Lesson video

Hello, my name's Mrs. Cornwell, and I'm really pleased to be working with you today.

We're going to use some of the things you already know to help you with some new learning.

And I know you're going to do really well, so let's go.

Today's lesson is called, count groups of 10 in decade numbers.

And it comes from the unit counting in 10 decade numbers.

By the end of today's lesson, you'll be able to recognise when you count in 10s and use your decade numbers to find out how many there are altogether.

So, the words that are going to be important for us today; represent, groups, and decade numbers, and we'll find out a little bit more about those words and use them throughout the course of the lesson.

So the first part of the lesson, we're going to count groups of 10 using decade numbers, and then we'll move on in the second part of the lesson to recognise in the pattern when counting decade numbers.

So in this lesson, you'll meet Laura, there you can see Laura, and Jacob.

Okay, and they'll be coming up throughout the course of this lesson, asking us different questions and showing us different things.

So Jacob has these straws for his party.

He puts them into groups of 10.

And there we can see he's put them into 10s there, hasn't he? How many 10s does he have? So, we can see the groups of 10 there, can't we? One 10, two 10s, three 10s, four 10s, five 10s.

Jacob says, "I wonder how many straws I have altogether? I will count to find out." And there they are, and how does he count them? When there are groups of 10, you skip count in 10s.

That tells you how many you have altogether.

10, 20, 30, 40, 50.

So Jacob says, "10, 20, 30, 40, 50." He counted in 10s and he found out he has 50 straws.

"I have 10 fingers on my hands." There we can see there, can't we? 10 fingers, so we've got groups of 10 there.

Jacob says, "The fingers are in groups of 10, so I can count them in 10s." We know when we've got groups of 10 we can count them in 10s, can't we? Because it's quicker, we can skip count.

So, 10, 20, 30, 40, 50, 60, 70, 80.

"There are 80 fingers altogether." Count how many children there are altogether.

So, we've got some buses here, haven't we? Three buses, and there's 10 children on each on each bus.

10, 20, 30, that's right.

The children are in groups of 10, so you can count them in 10s.

There are 30 children altogether.

How many pizza slices are there altogether then? So let's have a look, are they in groups of 10? Yes, I can see there are 10 slices in each pizza.

So, how many pizza slices are there all together here then? Let's count in 10s to find out.

Are the pizza slices in groups of 10? I've checked that, and they are.

So we can count them in 10s, can't we? 10, 20, 30, 40, 50, 60, 70.

The slices are in groups of 10, so you can count them in 10s, which we just did.

There are 70 pizza slices all together.

Well done.

Okay, we know a 10s frame has space for 10 counters.

Each of the 10s frames are full there, aren't they? "The counters must be in groups of 10, so I can count them in 10s." 10, 20, 30, 40.

So, we know there's 40 counters all together.

How many counters are there all together here then? So, we can see, let's have a look.

We can see lots of 10s frames, can't we? Are the counters in groups of 10? Yes, the counters are in groups of 10, so you can count them in 10s.

We know they're in groups of 10 because all of the 10s frames are full, there's no counters missing.

Okay, so we can count them in 10.

So let's get ready, are you ready? 10, 20, 30, 40, 50, 60, 70, 80, 90, 100.

There are 100 counters altogether, well done.

So that was much quicker, wasn't it? If we'd had to count each of those counters separately, it would've taken a long time.

But when we put them into groups of 10, it was much quicker and easier to count them.

How many beads are there altogether then? So, we know that when you get a bead string, it's in 10s, isn't it? We've got five red and five white on a bead string, and that makes a group of 10.

So let's have a look.

So, are the beads in groups of 10? Yes they are, we can see them there, can't we? The beads are in groups of 10, so you can count them in 10s.

10, 20, 30, 40, 50.

There are 50 beads altogether.

Here's Jacob again, and he says, "I will count the pencils in 10s." What mistake has been made, have you spotted anything there? That's right, the pencils are not in groups of 10, so you cannot count them in 10s, can you? If you count, there's only one, two, three, four, five pencils in each pot.

So you can't count them in 10s because there aren't 10 objects, are there, in each group.

A 10s frame has space for 10 counters.

Okay, we can see there's some 10s frames there, can't we? "Each 10s frame is not full." The counters are not in groups of 10, so you cannot count them in 10s.

Okay, so which groups can be counted in 10s? Now, it's your turn, so I'll give you a little bit of thinking time.

Look carefully at the pictures we can see there, okay? And then think about which groups can be counted in 10s.

