Lesson video

Hello, my name's Mrs. Hopper and I'm really looking forward to working with you in our maths lesson today.

We are going to be doing some counting, we're going to be looking at numbers, we're going to be thinking about numbers, and I hope we're going to have some fun as well.

So let's make a start.

Hello and welcome to this lesson from our unit composition of numbers 11 to 19.

In this lesson we're going to be explaining that the digits in the numbers 11 to 19 express a position on a number line.

So let's get on and see what our lesson's going to be all about.

We've got some key words.

They may be ones that you know, but let's practise them anyway.

So I'll say them first and then it'll be your turn.

So my turn, one more your turn.

My turn, one less your turn.

My turn, estimate your turn.

So you might say estimate.

Sometimes people say estimate as well.

So we'll have a think about what those mean as we go through this lesson today.

So look out for them.

Two parts to our lesson today.

We're going to start off by finding numbers on a number line.

And then in the second part there's that word estimating numbers on a number line.

So let's get on with part one of our lesson.

And we've got Alex and Aisha helping us in our lesson today.

So those numbers 11 to 19, we call the team numbers.

And so the team numbers are between 10 and 20 on our hundred square.

So let's have a look at them.

So there's 10 and 20 and our team numbers are in between.

And there they are.

So the team numbers start with a one digit, which represents 1 ten.

So we can think of them as 10 and a bit 10 and some more ones.

We can see them on a hundred square.

and there they are.

So let's count from 10 to 20 and think carefully about the order of the numbers as we say them.

So there's 10 and 20.

So let's count.

Are you ready from 10? So we start our count at 10 and we count 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20.

Well done.

Good counting.

Should we look at those numbers? There they are.

And those are our numbers between 10 and 20, our team numbers.

So as we said, team numbers are between 10 and 20 and they're made of 10 and a bit.

So you can see on our number line here, we've got one big jump of 10 and our team numbers are going to be an extra jump on from 10 all the way up to 20.

Let's use the stem sentence to help us think about the numbers bigger than 10 on the way up to 20.

So we are going to say, hmm is made of one 10 and hmm ones.

So what's the number after 10? We've got 11.

And we can complete our stem sentence.

11 is made of one ten and one one.

What's next? 12, that's right.

12 is made of one ten and two ones.

Let's carry on.

13 is made of one ten and three ones.

14 is made of one ten and four ones.

15 is made of one ten and five ones.

I hope you're saying these along with me.

Are you ready? 16 is made of one ten and six ones.

17 is made of one ten and seven ones.

18 is made of one ten and eight ones.

And 19 is made of one ten and nine ones.

Well done.

We've seen the 10 and a bit in our teen numbers.

There's numbers between 10 and 20.

So let's have a look at the first two rows of the hundred square.

So we've just snipped off the first two rows.

What do you notice? Hmm, I wonder what you can see.

What can I see there? I wonder what Aisha and Alex have seen.

Aisha says the team numbers all start with the digit one and we can see that in our second row all the way up to 20.

And Alex says the team numbers end in the same digit as the one digit numbers.

Oh, yes.

Can you see that pattern there? Let's have a look at a couple of examples.

So we've got a one in our one digit number and then 11, our number underneath, our number greater than 10 between 10 and 20 has one ten.

And at that same one in the ones.

Can we see any more? We look at four and 14, we can see that four in the one as the one digit number and the four being the one digit of our team number.

And let's look at nine and 19 as well.

Can you see that one digit number being repeated as the ones digit of our team number? Interesting.

And we can see all along the road that that's the case.

So we can use our knowledge of the numbers one to nine to help us find team numbers on number lines.

So let's see if we can use that to solve some problems. Right, we've got some gaps on our second number line here.

We've got two number lines, one going from zero to 10 and the next one going from 10 to 20.

And we've got some numbers marked.

And can you see that pattern that we were just spotting in the a hundred square with the one digit repeated in our two digit team number? What number comes next when we're looking at numbers on the number line and how do you know? And Aisha says, well we're sort of finding one more each time, one of our keywords.

And Alex says we can use the one digit numbers to help.

So let's have a look.

So let's have a look at that gap on our bottom number line.

Aisha's saying one more than one is two.

And we can see that on our top number line.

