Lesson video

Hello, my name's Mrs. Cornwell and I'm going to be helping you with your learning today.

I'm really looking forward to working with you.

I know you're going to work really hard and together we'll do brilliantly.

So let's get started.

So today's lesson is called Counting Efficiently in groups of two, five, and 10.

And it comes from the unit "Unitizing and coin recognition, counting in twos, fives, and 10s".

So in our lesson today, we're going to count efficiently in twos, fives, and 10s, and we're going to choose the most appropriate unit to count in.

Okay, so we'll be deciding whether we skip count in twos or fives or 10s.

And by the end of today's lesson, you should feel much more confident in deciding the most efficient way to count when you're counting larger groups.

So let's get started.

So our keywords today, we have 10s my turn, 10s your turn.

And twos my turn, twos, your turn.

Five's my turn, fives, your turn.

And skip count, my turn.

Skip count, your turn.

And efficiently, my turn, efficiently, your turn.

Well done, excellent.

So in the first part of our lesson today, we're going to identify the size of a group to count efficiently.

Okay, we're going to be deciding what would be the best way to skip count.

And in this lesson you will meet Sam and Jacob.

They're going to be helping us with our learning today.

So Jacob's mom has made some cakes for a party and there they are.

They look lovely, don't they? They've got lots of cherries on the top.

Jacob wonders how many cherries she has used.

Some says, let's find an easy way to count them all.

Now Jacob notices that there are 10 cherries on each cake.

So that's important.

That can help us, can't it? So we can see there are some stem sentences there.

There are groups of 10 cherries.

There are cherries all together.

So let's see how many groups of 10 cherries, how many 10s there are one 10, two 10s, three 10s, four 10s, five 10s.

So there are five groups of 10 cherries aren't there? The cherries are in groups of 10.

So we can count them in 10s, can't we? So that can help us count them more efficiently.

10, 20, 30, 40, 50.

So there are 50 cherries altogether.

Jacob's mom wonders if she has enough cherries left for another cake.

And there they are, the ones that she's got left.

10, 20, 30, 40, there are 40 cherries.

You have enough says Jacob.

But Sam says the cherries are not in groups of 10s, so we can't count them in 10s.

Did you spot that? We know that there are four groups of cherries, but let's see how many are in each group.

So we've got one group and that's a group of two, isn't it? And another group of two and another group and another group.

The cherries are in groups of two.

There are twos.

So I must count them in twos, not in 10s.

Two, four, six, eight.

So actually there are eight cherries altogether.

We have eight cherries and we need 10 cherries.

So there are not enough cherries for another cake are there? Jacob's mom makes some pizza for the party.

She needs enough slices for 30 people.

How can we count the slices of pizza efficiently says Sam.

If we know the size of the group, we can skip count in that number.

So let's see the size of each group.

So we can see one group and it has five slices of pizza in it, doesn't it? Then we've got two groups of five, three fives, four fives, five fives, six fives.

The slices of pizza are in groups of five.

So we can count them in fives.

Five, 10, 15, 20, 25, 30.

There are enough pizza slices for 30 people.

So Jacob is putting the drinks on some trays.

Can you see them there? And Sam says, I think we can count these in fives.

I wonder if we can.

And Jacob's noticed something important, have you spotted anything? That's right, the drinks are in groups, but the groups are not equal.

There isn't five, there aren't five in each group.

That means we cannot skip count to help us because to skip counting fives, every group has to have five, doesn't it? We cannot count them in fives.

We could count the groups of five in fives, couldn't we? And then add the extra cups on by counting in ones we could go five, 10, 15 and then we could count the extra one.

16, 17, 18, 19, couldn't we? So we could still count in fives, but not all the groups.

Okay, so now it's time to check your understanding again, for which of the pictures can we use skip counting to help us? So pause a video now, think about what we've learned so far to help you.

Okay, and then have a think about that.

Pause the video now.

Okay, and let's see what we thought.

That's right, A and C.

We can skip count groups A and C because each picture contains groups that are of equal size.

There are three groups of 10 melons.

We can count these in 10s.

And there are four groups of two cherries.

So we can count these in twos.

And the strawberries, the groups weren't all equal, were they? There weren't five in that middle group, so we couldn't skip count those.

