Lesson video

Hello.

My name's Mrs. Hopper and I'm looking forward to working with you in this maths lesson.

Are you ready to work hard, and have some fun as well, I hope? Let's get going and see what we're learning about in this lesson.

So this lesson is all about counting in groups of 10 and identifying how many groups there are, and it's part of our unit on unitizing and coin recognition and counting in twos, fives, and tens.

So by the end of this lesson, you'll be able to count in groups of 10 and identify how many groups there are.

So let's make a start.

We've got lots of keywords today, so I'll take my turn and then it'll be your turn to say them.

So our first keyword or set of words is groups of 10.

So my turn, groups of 10.

Your turn.

And our second key word is tens.

My turn, tens.

Your turn.

Our next one is decade numbers.

My turn, decade numbers.

Your turn.

And then we've got altogether.

My turn, altogether.

Your turn.

And our final keyword is efficiently.

So my turn, efficiently.

Your turn.

Well done.

Lots of keywords there, and we'll find out more about what they mean.

You may have come across some of them before in your learning, but look out for them.

They're going to be useful to us today in the lesson.

So there are two parts to this lesson.

We're going to count forwards and backwards in tens in the first part, and then we're going to group objects into tens to count efficiently.

So let's count forwards and backwards in tens to start with.

And we've got Sam and Jacob helping us in our lesson today.

So the children are counting forwards and backwards in tens on their 100 square.

So let's start from 10 and count forwards.

So we start at 10 and we count 10, 20, 30, 40, 50, 60, 70, 80, 90, 100.

Now let's count backwards from 100.

So we start at 100 and we count 100, 90, 80, 70, 60, 50, 40, 30, 20, 10.

Great counting, well done.

So Sam says, "What do you notice about the decade numbers?" I wonder what you've spotted.

They all end in a zero.

They have a zero in the ones place, in the ones column.

The decade numbers start in the same way as when we count the ones.

So if we look at the tens number, we can see that they start with a one, then a two, then a three, four, five, six, seven, eight, nine, all the way up to 90.

Let's count forward and backward in tens again, this time using the number line.

Are you ready? So we'll start our count at zero this time.

So 0, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100.

And should we count backwards? Are you ready? Starting with 100.

So 100, 90, 80, 70, 60, 50, 40, 30, 20, 10, and 0.

Great counting.

We know the tens digit tells us the number of tens.

So we can count in two ways.

We've been counting 10, 20, 30, 40 and so on up to 100 and back again.

Now let's see if we can count one ten, two tens, and count the number of tens.

So are you ready? Let's start at zero.

So zero, one ten, two tens, three tens, four tens, five tens, six tens, seven tens, eight tens, nine tens, 10 tens.

Well done.

Could you see the tens building up along the number line as well as counting how many tens we counted? Let's see if we can count backwards from 10 tens back down to zero.

Are you ready? So we start with 10 tens, nine tens, eight tens, seven tens, six tens, five tens, four tens, three tens, two tens, one ten, zero tens.

Great counting, well done.

So the children are playing a game where they hide the numbers and then find the missing number.

So we've got our numbers written out from zero all the way up to 100 counting in tens.

Let's see if we can work out which number has been hidden.

So let's play along with them.

Which number is hidden? I wonder if we can use our knowledge of that one ten, two tens, three tens and thinking about the tens number to help us here.

Hmm, I wonder what they're thinking.

Sam says, "I will count in tens to find out." But Jacob says, "I will think about the number of tens to help me." I wonder if you can think like Jacob.

So 80 has eight tens, so the next number must have nine tens.

It will be 90.

And there we are, there's 90.

So if you remember on the number line we were counting one tens, two tens, three tens, and then we got to eight tens and the next number would be nine tens, and we knew that that was 90.

Let's have another go.

Which number is hidden this time? So Jacob says 50 has five tens, so the next number must have six tens.

It is 60.

Should we see if he's right? He's right.

So Jacob used that counting with the number of tens to help us to find the missing number.

Time for you to check your understanding.

There are two numbers covered up here.

So which numbers are missing from the count? Pause the video, have a go, and then we'll check together.

How did you get on? Did you spot the two missing numbers? So here is the thinking that I had.

I knew 30 was missing, because 20 has two tens so the next number must have three tens.

It must be 30, and the missing number was 30.

So I wonder about that missing number at the other end of the line.

Ah, I knew 100 was missing, because 90 has nine tens so the next number must have 10 tens.

It must be 100.

I hope you got those two as well.

Did you use that thinking to help you? So we can count from different starting points.

We don't have to start at 0 or 100.

So I'm going to start my count from 30 and count on.

So I'm starting at 30, so I count on.

40, 50, 60, 70, 80, 90, 100.

Great counting.

