Lesson video

Hello and welcome to this lesson, finding the missing number from zero to 20.

By the end of this lesson, you'll be able to find missing numbers between zero and 20 on a number track.

So we'll be using the numerals this time.

So we'll be doing lots of counting forwards and counting backwards to work out what the missing numbers are.

There are three parts to our lesson today.

In the first part, you're gonna be spotting missing numbers between zero and 10.

In the second part, you're gonna be finding missing numbers between 11 and 20.

And in the final part, you're gonna be solving some missing number problems by counting forwards and by counting backwards.

So let's start our lesson in the first part.

So this is spotting the number from zero to 10.

So let's start by counting.

It says, "Can you help Jacob count up to 10?" We're going to count alongside the numerals.

Are you ready? So zero, one, two, three, four, five, six, seven, eight, nine, 10.

Well done.

Now then, can you help Jacob count back from 10 to zero? And again, we're gonna look at the numerals and count back with them.

Are you ready? 10, nine, eight, seven, six, five, four, three, two, one, zero.

Well done.

Now we're going to look for a missing number.

So if you look on the screen, you'll see all the numbers up to 10, but one of them is missing and there's a question mark instead.

So we're gonna count up and see if we can work out what the missing number is.

So let's count from zero up and see if you can spot what the missing number is, ready? Zero, one, two, three.

It's going to be four.

Four is missing because four is one more than three.

And the next number on there we can see is five, and four is one less than five.

Let's just click.

And there we are, we can see we're right.

The answer is four.

So the missing number in the first one is four.

Let's try a second one.

Can you find where the question mark is? So that's our missing number.

It's right in the middle.

So we could count forwards or we could count backwards to work this one out.

Let's count backwards this time.

So let's start at 10 and count backwards until we find that missing number.

Are you ready? 10, nine, eight, seven, six, five.

Oh, the missing number is five.

And it's five because five is one less than six and it's one more than four.

Let's try another one.

Well, this is right up the other end too so I can see where the question mark is.

So I'm going to count backwards from 10 'til I find it.

Are you ready? 10, nine, eight.

Yes, it's seven.

Seven comes before eight.

Seven is one less than eight.

Well done.

Now we're gonna check that you understand where the missing numbers are.

So I'm going to put some numbers on the screen.

You're going to work out what the missing number is.

Let's start, ready, so here are your numbers.

So there's four numbers on the screen.

Can we read them together, ready? Three, four, question mark, six.

So what is the missing number? What do you think it is? Let's have a little think.

And how do you know? Yes, it's five.

Five is one more than four and it's one less than six.

There it is, five.

Let's try a second one.

Let's put the numbers on the screen.

Right, we're counting backwards this time because we starting with a five.

Let's read those numbers together.

Five, four, question mark, two.

So what's the missing number? Five, four.

Yes, that's right, it's three.

And how do we know? Well, we know it's three because three is one less than four.

Three comes before four.

And three is one more than two.

There we are, so three is one more than two and one less than four.

Let's, oh, there's the three.

Let's try another one.

Right, five.

There are five boxes on the screen this time, and that question mark's right at the start.

So let's count backwards from 10 to see if we can work out what the missing number is.

Are you ready? 10, nine, eight, seven.

And the missing number is, yes, it's six.

And how do we know? Because six comes before seven and it's one less than seven.

Well done, there it is.

Last one.

So five numbers again, we've got starting on five.

We could start on five and go forwards.

Or we could count on nine and go backwards.

Let's start on five and count forwards this time, ready? Five, six, seven, question mark, nine.

So the missing number is, yes, that's right, it's eight.

And how do we know? Because eight is one more than seven and it's one less than nine.

So it becomes before nine and it is after seven.

Well done.

Now we've got a worksheet for you to do.

So on this worksheet, it's just like the activity we've been doing.

So you'll see you've got lots of number tracks.

There are four number tracks on the screen, and there's one missing number or two in the last question.

And you've gotta work out what those missing numbers are.

And you're going to decide whether it's easier to count forwards or whether it might be quicker to count backwards.

Pause the video now and you can work on your worksheets.

How did you get on? Were you able to work out the missing numbers? Here are the answers to task one.

