Lesson video

Hello, my name's Mrs. Hopper, and I'm really looking forward to working with you today in this lesson from our unit on comparing, ordering, and partitioning two-digit numbers.

Have you done lots of work with two-digit numbers before? I wonder.

Well, I hope you're ready to work hard and think hard today.

So let's make a start.

So in this lesson, we're going to be partitioning two-digit numbers into tens and ones using place value resources.

And we're going to be representing this on part-part-whole models and in bar models.

So I'm sure you are familiar with part-part-whole models and bar models as well.

So let's have a think about our two-digit numbers and partitioning them into tens and ones.

We've got some keywords in our lesson today.

We've got partition, combine, parts, and whole.

So I'm going to say them and then it'll be your turn.

So my turn, partition, your turn.

My turn, combine, your turn.

My turn, parts, your turn.

My turn, whole, your turn.

Excellent.

I'm sure you've come across those words before, but look out for them in our lesson today.

You're going to be using them when you're talking about your numbers.

So there are two parts to our lesson today.

In the first part, we're going to be finding the missing whole.

And in the second part, we're going to be finding a missing part.

So let's make a start.

And we've got Izzy and Lucas helping us with our learning today.

Lucas needs 36 straws for his art project.

They are grouped in tens with some extra ones.

So we need 36.

Izzy says, "I wonder how many groups of ten and how many ones you'll need." Lucas says, "I know 36 is the same as 3 tens 6.

I will collect 3 tens and 6 ones." So there's 1 ten, 2 tens, 3 tens, and 1, 2, 3, 4, 5, 6 ones.

Lucas uses a bar model to show how to partition his 36 straws back into tens and ones.

So there, you can see his 36 straws in the whole of his bar model.

36 is the same as 3 tens 6, and he's got a Gattegno chart there.

3 tens and 6.

I will partition 36 into 30 and 6.

So there's our 30 and there's our 6.

So 30 is apart and 6 is apart.

If we combine the tens and the ones again, what will the whole amount be? Well, we haven't lost any straws, have we? 3 tens is the same as 30, and there are 6 ones.

So there will be 36.

30, 6, and there they are, back in the whole.

And we can represent that using our digits.

So there's 36.

Izzy needs 24 straws for her project.

So there we've got the number 24.

And we've got a Gattegno chart.

So we can think about how that number's made up.

She taps it on her Gattegno chart, 40 and 2.

Hm.

"I will need 4 tens and 2 ones," says Izzy.

Ooh, can you spot something here? 4 tens and 2 ones? Hm.

What mistake has been made? Ah, Lucas says, "4 tens and 2 ones is the same as 4 tens 2, or 42." 4 tens is the same as 40, and another two, 42.

Ah, Izzy says, "I forgot to think about what each digit in the number represents." She saw a 2 and a 4, but she didn't think about what they represented.

So let's try again.

We can use the part-part-whole model to help us to partition 24 into the tens and ones more easily.

So she's also used her place value chart there to show 24.

24 is equal to 2 tens, which is 20, and 4 ones, which is 4.

The 2 represents 2 tens and it has a value of 20.

There it is.

And there's our 20 straws, 2 tens.

The 4 represents 4 and it has a value of 4, and there are 4 ones.

Now, I can easily see that 24 partitions into 20 and 4.

If we combine 20 and 4 again, what will the whole amount be? Well, there's 20 and 4, so the whole amount is 24.

Lucas uses base 10 blocks to partition a different two-digit number into tens and ones.

Can you see the number he's got there? He says he's going to use a bar model.

So his whole number is 46, one part is 40 and the other part is 6.

Let's combine the parts to make the whole.

Izzy says, "There are 4 tens, which is 40," and she's represented them on the place value chart, "and 6 ones, which is 6." And we can see those in the base 10 resources that Lucas was using.

So this is equal to 46 altogether.

So 46 is our whole.

Our tens part is 40 and our ones part is 6.

The 4 represents 4 tens and has a value of 40.

The 6 represents 6 ones and has a value of 6.

Izzy puts some tens and ones into the parts on her part-part-whole model.

So there are some tens and there are some ones.

Let's combine the parts to make the whole.

She says, "We can use the stem sentences to help us." So here there are.

So here's stem sentence.

There are hm tens, which is hm, and hm ones, which is, hm.