Okay, what do we think then? So did you spot it? That's right, hey, the first A there can be counted in 10s because we can see that there are 10 fingers on each pair of hands there, aren't there? Okay, how many groups of 10, how many 10s are there there, do you think? That's right, there are three 10s, aren't there? We can see three pairs of hands.

And then you can see on the other pictures, there aren't 10 fingers held up.

So there's not 10 in each group, so they can't be counted in 10s, can they? Okay, so how many straws are there here? So, we know the straws are bundled into 10s, aren't they? Jacob did that earlier.

So, we've got one, two, three, four, five, six, seven.

"I can count seven straws," says Jacob.

What mistake has been made there? That's right, the straws are in 10s, so you count them in 10s, not in ones, don't you? So there's seven groups of 10.

There's seven bundles, but there are 10 in each group, so you have to count them in 10s.

So, 10, 20, 30, 40, 50, 60, 70.

There are 70 straws altogether, aren't they? And there's Jacob saying, "I can count 70 straws." When objects are in 10s, we count them in 10s.

So there's some 10s frames, they're all full.

10, 20, 30, 40.

When objects are in ones, we count them in ones.

So there's four count as one, two, three, four.

Who is right then, the picture shows five pencils.

So there's Laura, and she's saying that there's five pencils there, and Jacob's saying, "The picture shows 50 pencils." What do you think, explain how you know.

That's right, there are five groups of 10, aren't there? So when objects are in 10s, we count them in 10s.

There are five packets, but there are five 10s, aren't they? Okay, not five ones.

So, 10, 20, 30, 40, 50, there are 50 pencils altogether.

Okay, so we've got three pictures here, haven't we? And it says, "Which picture shows the number 30?" So, we've got some pencils that are in groups of 10, in packets of 10, 10 pencils in each packet.

And we've got some single pencils there, and then we've got some more pencils in packets of 10.

So which picture will show the number 30? That's right, remember when objects are in groups of 10, we can count them in 10s, can't we? So, we can see that first picture, that is in groups of 10s, so we can count it in 10s.

10, 20, 30, it must be that one.

The second picture, those pencils are in ones.

When objects are in groups of one, then you count them in ones, so that would be one, two, three.

And then we can see the last picture does have pencils that are in groups of 10, but when we count them, it doesn't come to 30, does it? It's 10, 20, 30, 40, 50.

That's right, well done.

So now it's your turn.

Okay, so here we have, it says, "There are 10 slices in each pizza.

How many slices of pizza are there all together?" And there's Jacob and he's saying, "One, two, three, four, five, six, seven, eight, nine.

There are nine pizza slices all together." Is Jacob right? How can you find out if he's right, if there are nine slices altogether, what do you need to do to find out? So have a little bit of a think.

I'll give you some thinking time and then we'll go through it together.

Okay, so let's see how we got on then.

So, how many slices of pizza are there altogether? Well, we know that there are 10 slices in each pizza, so each pizza is one group of 10.

So, we can count them in 10s, can't we? So there are nine groups of 10, but to find out how many altogether you must count in 10s.

So, 10, 20, 30, 40, 50, 60, 70, 80, 90.

There are 90 slices altogether.

So, Jacob found out that there were nine pizzas, didn't he? But he forgot that there were 10 slices in each pizza, so he had to count them in 10s because they were in groups of 10.

So your task for the first part of today's lesson then is to look to see if the objects are in groups of 10.

Count in 10s or ones to see how many are in each group.

So you can see that there are some groups, and then there's a box next to each group.

And you count them, and you think, "How am I going to count those to find out how many are there all together?" Okay, so pause the video now and have a try at that.

So let's see how we got on then.

So, we have to decide how we're going to count the groups, don't we? So let's have a look at the party hats, are they in groups of 10, are they 10s? No, they aren't, there's not 10, there is less.

So let's count and see how many there are.

One, two, three, four, five, six, seven.

We can see that there are seven party hats.

We counted them in ones, didn't we? Now, let's look at these cubes, are they in groups of 10? So, we need to separate and count, so let's count how many groups.

We can't separate them, but we can count how many cubes, can't we, are in each group.

So, one, two, three, four, five, six, seven, eight, nine.

I can see that there are 10 in each group, so we can count them in 10s, we can say 10, 20, 30.

Well done.

What about the pens, are they in 10s? No, they're just single pens there, aren't they? So, we count them in ones One, two, three, four, five, six pens there, aren't there? Now, let's have a look at these counters underneath number four.

So we've got one, two, three, four, five, six, seven, eight, nine, 10.

Ah, so we just write 10, don't we? Just that is actually one group of 10, but we had to count each counter in turn, didn't we, to find out that there was a 10 there, so we just count 10.

Let's have a look at number five then with the 10s frames at the top.