I've shared them on the screen now.

Let's look at that first number track.

Did you start at zero and go forwards or did you start at 10 and count backwards? Might've been easy to count backwards because the missing number's right at the end near to 10.

It's the number before 10.

So we would be able to go 10, nine.

What about the second one? Did you count forwards or did you count backwards? If you counted backwards, you could have said 10, nine, eight, the missing number is seven.

Now, for the third one, you might have counted forwards because it would probably be easier.

So you'll be able to go zero, one, two, three, four, five, six, seven, eight, nine.

And the number after nine is 10.

So there's the missing number.

And on the final one, we had two missing numbers, and they were four and eight.

So you could have counted forwards or backwards to work them out.

Did you get them all right? Well done.

We've now finished the first part of our lesson.

We're moving on to the second part where we'll be finding missing numbers from 11 to 20.

Let's start off by counting from 11 through 20.

We're gonna count forwards and then we're gonna count backwards.

So let's start by counting forwards from 11 to 20, ready? 11, 12, 13, 14, 15, 16, 17, 18, 19, 20.

We counted along the number track.

Now we're going to count backwards from 20 using the numerals, count back from 20, and we're gonna stop at number 11.

Are you ready? 20, 19, 18, 17, 16, 15, 14, 13, 12, 11.

That's where we're gonna stop.

So we know that we can count forwards and backwards to work out missing numbers.

Now then, on the screen, you can see the number 14.

There are two missing numbers this time.

We can count forwards and backwards to work out the missing numbers.

So our first question is what number comes before 14? We're counting backwards from 14.

The first number we would say would be, after 14, would be, yes, it would be 13.

We're counting backwards, say 14, 13, 12, 11, 10.

Now, which number comes after 14? So when we're counting forwards, we'd say 13, 14, 15.

Let's try another one.

This time, you can see number 17 on the screen.

So again, we're gonna count forwards and backwards to work out the numbers on either side.

So let's start by thinking which number comes before 17.

So what is one less than 17? So if we're counting backwards, we'd say 17, 16.

That's right, so 16 comes before 17.

And then if we're counting forwards, what number comes after 17? What number is one more than 17? We'd say 16, 17, yes, it's 18.

Well done.

Now let's check.

Now, this time, it's a little bit more tricky because we don't know where it is, and it says, "If 17 is one of the numbers, what could the others be?" So we don't know if 17 is first number, the second number or the third number.

So pause the video now and see if you can figure out what the numbers could be.

So how did you get on? What numbers did you find? Did you place 17 as the first number, in which case you would have 17, 18, 19 because 18 is one more than 17 and 19 is one more than 18.

Or did you find a different answer? If you put 17 in the middle, you could have had 16, 17, 18.

So one less than 17 is 16 and one more than 17 is 18.

And you could put 17 on the other side.

So then you'd have had to count back, would you say 17, 16, 15.

So there's three different answers that you could have had.

Let's try another question.

This time it says, "If 13 is one of the numbers, what could the others be?" So remember you've got to move 13 and put 13 into the different positions and decide whether it's gonna be the first number, the second number or the third number.

Pause the video now so that you can have a go.

So which missing numbers did you find? Where did you place number 13? Was it in the left hand column, in the middle or on the right? You may have put 13 as your first number, in which case you could count on from 13, counting forwards, and you'd be able to say 13, 14, 15 because 14 is one more than 13 and 15 is one more than 14.

Did you find another way? Did you put 13 in the middle? If you put 13 in the middle, then you would be able to count backwards from 13.

One less than 13 would be 12 and one more than 13 would be 14.

And if you put 13 on the far side, then you'll be able to count backwards from 13.

And so you'd have 13, 12, 11 because one less than 13 is 12 and one less than 12 is 11.

Well done.

Did you find all those ways? Let's try this one.

So if 16 is one of my numbers, what could the other numbers be? Pause the video so you can see if you can find the three different solutions.

So did you find all three solutions? So one of them would be 16 at the front.

So you'd have 16, 17, 18 because 17 is one more than 16 and 18 is one more than 17.

If you put 16 in the middle, you'd have 15, which is one less than 16, and you'd have 17, which is one more than 16.

