Lesson video

Hello there, I'm Mr. Tilstone.

Money is a huge part of the world we live in in our day-to-Day lives.

So it's my great pleasure to be teaching you a lesson all about money today.

So if you're ready, let's begin.

Our lesson outcome for today, what we'd like you to say by the end of the lesson is, "I can use knowledge of subtraction to calculate change when paying with whole pounds or notes." We've got some important mathematical vocabulary today, so I'm going to introduce it to you using my turn, your turn, are you ready? So we've got difference, change, number bonds.

And let's find out what those words mean shall we? So the result of subtracting one number from another is the difference.

So for example, the difference between eight and three is five.

That's a simple example.

In money change is, it's a word you might have heard before is the difference between the amount of money you use to pay and the value of what you are buying.

And a shopkeeper will give you change if the value of the money you hand over is worth more than the value of your shopping.

And number bonds is something you've been learning about for quite a long time now.

Number bonds are pairs of numbers which sum together to make another number.

So let's give you a really simple example that you might have explored when you were younger.

Number bonds to 10 include three and seven and one and nine.

Our lesson today is going to be split into two different parts.

One is calculating change when paying with a one pound coin.

So we're going to focus on that skill.

And then after that we're going to look at calculating change when paying with multiples of one pound and with notes.

But let's begin with calculating change when paying with a one pound coin.

Are you ready? We've got a helper in today's lesson.

You might have met him before.

This is Andeep.

So you've hopefully encountered this coin quite recently.

This is a one pound coin.

Andeep is shopping and he's got a one pound coin in his pocket.

He would like to buy this cake and that cake costs less than one pound.

It costs 70 p.

So he can pay with his one pound, but that means he's going to get some change.

He's gonna get some money back.

The change will be the difference between the cost of the cake and one pound.

So we're starting with some fairly easy arithmetic.

It will get a bit harder.

So this relationship can be represented using a bar model.

So on the top we've got the amount paid and that's equal to the bottom of the bar model, which is the cost of the item and the change.

So you can calculate the change that Andeep will get back using that bar model, that principle.

Let's start to fill in the parts of the bar model.

So the amount paid is one pound, that's the amount that Andeep handed over to the shopkeeper.

What's about the cost of the item? Well, the cake costs 70 p.

So we can fill in that part of the bar model two.

And you might notice we've got a number line in the bottom right that we're starting to fill in to go along with it.

So the cost of the item is 70 p and the amount pays one pound.

So all that's left now is to work out the change to calculate the change.

So 70 p plus 30 p equals one pound.

So Andeep will get 30 pence change.

So changes the difference between two values.

The difference between two numbers can be calculated using a count on strategy.

So we've counted on from the 70 p, which was the cost of the item, to one pound, which is how much Andeep gave.

And that gives us 30 pence.

So here we are.

These are the coins that you might have got back.

There are other possibilities too, but we're just going to focus on the 10 pence as for now.

Okay, let's step up slightly with the level of the arithmetic there.

That was pretty straightforward.

So this time Andeep would like to buy a pen.

We're going to calculate the change he'll get back.

So he's still spending one pound.

The pen costs 65 pence.

So looking at our bar model, we can fill in the cost of the item that's 65 pence.

And you see we've still got a gap there, which is the change.

So just like before, we can calculate that using a count on strategy.

Counting on from 65 pence to one pound.

It may help or it may not help to think of the one pound as 100 pence, but either way we're counting on.

So from 65 p to 70 p and then from 70 p to one pound.

Counting on from 65 p to 70 p is 5 p.

And then counting on from 70 p to one pound is a 30 p difference.

So altogether the change is 35 pence.

And that's one example of the change that he might have got back from the shopkeeper.

Now Andeep is feeling pretty clever.

He's feeling pretty fluent and he feels like he can apply some knowledge here.

'Cause he says, "I can do that automatically without a number line." Because he knows his number bonds to 100 Andeep new that 65 plus 35 equals 100.

So therefore 65 p plus 35 p equals 100 p or one pound.

So if you are good with your number bonds, you may not need to draw a number line.

Now your turn.

Let's see what you've understood so far.

Lucas tries Andeep's method.

Is he correct? So we've got a banana here that's costing 35 pence and we're still using the one pound coin.

Lucas says I will get 75 p change because 75 p equals 35 p, which is 100 p, which is one pound.

So is Lucas correct or not? He's tried using number bonds.

Pause the video and have a think.

How'd you get on with that? Let's have a look, shall we? No, he's not right.

Lucas has remembered that 70 p plus 30 p is one pound.

So he's got some kind of knowledge of number bonds there, but then he not added the 5 p and the 5 p together.

So in fact 65 p plus 35 p equals one pound.

So his change is 65 p.

So 65 and 35 go together, not 75 and 35.

So just be careful with that if you're using your number bonds.

Time to put these skills into practise.

