Lesson video

My name is Miss Coe.

I'm really, really excited to be working with you, on this lesson today.

If you're ready, let's get going.

So, welcome to this lesson today, which is all about three digit numbers.

By the end of this lesson, you will be able to count forwards and backwards, in twos and 20s, fives, and 50s and 25s.

Lots of counting, in this lesson.

So if you're ready, let's get going.

We have two key words for today's lesson, multiple and pattern.

I'm going to say the word, and I'd like you to say them back to me.

Are you ready? My turn.

Multiple.

Your turn.

My turn.

Pattern.

Your turn.

Great job.

Let's have a look at what those words mean.

A multiple, is the result of multiplying a number, by another whole number.

So 10, 20, and 30 are all multiples of 10.

And two, four, six and eight, are all multiples of two.

A pattern is when objects, or numbers, are arranged following a rule.

A pattern is a repeated set of numbers, shapes, or objects.

So our lesson today, which is counting forwards and backwards, is going to be in two parts.

For the first part, we're going to look at counting in twos and 20s, and then we're going to look at counting in fives, 50s and 25s.

As I said, we're going to be doing a lot of counting, so I hope you've got your great counting voices with you.

Let's get started in the first part of our lesson.

In this lesson, we're going to meet Sofia and Andeep, and they are going to be helping us with our counting.

Andeep is counting in multiples of two.

He says, that the ones digits appear in a pattern, when you count in twos.

Let's have a look.

We're going to count in twos.

Can you count with me? Are you ready? Two, four, six, eight, 10, 12, 14, 16, 18, 20.

Let's look at those ones digits.

Can you see the pattern, as well? Sofia says, the ones digits are always two, four, six, eight or zero.

So all multiples of two, end that way.

The pattern repeats, any time you count in twos.

Sofia counts in two, from a different multiple of two.

So Sofia is going to start at 50.

Let's try counting together.

Think about what our next number's going to be.

What is two more than 50? Are you ready? 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70.

Great counting.

Andeep counts in twos, from another multiple of two.

He's going to start at 74, which is a multiple of two.

So again, count with me.

Are you ready? 74, 76, 78, 80, 82, 84, 86, 88, 90, 92, 94.

Well done.

Let's look at those patterns, for a moment.

Can you see, how the ones digits are always zero, two, four, six, eight? And that pattern repeats.

So even when Andeep started as a number ending in four, we have four, six, eight, zero.

Then we have two, four, six, eight and so on.

Well done, if you spotted that pattern.

Sofia is counting in twos.

She's going to start at 260, a different multiple of two.

We're going to count with her.

Think about what the next number will be.

What is two more than 260? Are you ready? Let's go.

260, 262, 264, 266, 268, 270, 272, 274, 276, 278, 280.

Well done, if you kept up with me.

Andeep's also going to count in twos, and he's going to start from another multiple of two, he's going to start at 492.

Again, think about what the next number will be.

What's two more? Count on, in your head.

Are you ready? 492, 494, 496, 498, 500, 502, 504, 506, 508, 510, 512.

Well done.

Now, even though these are three digit numbers that we're counting in, the same thing happens with the ones.

We can see, zero, two, four, six, eight repeating.

Andeep says that his count was a bit trickier, because it crossed the hundreds boundary.

But it doesn't matter.

We can still see that pattern happening.

Time to check your understanding.

Sofia counts in twos.

I'd like you to say her count.

She's going to start at 564, and count in twos, to 574.

I'd like you to say that aloud.

Pause the video here, and have a go.

And, how did you get on? Let's say the count together.

Are you ready? 564, 566, 568, 570, 572, 574.

Well done, if that was the count that you said.

This time, Sofia is counting backwards, in twos.

She's going to count back, from 344.

So she's still starting at a multiple of two.

Now, this time is going to be a little bit trickier, because we're counting backwards, but think about, what is two less than 344? I'd like you to try and count with me.

Are you ready? 344, 342, 340, 338, 336, 334, 332, 330, 328, 326, 324.

Well done, if you managed to count backwards.

Andeep is also going to count backwards, but he's going to start from 808.

Goodness me.

Let's try and count with him.

Remember, we're counting backwards.

So what is two less than 808? Are you ready? Let's go.

808, 806, 804, 802, 800, 798, 796, 794, 792, 790, 788.

Well done, if you kept up with that, because we had to cross the hundreds boundary, going from 800 to 798, which can be really tricky.

Time to check your understanding.

Count backwards in twos.

