Lesson video

Hello, my name's Mrs. Cornwell, and I'm going to be working with you today and we're going to be finding out all about money.

Okay, so I would imagine you already know quite a lot about money because we see it all around us every day, don't we? All different types of coins and notes.

So we're going to find out how we can use money in different ways.

We can use it to pay for items, we can add up how much money we've got, and so the learning we do today is going to be really useful for us, isn't it? So I'm really looking forward to you working with you.

I know you'll work really hard, so let's get started.

Okay, so today's lesson is called Find and Make Amounts Within 20 Pence, and it comes from the unit Unitizing and Coin Recognition: Value of a Set of Coins.

Okay, so in our lesson today, we're going to calculate and make given amounts, but this time within 20 pence, and that will help us to work much more confidently with money, won't it? So our keywords today are total value.

My turn, total value, your turn.

And efficiently.

My turn, efficiently, your turn.

Well done.

Okay, so the first part of our lesson is where we're going to pay for items up to 15 p in the most efficient way.

In this lesson, you'll meet Sofia and Jacob, and they will help us with our learning.

So the children make a new shop in the dressing up area.

Okay, here it is.

And Jun says Clothes are more expensive.

We will need lots of coins to pay for these.

Do you agree with Jun? Remember, we can try and use coins with a greater value to work more efficiently, Sofia reminds us.

Let's see how we can pay for the hat.

Okay, we can see the hat costs 11 p, "I will use one p coin," says Jun.

"I wonder how many I will need." So he's chosen to use 11 one pence coins, hasn't he? Hmm, do we think that's the most efficient strategy? "That is a lot of coins to carry.

It is not the most efficient way to pay," say Sofia.

Hmm, "We know each group of two pennies has the same value as a two p coin.

I think it would be more efficient to use some two ps," says Sofia, so let's see what she does.

So she swaps each set of two one pennies for a two pence coin, doesn't she? "That is still quite a lot of coins.

You may drop some," says Jun.

Let's see if there is an even more efficient way to pay.

To work efficiently, we need to use fewer coins to pay.

That means we must try to use coins with a greater value.

What is the greatest value coin that is less than 11 p? Hmm, can you think of one? "We could use a 10 p," says Jun, so we could use a 10 p coin, couldn't we? And then what else would we need? We know adding one gives one more, so we can add one p to reach a total value of 11 p, and now we've paid for the hat in a really efficient way, haven't we? Using only two coins.

"We used only two coins.

We found the most efficient way to reach 11 p." Sofia thinks they can use the same strategy to find the most efficient way to pay for the hat.

Do you agree? So the hat costs 12 p.

"I think we can because 12 p is more than 10 p," says Jun, "If 12 p is the whole amount, then 10 p is a part." "We can use a part-part-whole model to help us." So there we've got 12 p as the whole and 10 p as a part.

"I wonder what the other part will be." So we've got 10, haven't we? And to make 10 into 12, we need two ones, don't we? So we can combine a 10 and a two to reach a total value of 12, and we can use a two p rather than two one pence coins because that would be more efficient, wouldn't it? So well done, yes, we can use that strategy to pay for the cap, can't we? Jun thinks he can use exactly the same strategy to find the coins to pay for the sunglasses.

Let's see if he is right.

So the sunglasses cost 13 p, what do you think? "I can definitely use a 10 because 13 p is greater than 10 p," he says.

If 13 p is the whole amount, then 10 p is a part.

"Let's show this on a part-part-whole model." So there's 13 p as the whole amount and 10 p is a part.

"If 13 is the whole and 10 is a part, then the other part is three," says Jun.

So we know that if we've got ten, three more make it into 13.

"We know that 10 add three is equal to 13." How will we make this with coins? Because we know there isn't a three pence coin, is there? It doesn't exist.

Sofia says, "I would use a two p and a one p," and then that would be the most efficient strategy, wouldn't it? So well done if you thought of that.

Now we have 13 p.

So now it's time to check your understanding.

Which coins would you use to pay for the T-shirt in the most efficient way? So the T-shirt costs 14 p, doesn't it? So look at the coins there and think about which set would pay most efficiently for the T-shirt.

Okay, so pause the video now while you think about that.

Let's see what you thought.

Did you think C? So we've got a 10 and two two p coins, and that's the fewest amount of coins you can use to make 14 p, so it is the most efficient strategy, isn't it? All the coins have a total value of 14 p, but C uses the fewest coins so it's the most efficient.

Sofia uses up all of the 10 p coins from the till.

How else could she pay for the T-shirt? "I would still partition 14 p into 10 p and four p," says Jun.

That's still a useful strategy.

"I know how to make 10 p and I know how to make four p, so I can make 14 p." Let's think about the most efficient way to make 10 p.

I need to find the greatest value coin that is less than 10 p, because we don't have any 10 p coins, do we? So what would that be, do you think? That's right, that's five p.

Double five p will be 10 p.

Now, let's think about the most efficient way to make four p.

I need to find the greatest value coin that is less than four p.

So that is two p.

So we would need double two p is four p.