And finally if you put it on the other end, you'd be able to count backwards because you'd be able to use your counting backwards to help you.

So you'd be able to go 16, 15, 14, done.

Right, this time you've got four spaces.

It says, "If 15 is one of my numbers, "what could the other numbers be?" So there's gonna be a few different solutions to this one.

See if you can have a go.

So pause the video now while you see if you can work out some of those solutions.

Did you manage to find four solutions? Let's have a look at the ones that you found.

Let's see if you've found this one.

So the first one I found, I put 15 in the first box.

So it made 15, 16, 17, 18, and I could count forwards from 15 to work out the three missing numbers.

Did you find that one? Did you find any others? Did you find this one? So I moved 15 into the second box.

So my answer was 14, 15, 16, 17.

So I could count forward from 15 to find 16 and 17, and then I counted backwards from 15 to find 14.

What about this one? So this time, 15 is in the third box, so I could count forwards to find 16, and then I counted backwards from 15 to find 14 and 13.

And finally, I put 15 in the fourth box.

And this time, I just had to count backwards.

So I started on 15 and counting backwards from 15, we say 15, 14, 13, 12.

Did you find all of those solutions? Well done.

It's now time for task two.

For this task, your teacher or your adult will have some bead string cards which represent the numbers 11 to 20.

To explain this task, I have chosen the bet string that represents number 13.

You'll also have a worksheet just like the one on the screen.

You'll need to put the bead stringing card in the middle of the first row, and then you can work out one more and one less.

In this example, because I chose number 13, I need to find one more than 13 and one less than 13.

And then in the empty spaces, I'm gonna draw a picture of one more and one less.

Now then, in the second row, I've got to move my bead string card and put it in the one less column.

Now I've got to work out what goes in those empty boxes on the side.

So in a way, I've got my one less already, so I now need to think what's the next number? What's one more than 13 and one more than that number? And in the final one, you can see I put the bead string card in the one more column, so that one, I'm going to have to count backwards.

The bead string cards that you're going to have are gonna be like these.

So you'll be able to choose one of those different bead stringing cards as your starting point.

Pause the video now so that you can have a go on this activity.

How did you get on? Which bead string card did you choose? Let's go through the answers for this example.

So do you remember I chose bead string number 13.

So the first thing I had to think about is so what is one less than 13? What number comes before 13? So I need to count backwards.

So I've got a picture here to represent the number 12 because 12 is one less than 13.

Then I had to think what is one more than 13? So the next number after 13 is 14.

So there's my picture to represent number 14.

Now, in the middle column, you can see 13 is in the one less column.

So now I need you to think what is one more than 13, which is 14.

And so counting forwards again, one more than 14 is 15, and there's my 15 beads on the bead string.

Now, in the final one, my 13 is in the one more column down at the bottom.

So now I've got to count backwards.

So I've got to go less, I've got to think there's my one more.

So 13 is in the one more column.

So one less than 13 is going to be 12, and one less than 12 is going to be 11.

How did you get on? Which one was the trickiest to do? We've now finished the second part of our lesson, and we're moving into the final part, where we will be solving missing number problems. So on the screen in front of you, you can see some number cards and the number cards are representing the numbers from zero through to 20.

You can also see a bead string, and the bead string is representing the number nine.

So we think about this, we're solving the problems here.

We think eight is one less than nine and 10 is one more than nine.

So we're able to use our knowledge of counting forwards and backwards to work out which numbers are on either side of nine.

So which one is less than nine and which one is more than nine? Let's try another one.

This time, the bead string is representing number 16.

Can you find 16 on the number track? So now then, we can think about which number is one less than 16 and which number is one more than 16? So 15 is one less than 16.

If we're counting backwards, we'd say 16, 15, 14 to 13.

And to find one more, we're going to count forwards.

So if we're counting forwards from 16, we'd say 16, 17.

So 17 is one more than 16.

Let's try this one together too.

So this time, our bead string is representing the number 18.

So now we know that if we count backwards from 18, we'll get to number 17 because 17 is one less than 18, the number before 18.

So we count 18, 17, 16.

And to find the number one more, we count forwards.

So if we're counting forwards from 18, the next number we would say would be 19 because 19 is one more then 18.