Well done if you spotted that.

So the food and the drink is almost ready for the party.

And there's Sam, she says, let's count to see how much of each item we have.

We will have to look carefully at the number in each group so we will know how to count them.

Because you have to think about the size of the group to help you how to skip count, don't you? The chocolates are in groups of.

So we can count them in.

What do we think? That's right, the chocolates are in groups of 10.

So we can count them in 10s.

10, 20, 30 chocolates.

What about the apples then? What do we think the apples are in groups of two.

That's right.

So we can count them in twos, that's right.

Two, four, six apples, well done.

And what about the drinks? The drinks are in groups of, that's right, five.

So we can count them in fives, five, 10, 15.

Excellent, well done.

So now it's time to check your understanding of that.

Complete the stem sentences, then skip count to find out how many are in the group all together.

Okay, so the ice creams are in groups of.

So we can count them in.

Pause a video now while you try that.

Okay, and let's see how you got on.

So the ice creams are in groups of five, that's right.

So we can count them in fives.

So let's count them in fives.

Five, 10, 15, 20, 25.

So there were 25 ice creams all together.

So well done if you spotted that.

So Jacob is counting some of the food and drink items and Sam tries to guess which item he is counting, five, 10, 15 he says, I wonder which he's counting.

Is he counting the chocolates, the apples or the drinks? And Sam says you are counting in fives.

You must be counting the drinks because they were in groups of five, weren't they? Two four, six says Jacob.

That's right, you are counting in twos.

You must be counting the apples says Sam.

And then Jacob says 10, 20, 30.

That's right, Sam says you are counting in 10s.

You must be counting the chocolates.

So Sam and Jacob play another game.

They skip count and tell their partners one of their numbers, their partner has to guess the number they were skip counting in.

So let's have a look what they did.

So Sam said the number 25 and Jacob said, oh you must be counting in fives because he knows you say 25 when you counting fives.

Then Jacob said the number 20.

Oh, now Sam's thinking that's a bit more tricky.

I wonder why, that's right because you say 20 when you're counting fives and 10s but also in twos.

So we don't know which one it is.

She needs another clue, doesn't she? I also said the number 16 says Jacob.

So is that helpful? That's right, that helps us because now Sam knows you must be counting in twos.

We say 16 when we're counting in twos, don't we? But not in fives and 10s.

The children decide to sort their numbers on a table and we've got a table with counting in twos, counting in fives and counting in 10s there.

And we've got some numbers to sort.

Let's sort the numbers according to whether you say them when counting in twos, fives or 10s.

So 15, what do we think? That's right, when we count in fives, the one digit is either zero or five, so we must say 15.

What about 16? That's right, you say 16 when you're counting in twos.

When we count in twos, the one digits follow the pattern, two, four, six, eight or zero.

So we must say 16.

What about 20 then? That's right, you say 20 when you're counting in 10s, don't you? When we count in 10s, the ones digit is always zero.

So we must say 20, it's a decade number isn't it? Could 20 go anywhere else do you think? That's right, it could also go in counting in twos.

When we count in twos the ones digit follows the pattern Two, four, six, eight or zero.

So we must say 20, could 20 go anywhere else? Could it go in the counting in fives? That's right, yes it could, when we count in fives, the ones digit is either zero or five so we must say 20.

So now here's a check of your understanding, sort these numbers according to whether you say them when counting in twos, fives or 10s.

So there's 25, 14 or 30.

So pause the video now while you sort those.

Okay, and let's see how we got on.

So 25, that's right, you would say it when counting in five.

So when we count fives, the ones digit is either zero or five.

So we must say 25, what about 14? That's right, when we count in twos, the one digit follows a pattern two, four, six, eight or zero, so we must say 14.

What about 30 then, when we count in 10s, the ones digit is always zero.

So we must say 30, could 30 go anywhere else? That's right, when we count in twos, the ones digit follows the pattern, two, four, six, eight or zero.

So we must say 30 when we count in twos as well.

What about counting in fives, do we say 30 then? That's right, when we count in fives, the ones digit is either zero or five.

So we must say 30 then as well.

So well done if you spotted that.

So here's a task for the first part of our lesson today then, skip count each group in the most efficient way to find the amount altogether.