I'd like you to count back from 418, to 408.

Pause the video now, and have a go.

Welcome back.

How did you get on? Let's count back, together.

Are you ready? 418, 416, 414, 412, 410, 408.

Well done, if you said that count.

Andeep says, that you can use counting in twos, to help you count in multiples of 20.

He says the 10s digits appear in a pattern, when you count in 20s.

And I'm wondering if you can spot what's similar to counting in twos.

So we are going to count in 20s, from 20.

I'd like you to try and count with me.

Are you ready? 20, 40, 60, 80, 100, 120, 140, 160, 180, 200.

Well done.

Think about what you notice here about the 10s digits, when we're counting in 20s.

The 10s digits is always a two, four, six, eight or zero.

So when we counted in twos, the ones digits have that pattern.

Now we're counting in 20s, the 10s digits have that pattern.

That pattern repeats, any time you count in 20s.

Sofia uses base 10 blocks to represent counting in 20s, from a different multiple of 20.

She's going to start the count at 200.

So, she's representing it in base 10 blocks.

Let's see, if you can count with me.

Are you ready? 200, 220, 240 260, 280, 300, 320, 340, 360, 380, 400.

Look at those 10 digits, and the pattern that you can see there.

Sofia is counting in 20s, and this time she's going to start at 500.

Let's see, if we can count together.

What will be the next number? What is 20 more than 500? Are you ready? Let's go.

500, 520, 540, 560, 580, 600, 620, 640, 660, 680, 700.

Well done, if you kept up with that count.

Andeep is counting in 20s too, and he's going to start at 760.

Let's see, if you can count with me.

Are you ready? 760, 780, 800, 820, 840, 860, 880, 900, 920, 940, 960.

Well done.

Again, look at that pattern in the 10s numbers.

In both cases, even though we haven't started the same 10s number, we can see that zero, two, four, six, eight pattern all the way through.

Time to check your understanding.

Count in 20s.

I'd like you to start at 420, and count to 520.

Pause the video here, and have a go.

How did you get on? Let's count together.

Are you ready? 420, 440, 460, 480, 500, 520.

Well done, if you said that count.

So this time, Sofia is counting backwards in 20s.

She's going to count back from 400.

And this is tricky.

Think about, what is 20 less than 400? Maybe count back in 10s? Are you ready to count with me? Let's go.

400, 380, 360, 340, 320, 300, 280, 260, 240, 220, 200.

Well done.

Counting back can be really tricky.

Andeep is also counting back in 20s, and he's going to count back from 240.

Hmmm? Sofia said 240 too, so maybe we can use that to help us.

Are you ready? 240, 220, 200, 180, 160, 140, 120, 100, 80, 60, 40.

Well done, if you kept up with that count.

Now, in Andeep's pattern, he goes from three digit numbers, to two digit numbers.

But, if you focus on the 10s digits, you'll see that pattern still stays the same.

We still have a zero, two, four, six, eight pattern.

So now, we're going to think about counting in twos and 20s, in a slightly different way, by thinking about completing number tracks.

Can you spot multiples of two and 20? So, let's think about counting in twos or in 20s, and we can count forwards, and backwards, to find the missing numbers.

So, here is our number track.

We have 194 to start with, and then we have two missing numbers, for 200, a missing number, 204, 2 missing numbers and 210.

We're going to use our counting, to complete those number tracks.

Now, if I look at the numbers involved, I can see at the end of the numbers, I have a four, a zero, a four and a zero.

Now, I know that multiples of two end in zero, two, four, six or eight.

So I think we're counting in twos.

So, let's see.

We can count in twos from 194.

So my next number would be 196.

And then, we've got one more step before 200, so 198, 200.

Perfect, I think we're counting in twos.

So, we know that.

We can complete the rest of the number track.

200, 202, 204, 206, 208, 210.

So, we can use what we know about the numbers that we've got, to find the missing numbers.

Let's have a look at another example.

We have 320, 360, 380, and 440 on our line.

Now, these all end in zero.

So I think, let me look at the 10s.

Hmmm.

I can see a pattern there.

I've got two 10s, six 10s, eight 10s, and then four 10s.

I know, that multiples of 20, have a 10s digit of two, four, six, eight or zero, so I think we're counting in 20s.

Let's have a look.

We can count backwards, from 320, in 20s, to see.

So 320, 300, 280.

We can then count forwards from 320.

So 320, 340, 360, 380, 400, 420.

We've filled out another number track.