I'm going to count back from a different starting point this time.

I'm going to start counting back from 90.

So I start my count at 90 and I count back.

80, 70, 60, 50, 40, 30, 20, 10, and 0.

Excellent.

So we don't have to start at zero, we don't have to start at 100.

We can count on or back in tens from any starting point.

Now let's count with the number of tens.

So you can see here that my number line shows those number of tens, and I've got five tens showing.

So I'm going to start my count from five tens.

So from five tens, I count on.

Six tens, seven tens, eight tens, nine tens, 10 tens.

And I'm going to count backwards this time, so I start my count at seven tens and I count back.

Six tens, five tens, four tens, three tens, two tens, one ten, zero tens.

I wonder if you can think what those counts would've been like if we'd said those decade numbers, those 10, 20, 30, 40, 50 numbers, as well as the two tens, three tens, four tens numbers.

Let's count from different starting points on a Gattegno chart.

So the Gattegno chart shows us our ones, our tens numbers, our decade numbers, and our hundred numbers as well.

So let's count from different starting points on the Gattegno chart.

We're going to start from 50.

So let's count on from 50.

60, 70, 80, 90, 100.

Now let's count the number of tens.

So we started on 50, which is five tens.

So let's count on.

Six tens, seven tens, eight tens, nine tens, 10 tens.

And can you see that in our five tens, 50, you can see that number of tens repeating in the number 50 and in the five tens? So what do you notice about the numbers when you count in tens? So we've counted in tens and we've counted the number of tens.

What did you notice? Did you notice that the number of tens is the same as the digit at the start of the decade number, that 10, 20, 30, 40, 50 number? So we started counting at five tens, and the digit at the start of 50 is a five, showing us that we've got five tens.

Sam is counting forwards from the number shown on her Gattegno chart.

So she's counting forwards from 60.

So there's three possibilities there, but one of them cannot be correct.

So which one is not correct if Sam is counting forwards from 60 on the Gattegno chart? Time to check your understanding.

So pause the video and decide which one cannot be correct.

How did you get on? Which one did you think could not be correct? Ah, it was A, wasn't it? Sam was counting forwards.

Sam is counting forwards from 60, so her count can't go 50, 40, 30.

Her count could go 70, 80, 90, or seven tens, eight tens, and nine tens.

So well done if you spotted that A was counting backwards and not forwards.

Let's count backwards from different starting points.

Let's count backwards from 70.

So we start our count at 70 and we count 60, 50, 40, 30, 20, 10.

Now let's count the number of tens.

So we started with seven tens and we counted backwards, six tens, five tens, four tens, three tens, two tens, one ten.

What do you notice about the numbers when you count backwards in tens? So the decade number, that 10, 20, 30, 40, 50, 60, 70 number, starts with the number of tens in the number.

So seven tens has seven at the beginning of 70 and six tens has six at the beginning of 60.

And as we count backwards, that number gets smaller by one each time.

And Jacob says, "This can help me when I count in tens." So, he's going to do some counting.

He's going to count backwards from the number shown on his Gattegno chart.

So he's counting backwards from 60.

So there's A, B, and C.

Which of them cannot be correct? Which is not correct if he's counting backwards from 60? Time to check your understanding.

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

How did you get on? Did you spot that B couldn't be correct? Jacob is counting backwards from 60.

He would have to be counting forwards for 70, 80, and 90 to be the next numbers that he said.

But the other two do work.

He can count backwards from 60 to say 50, 40, 30 in C, or he can count the number of tens.

He's on 60, which is six tens.

So he would count backwards, five tens, four tens, three tens.

But B is counting forwards, so I hope you spotted that.

The children are counting backwards in tens.

Oh, but one of them has made a mistake.

Can you spot who's made the mistake? Let's have a look.

So Sam is counting backwards.

Let's count with Sam.

So Sam says "90, 80, 70, 60." And Jacob's counting backwards and he says, "80, 70, 60, 40, 30." Hmm, who's made the mistake, do you think? It was Jacob.

Jacob's missed out a number, hasn't he? We can see that he's counted 80, 70, 60, but then he's gone to 40.

He's missed out 50, he's missed out the five tens.

We know that five tens is one ten less than six tens, so Jacob should have said 80, 70, 60, then 50, and then he can carry on his count, 40, 30, and maybe all the way back to zero.

So can you spot the mistake here? So when you're counting backwards in tens, which of the following is incorrect? So is it A, B, or C? Time to check your understanding, so pause the video and then we'll have a talk about it together.

How did you get on? Did you spot the one that was not correct? It was A, wasn't it? 20, 90, 80, that doesn't work, does it? If we're counting backwards, our numbers are getting smaller each time, but 20 is smaller than 90, so we should have had 100 there.