Okay, so have a look at the amount in each group to decide how to skip count them and then you can find out how many there are altogether.

Okay, so you've got three examples there.

And then you have got another three questions there to answer as well.

So pause the video now while you try that.

Okay, and then we can see the drinks here.

Okay, so first of all, when I looked at these drinks, I thought they looked a bit like a 10s frame, but when I counted across I could see that there weren't five in each row, so I couldn't count them in fives or 10s.

But when I looked I could see that looking downwards, they are in twos.

So I could count them in two.

So we could say two, four, six, eight, 10, 12, 14.

There are 14 drinks altogether.

And then looking at the strawberries, again, if I look down I can see that they're in groups of five.

So five, 10, 15, 20, 25, 30, 35.

There are 35 strawberries altogether.

Okay, so if we look at this last example then here, if we look at the cups, I can see that I can put them into groups of 10.

So we can say 10, 20, 30, 40.

So there are 40 cups altogether, so well done.

You've worked really hard with your skip counting so far today, haven't you? Well done, so now in the second part of our lesson, we're going to be choosing the most efficient way to count.

Okay, so Sam and Jacob collect the empty cups at the end of the party.

There they are, Sam says there are 20 empty cups, but Jacob wants to check how can he check? I wonder what should he do? He's saying should I count them in twos or fives or 10s? Which will be the most efficient way to count? Let's try counting in twos.

Two, four, six, eight, 10, 12, 14, 16, 18, 20.

That took a long time.

Say Sam, let's try counting in fives.

five, 10, 15, 20.

Well that was quicker, wasn't it? Let's try counting in 10s.

10, 20, counting in 10s takes the least amount of time.

There are more in each group so you can count them more efficiently.

It is quicker and more accurate if you can put them into 10s, to count them in 10s, isn't it? Jacob puts the empty plates left at the end of the party into twos.

Can you see, he's put them into twos by colour you can see them, can't you? He says this will be the most efficient way to count them.

Do you agree? What do you think about that? Counting them in twos will take ages, says Sam, I can count them in a more efficient way.

I wonder how Sam's going to count them.

I can see you've put them into 10s, says Jacob.

There, and you can see, we can put a 10s frame on to show that, can't we? The groups are larger so there will be quicker to count, 10, 20, 30, 40.

Do you think it you would've still got the same answer if he'd counted them in twos, you wouldn't you? Because there are the same amount there all together, but it is more efficient to count them in 10s.

So now it's time to check your understanding again.

There are 40 strawberries in the picture.

What would be the most efficient way to skip count them? Okay, so in twos, in fives or in 10s.

So pause a video now while you think about that.

Okay, and what did you think? That's right, 10s is the most efficient way to count them.

You could go 10, 20, 30, 40.

When you count in 10s, there are more in each group so you can count them more efficiently.

Okay, so the children play a game at the party where they have to predict which animal will jump the furthest.

So we've got bird, puppy and frog.

Each creature takes two jumps along the number line and let's see who will reach the highest number.

So bird jumps in twos, puppy jumps in fives and frog jumps in 10s.

So he is bird.

So I wonder what after two jumps, what number bird will reach? That's right, two, four.

So there's bird saying I reached four.

Now let's see what puppy reaches after two jumps.

So she jumps in fives, five, 10.

So poppy saying I reach 10.

And then how about frog? What do we think frog will reach? So he went 10, 20, frog saying I reach 20 so we can see, can't we, frog reached the highest number.

He reached 20 because his jumps were greater in size, weren't they? His jumps were of 10.

So now it's time to check your understanding again.

This time each animal took three jumps, which animal will jump the shortest distance.

So it's not the longest distance this time, it's the shortest distance and there's frog reminding us I jump in 10s, Puppy saying I jump in fives and Bird saying I jump in twos.

But you may perhaps draw the jumps on on an empty number line to help you with that.

So pause the video now while you have a try at that.

And let's see how we got on, what did you think? That's right, bird would jump the shortest distance.

And let's have a look.

There's frog with three jumps of 10 that got him to 30 and then puppies jumps were shorter, they were only five.

Three jumps of five got her to 15 and then bird here had three jumps of two.

So that only got them to six, didn't it? So well done.

That was the shortest distance.

Bird reached the lowest number because her jumps were smaller in size.