One more than one is two.

So what's going to be one more than 11? Alex says, so 12 is one more than 11.

As we can see that one is increasing to a two.

One more than one is two, so 12 must be one more than 11.

Let's have a go at another one.

Aisha says one more than four is five.

How can we use that to help us with the bottom number line? What's one more than 14 going to be? Ah, Alex says so 15 is one more than 14.

If one more than four is five, then 15 must be one more than 14.

And let's have a look at the final one on here.

So seven.

And Aisha says, well, one more than seven is eight.

So can we fill in that gap next to 17? Yes.

Alex says 18 is one more than 17 and we can see that seven, eight pattern repeated in our team number, like we could with the 14 and 15 and the four and five and the 11 and 12 and the one and two.

Time for you to check your understanding.

Can you use that idea of one more and the number that comes after to say what comes after 17? So pause the video, have a go and then we'll look at it together.

How did you get on? Did you see that it was 18 and Aisha's saying one more than seven is eight.

So Alex is saying, so 18 must be one more than 17.

Well done if you've got that right.

So we can use one more and one less to help us to order numbers.

So let's look at these two strips of numbers with teen numbers in them and let's start with the middle one and think how we can think about the one more and the one less to describe the numbers we've got there.

So let's start with 14 and we can say that 15 is one more than 14 and we can also say that 13 is one less than 14.

Let's have a look at the other strip and start with 16.

So what can we say here I wonder? Well we can say that 17 is one more than 16 and 15 is one less than 16.

So we can use that idea of one more and one less to check that we've got our numbers in the correct order.

So we can find numbers using one more and one less.

We can say that 12 is one more than 11 or 11 is one less than 12.

We can say that 12 is one less than 13 and 13 is one more than 12.

Let's have a look at the 18.

What can we fill in around 18? So we can fill in the 17, can't we? We can say that 18 is one more than 17 or 17 is one less than 18.

And what about the gap the other side of 18, what's that number going to be? It's 19, isn't it? So we can say that 18 is one less than 19 or 19 is one more than 18.

So we can use that idea of one more and one less to fill in gaps on a number line.

So where's 15 on the number line? Well we can see it there.

What's special about 15? Hmm.

So we can use it to find missing numbers.

So, let's look at the gap next to 15.

What can we say? The number in the gap is 14 because we know that 15 is one more than 14 or 14 is one less than 15.

And what about the other side of 15? Ah, so we can say that 15 is one less than 16 or 16 is one more than 15.

We can also say that 15 comes between 14 and 16.

So you can see there 15 is in the middle between 14 and 16.

So we can use the number line to find where the numbers go and we can see which numbers they are between.

And you can see there we've jumped from 14, one more is 15, one less is 13, and from 16 one more is 17 and one less is 15.

We can also say 14 comes between 13 and 15.

So what can we say about 16 do you think? That's right, 16 comes between 15 and 17.

What other numbers can you describe? I wonder if you could pick some other numbers on the number line and describe what's one more, what's one less and what's in between.

Time to check your understanding.

Where do these numbers go on the number line and how do you know? And we can use that idea of one more, one less or in between.

So pause the video, have a go and then we'll talk it through together.

How did you get on? Did you work out where those numbers go? So there's 13 and 13 we can say comes between 12 and 14.

We could also say that 13 is one more than 12.

And what about 16? Well we might know that 16 comes between 15 and 17 and there's the 17 going in, but we can also say that 16 is one more than 15.

And what about 19? 19 comes between 18 and 20 and we had those numbers both on the number line.

But we can also say that 19 is one less than 20.

So different ways to describe how we know where those missing numbers go on the number line.

Thinking about one more, one less or numbers in between.

Time for you to do some practise.

So you are going to fill in the missing numbers in the sequences and explain how you know.

So you might want to use that idea of one more, one less or in between to say how you know what the missing number is.

And for the second part, you are going to find these numbers on the number line and complete the stem sentences.

So you're going to think about how those numbers are made, one 10 and hmm ones and which numbers it is between on the number line.

So pause the video, have a go at your tasks and then we'll talk them through together.