But B was correct, 70, 60, 50, seven tens, six tens, five tens.

And C was correct, 30, 20, 10.

So A was incorrect.

And yes, we should have started with 100, 10 tens, then nine tens, then eight tens.

Time for you to do some practise.

There are some tracks here with the decade numbers when we're counting in tens, but there are some gaps, and your job is to count in tens to fill in the missing numbers, to fill in the gaps.

So that's part one.

And then for the second part, somebody has dropped all those decade numbers.

Oh dear! And we've got some spaces there to put them in order from the largest to the smallest.

So we're going to start with the biggest number and then work backwards.

So we are going to count backwards for part two.

Pause the video now, have a go at your practise tasks, and then we'll look at them together.

How did you get on? Did you manage to fill in the gaps? Let's look at them together.

So for question one, you were filling in the missing numbers.

So for A, we'd started with 10, 20, so we carried on 30, 40, 50, 60.

For B, we were counting up to 100, so where are we going to start? So we can count backwards to fill in these missing numbers.

100, 90, 80, 70, 60, 50.

So let's look at C.

We've got 40, 50, 60, 70, 80, 90, 100, so we could count forwards for that one.

I wonder what's going to be best in D? I think counting backwards might help us here.

We've got 100, 90, 80, 70, 60, 50.

So there's a gap at the beginning of E, isn't it? But it's the number before 50 when we count, and 50 is five tens, so the one before must be four tens, so it must be 40.

So we've got 40, 50, 60, 70, 80, 90, 100.

Now, for two, we dropped some number cards, haven't we? We've got to put them in order from the largest to the smallest.

So looking at those numbers, I think 100 is the largest, so I'm going to put 100 first.

And then if I'm counting backwards in tens, my count would go 90, 80, 70, 60, 50.

So my cards are now in order.

I hope you did well with those.

Let's have a look at what's in part two of our lesson.

So in the second part of our lesson, we're going to be grouping objects in tens to count efficiently, and efficiently means doing the job quickly and without spending time doing things we don't need to do.

So let's see how we're going to count our objects in groups of ten efficiently.

Jacob is counting the counters.

Gosh, there's a lot of counters there on the screen.

I don't think I can count all those just as they are.

He's starting, "one, two, three, four, five," he says, and Sam says, "That will take you ages and you might lose count." I wonder what Jacob can do.

He says, "Perhaps I should put my counters in groups of 10." And can you see, we've got some tens frames there on the screen to help us.

Sam says, "That's a good idea." So let's have a go.

Let's see how Jacob gets on.

So he's put 10 counters into one tens frame and his other counters fit into the other tens frame.

Sam says, "Now you can count them more efficiently." So now we know that each tens frame has got 10 counters in it we can count in tens.

So 10, 20.

So how many counters has Jacob got? Jacob's got 20 counters.

And he says, "There are 20 counters." When objects are in groups of 10, we can call them tens.

So here we've got some straws bundled together in groups of 10.

So we're going to count and use our stem sentences.

We're going to count the number of tens.

So we're going to fill in the sentence, there are hmm tens.

And then we can think about counting in tens to find out how many straws there are altogether.

So we can count the number of bundles of straws, the number of tens, and then work out how many straws there are altogether.

So are you ready to count the number of tens? Okay, let's count them.

Let's find out how many tens there are.

One ten, two tens, three tens, four tens, five tens, six tens, seven tens, eight tens, nine tens, 10 tens.

So we can fill in our stem sentence.

There are 10 tens.

But how many straws are there altogether? We'll need to count in tens to work out, because in one bundle of straws there will be 10 straws, so one 10 is the same as 10 straws.

So let's count in tens to work out how many straws there are altogether.

Are you ready? Let's count.

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

There are 100 straws altogether.

So we've counted the straws in two ways.

We've counted the number of tens and then we counted in tens to find out how many straws there are altogether.

We have 10 fingers on our two hands.

Can you show me your 10 fingers? So we're going to count these hands, we're going to count them in groups of 10.

So we're going to think of the two hands together.

So we're going to work out how many tens there are and fill in the stem sentence, there are hmm tens, and then how many fingers there are altogether.

There are hmm fingers altogether.

So are you ready to count the groups of 10? Let's go.

Jacob's gonna help us.

One 10, two tens, three tens, four tens, five tens.

So we can fill in our stem sentence, there are five tens.

Now we want to know how many fingers there are altogether, so we're going to have to count in tens to find out.

So are you ready to count another way, find out how many fingers there are altogether? Jacob says, "The fingers are in groups of 10, so I can count them in tens." So let's count.

10, 20, 30, 40, 50.

So there are 50 fingers altogether.

So we can count the number of tens, but once we know we've got groups of 10, we can count in tens to work out how many there are altogether.