Now then, we've got some missing numbers here for you.

Have a look on the screen, this is to check.

Now can you see there are three numbers that are missing this time? We've got a question mark, and we've got 12, a question mark, 14, and another question mark.

And we need to work out what the missing numbers are.

And we've got a sentence underneath.

So something is more than something and something is one less than something.

Pause the video now, see if you can work out what the missing numbers are.

So did you use those sentences to help you? Were you able to work out the missing numbers? So I think the first sentence I'm going to use is the one less than because that first number there is one less than 12.

So what is one less than 12? So one less than 12 would be, yes, it'll be 11.

So now I've got the start of my pattern.

I might be able to work out what those numbers are.

So if I know the first number is 11, I can count forward, I can go 11, 12.

So the next number should be, yes, it'll be 13 because 13 is one more than 12.

And I can carry on my count.

So 11, 12, 13, 14.

So the final number's going to be 15 because 15 is one more than 14.

So the sentences can really help us work out what those missing numbers are.

Let's try a second one.

So remember to look at those little sentences underneath to help us.

We've got the first number this time.

So you might be able to count forwards to work out the missing numbers.

So you'll be finding what is one more than each time.

Pause the video now so that you can solve this puzzle.

How did you get on? Did you manage to work it out? Did you count forwards to work it out? So I suspect you started on the seven.

So one more than seven is eight and one more than eight is nine.

Then we've got 10.

So one more than 10 would be 11.

Fantastic, did you get that right? And did the sentences help you? Let's try this one here.

Oh, we've got lots of question marks.

We've got the number 17 and the number 19.

Pause the video and see if you can figure out what the missing numbers are.

How did you get on with that one? It was quite tricky, wasn't it? Where did you start? I started by using that sentence one more than, and I looked at number 12 and I thought, what is one more than 12? So I could count forwards from 12.

So counting forwards from 12, the next number is, yes, it's 13.

And then I thought I can count backwards now, so I can think what is one less than each time so I can count back from 13.

Let's do it together.

So we'd say 13, 12, 11, 10, 9, and we've solved it.

Did you get that right? Fantastic.

Now then, got task three, and for task three, you're going to have a handout with these number tracks in front of you, and you can see each of the number tracks has got some missing numbers.

So I want you to see if you can figure out what the missing numbers are.

So you can count forwards or you can count backwards if that's easier.

Pause the video now and see if you can work out the missing numbers.

So let's have a little look at the missing answers, shall we? So for the first one, did you go forwards or did you go backwards? So we've got eight, 10 and 12.

So we've got two missing numbers.

So for this one, I think it might easier to go forwards.

So we're counting one more each time.

So one more than eight would be nine.

So we could go eight, nine, 10, 11, 12 because 11 is one more than 10.

Let's look at the second one.

So we've got 12 or we've got 15 and 16.

I'm going to count forwards again on this one too.

So what number comes after 12? The number after 12 is 13, and the number after 13 is 14.

So we can check, we can say 12, 13, 14, 15, 16.

So we got that one right too.

Now let's look at the third one.

Oh, we don't know the first number, but we do know the last number.

So this time, I think I might count backwards.

So we've got 17, so I now need to think what is one less than 17.

So one less than 17 would be 16.

So I can count backwards.

We could go 17, 16, 15, 14, 13.

Did you get that one? Now let's look at this last one, oh, we've got a number in the middle.

Don't know either end.

So I think we might start by going forwards from 18 to see what the end number is.

So what's one more than 18? One more than 18 is, yes, it's 19.

So now I've got the last two numbers, I could count back.

So I could go 19, 18, 17, 16, 15.

Did you work that one out too? Well done.

We've now reached the end of our lesson.

We've been solving lots of different missing numbers problems from zero to 20.

So we've realised that we can solve these problems by counting forwards or counting backwards.

And when we're counting forwards, we're thinking what number is one more than.

And when we're counting backwards, we're thinking what number is one less than.

So when we're thinking about these numbers that are next door to each other, they're called consecutive numbers because they're numbers that are next to each other and they've got a difference of one.

Well done, thank you for working so hard during this lesson.

I look forward to working with you again soon, bye.