Now, it's your turn to have a go.

Complete the number tracks.

So think about whether you're counting in twos or 20s, and you might want to count forwards, or backwards, to find the missing numbers.

There are two separate ones for you to have a go at.

Pause the video here, and have a go.

Welcome back.

How did you get on? Let's look at that first one.

We have 680, 700, 740.

The ones digit is always the same, so I think we're counting in 20s.

I can count back from 680, to get 660.

And then, I can count forwards from 700.

Count with me.

700, 720, 740, 760.

Now, the second number track was in twos, because the ones digits was telling me that.

So, we've got 616, 618, 620, 622, 624, 626.

Well done, if you've got those correct.

Time for your practise task.

For question one, I'd like you to complete the number tracks.

So for A, B, C, and D, you have different instructions.

So if we look at 1A, you're starting at 100, and you need to count forward in twos.

So listen to the instructions, and the starting points carefully, to work out what you need to do.

Question two, you need to complete the number tracks.

So, we're either counting in twos or 20s.

Remember, you can count forwards or backwards.

Have a real close look at those numbers.

What are they telling you, about whether they're multiples of two, or multiples of 20? For question three, I'd like you to think about what the missing numbers are.

Show what the count would be, in twos and 20s, says Andeep.

So you have 360 there.

What would the missing numbers be, if you were counting forwards and backwards, in twos? And then what would it be, if you're counting forwards and backwards, in 20s? Once you've done that, think about what you notice.

Pause the video here, have a go at those three questions, and come back, when you're ready for some feedback.

And welcome back.

How did you get on with those tasks? Here are the completed number tracks for question one.

So pause the video here, and mark your work.

And, let's look at number two.

So if we look at the first number track, we can see that we have 210, 216, 220 and 222.

The ones digits told me that we were counting up in twos.

So our missing number track, altogether, if we count together, we have 210, 212, 214, 216, 218, 220, 222, and 224.

Well done, if you got those.

I'd like to look at the one starting 788.

I think this was a bit trickier.

Again, the numbers that we had, 794, 796 and 802, told me that we were counting in twos.

But what was tricky here, is when we had to cross the hundreds boundary.

So we had 794, 796, 798, and then, 800.

Well done, if you've got all of those correct.

For question three, the missing numbers are there.

So, take a moment to check your work.

And we're going to think about what we noticed in a second.

So, you might have noticed lots of different things, but Andeep looked at the numbers around 700, and he said, the numbers around 700 looked very similar.

So, if we think about 700 and 702, 700 and 720, 704 and 740, they have the same digits, don't they? They're just in a different order.

So well done, if you spotted something like that.

And you've also spotted, that all the multiples of two, have the same ones digit pattern.

So, if we look across the two top number tracks, you can see that six, eight, zero, two, four pattern every time.

Well done, if you spotted that.

Let's move on to the second part of our lesson, where we're counting in fives, 50s and 25s.

I hope you're ready to count some more.

Sofia counts multiples of five.

And she says, there is a ones digit pattern, when you count in fives.

So we had a ones digit pattern, in twos.

I wonder if you can spot the ones digit pattern, when we count in fives? So we're going to count in fives, starting from five.

Are you ready? Let's go.

Five, 10, 15, 20, 25, 30, 35, 40, 45, 50.

Well done.

What pattern can you see, in the ones digits? Well, Andeep is reminding us, that when we count in multiples of five, the ones digits are always five, or zero.

So it's a good way to check your work.

If your answer doesn't have a five, or a zero, it's not a multiple of five.

This pattern repeats, any time you count in fives.

Every other number is a multiple of 10, as well.

So, we have 10, 20, 30, 40, 50.

So that's a good way to check, too.

Sofia count in five, from a different multiple of five.

She's going to start at 230.

So, we're going to count together.

Think about, what is five more than 230? Think about that pattern, in the ones digits.

Are you ready? Let's go.

230, 235, 240, 245, 250, 255, 260, 265, 270, 275, 280.

Well done, if you kept up with that count.

Andeep is going to count from a different multiple of five.

He is going to start at 680.

So, let's count together.

Are you ready? 680, 685, 690, 695, 700, 705, 710, 715, 720, 725, 730.

Well done, if you kept up with that count.

Andeep said, that his count was tricky, because it crossed a hundreds boundary.

Now, it's time to check your understanding.

Sofia is going to count in fives, and you are going to say the count.

We're going to start at 555, and count to 580.

Pause the video, and have a go.

And, how did you get on? Let's count together.