So each 10s frame is full, so we know that they're in groups of 10, so we can count them in 10s, can't we? 10, 20, 30, 40, 50, 60, 70.

There's 70 counters there.

Let's have a look.

We can see the straws are also in 10s, aren't they? So, we can count them in 10s as well.

10, 20, 30, 40, 50, 60, 70, 80, 90, 100.

So, we can see there's 100 there, that's right.

And then the bead string at the bottom.

Is this in 10s, let's have a look.

Yes, we can see there's one 10, two, three, four 10s, so we can count it in 10s.

10, 20, 30, 40.

Well done, excellent, you've worked really hard on that.

So let's have a look now at the next part of the lesson, where we recognise the patterns when counting decade numbers when counting in 10s.

So let's skip count in 10 then.

So, we'll go, start at zero, and 10, 20, 30, 40, 50, 60, 70, 80, 90, 100.

Okay, so let's have a look at those decade numbers.

What do you notice about them all? What's the same about them all and what's different? That's right, so what's the same is that they all end in a zero.

That's how we know they're a decade number, they all end in a zero.

Okay, what's different about them all? That's right, so they all have a different number before the zero, don't they? The part of the number that's different, and that tells us which decade number it is.

Some of the decade numbers tell you how many 10s they have.

So six-ty, six 10s.

Seven-ty, seven 10s.

Eight-ty, wonder what that's going to be.

Eight 10s, that's right.

And nine-ty, nine 10s.

Well done, so we can spot a bit of a pattern there, can't we? Look at the number 80, and we can see it's represented with straws there.

We can see that the straws are in 10s, aren't there? And there's eight 10s.

So, what does the eight represent in that number? That's right, it represents a number of 10s.

We can see that there's eight 10s there, can't we? Okay, and there's Laura saying, "Eight-ty, eight 10s." We know it's a decade number because it ends in zero.

Okay, look at the number 60, and we can see the pencils there, can't we? And they're in groups of 10, and there's Laura again to help us.

"What does a six represent?" That's right, it represents a number of 10s, there are six 10s.

Six-ty, six 10s.

We know it's a decade number because it ends in zero.

So we know the zeros telling us it's a decade number and the six is telling us the number of 10s.

Look at the number 90, so, I wonder.

It is a mmh number.

So think about what the zero tells us.

It is a decade number, that's right.

And the nine represents, what does that nine represent? That's right, the nine represents nine 10s.

And you can see the nine 10s there.

The nine pencil packets, can't you? Nine groups of 10.

And there's Laura reminding us, "Nine-ty, nine 10s." We know it's a decade number because it ends in zero.

Here's Jacob and he's saying, "I wonder how many packets of pencils I will show to represent this number?" So, we've got 80, and then afterwards we've got 60.

How many packets of pencils do you think we'll need to represent 80, how many 10s? That's right, the number eight represents eight 10s.

So you need eight packets of 10 pencils, don't you? And then for 60, the number six represents six 10s, so you need six packets of pencils, six 10s.

Okay, so now it's your turn again.

So look at the number.

We can see the number there, can't we, 70? Okay, and you've got some pencils there to represent that 70.

So, what can you tell me about this number? And then I'd like you to use the stem sentences to describe it.

So, we've got, "It is a mmh number, it has mmh 10s." So have a think now, take a little bit of time, and then we'll have a look together.

Okay, so how did you get on? So, first of all, it is a mmh number.

So look at the number 70, and what do we know about it? That zero tells us it is a decade number, doesn't it? So it is a decade number and it has mmh 10s.

So if we look at the other digit in the number, the seven, we know that that seven represents seven 10s, doesn't it? So it has seven 10s, well done.

Okay, so another task for you to have a try at.

How many 10s are in each number? So you've got to match the decade number to the number of 10s.

So have a try, I'll give you some thinking time and then we'll go through it together again.

Okay, let's see how we got on, so we can see we've got 60.

So would you match 60 to eight 10s, seven 10s, or six 10s? That's right, we know that the six represents six 10s, don't we? So that should go to six 10s.

What about 80? So think eight-ty, eight 10s.

That's right, so that will go to eight 10s.

And what about 70? That's right, the seven represents seven 10s, doesn't it? Seven-ty, seven 10s.

"These numbers seem more tricky, I wonder why?" So, we've got 50, 20, and 10.

What's different about these numbers, I wonder? Okay, so we can see 50 has five 10s, doesn't it? But the start of these numbers sound different to the number of 10s in that number.

We don't say five-ty, we say 50.

So these ones are a little bit more tricky, aren't they? The number five represents five 10s, there we go.

And then 20 again, we don't say two-ty, do we? We say 20.