How did you get on? Did you fill in the missing numbers? And how did you know? Did you know that it must be 12 because 12 is between 11 and 13? Did you know it was 12 because you know that 12 is one more than 11 or one less than 13 is equal to 12? So hopefully you found all those missing numbers and you used your knowledge of one more, one less and numbers in between to help you.

And for the second part, you had to find the numbers on the number line and explain how you knew.

So you can see there are arrows showing us where those numbers sit on the number line.

So let's think about those stem sentences.

Our first one was 11.

11 is made of one ten and one one and it is between 10 and 12.

What about 13? How many tens? Well we know it's one 10.

How many ones? That's right, three ones.

So one ten and three ones and it's between 12 and 14.

What about 15? We know it's one 10, but how many ones? Well done, it's five ones.

So 15 is made of one 10 and five ones and it is between 14 and 16.

About 17.

One ten and seven ones, well done.

And it's between 16 and 18.

And 19 is made of one 10 and nine ones and it's between 18 and 20.

And can you see the number of ones? Could you spot them in the numerals that make up your digit? So in 15, one ten and five ones.

And we can see the five ones there clearly in our number 15.

Well done.

Onto the second part of our lesson where we're going to be thinking about estimating numbers on a number line.

So we've only got 10 and 20 now, where is 15 on the number line and how do you know? What could we do to find out? Well we could count on couldn't we? Because we've got the marks there so we could count on and if we did, we'd find out that this is where 15 goes.

There it is on the number line.

15 is a teen number and it comes between 10 and 20.

That's right, so we know it's on that number line.

What's important about 15 is it is halfway between 10 and 20.

It is the midpoint we call it.

So if we needed to rest halfway between 10 and 20, we'd rest at number 15.

And it's useful number 15 in the middle there because we can use it to help work out where other numbers go on our number line.

Oh, now this number line's a bit different, isn't it? And we say here we can show that midpoint where 15 is when the line doesn't have any marks on it as well.

So we've got to work out where's it going to go.

So Aisha says 15 is the midpoint, it's halfway between 10 and 20.

So can we imagine halfway on that number line? There it is, so there's 15.

And Alex says this can help us to estimate the position of other numbers.

Hmm, what do we mean by estimate? Well we haven't got any marks there so we might not be absolutely in exactly the right place, but an estimate is just about the right place.

It's a good guess as to where that number is, a guess that we've used some other ways of thinking to help us to make sure that that number is as close to being in the right place as we can.

So estimating is getting just about the right answer.

So let's have a think how we can estimate.

So we can estimate where numbers go on the number line and we can see if they come before or after that midpoint of 15.

So let's have a go.

I wonder what's there.

So Aisha says this number is before the midpoint, so it could be 14.

What about this one here? Alex says this number is after the midpoint, so it could be 16.

They're not very far away from 15, are they? But one of them is before 15, so less than 15 and one of them is after 15, so it must be more than 15.

So where is 14 on the number line and how do you know? Is it before or after the midpoint? Aisha says 14 is between 10 and 20.

Yep, so it's definitely on this number line, isn't it? Alex says 14 is nearer to 10 than 20.

Hmm, how does he know that? Well, it's less than 15, isn't it? So it's got to be in that bit between 10 and 15.

And Aisha says 14 is near the midpoint 'cause it's not far from 50, is it? And Alex says 14 is one less than 15.

So can you see, by the way, they've talked about the number, they've started thinking, yes, it's on this number line, it's in that part of the number line, but it's very close to this because they know that 14 is one less than 15.

So 14, a good estimate is that 14 is about there on the number line.

Where is 19 on the number line and how do you know? Is it before or after the midpoint? Have a think.

Hmm, I wonder what Alex and Aisha are going to help us to think about.

So she said well 19 is between 10 and 20 so we know we've got the right number line.

Alex says though this time 19 is nearer to 20 than 10.

And you might know that just from your counting, won't you? And she says 19 is nearer to 20 than it is to 15.

We have to count quite a long way on before we get from 15 before we get to 19.

Ah, this is the really key bit though, isn't it? Alex says 19 is one less than 20, so we know it's going to be very close to 20.

This is a good estimate of where 19 goes on the number line.

Time for you to check your understanding.

So think about all the things that Alex and Aisha had said to estimate where the numbers go on the number line.