So we are going to fill in the gaps.

So there are 6 tens, which is 60, and there are 3 ones, which is 3.

This is equal to hm altogether.

What's our missing number here? So this is equal to 63.

63 altogether.

So there's our whole.

Let's think about what those numbers represent.

The 6 represents 6 tens and has a value of 60.

And those were our 6 base 10 blocks showing our 6 tens.

And the 3 represents 3 ones and has a value of 3, and there were our 3 ones.

And when we combined them, they were equal to 63.

Izzy decides to rearrange the parts in a different order.

Oh, so she swapped her ones and her tens.

Does that change the number? "If I combine the parts, the whole will still be 63," Izzy says.

Is she right? Well, the 6 still represents 6 tens, which is 60, and the 3 still represents 3 ones, which is 3.

So, yes, our whole still represents 63.

Izzy says, "There are still 6 tens and 3 ones.

so they still represent 63 altogether." And there they are.

Time to check your understanding.

You are going to complete the stem sentences to describe the part-part-whole model, and then say what each digit in the number represents and describe the value.

So there's our stem sentence, there's our part-part-whole model.

Pause the video and complete the stem sentence.

How did you get on? So we could see there are 2 tens, which is 20, and 9 ones, which is 9.

So this is equal to 29 altogether.

And we can see that represented in our part-part-whole model.

The 9 ones are the first part represented in our part-part-whole model, but that doesn't matter.

We've still got 9 ones and 2 tens, which is 29.

The 2 represents 2 tens and has a value of 20.

The 9 represents 9 ones and has a value of 9.

Lucas uses base 10 blocks to help him find the missing whole in the part-part-whole model.

What mistake has been made? Hm, what's he done? Let's use the stem sentence to find out.

So there are 6 tens, which is 60, and there are 8 ones, which is 8.

Whoa! Can you see the mistake that has been made that this is equal to 68 altogether? The 6 represents 6 tens and has a value of 60, the 8 represents 8 ones and has a value of 8.

Ah, Lucas says, "I forgot to think about what each digit represents.

There are 6 tens and 8 ones.

So the whole was 68, not 86.

Time to check your understanding.

Use the stem sentences to find out which part-part-whole model is incorrect.

So we are looking for the mistake here.

Pause the video, have a go at using the stem sentence, and find the one which is incorrect.

Find the mistake.

How did you get on? Did you remember to think about what each digit in the number represents? So let's have a look, which one was incorrect? So let's have a look at the first one.

There are 70 tens, which is 70, and 2 ones, which is 2.

This is equal to 72 altogether.

That looks right to me.

That one's correct.

So let's look at B.

There are 3 tens, which is 30, and 9 ones, which is 9.

This is equal to 39 altogether.

Oh, can you see what's happened there? We haven't got the value of the digits correct, have we? So this is not correct as it is.

What is our whole here? The whole should be 39, and now it is correct.

And let's just check C as well.

What have we got in C? There are 4 tens, which is 40, and 5 ones, which is 5.

This is equal to 45 altogether, so that one is correct.

So B was incorrect, but we've now corrected it.

Well done if you spotted that.

Izzy has some 10 p coins and Lucas has some 1 p coins.

They put them together to see how much money they have altogether.

Let's use the stem sentences to help us.

There are 5 tens, and let's put it on the place value chart as well.

So there are 5 tens, which is 50, and there are 7 ones, which is 7.

This is equal to 57 altogether.

So let's think about what those digits represent.

The 5 represents the 5 tens and has a value of 50, and 7 represents the 7 ones and has a value of 7.

And we can see that this time, with our 5 10 p coins and our 7 1 p coins.

Time to check your understanding.

Can you complete the stem sentences to find the missing whole and work out whether it is A, B, or C? So pause the video, have a go, and we'll come back and find out the answer together.

How did you get on? So we can see in the bar model that there are 6 tens, which is 60, and there are 4 ones, which is 4, and this is equal to 64 altogether.

6 represents 6 tens and has a value of 60, the 4 represents 4 ones and has a value of 4.

So which was correct? That's right, B was correct.

64 was our missing whole.

Time for you to do some practise.

Use base 10 blocks, combine the tens and the ones to find the whole amount in each representation.

Remember to use the stem sentences and place value chart to help you.

And there's our stem sentence.