So we've been looking at calculating change when paying with a one pound coin.

So over to you.

So let's start with this pineapple, it costs 75 p.

What's your change going to be? Now you might notice some of the steps are there for you already.

So you just need to fill in the gaps, the blanks.

And then we've got this pencil that costs 57 pence.

The arithmetic's a little bit harder there isn't it? So can you work out what all of the blanks need to be and then calculate the total change? And then with number two, we've got the number line there but not the jumps.

So you've got to figure out the jumps this time.

So 53 p is the cost of the orange.

What's the change? Filling the number line.

For the output, it's 26 pence.

What's the change? And for the grapes, 84 pence.

So what are the two missing gaps worth? And finally for this cycle task A3, calculate the change for this item when paying with a one pound coin, drawing a number line.

So this time you've gotta do the whole number line yourself.

So good luck, pause the video, see you shortly.

How did you get on? Are you ready for some feedback? Let's have a look.

So A1, the missing parts of the number line were 5 p and 20 p.

So the total change there is 25 p.

The missing parts of the number line for the pencil example were 57 p, which if you had 3 p gives you 60 p.

And then if you add another 40 p, it gives you one pound.

So the total change for that, if you add the 3 p and the 40 p is 43 p.

And here with the orange 53 p plus 47 p equals one pound.

And for the apple 26 p and 74 p gives you one pound.

So you're applying your number bonds knowledge there really.

And then for the grape example, same thing again.

So 84 p plus 16 p gives you one pound.

For number three, the missing parts of the number line were as follow.

So we start with 64 p, add 6 p gives you 70 p, add 30 p gives you one pound.

6 p plus 30 p equals 36 p.

Okay, so we've looked at calculating change when paying with a one pound coin.

I wonder if we can apply similar skills to paying with multiples of one pound and paying with notes.

Well let's find out, shall we? So this time the item which is a book cost three pounds four to we're going to calculate the change that will be given if you paid with a five pound note.

So you might notice the bar model's exactly the same as before.

We've got the amount paid on the top, which is five pounds this time, cost of the item is three pounds 40.

And we're calculating the change and this is how we do it.

So just like before we start with the value of the item that we're purchasing.

So that's three pounds 40 on the left hand side of the number line.

And then on the right hand side, the amount that we're giving, so that's five pounds.

And then we're going to take a jump, first of all from three pounds 40 to four pounds, which is a 60 p jump.

And then we're going to jump from four pounds to five pounds.

That's pretty straightforward.

That's a one pound jump.

Now if we combine those together, one pound plus 60 p gives us one pound 60.

So the change is one pound 60.

Okay, we'll stick to five pounds then.

But let's change the value of the item.

This time, the scissors cost two pounds 98.

We're going to use the same strategy as before.

So two pounds 98 and we're gonna count on to five pounds.

So 2 p would take us to three pounds and then a two pound jump would take us to five pounds.

Let's have a look at how I've expressed a change.

Is that right? Does that look right? Hmm, don't think it does, does it? Two pounds plus 2 p equals two pound 2 p.

But is that how you write two pounds, 2 p? No it's not.

If you remember, we need to use two decimal places to represent the number of pence.

So that's how we write two pounds two.

And now the calculation's correct.

Let's change the note that we're using to pay for the goods.

So Andeep this time has a 10 pound note, but we're going to use the same strategy.

He spends seven pounds 48 on various items for his pencil case.

How much does he have left? Well, just like before, we can use a number line for this.

Start him with seven pounds 48, and finish him with 10 pounds and we're gonna work out the difference.

And the difference will be the change.

Now we could do, if you can one leap, one jump, to go from seven pounds 48 to eight pounds.

If you are good with your number bonds to 100, you could do that in one 'cause 48 and 52 go together.

So therefore seven pounds 48 plus 52 pence gives us eight pounds.

And then we take a leap from eight pounds to 10 pounds.

So that's a simple jump of two pounds.

And all we have to do then is combine them together.

So two pounds plus 52 p gives us two pounds 52.

So he is got two pounds 52 left.

Now your turn, let's check your understanding.

So Andeep's got 20 pounds this time.

Calculate the change he would receive if his shopping costs 13 pounds 74 and you're going to draw a number line to show you are working.

Pause the video, have a go.

How did you get on? Let's have a look.

So our number line looks like this with 13 pounds 74 on the left hand side, 20 pounds on the right.

And then we're going to make a couple of jumps.

So we could jump from 13 pounds 74 to 14 pounds, that's a 26 pence jump.

And then from 14 pounds to 20 pounds, that's a six pounds jump.

Combine them together and we've got six pounds 26.

He receives six pounds 26 in change.

Let's try some independent practise, shall we? So for task B1, filling the ball models, using either mental methods or number lines.

So for A, the amount paid was five pounds and the cost was three pounds.

So what's the change, what's the difference? And you might be able to do that in your head without a number line.

I suspect you probably can.

