

To measure using metres, you could have things like the length of a room, the height of a garage roof, the length of a field, the width of a school hall, the distance you can run in a minute or the length of the fence around the park.

Distances that are quite long is what we are looking for when you choose to measure using metres.

In the second column, measure using centimetres, you're looking for lengths that are shorter, for example, the length of a pencil, the height of a toy car, the length of an eraser, the width of a book, the distance a snail moves in one minute or the length of the fence around a toy farm.

Remember that it is possible to measure any length in metres or centimetres, but usually one unit will be more helpful to choose than the other.

Well done if you thought really carefully about using metres when you want to measure a longer length and centimetres when you want to measure something shorter.

Now that you are at the end of the lesson, you have learned that metres and centimetres are both standard units of measure that can be used to measure length.

All of these lengths are about 1 metre, the length of a guitar, the height of a 5-year-old, the width of a staircase, the length of a large dog like a German Shepherd police dog and the height of a door handle.

Metres are usually used for measuring longer lengths.

For example, the height of a ceiling or the length of a room, centimetres are useful for measuring shorter lengths such as the height of a water bottle or the length of a pencil.

Well done for thinking so carefully about the different units of measure for length today.

You have done some excellent work.

Well done.

I hope that I will see you again soon for some more maths learning.

Bye, everybody.