Lesson video

Hello there.

My name is Ms. Coe, and I'm really, really excited that you've chosen to learn with me today.

We're thinking about addition and subtraction within 10.

If you're ready for this super exciting lesson, then let's get going.

So by the end of this lesson today, you will be able to say that you can solve problems using known addition and subtraction facts within 10, and we're going to be using lots of the strategies that you have thought about so far.

There are some key words for this lesson.

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

My turn, visualise, your turn.

My turn, represent, your turn.

My turn, calculate, your turn.

My turn, check, your turn.

Great work.

I want you to listen out really carefully for these words in the lesson today and see if you can use them yourselves when talking to your friends about your learning.

This lesson today is all about problems involving addition and subtraction facts within 10, and it has two cycles.

In the first cycle, we're going to be visualising and representing problems. Visualising just means being able to represent them or see them in a certain way.

And then we're going to move on to calculate and check our answers.

Let's get started with our first lesson cycle.

Jacob and Sam want to share their learning with Laura and Lucas, so they decide to become tiny teachers, so they're going to be helping them through a series of problems. Let's see if we can help Laura and Lucas as well.

If we want to be able to solve problems using what we know, we first need to be able to visualise the problem, so that means we need to be able to imagine it in front of us.

Let's look at some of the pictures that we can see.

I can see six eggs.

Now if I'm visualising, I'm imagining those eggs.

I'm thinking about what it might be like to pick them up, how they might feel.

Are they heavy or light? So I'm imagining what I might do with those six eggs.

Laura began to complete a jigsaw.

Have you ever completed a jigsaw? Jigsaws have different pieces that you put together to make a drawing or pattern.

In this case, I can see that Laura's jigsaw has some sea and a lighthouse.

The box says that the jigsaw should have eight pieces in it.

It is a jigsaw made of eight pieces, but she's used all the pieces, and she only has six pieces.

I can see there she has six pieces to her jigsaw.

How many pieces will she need to find to complete her jigsaw? We can use a bar model to represent this particular problem.

Laura says she's represented this problem with counters.

Eight is the whole and six is a part.

Remember there were eight pieces altogether and Laura has six of them so far.

Here is our whole of eight counters, and we've put that in the top of our bar model, and we know that one part is six, so represented that with six counters in one of the parts.

Jacob says that he has used numerals.

There should be eight pieces, and we only have six.

So he has written a whole of eight and one of the parts of six.

Now he says we can easily see the calculation we have to do.

So in either bar model we can see that we have a missing part.

Let's look at a different problem.

We are thinking about building towers made of cubes, and you can see there that Jacob has the class tower record.

He made a tower of eight blocks.

That is the class record.

Well done, Jacob.

Sam and Lucas each build their own towers to try and beat that class record.

I wonder if they can do it.

Here's Sam's Tower, and she says that my tower is only four blocks tall.

This is Lucas's tower.

Lucas's tower is five blocks tall.

Their towers alone aren't enough to beat the record.

Remember the record is eight blocks, but Sam says we can put the towers together.

I wonder what will happen if they put the two towers together.

Will this new tower be tall enough to beat the class record? Hmm, how might we visualise or represent this problem? So we need to be able to represent it using what we know.

Let's use a bar model to represent the problem.

Sam says that she built a tower that was four blocks tall, and Lucas built one that was five blocks tall.

So they are the parts, and we need to find out how tall the tower is going to be.

So we need to find the sum or the whole.

One of our parts is four.

The other part is five, and we need to work out the whole, what is the sum or the total of the blocks altogether.

Remember they're trying to work out if it's going to beat eight blocks.

Hmm, I think it might.

Time to check your understanding.

This time the class is sorting things out that they can donate to the local charity shop.

The children collect together 10 books, and they decide of those 10, three of them can be donated.

How many books are left in their classroom? I would like you to imagine that problem.

Can you imagine the books? Can you imagine what we're doing with the books? And then I'd like you to represent it as a bar model.

Pause the video here and have a go at imagining and representing.

Welcome back.

How did you get on? So let's think about our problem.