For B it the cost is six pounds, but the amount paid is 10 pounds.

So what's the change? What's the difference? For C, the amount paid is 10 pounds, but the cost is three pounds 40.

So it's getting a little bit harder in terms of the arithmetic involved.

And again, if it's too difficult to do in your head, use a number line.

for D, two pounds 88 this time what paying with five pounds.

For E, the amount paid is 10 pounds and the change this time has been given but not the cost.

So you're gonna have to do some thinking about that one.

So the change is 3 pounds 68, what must the item of cost? So I'll give you a little clue.

If you think about what amount goes with 3 pounds 68 to make 10 pounds, that will help.

And then for F, we know the cost is 3 pounds 65 and the change is 16 pounds 35.

So what was the amount paid? And for B2, find the amount of change I would get from a five pound note if I spent the following amount.

And you might notice a little pattern here.

So five pounds take away 99 p equals something, five pounds take away one pound 99 equals something.

So think about what's changed between those two.

Five pounds take away two pounds 99 equals something.

Five pounds take away two pounds 98 is something.

And then finally, five pounds take away something is one pound 1 p.

So think about that.

That's probably the most difficult one.

For task B3, you have got five different statements and you have to say whether they're true or false.

So five pounds take away two pounds 30 equals three pounds 70, true or false? 10 pounds take away one pound 70 equals eight pounds 30, is that true or false? Three pounds 90 plus one pound 10 equals five pounds, true or false? Seven pounds 60 plus three pounds 40 equals 10 pounds, true or false? And then finally, we've got a problem in context here, which is that I buy a cup of coffee that costs two pounds 20 and I pay with a 10 pound note and get eight pounds 80 changes.

Is that true or false? And if it's false, you might need to think about why that's false if you can explain that.

For number four, we've got some word problems here.

So Izzy's got five pounds to spend in the joke shop.

She wants to buy a pot of slime for 99 p and a water pistol for three pounds 50.

How much change will she get? So you're going to have to do some combining there before you calculate the change.

When Izzy gets the checkout, she finds that the water pistol is in the sale and it only costs three pounds.

Will she have enough to buy another pot of slime? So it is time to apply all of those skills.

Pause the video, good luck, and I'll see you soon for some feedback.

Are you ready for some feedback? How did you get on with that? Let's have find out, shall we? So for 1a, the change is two pounds.

For B it is four pounds.

For C, the change is six pounds 60.

E had to do a bit more thinking about, but the cost will be six pounds 32 because those two, when you add them together equal 10 pounds.

And then for F, the amount paid will be 20 pounds.

Because if we combine those two values, it gives us 20 pounds.

At task B2 well done if you spotted a patterning going on here.

So five pounds take away 99 p is four pounds one.

Five pounds take away one pound 99.

So the subtrahend increased by a pound there.

So that gives us three pounds one.

Five pounds take away two pounds 99 gives us two pounds one.

Five pounds take away two pounds 98.

There's only a penny difference between that and the previous one.

So that gives us two pounds two.

And then finally five pounds take away three pounds 99 gives us one pound one.

And for B3, the first one was false, two pounds 30 subtracted from five pounds doesn't give you three pounds 70.

So in fact two pounds 30 and two pounds 70 goes together to give you five pounds.

So that's what the change will be two pounds 70.

For the second one, 10 take away one pound 70 is eight pounds 30, three pounds 90 plus one pound 10 is five pounds.

Seven pounds 60 plus three pound 40.

That doesn't give you 10 pounds.

In fact that gives you 11 pounds.

And I'll buy a cup of coffee that costs two pound 20.

I pay with a 10 pound note and I get eight pound change.

Eight pounds 80 change, that's false.

You get seven pounds 80 change.

For task B4a, well done if you applied a strategy of adding one pound and taking away one penny.

That's called the adjusting strategy.

And then words out that the change would be 51 pence.

And B, yes, she will have enough to buy another pot of slime, but only just with 1 p change.

And so we've come to the end of our lesson.

You've been a superstar, well done.

So our lesson today has been about using knowledge of subtraction to calculate change when paying with whole pounds or notes.

We started the lesson looking at the change that you'll get from paying one pound.

The rest of the lesson was devoted to multiples of one pound and to notes.

So things like five pounds, 10 pounds, 20 pounds.

When calculating change, a useful strategy is to count on from the cost of the item to the amount given to the shopkeeper.

This can be done with a number line.

So in this example here, the item costs three pounds 40, you pay the shopkeeper five pound and the shopkeeper would've given you this back.

That've started by giving you 60 p back to take you to four pounds.

And then from four pounds to five pounds is one pound.

So that's one pound 60 altogether.

And some people call that the shopkeeper method.

However, it can also be done mentally using knowledge of number bonds to five, 10, 20, and 100.

I really enjoyed teaching you today's lesson about money and I hope to see you again soon.

Take care and goodbye.