Lesson video

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

I'm really looking forward to working with you.

We're going to use lots of the things we already know to help us with some new learning and I know you're going to do really well.

So let's get started.

Welcome to today's lesson, which is called partition the whole into two parts and express as a subtraction equation.

And it comes from the Unit: Additive Structures: Addition and Subtraction.

In today's lesson, we're going to look at subtraction, what that means and how it can be represented.

So let's get started.

So our keywords today, the words important for our learning are subtract my turn, subtract your turn.

And minus sign my turn, minus sign your turn.

And minuend my turn, minuend your turn.

And subtrahend my turn, subtrahend your turn.

And difference my turn, difference your turn.

Well done.

Okay, so in the first part of today's lesson, we're going to look at the use of the minus sign and really get to understand how we use that and why.

In our lesson today, we'll meet Jun and we'll meet Izzy.

They'll help us with our learning.

So there are eight apples.

Five have been eaten.

How many have not been eaten? Explain how you can find out.

To find out, you must partition the apples that have not been eaten from the whole group.

Then you'll find out how many apples are left from the whole group.

And there we can see we've partitioned, some haven't we.

Now, I can see how many have not been eaten.

We partitioned the five that have been eaten to find out.

So there are eight apples.

Five have been eaten.

So three apples have not been eaten.

When we partition to find one part of the whole amount, it is called subtraction.

When we add, we combine the parts to make the whole amount.

When we subtract, we partition the whole group to find one part.

When we subtract, we use this symbol.

This symbol is called the minus sign.

When we see it, we say minus, subtract or takeaway.

And today, we will say minus.

We can use this to show that one part has been partitioned from the whole group.

And there we can see, can't we? Five apples have been partitioned from the whole group.

Let's practise.

How will we say this? That's right, we say eight minus three.

It tells us that three apples have been partitioned from the whole group.

How will we say this? That's right.

We say eight minus four.

It tells us that four apples have been partitioned from the whole group.

How will we say this? That's right.

We say eight minus seven.

It tells us that seven apples have been partitioned from the whole group.

So now it's time to check your understanding.

Which of the following would you use to show how many have been partitioned from the whole group in this picture? So pause your video now while you have a think about that.

Okay, so let's see which one did you choose? So we had five minus three, five minus four or five minus two.

And when we look, we can see that two have been partitioned from the whole group.

So it will be five minus two.

Well done.

It's that one, wasn't it? We can represent subtraction as an equation.

So we can see there eight minus five is equal to three.

What do you think each part of the equation represents? The eight represents the whole group of apples.

That's right.

The five represents the apples that were partitioned from the rest of the group.

And the three represents the rest of the apples in the group, doesn't it? When we know the whole and we know one part, we can subtract to find the other part.

There are six dogs, two are lying down.

How many are not lying down? "If we know the whole and we know one part, we can subtract to find the other part," says Izzy.

There are six dogs in the whole group, two are lying down, so we will partition those two, that part from the whole group.

Now, you can easily see how many are not lying down.

Let's represent this as a subtraction equation.

There are six dogs in the whole group.

We know that two are lying down, so we can partition this part from the whole group.

We can say six minus two.

We can see that there are four dogs in the other part of the group.

So we can say six minus two is equal to four.

There were four remaining in the other part of the group.

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

So we've got an equation here.

It says seven minus four is equal to three.

Which picture represents this equation? So pause the video while you have a think about that.

Okay.

And let's see, what did you think? Did you spot it? That's right.

So we had seven in the whole group there and then four were partitioned off, so that's seven minus four.

And then we can see there were three in the rest of the group, the remaining part of the group.

So seven minus four is equal to three.

Well done.

And here's the second part of your check.

There are seven candles, four of them have been lit.

How many have not been lit? Which equation would you write to represent this? And we can see the picture.

You have to pick the correct equation.

Pause the video while you do that.

Okay, so which one did you pick? That's right, there is seven in the whole group and four were partitioned off, weren't there? So seven minus four is equal to three and that.