We had 10 books, and three of them went to the charity shop.

So 10 is the whole because there were 10 books altogether and you should have written that in your bar model as the whole.

So the top bar in this case, three of them were donated.

So three is one of the parts, and we had a part filled in our bar model and we don't know the other part.

We don't how many books were left.

So that is the missing part.

Well done if your bar model looked like mine.

You might have visualised or imagined 10 books altogether and then removing three books with the rest of them being left on the shelf.

Time for your first task, can you create your own problem for a friend? I'd like you to choose two numbers from zero to 10.

You can use addition or subtraction and ask your friend to visualise the problem and then represent it using what they know.

I wonder if you can really challenge your friend to think about how they're going to visualise it and represent it.

I wonder if you can use bar models.

Pause the video here, and I'll see you shortly for some feedback.

How did you get on? Did your friend visualise, imagine the problem really well? Remember, your problems will have looked very different to ours because you might have imagined and you might have come up with different contexts, but in my case we had, there were three otters swimming in the river and then four more otters came to join them.

So I'm visualising, I'm imagining those three otters playing around, splashing around in the river, and then I'm imagining four more otters, bounding around and coming to join them in the river.

How many otters are in the river now? So you might have represented this on a bar model.

In this case three is a part, four is a part, but we don't know what the whole is.

So we've filled in our parts and our missing whole.

Your problem might have included subtraction or a missing part.

Let's move on to the second part of our learning where we're going to be calculating and checking our answers.

Let's revisit our problems. So remember Laura began to complete a jigsaw.

If you remember the box said it should have eight pieces in it, but she made her jigsaw and only had six of the pieces, and she wanted to know how many more pieces she would need to complete her jigsaw.

So we visualised the problem and then represented it as a bar model.

We knew that the whole was eight, and we knew that one part was six.

So Laura is reminding us that because we know a whole and a part, we need to subtract the part from the whole.

We need to calculate eight minus six.

Hmm, how are we going to do that? We can do this by thinking about the strategies that we know and choosing the best strategy to calculate eight minus six.

Laura and Jacob work together to calculate Laura's problem.

Remember we are finding eight minus six is equal to, hmm.

Jacob says that eight and six are both even numbers.

So Laura suggests that they look on a number line to find eight and six.

Here's our number line.

Here is eight, and here is six.

Jacob reminds us that these two numbers are consecutive even numbers.

Six is the even number before eight.

So he knows that their difference must be two.

Remember when you have consecutive even numbers, even numbers next to each other, they have a difference of two.

So if the difference of two, that means that eight subtract six is equal to two, that means that we can answer our problem.

We can fill in the missing parts of our bar model.

We know that eight is the whole, six is a part, and two is a part.

Two is the missing part of the bar model.

Jacob says that we can actually use that completed bar model to then check that we are correct.

Hmm, I wonder how he's going to do that.

So we know that if we add the parts together, we should get the whole, so we can do six plus two and it should be equal to eight if they're correct.

What do you think? Did they get it correct? Two more than an even number gives us the next even number says Jacob.

So two more than six is equal to eight.

That means that we must be correct in our thinking.

That means that eight minus six is equal to two.

They have solved the problem.

And then we can answer our problem.

Remember we're thinking about those jigsaw pieces.

So Laura needs two more pieces to complete her jigsaw.

Let's look at another of our examples.

Remember Sam and Lucas were building their own towers to beat the class record.

The class record was eight blocks.

They realised that their towers alone weren't enough, so they put them together, and they want to see if that was enough to beat the class record.

So remember that this time the parts were four and five.

Those were the towers that they built that they were putting together, and so we're being reminded by Lucas that we need to calculate four plus five.

We need to add those parts together to find the sum or the whole.

They can do that by choosing the best strategy for four plus five.

I wonder if you can think about the strategy that you would use to find the sum of four and five.

Lucas and Sam work together to calculate to see if their new tower will beat the classroom record.

Sam says that five is one more than four so we can use a near double to solve it.