So now we know we've found the most efficient way to make 14 p, haven't we? We found the most efficient way to make 14 p without using a 10 p coin.

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

What is the most efficient way to pay for the sunglasses without using a 10 p coin? So use a part-part-whole model to help you, and you can use coins as well if you want to, couldn't you, to help you.

So pause the video now while you try that.

Okay, so let's see how you got on.

So first of all, you needed your part-part-whole model 13 p was the whole amount, and we knew 10 p was a part, and the other part was three p, wasn't it? Okay, so we have to be thinking about the most efficient way of making 10 p and the most efficient way of making three p.

So we know the easiest way to make 10 p without a 10 p coin is two fives, so it has to be either A or C.

And then the most efficient way to make three p is a two p and a one p, so it must be C.

Okay, so here's the task for the first part of our lesson today.

The children want to buy a new T-shirt.

How many different ways can they pay for it? The T-shirt costs 15 pence, doesn't it? Find all the ways you can pay for it.

What is the most efficient way? Jun says, "I will try to find six different ways to pay." Okay, and also think about what is the least efficient way.

"Remember to write the value of the coins each time." Okay, so you're recording each way as you do it.

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

So you may have done this.

So 15 p, you could have used a 10 p and a five p, couldn't you? You could have used three five ps, you could have used a 10 p, two two ps, and a one p.

You could have used two five ps, two two ps, and a one p.

You could have used seven two p coins and a one p as well, couldn't you? What is the most efficient way? That's right, the 10 p and the five p because it uses the fewest amount of coins, the least amount.

What is the least efficient way? That's right, 15 and one p coins wouldn't be efficient at all.

You've got lots of coins there.

They would be very hard to count and you may drop some.

Okay, let's look at the second part of our lesson now then.

Pay for items up to 20 p in the most efficient way.

So the children think the clothes are too cheap so they increase their prices.

"I buy one of these items using only two coins," says Jun.

Which item does he buy, I wonder.

Can you spot it? "Let's think about the cost of each of these as a part-part-whole model," says Sofia.

We can partition the cost of the items into 10 and a bit to help us imagine the coins.

So 18 p will be partitioned into, 18 is made of 10 and eight.

So we would partition it like that, wouldn't we? So there is a 10 p coin but no eight p coin.

So Jun did not buy the hat.

Okay, let's try the cap.

So 17 can be partitioned into, 17 is made of 10 and seven.

So it's partitioned like that into 10 and seven.

There is a 10 p coin, but no seven p coin.

He did not buy the cap.

Okay, what about the sunglasses? So we know they cost 16 p.

Okay, 16 is made of 10 and six, so we can partition it into 10 and six, can't we? There is a 10 p coin but no six p coin.

Jun did not buy the sunglasses.

So what about the T-shirt? So the T-shirt costs 15 p.

15 is made of 10 and five, so we can partition it like that, can't we? There is a 10 p coin and there is a five p coin.

He must have bought the T-shirt, so well done if you spotted that.

Sofia wants to buy the hat that costs 18 pence.

What coins should she use? So she's saying I can partition 18 into 10 and eight, and there we go, look.

"I can use a 10 p coin to make 10 p.

Eight is an even number, so I could count in twos to make eight p." Two, four, six, eight.

Jun has a different way to pay.

"I will use a 10 p coin to make 10 p, but the greatest value coin that is less than eight is five p, so I'll use a five p coin." I wonder what other coin he needs.

"I know that eight p can be partitioned into five p and three p," he says, so what coins will have a value of three p? That's right, "I will use a two p and a one p," says Jun.

So well done if you did that.

So here's a task for the second part of our lesson.

The children add a new item to their shop.

It's a bag which costs 20 p.

Okay, and you can see there that each time they pay with it using a different number of coins, so the first time they pay for it with two coins and then three coins and so on.

So let's investigate to see if we can make 20 p using a given number of coins, okay? So you can get the coins out to help you with this, and let's see if you can find out the coins that the children used.

All right, so pause the video now while you try that.

So let's see how you got on.

You may have done this.

So for two coins, the only way was 10 p and 10 p, wasn't it? For three coins, it would've been 10 p, five p, and a five p.

For four coins it would've been five p, five p, five p, five p, wouldn't it? And for five coins, it would've been a 10 p, a five p, a two p, another two p, and a one p.

Six coins, you can see three five pence coins there, two two pence coins, and a one pence.

And seven coins, 10 pence, and then four two pences and two one pences.

And for some of those you may have found other possibilities as well, but those are some examples of right answers.

Okay, so well done if you found those.

Okay, so let's look at what we found out in today's lesson then.

So you can use different coins to make the same total value.

It is more efficient to use fewer coins to pay for an item.

It is more efficient to use coins of a greater value when you can, and when paying for items between 10 p and 20 p, partitioning the price into 10 a bit can help you work more efficiently, can't it? So well done.

So hopefully you're feeling much more confident about using coins in the most efficient way, and you'll be able to help when you're counting out coins and playing with money, so well done.

Excellent work.

I've really enjoyed today's lesson.