So three remaining candles that weren't partitioned.

Well done.

What does each part of the equation represent? So the seven represents and the four represents and the three represents.

Pause the video now while you complete those stem sentences.

Okay, so what did we say the seven represents? That's right.

The seven candles in the whole group.

The four represents the four candles that were partitioned from the group and the three represents the three candles that were not lit.

That were remaining in the rest of the group.

So well done if you got that.

When objects look the same, if we know the whole and we know one part, we can subtract to find the other part.

Solve the equation, five minus three is equal to? So what will we do? There are mm cups in the whole group.

That's right.

There are five cups in the whole group.

Mm cups is the part that must be subtracted from the whole group.

So how many must be subtracted? That's right, it's five minus three.

So three cups must be subtracted.

We've partitioned them there, haven't we? We can represent this as five minus three and then we can easily see now that the remaining part is two.

Well done.

Five minus three is equal to two.

So now let's solve this equation.

Five minus four is equal to.

So let's complete the same sentences.

There are five cups in the whole group.

Four cups is the part that must be subtracted from the whole group.

We can represent this as five minus four.

Now, we can easily see the other part is one.

Five minus four is equal to one.

Well done.

Look at each equation and tell Jun how many counters to partition from the whole group.

So we can see he's got a whole group of six there, hasn't he? Then solve the equation.

So six minus two is equal to how many should he's partition? We'll turn them over to show that we've partitioned them.

That's right.

Six minus two.

And then we can easily see that it is equal to four.

That's right.

Six minus three is equal to.

So let's partition three.

And we can easily see that there are three remaining in the rest of the group.

Six minus three is equal to three.

Six minus four is equal to.

That's right.

We can easily see when we partition four that there are two remaining in the group.

Six minus five.

That's right.

We can easily see now that there is one remaining, so six minus five is equal to one and then six minus six.

So if we partition the whole set, turn them all over, we can see that there are none remaining, so six minus six is equal to zero.

Well done.

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

Read the equation and subtract the part shown from the whole group to solve the equation.

Four minus three is equal to.

Okay, so pause the video while you try that.

Okay, so what did we say? Four minus three.

So how many did we need to partition? That's right.

We needed to partition, we needed to subtract three, didn't we? Four minus three is equal to.

And we can now clearly see that there is one remaining in the rest of the group.

So well done if you got that.

So your task for the first part of today's lesson is to match each picture to the equation that represents it.

Okay, so pause the video now while you have a try at that.

Don't forget when you've matched it, you can solve the equation as well, can't you? Using the picture.

So have a try at that.

So the second part of your task is to read each equation and subtract the part shown from the whole, then solve the equation.

Okay? So pause the video now while you try that.

So let's see how we got on with the first part of our task.

Then match each picture to the correct equation.

So in the first example, we can see that there are a group of six apples, okay? And three of them have been partitioned.

They've been subtracted, haven't they? From the rest of the group.

So that would be six minus three is equal to, and then we can see that it is equal to three.

There are three remaining in the rest of the group, aren't there? Okay, and then the next example, we can see that there are three in the whole group and two have been subtracted.

So three minus two is equal to, and we can see that it's one, can't we? Well done.

Okay, the next example, we can see that there are eight in the whole group and three have been subtracted.

So we've got eight minus three is equal to, and we can see that it's five.

And then lastly, we've got five in the whole group, haven't we? So we know it's five and then we can see that two have been subtracted.

So five minus two is equal to three.

Well done.

So let's see how you got on with the second part of our task today.

So you can see we have a whole group in part A of six apples, didn't we? And it says six minus two is equal to, so I subtracted two, okay? You may have subtracted a different two.

It doesn't matter, does it? Which two you subtract? So six minus two and you can clearly see that the other part, the remaining part is four.

Well done.

Okay, then part B, three minus one is equal to, so subtract one and you can see that there are two remaining in the group.