Are you ready? 555, 560, 565, 570, 575, 580.

Well done, if that's the count that you said.

Sofia is now going to count backwards in fives, and she's going to start from 370.

Let's try her count, together.

Are you ready? 370, 365, 360, 355, 350, 345, 340, 335, 330, 325, 320.

(sighs) Phew.

Well done.

Lots of numbers there.

But do you notice, how the ones digits, that pattern remains? We have zero, five, zero, five all the way through.

Andeep's also going to count backwards in five.

Now, he's going to start from 415.

So, let's count together, from 415.

Are you ready? 415, 410, 405, 400, 395, 390, 385, 380, 375, 370, 365.

Well done.

Now, it's your turn, to count backwards in fives.

So, Sofia would like you to count back, from 410 to 385.

Pause the video, and have a go.

Welcome back.

How did you get on? Let's count together.

Are you ready? 410, 405, 400, 395, 390, 385.

Well done, especially for crossing that a hundreds boundary.

Sofia says, that you can use counting in fives, to help you count in multiples of 50.

So, remember earlier, we looked at twos and 20s.

We're now going to look at fives, and 50s.

She says, the 10s digits appear in a pattern, when you count up in 50s.

Let's have a look.

Let's count together in 50s.

Are you ready? 50, 100, 150, 200, 250, 300, 350, 400, 450, 500.

Can you spot the pattern in the 10s? Andeep says, just like with the ones digits, when we counted up in fives, the 10s digits are always a five, or a zero.

This pattern repeats, any time you count in 50s.

And every other number is a multiple of 100, this time.

So 100, 200, 300 and so on, are multiples of 100.

Sofia is going to use base 10 blocks, to represent counting in 50s.

So, let's just double check that count together.

Are you ready? 50, 100, 150, 200, 250, 300, 350, 400, 450, 500.

Can you see, how every other time, we made a multiple of 100? Sofia counts forward in 50s, from a different multiple of 50.

So, she's going to start at 400.

I'm sure you know the drill by now.

Let's count together.

Are you ready? 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900.

Well done.

Andeep is going to count, ooh, backwards in 50s.

And, he's going to start at 650.

Now, I can see 650 in Sofia's count.

So, I think that's gonna help us out, to begin with.

Are you ready? 650, 600, 550, 500, 450, 400, 350, 300, 250, 200, 150.

Well done, if you kept up with that count.

And just take a moment, to notice that 10s digit.

We've got that five-zero pattern.

I've also noticed, that the ones digit, is always zero.

I think that might be useful too.

Time to check your understanding.

I'd like you to count forwards, in 50s, starting at 400, and ending at 700.

Pause the video, and have a go.

Welcome back.

How did you get on? Let's count together.

450, 500, 550, 600, 650, 700.

Well done.

Sofia says that you can use counting in 50s, to help you count in 25s, this time.

Let's have a look at that.

She says, the same 10s and ones digits appear in a pattern, when you count in 25s.

So, let's see if we can count in 25s, together.

Are you ready? 25, 50, 75, 100, 125, 150, 175, 200, 225, 250.

So, can you see the same 10s and ones digits, that appear in each of those numbers? The 10s and ones digits are always 25, 50, 75 or zero.

This pattern, like all of the other patterns we've looked at today, repeats any time you count in 25s.

And to help us out, every other number is a multiple of 50.

So we've got 50, 100, 150, like how we were counting before.

Sofia is going to use base 10 blocks again, to help us show that relationship.

This time, she's going to start at 200.

So, let's have a look.

Let's count together.

200, 225, 250, 275, 300, 325, 350, 375, 400.

Can you see how those 25 build up, to make multiples of 100, and also multiples of 50? Sofia counts in 25s, and this time, she's going to start from 500.

Let's see if we can count with her.

Are you ready? 500, 525, 550, 575, 600, 625, 650, 675, 700.

Well done.

Andeep's also going to count in 25s, and he's going to start at 750, so, a bit higher than Sofia.

Let's count together.

750, 775, 800, 825, 850, 875, 900, 925, 950.

Even though we've started at different multiples of 25, we can still see that same pattern, in the 10s and ones.

Sofia is counting backwards, in 25s.

And she's going to count back from 250.

Let's try and count together.

Are you ready? Let's go.

250, 225, 200, 175, 150, 125, 100, 75, 50.

Well done.

Andeep is going to count back from 975.

But we can use those patterns, to think about what our next numbers will be.

Let's count together.