Lucas is saying, well, which double fact should we use? Can you think of the double fact that is near to four plus five? Sam says that she knows that double five is 10, so five plus five is equal to 10, so she's going to use that one.

Double five is 10 and we can show that on a 10 frame.

And we know that one of the add-ins in our actual problem is one less.

So that means the sum of four and five will be one less.

One less than 10 is nine.

So four plus five is equal to nine.

Nine is the whole.

So Lucas and Sam have a new tower of nine blocks, and Sam's saying, well, the classroom record, remember Jacob set that, was eight.

So have they beaten the record? What do you think? Our new tower she says is now nine blocks tall.

The whole is nine.

Have they beaten the record? Let's have a look.

That's Jacob's Tower.

That's the new tower.

Yes, one more than eight is nine.

So they have beaten the record.

Well done you two.

They're the new record holders.

Sam seems very excited about that.

Time to check your understanding.

The children collect together 10 books.

Three of them can be donated to a charity shop.

How many books are left in their classroom? Remember that we know in this case the whole and one of the parts.

So we need to calculate 10 subtract three is equal to hmm.

What strategy could be used to calculate 10 subtract three? Pause the video and have a go at this.

Welcome back.

How did you get on? Well, Sam and Laura share how they calculated it.

You might've done it this way.

You might've chosen a different way.

Laura says that the whole is 10 so we can use our knowledge of number pairs to 10 to help us.

Laura knows that seven and three are a number pair to 10.

Seven plus three is equal to 10, so therefore 10 subtract three is equal to seven.

Seven is the missing part.

Sam did it a different way.

Sam used the number 10 shape, and so you can check to see if you're correct this way.

She's going to place a number three shape on the top and that shows us the number shape that's needed to pair with three to equal 10.

And we can see that we need a number seven shape to pair with three.

So therefore 10 subtract three must equal seven.

We can see there that those two parts add together to make 10, so therefore 10 subtract three is equal to seven.

Well done if that's what you've got.

Now it's time for you to have a go.

Earlier you visualised and represented some different problems. Remember you set your friends some problems for them to visualise and represent.

So now you're going to calculate and check those problems. Think really carefully about the strategy that you're going to use to solve the problems. So remember Lucas visualised and represented this problem.

He imagined three otters in a river, and then he imagined four more otters coming to join the fun.

He then wanted to find out how many otters there were altogether.

So he visualised that problem and then he represented it in a bar model.

So now he's got to calculate the sum and then check it.

Remember you did addition and subtraction problems. So you might have to calculate the sum or the difference.

Pause the video here and come back when you're ready for some feedback.

How did you get on? Did you choose some really good strategies to solve your problems? Remember, you will have done lots of different problems. In this case, Lucas had his problem with his otters.

He had three otters in the river, four more otters joined the river, and he wanted to find out how many otters there were then.

So he said three is a part, and four is a part.

So he needed to find the whole.

He had to work out three plus four is equal to hmm.

I wonder what strategy he's going to use.

Lucas said that he can see a near double because four is one more than three.

So he's going to use double three to help him calculate three plus four.

He knows that double three or three plus three is equal to six, and we can see that on the 10 frame here.

Now the first add-ins are the same, but the second add-ins in our problem, one of the add-ins is one more.

So that means that the sum will be one more than six.

The sum of three and four will be one more than six.

Let's add one more.

And we know that one more than six is seven.

So three plus four is equal to seven.

Seven is the whole.

Now remember this is just Lucas's example.

You'll have done lots of different things.

We can use that information to fill in our bar models.

So the whole was seven, and we know that there were seven otters swimming in the river.

We've come to the end of our lesson, and I hope you've enjoyed solving and visualising problems, and I hope you set lots of fun problems for your friends to solve.

Let's summarise our learning.

We can visualise or imagine a problem to help us understand what it's asking us to do.

We can represent addition and subtraction facts using bar models and manipulatives, and we can calculate using lots of different strategies to solve addition and subtraction problems within 10.

Thank you so much for learning with me today.

I've had lots of fun, and I hope you did too.

See you next time.

Bye.