Sam says, "I think you may have miscounted." Oh, I thought we counted quite carefully.

Hmm.

Let's check that we've counted accurately.

So accurately means we know we've got the right number, and we might well check to make sure that we've done it correctly.

So let's count again.

10, 20, 30, 40, 50.

I think that's what we had before, isn't it? Jacob says, "I will check I'm accurate by counting backwards." So he's going to go backwards from 50 to see if he gets back to that first 10.

So are you ready to count backwards with him? 50, 40, 30, 20, 10.

Sam says, "You counted back to 10, you must be right." Oh, phew! So we had counted accurately after all.

That's good.

Time to check your understanding.

There are 10 cherries on each cake.

So which of the following describes the groups shown in the picture? So we're thinking about groups of 10, how many altogether? So have a look at A, B, and C and see what you think is correct.

So A says there are 60 tens, there are six altogether, B says there are six tens, there are 60 altogether, and C says there are three tens, there are 30 altogether.

So think about those stem sentences, look at the cherries on those cakes, pause the video and decide whether A, B, or C is correct.

How did you get on? Which did you decide was correct? That's right, it was B, wasn't it? There are six tens, there are 60 altogether.

So there are 10 cherries on each cake, and we've got six of those cakes.

So there are six tens and there are 60 cherries altogether.

Jacob is counting the spots on the tokens, and he wants to know how many tens there are and how many spots there are altogether.

He says, "The spots remind me of a tens frame." Oh look, there is a tens frame.

And if we take away the frame and turn the counters black, you can see that we've got the same picture.

So he says, "I can count them in tens." Let's complete the stem sentences.

There are hmm tens.

There are hmm spots altogether.

So should we count the tens first? Let's count.

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

So we can complete our stem sentence.

There are seven tens.

Now, how many spots are there altogether? What are we going to need to count this time? That's right, we're gonna have to count in tens this time.

Now, are you ready to count? 10, 20, 30, 40, 50, 60, 70.

So there are 70 spots altogether.

There are seven tens and there are 70 spots altogether.

Time to check your understanding.

Look carefully at that picture and tell how many tens are shown.

So is it A, B, or C? Pause the video and have a look.

How many tens are shown? How did you get on? Were you tempted to say 80? Ooh, there might be 80 spots, but there aren't 80 tens, are there? Well done.

Yes, there are eight tens.

If we counted each of our circles with the 10 dots we would see that there are eight of them.

So there are eight tens.

Time for you to do some practise.

So use each picture to complete the stem sentences.

There are hmm tens.

There are hmm altogether.

So we've got bundles of 10 straws, we've got 10 cubes in a row, and we've got packs of 10 pencils there.

So how many tens are there and how many are there altogether? And for the second part, you're going to put a ring round each group of 10 counters and then count the tens.

So there's lots of counters there.

Can you find a way of organising them into groups of 10? And then you can count them in tens.

And the same stem sentences are there.

There are hmm tens.

There are hmm altogether.

Pause the video, have a go at your practise tasks, and then we'll look at them together.

How did you get on? Did you spot in A that there were 10 bundles of straws, so there are 10 tens? And when you counted in tens, you would've counted there were 100 altogether, so 100 straws.

So in B, could you see that there were six groups of 10 of our cubes together? And if we count in tens, there'd be 60 cubes altogether.

And in C, we had our packs of 10 pencils.

So we can see that there are five tens this time.

And when we count in tens, there are 50 altogether.

There are different ways to put rings around these counters, but this is how we saw them.

So you could have said, here is one ten, two tens, three tens, and four tens.

So four tens, and if we count in tens, 10, 20, 30, 40, there are 40 altogether.

Then we've got one ten, two tens, three tens, four tens, five tens this time.

And if we count in tens, there are 50 altogether.

And for C, we've got one ten, two tens, three tens, four tens, five tens, and six tens.

So there are six tens.

And if we count in tens, 10, 20, 30, 40, 50, 60, there are 60 counters altogether.

Did you see that the number of tens went up by one each time? And so that number at the start of our decade number was a four for 40, a five for 50, and a six for 60 showing us that we had four tens, then five tens, and then six tens.

Well done if you got all of those right.

So we've come to the end of our lesson on counting efficiently in groups of 10.

Thank you for all your hard work.

I've really enjoyed working with you today.

So what have we learnt? We've learnt that objects can be put into groups of 10 to make them easier to count, that groups of 10 can be called tens.

We can count in tens instead of ones to help us count more efficiently, like we did with those last activities counting the counters.

And we can count back in tens to check that we have counted accurately.

So we've counted groups of 10, we've counted in tens, and we've put things into groups of 10 to make them more efficient to count.

You've worked really hard today, it's been great fun, and I hope I get to work with you again soon.

Bye-bye!.