975, 950, 925, 900, 875, 850, 825, 800, 775.

Now, I know we've done a lot of counting, but hopefully, you can still see that pattern, in 10s and ones.

Time to check your understanding.

I'd like you to count backwards, in 25s, from 625, to 500.

Pause the video here, and have a go.

Welcome back.

How did you get on? Hopefully, you said the following.

625, 600, 575, 550, 525, 500.

Well done.

We can also complete number tracks.

And we can count in fives, 50s or 25s, to find missing numbers.

And, Andeep is reminding us, that as before, we can count forwards and backwards.

So, looking at our number track, we have 450, 500 and 600 as the given numbers.

Now, if I think about 450 to 500, is that a step of five? What's five more than 450? No, that doesn't work.

Is it a step of 50? I think it is.

Let's check.

We can count backwards from 450, in 50s, 400, 350.

And then, I can find the missing number, by counting on.

500, 550.

That number track definitely looks right, now.

Let's look at this example.

Now, in this one, I have 195, 205 and 210.

Now, I know that when I count in fives, my ones digit is a five, or a zero.

So, we're counting in fives here.

So, we can count on, from 195.

Let's count together.

195, 200, 205, 210, 215, 220.

Well done.

Final one, now.

We've got, hmm, bigger numbers there.

Oh, but I think I can see something.

If you look at 825 to 850, we've gone up by 25.

So, we're counting in steps of 25.

And we can count back from 750, 725.

And then, we can count on, forwards, from 750.

775, 800.

That completes my number tracks.

Time to check your understanding.

Complete the number tracks.

So, you need to think about whether the count is in fives, 50s or 25s.

And remember, you can count forwards, and backwards, to find the missing numbers.

Pause the video here, and have a go, at finding the missing numbers on this track.

And, how did you get on? So, looking at those numbers, I have 75, 100.

That's a jump of 25.

So, I'm counting in 25s.

I can count back, from 75, to get to 50.

Then I can count on, 100, 125, 150, 175.

Well done, if you spotted those missing numbers.

Onto your final task, for this lesson.

For question one, I'd like you to complete the number tracks.

So we're counting forwards and backwards, in fives and 50s.

So, have a go at those.

For question two, I'd like you to complete the number tracks.

So, be really careful this time.

What are we counting in? Are we counting in fives, 50s, or 25s? Remember to look for clues, in those numbers.

So the first one, I can definitely see something, in those ones digits.

For question three, you have the same number tracks, three times.

So you've got 150 three times over, and 400 three times over.

I'd like you to fill them in, counting in fives, 50s and 25s.

So, with the 150 one, the first one, you can count forwards and backwards in fives.

The next one, forwards, backwards in 50s, and then, forwards, backwards in 25s.

And again, think about what do you notice, once you've done that.

Pause the video here, and have a go at these three tasks, and I'll see you shortly, for some feedback.

Welcome back.

How did you get on? So, for question number one, here are the completed number tracks.

So, pause the video here, if you need to, to mark your work.

Moving on to question two, these are the completed number tracks.

So remember, you had to really think hard, about what you were counting in.

The first one.

I knew we were counting in fives, because the ones digits were fives, and zeros.

So, I could count backwards, from 205, to get to 200.

And then, I could count forwards in fives, to find the missing numbers.

Let's have a look at the last one.

We had 875, 925 and 950 as our given numbers.

Well, I could see that 925 and 950, it was a jump of 25, so I was counting in 25s.

So again, I could count forwards and backwards, to find the missing numbers.

Well done, if you managed to find all of those missing numbers.

For three, your number track should've looked like these.

And, I was really interested in what you noticed.

So, Andeep noticed that some numbers are in more than one pattern.

So if we look, for example, at the left hand side, where you've got your 150 tracks, 100 appears in the bottom one, and in the middle one.

Slightly different places, but they appear in both.

So, you might have spotted some repeating numbers, in your tracks.

We've come to the end of the lesson.

And I'm really impressed, with how much counting you have done today.

Well done.

Let's summarise our learning.

The ones digits, when we count in twos, follow the patterns of two, four, six, eight and zero.

And then, when we count in 20s, the 10s digits follow that pattern.

When we count in fives, the ones digits follow the pattern of five and zero.

And then, the 10s digits do that, when we count in 50s.

When we count up in 25s, the 10s and ones digits are always 25, 50, 75 or zero.

Thank you so much, for all the effort that you've put into this lesson today, and I look forward to seeing you again soon.