Have a think and talk to somebody about where you think 11 goes on this number line and how you know.

So pause the video, have a go and then we'll have a talk about it.

How did you get on? I wonder if you had some of these conversations and said some of these things as well.

Aisha says it is between 10 and 20, so we've got the right number line.

Alex says it's nearer to 10 than 20.

11 is nearer to 10, isn't it? It's nearer to 10 than 15, Aisha says.

So we know it's going to go further towards the 10 end of our number line even than towards 15 in the middle.

And then Alex says, well 11 is one more than 10.

So we know that it's just beyond 10.

So I wonder if you use some of that thinking and some of those sentences to help you to decide where 11 goes on the number line.

Oh, now.

This one's not very close to anything, is it? So I wonder what number this is.

Can we estimate what number is being shown by the arrow? How do you know? Is it before or after that midpoint of 15? Aisha says it's more than 15 but less than 20.

So it's between 15 and 20.

Alex says it's a bit nearer to 15 than it is to 20.

Hmm, I wonder what that tells us.

Aisha says 16 is one more than 15, but it's further away than that.

So Alex says, I estimate that the number is 17.

So he thinks that that arrow marks 17.

I think that sounds about right.

Aisha said something interesting, saying 16 is more than 15, but it's only one more and that the mark was showing a number that was a bit further away.

And so then Alex thought, well, if it's not 16, maybe it's 17.

Still just about closer to 15.

Your turn to have a go.

So can you estimate what number the arrow is pointing to on the number line? How do you know? Is it before or after the midpoint? Where would the midpoint go on our line? Where would 15 go? So pause the video, have a think, have a chat to somebody and when you're ready, we'll go through the answer together.

How did you get on? What did you think? Did you put 15 in to help you? Hmm, so Aisha says it is between 10 and 20.

Alex says it's nearer to 20 than 10.

And Aisha says, well it's between 15 and 20.

And Alex says, yes, but I think it's nearer to 20 than to 15.

Hmm.

He says, 18 he thinks is a good estimate.

I think he's about right as well, isn't he? He's definitely more than 15.

And it's probably closer to 20 than it is to 15.

So 18 is quite good.

Not right next to 20 'cause that would be 19.

So 18 is a good estimate.

Time for you to have some practise.

You are going to estimate where these numbers go on the numbers line.

So are the numbers between 10 and 15 or between 15 and 20, which side of the midpoint do they go? Are they closer to the midpoint or are they closer to 10 or closer to 20? Think about what you know about these numbers to help you to estimate their position and see if you can then compare your answers with a friend and discuss who you think has the best estimate.

And for the second part, you are going to draw your own number line from 10 to 20 and mark in all the team numbers and explain to somebody how you knew where to put all the numbers.

And we've given you an example here, but we've put 15 on as well.

But you are going to draw in your own number line from 10 to 20 and mark on all the team numbers.

So pause the video, have a go at your tasks and then we'll have a look through them together.

How did you get on? Did you estimate the position of these numbers? Were yours in about the same place that I got them? And here we've got some thinking.

I knew that 13 was one more than 12, so they went next door to each other.

I knew that 19 was one less than 20, so it went before.

And 16 is after 15 and I left a little gap between them.

So thinking about the gap maybe rather than the one more, one less there.

So lots of different ways you might have thought about where to estimate your numbers.

And then you were drawing your own number line from 10 to 20 and putting on your numbers.

We've done a very accurate one here with the midpoint of 15.

And Aisha says, I knew the midpoint was 15.

And Alex says, I used the midpoint to help me mark the other teen numbers.

I wonder how you got on.

I hope you enjoyed it and thank you for working so hard.

So we've come to the end of our lesson today, explaining about the digits in the numbers 11 to 19, and knowing that they can be positioned on a number line and we can use the digits to help us to position those numbers.

We said the teens numbers as one ten and hmm ones.

And we know that that helps you to position them on a number line line.

We've also learned that there's a link with the position of the numbers one to nine on a number line and the numbers 11 to 19.

And we could see that repeating pattern in our ones digits.

And knowing that one more and one less than a number to 20 can help you to estimate the position of team numbers on a number line.

Thank you for your hard work and your thinking today and I hope I get to work with you again soon.

Bye-bye.