And then C, you can say eight minus four is equal to, so when you subtract four, you can see that there are four remaining in the rest of the group.

Then part D, five minus one is equal to, and you can see when you subtract one, there are four remaining in the group.

And then we have seven minus four is equal to, and when you subtract four, you can see that there are three remaining in the rest of the group.

And then finally 10 minus four is equal to, so when you subtract four, you can see that there are six remaining in the other part of the group.

So well done.

Okay, so the second part of our lesson, we're going to have a look at write equations that represents subtraction stories.

Each part of a subtraction equation has a special name.

Okay, so we can see an equation there.

Seven minus three is equal to four.

Seven is the minuend.

It represents the whole group.

Three is the subtrahend.

It represents the part to be subtracted from the whole.

And four is the difference.

It represents the part that remains in the rest of the group.

What is the subtrahend then in this equation? Six minus two is equal to four.

In a subtraction equation, the number we subtract is called the subtrahend.

It is the part of the group that has been partitioned from the whole, isn't it? So two is a subtrahend, it represents the part to be subtracted from the whole, and there we see.

What is the subtrahend in this equation then? Eight minus four is equal to four.

Mm is the subtrahend.

It represents the part to be subtracted from the whole.

So which part needs to be subtracted from the whole? That's right.

Four is a subtrahend, isn't it? There it is.

In a subtraction equation, the whole group is called the minuend.

What is the minuend in this equation? Six minus two is equal to four.

So mm is the minuend.

It represents the whole group.

That's right.

Six is in the whole group, isn't it? So six is the minuend.

What is the minuend in this equation? Eight minus four is equal to four.

So mm is the minuend.

It represents the whole group.

That's right.

Eight is the minuend.

What is the difference then in this equation? So six minus two is equal to four.

So mm is the difference.

It represents the part that remains.

That's right.

Four is the difference.

It represents the part that remains in the rest of the group, doesn't it? What is the difference in this equation? Eight minus four is equal to four.

So mm is the difference.

It represents the part that remains.

That's right.

Four is the difference, isn't it? That was the part of the group that remained when we subtracted four.

Okay, so now it's time to check your understanding again.

Match the parts of the equation to the correct description.

Okay, so we've got a picture there and we can say, the equation is three minus one is equal to two, okay? So you've got to match the difference, the minuend and the subtrahend to its correct meaning.

So one of them means the whole group of cars, one of them means the one car that was subtracted, and one of them means the two cars that remain.

So pause the video now while you match them up.

Okay? And let's see how we got on.

So the difference is the two cars that remain, isn't it? That's right.

The minuend is the whole group of cars.

That's right.

And the subtrahend is the one car that was subtracted.

Excellent.

Well done.

There are six balloons altogether in the whole group here.

Can you see them? Three are blown up.

How many are not blown up? When we write a subtraction equation, first, we need to describe the minuend.

Then, we must remember to think about the subtrahend and the difference.

So we're thinking about how we write the equation now, aren't we? So let's write the equation.

We can represent this as mm minus mm is equal to mm.

So it will be six minus three is equal to three.

That's right.

What does each part of the equation represent? The six represents the total number of balloons altogether.

That's right.

The three represents the three blown up balloons 'cause that was the part we knew.

And the other three represents the three balloons that have not been blown up.

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

Tell a story to describe this picture.

Then, use the stem sentences to help you write the equation.

So there's a stem sentence look and that can help you.

There are mm candles altogether in the whole group.

Mm have been lit.

How many have not been lit? So pause the video now while you tried that.

Okay, so how did we get on? Let's have a look.

So let's use our stem sentence.

There are seven candles altogether in the whole group.

Five have been lit, so how many have not been lit? So how many do we think it was? That's right.

We can see when we partition five off, two candles haven't been lit.

We can represent this as seven minus five is equal to two.

That's right.

So seven minus five is equal to two.

Look at the equation and say which part of the story each number represents.