So here's Sam and Jacob again.

Sam counts in fives and Jacob counts in 10s.

Each time mom claps they each say a number, who will say 30 first.

So there they are, and let's see.

So when Sam says, Jacob says 10, when Sam says 10, Jacob says 20.

'Cause he's counting in larger jumps, isn't he? And when Sam says 15, Jacob says 30.

So Jacobs there saying, I said 30 first because I was counting in greater steps.

10s are bigger than fives, aren't they? They're larger.

So well done if you notice that.

So now it's time to check your understanding again.

This time Jacob counts in twos and Sam counts in fives.

Who will say 20 first, explain how you know.

Okay, so it shows us on the screen there that Jacob is counting in twos and Sam is counting in fives.

So have a think about that, who will reach 20 first? Pause the video now while you try.

So when Sam says five, Jacob says two.

And then when Sam says 10, Jacob says four.

When Sam says 15, Jacob says six.

And when Sam says 20, Jacob says eight.

So we can see that Sam got to 20 first.

Sam will say 20 first because she was counting in greater steps, wasn't she? Okay, so here's the task for the second part of your lesson.

You've got to decide whether the children have counted in the most efficient way.

So you can see the children there are telling you how they counted the objects.

So Sam's saying, I counted the strawberries.

She's saying I counted in twos.

So you've got to decide, have a look at the strawberries and decide that is the most efficient way.

And then if you think it is, give it a tick.

And if you think it isn't, you give it a cross.

Give it a cross, okay? Then you've got to prove it by circling the groups to show the most efficient way to count, okay? And do that for each example.

So you've got these three examples here, and then you've got three more as well.

So pause the video now while you try that.

Okay, let's see how you got on.

So you may have done this.

So here's Sam with the strawberries and she said she counted in twos.

Two, four, six, eight, 10, 12, 14.

And so that was the most efficient way, wasn't it? Because you don't say 14 when you count in 10s or fives, do you? So two must have been the most efficient way there, okay? And then we've got Jacob here with the melons saying I counted in fives.

So five, 10, 15, 20, 25.

So again, that was the most efficient way.

You wouldn't say 25 when you counted in 10s, would you? So fives must have been the most efficient way there.

And then here's Jacob saying I counted in fives here.

Now I can see some groups of five there and I can also see some groups of two.

But is that the most efficient way? That's right, you may have spotted it.

We can group them into 10s, which is more efficient because they're larger groups.

10, 20, 30, 40.

So Jacob didn't count in the most efficient way because he counted them in fives, didn't he? Counting in 10s was the most efficient way to count the apples.

Okay, and then let's look at these examples.

There's Sam saying she counted the ice creams in 10s.

So is that the most efficient way? 10, 20, 30, yes it was.

And then we've got the cups there and we can see groups of two there.

And if you look carefully going down, you can also say see groups of five, but is that the most efficient way? So we can see, we could have put the cups into groups of 10, which is a larger group.

So that's more efficient and quicker to count, isn't it? So Sam wasn't right to count them in twos, counting in 10s was the most efficient way to count the cups.

And finally we've got the drinks here and Jacob says he counted those in 10s.

And if we look there, we can see it looks a bit like a 10s frame, but are there five on each row where there aren't, are they? So not 10 altogether, so we can't count it in 10s.

So what would be the best way to count there? That's right, two, four, six, eight, 10.

So you would put them into groups of two to count them in twos, wouldn't you? So Jacob wasn't right to count them in 10s.

The drinks were not in groups of 10s, so they can't be counted in 10s.

Counting in twos was the most efficient way to count the cups, wasn't it? So well done with that.

You've done some excellent work today and being able to think about the best way to skip count so you can count most efficiently and you're more likely to be able to count quickly and accurately.

So well done.

So now let's see what we've learned today.

The amount in a group can tell you whether to skip count in twos, fives, or 10s.

The pattern of the ones digits can help you recognise groups of two, five or 10.

And it is more efficient to count in groups of a larger size, isn't it? When there are an equal number of groups, the larger the size of each group, the greater the amount altogether.

Okay, so well done, you've worked really hard there today and you should be feeling much more confident and hopefully when you're counting larger groups, you'll be able to count really efficiently, won't you? Excellent.