And for part two, you're going to work with a partner.

And you'll need a bag of base 10 blocks.

You'll need 9 tens and 9 ones.

And Izzy says, "I will draw a part-part-whole model, choose some blocks from the bag, and put the tens in one part of my part-part-whole model and then the ones in the other part." So she's going to create a part-part-whole model using the base 10 blocks.

Lucas says, "I will draw a the part-part-whole model or a bar model and write in the parts I can see." So he's going to write them in using digits, and Izzy's going to make the number using the base 10 blocks.

And then Lucas says, "I will find the missing whole and write the number to represent it." So let's have a look at an example 'cause there was a lot to remember there.

So Izzy has taken out some tens and some ones and put them into her part-part-whole model.

Lucas says, "I will draw the part-part-whole model or bar model and write in the parts I can see." So he's done a part-part-whole model.

So he can see 5 tens, which is 50, and 6 ones, which is 6.

Then I will find the missing whole and write the number to represent it.

And he says that he knows that represents 56.

So that's what you are going to have a go at for part two of your practise.

So pause the video, have a go, and we'll come back for some feedback.

How did you get on with question one? You had to work out what the missing whole was in each of these bar models and part-part-whole models.

So let's have a look at A.

In A, there are 3 tens, which is 30, and 2 ones, which is two, and this is equal to 32 altogether.

30 and 2 is equal to 32.

Let's look at B.

There are 2 tens, which is 20, and 6 ones, which is 6.

This is equal to 26 altogether.

2 tens are 20, and 6, 26.

What about C? In C, there are 5 tens, which is 50, and 9 ones, which is 9, this is equal to 59 altogether.

50 and 9, so are whole is 59.

And what about D? There are 4 tens, which is 40, and 3 ones, which is 3, This is equal to 43 altogether.

40 And 3 is equal to 43.

So then for question two, you are having a go at pulling out some tens and ones, and then with your partner working out what the whole was together represented as a number.

So here's Izzy.

She said, "I chose some blocks and put the tens in one part of my part-part-whole model and the ones in the other part." So there are her tens and ones.

And Lucas says, "I drew a part-part-whole model and wrote in the parts I could see," so he could see 50 and 6, "and then I found the whole and wrote the number to represent it." And the missing whole was 56.

I hope you had fun playing that game and I hope you were able to find the whole successfully.

Let's move on to part two of our lesson, finding a missing part.

Izzy puts her base 10 into the part-part-whole model and writes her number to represent it.

Lucas partitions the tens.

So Izzy made 78, and she gave us our whole of 78.

So Lucas has partitioned the tens, so there are 7 tens.

"I wonder what the missing part must be," he says.

Izzy says, "The missing part must be 8 because 78 is 7 tens, or 79, and 8 ones." So 7 tens and 8 ones.

So the missing part must be the 8 ones.

She says, "I can prove it on a Gattegno chart.

7 tens 8 is the same as 78." So she tapped the 70 and the 8, 7 tens and 8.

Lucas wants to buy this toy from the toy shop.

He already has 2 10 p coins.

You can see them there on the screen.

Let's find out how many more one pennies he needs.

He says, "I'll draw a part-part-whole model to help me represent the problem." So there's his part-part-whole model, and he knows that one of his parts is those 2 10 ps.

And he also knows that the car costs 28 p, so he knows the whole and one part.

So the car costs 28 p, that is 2 tens, or 20 p, and 8 ones.

So he knows that 28 is a 20 and 8 ones.

So the missing part must be 8 one pennies, or 8 p.

And there they are.

Now, he's got enough money to buy the car.

Time to check your understanding now.

Which picture shows the missing part of the part-part-whole model?" Is it A, B, or C? And remember, you can use base 10 blocks, a Gattegno chart, or replace value chart to help you.

So pause the video, have a go, and then we'll look at the answer together.

How did you get on? Did you spot that it was B? 53 is 5 tens, or 50, and 3 ones.

So the missing number must be 3 ones.

We already had 5 tens in our part-part-whole model.

There they are, the 3 ones that were missing.

Lucas partitions a different number and hides one part.

What's the missing part this time? Izzy says, "The missing part must be 30 because 35 is 3 tens or, 30, and 5 ones." So let's look at that on the place value chart.

3 tens, or 30, and 5 ones.