So it doesn't sound the same when you say it, the clue isn't the same.

But when you see it written down, you can see there's a two, and that two represents two 10s.

And then 10, the number one represents one 10, doesn't it? Okay, so that means we've got one packet of 10.

Well done.

So here we've got Jacob, and he's asking us, "What is different about this number?" So we've got the number 100 there, haven't we? What's different about 100 from the other decade numbers that we've looked at? That's right, it's got three digits in it instead of just the two, hasn't it? And what's the same about it? That's right, it ends in a zero, doesn't it? And the position of zero tells you it's a decade number.

It's got a zero at the end of it, so that tells us it's a decade number And the 10 represents 10-10.

So it's exactly the same as the other decade numbers, it ends in a zero, and then the other digits tells you how many 10s is in that number.

So we can see there it's got 10 10s, hasn't it there? So even though it looks a little bit different from the other decade numbers, it works in just the same way, it follows the same pattern.

And when you say this number, you say 100, don't you? But it also means or represents 10 10s.

So your turn again, okay? So, I want you to think about how many 10s are in each of these numbers, and I'll give you a little bit of thinking time.

So these are the numbers that are a little bit more tricky because you can't hear the number of 10 10s when you say it, can you? So, we've got 50, 20, and 100.

So have a little think about that, and then we'll go through it together.

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

So 50, 50.

So when you say 50, you can't hear, can you, how many 10s there are? But when you look at it, you can see there's a five, and the five represents five 10s.

So 50 will go to five 10s.

20, again, when you see it written down, you can see that the two represents two 10s.

And then 100, we've got a zero because it's a decade number, but then we've got a 10 in front of that zero, haven't we? So that represents 10 10s.

Well done, that's excellent work.

Now, look at the number 30.

So, we can see the number 30 there, can't we? What can you tell me about this number? So it, again, you can't, when you listen to it, it doesn't tell you so clearly how many 10s are in it.

But when you look at it, you can work it out, can't you? So use the stem sentence to help you.

It is a mmh number, it has mmh 10s.

So have a thinking time now, and then we'll go through it together.

Okay, so 30, it is a, so we know the zero tells us it is a decade number, and the three tells us it has three 10s, the three represents three 10s, doesn't it? So, your task for this second part of the lesson here then, we've got some more pictures, haven't we? And it says, "Cut out the pictures and match them to the correct decade number." So, you have a table like this with the decade numbers in, and you've got to have a look at the pictures that you've got, and count them up, and then match it to the correct decade number.

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

So let's have a look together at this then.

So if we have a look next to the number 60, we know the six represents six 10s.

So there we can see that there are six 10s next to the 60.

And if we counted in 10s, we would find out there were 60 altogether, wouldn't we? 10, 20, 30, 40, 50, 60 when we count the groups of 10, well done.

Next to the 50, we know the five represents five 10s, don't we? And if we counted all those pencils altogether, we can count them in 10s because they're in 10s.

We should get 50, shouldn't we? 10, 20, 30, 40, 50, that's right.

Then we've got 20 there, haven't we? And if we have a look, we know the two represents two 10s, don't we? Okay, and if we count those beads in 10s, we'd say 10, 20.

So, we know that we're right.

Next to number 80, so the eight represents eight 10s.

So we can see that we've got eight groups of 10 there, haven't we? And if we count them up in 10s, we'll find we have 80 altogether.

So let's check, 10, 20, 30, 40, 50, 60, 70, 80, well done.

And then here we've got 100, haven't we? Now, we know before the zero there's a 10.

Okay, so that represents 10 10s, doesn't it? And if we count up these straws, there should be 100 altogether, so let's count and check.

10, 20, 30, 40, 50, 60, 70, 80, 90, 100.

Excellent.

And then lastly here on the table, 30.

So we know that three represents three 10s, and we can see we've got three 10s there, haven't we? And if we count the flowers up, there will be 30 altogether.

We can count them in 10s because there's 10 in each group.

So let's do that, 10, 20, 30.

Excellent, so you've worked really hard today, and found out lots about counting larger groups of objects.

That will be really useful to you in some of your future work, won't it? So well done.

So let's find out what we've learned today.

Let's just think about what we've found out.

So, when we've been counting groups of 10 in our decade numbers, we found out you can count groups of 10 in two ways, can't you? You can count them in groups of 10 or you can count them in 10s.

You can count groups of 10 using decade numbers.

We know that we use our decade numbers, and we know how to recognise those decade numbers as well, don't we? And you can look at the digit before zero to find out how many 10s are in a decade number and what that digit represents.

Okay, well done.

You've worked really hard today, and I've really enjoyed working with you.