So think about what the seven represents, what the five represents, and what the two represents? Pause the video now while you do that.

Okay, so let's see.

The seven represents the total number of candles altogether.

That's right.

The five represents the five candles that are lit or the five candles to be subtracted.

And the two represents the two candles that are not lit, which are the two candles remaining in the rest of the group, isn't it? Well done.

Let's tell a subtraction story, then write the equation.

There are five bananas altogether.

Two have been peeled.

How many have not been peeled? We can write this as mm minus mm is equal to mm.

So we can write this as five minus two is equal to three.

That's right.

And there's how we write it as our equation? So here's another problem.

There are seven boxes, two are open.

How many are not open? Izzy writes an equation to represent this problem.

What mistake has been made? Have a look at that equation.

That's right.

Did you spot it? She did not write the minuend first, did she? So let's have a little look at getting at this problem.

And let's help Izzy write the equation.

There are seven boxes altogether, two are open and five are closed.

So we've got the two that are open partitioned there, haven't we? We've subtracted those.

We can represent this as seven minus two is equal to five.

So seven minus two is equal to five.

That's right.

Because we have to start with the whole group, don't we? And subtract from that.

Okay, so now it's time to check your understanding again.

So solve the problem by writing a subtraction equation.

Use the stem sentences to help you.

So the problem is there are 10 hats.

Seven have stripes.

How many do not have stripes? Okay, and there are stem sentences there.

There are mm hats all together.

Mm, hats are stripy.

How many are not stripy? And then you have to say, we can represent this as mm minus mm is equal to mm, and write the equation.

So pause the video while you try that.

Okay, and how did we get on? Okay, let's have a look then.

So there are 10 hats altogether.

Seven hats are stripy.

How many are not stripy then? So we can represent this as 10 minus seven is equal to, and we can see that it's three, can't we? And our equation will be 10 minus seven is equal to three.

Well done.

So your next task then is here.

So in each picture, draw a ring round a part of it, one part of it to subtract it from the whole group.

So you can choose how many are going to be in the part you subtract, then write and solve the equation.

Okay, once you've finished, you may want to try to write some equations that will all have the same difference when you subtract a part.

So that would mean they would all have the same amount remaining when you subtract, okay? So pause the video now and have a try.

Okay? So let's see how we got on it in that then.

Okay, so you may have subtracted a different part to me, but I'll show you an example of what I did.

So in this first one, part A, we knew there were four in the whole group, so you would have to have that, wouldn't you? And then I decided to subtract three.

So I said four minus three is equal to, and I subtracted three, you may have subtracted another amount.

So four minus three is equal to one.

And then for the birds, I decided to subtract four.

So I said six minus four is equal to, and then I could see that it was two remaining.

And then for this one I said two minus two is equal to.

So I subtracted the whole group there and it was equal to zero.

I subtracted the whole group.

Okay, and then for the balloons I said eight minus two is equal to, and I could see it was six and then seven minus four is equal to three.

So then 10, I subtracted five.

So 10 minus five is equal to five.

Well done.

I wrote some equations that had a difference of zero when you partitioned one part from the whole.

So here they are.

So I said four minus four would be equal to zero.

We take away the whole group.

Then there'd be none left, would there? Six minus six is equal to zero.

And then this one would be two minus two is equal to zero.

I wonder what this one would be.

That's right.

Eight minus eight is equal to zero.

And seven minus seven is equal to zero.

And 10 minus 10 is equal to zero.

So well done if you did that.

And you may have found some other equations that all had the same difference as well.

So well done.

Excellent.

You've worked really hard.

So let's see what we found out in today's lesson.

When you know the whole and one part of the whole, you can use subtraction to find the missing part.

This can be represented with a subtraction equation.

The minus sign can be used to show that one part has been partitioned or subtracted from the whole group.

And each part of a subtraction equation has a special name.

Okay, so well done.

I've really enjoyed working with you today.

You've worked really hard and we've found out lots about subtraction, haven't we? So well done.