We've got the 5 ones, so we must be missing 3 tens.

And she says, "I can prove it on a Gattegno chart.

3 tens 5 is the same as 35." So she'd have tapped the 30 and the 5, and the 30 is 3 tens.

Izzy wants to buy this toy from the toy shop.

It's a bear.

It cost 67 p.

She already has 7 1 p coins.

Let's use a bar model to find out how much more she needs.

So she's drawn her bar model.

So we know that the whole price of the toy is 67 p, and that she already has 7 1 ps.

So the teddy cost 67 p.

"The 7 one pennies represents the 7 ones, so I have all the ones I need.

I must find the tens," she says.

The missing part must be 60 because 67 is the same as 6 tens, or 60, and 7 ones.

6 tens 7 is the same as 67.

So there are her 6 tens, this time, 6 10 ps.

Time to check your understanding.

Which picture shows the missing part of the bar model? So we've got our whole is 82, and we can see one part.

So is it A, B, or C that shows the missing part of the bar model? And remember, you can use base 10 blocks, a Gattegno chart, or a place value chart to help you.

So pause the video, have a go, and we'll look at the answer together.

How did you get on? Did you spot that it was B? We had 82, and one of our parts was the 2 ones.

So we needed the 8 tens.

82 is 8 tens, or 80, and 2 ones.

The missing number must be 8 tens, and there they are.

Lucas says he can partition this number like this, 4 and 1.

Hm, what's his mistake? Oh, well, Lucas says, "That can't be right.

4 ones plus 1 one is equal to 5 ones." And he says, "I've spotted my mistake.

The 4 in 41 represents 4 tens, not 4 ones." And we can see that in our place value chart.

4 tens represents 40.

So the 4 represents 40, and then we've got our extra one.

4 tens 1 is the same as 41.

The missing part must be 40 because 41 is 4 tens, or 40, and 1 one.

Time for you to do some practise now.

Use base 10 blocks and partition the tens and ones to find the missing part in each representation.

Remember to use the stem sentences to help you.

And you've also got a place value chart there as well.

And for part two, you're going to match the missing part to the correct bar model and explain how you know you are right.

So pause the video, have a go at those practise tasks, and we'll get together for some answers.

How did you get on? So let's look at question one, you are finding the missing part.

So in A, 28 is equal to 2 tens, or 20, and 8 ones, which is 8.

So the missing part must be 8 ones.

And we can see there, 2 tens, which is equal to 20, and 8 ones.

So our missing part was 8 ones.

What about B? 69 is equal to 6 tens, or 60, and 9 ones.

So the missing part must be the 60.

We've got 9 ones already.

6 tens and 9 ones.

And there are 6 tens.

What about C? 37 is equal to 3 tens, or 30, and 7 ones.

So the missing part must be 30.

3 tens is equal to 30 and 7 ones.

So a missing part is those 3 tens.

And what about D? Are we missing the tens or the ones? Well, 52 is equal to 5 tens, or 50, and 2 ones.

So the missing part must be the 2 ones.

We've already got the 5 tens.

5 tens is equal to 50, and our missing 2 ones, and there they are.

So here we had to match the missing part and put it into the part-part-whole model.

So what was missing from A? We had a whole of 23, we had 2 tens, so we were missing 3 ones.

For B, we had a whole of 57, we had 7 ones, so we must've been missing the 5 tens.

And for C, 32, we had 2 ones.

So we must've been missing the 3 tens.

For D, we had 48, so we've had 4 tens in the part, and we needed 8 ones in the other part.

In E, our whole was 36, and we had 6 ones, so we needed 3 tens.

And for F, our whole was 85.

We could see the 5 ones.

So our missing part was the 8 tens.

And I hope you also explained how you knew using language like the language I used when I was matching the missing parts.

So we've come to the end of our lesson.

We've been partitioning two-digit numbers into tens and ones using place value resources.

We've been finding missing wholes and missing parts.

And we've been thinking really carefully about what each digit in a two-digit number represents.

So we've learned that two-digit numbers can be partitioned into tens and ones.

The order of the digits tells us their value.

And we can use a Gattegno chart or a place value chart to help us to remember what the digits in a two-digit number represent.

Thank you for all your hard work and your good thinking today.

I hope you've enjoyed the lesson too, and I hope I get to work with you again soon.

Bye-Bye!.