Lesson video

Hi, everybody.

Welcome to your unit on number sense.

Today we're going to be looking at using an adding on strategy to find the difference between numbers.

And we're going to be doing a little bit of shopping, which I'm very excited about.

So before we begin, put on your hats, tighten your ties, and tell the computer, now I'm a mathematician.

Let's get started with our lesson.

So here on the screen, we have our lesson agenda for today.

First we're going to be using our star words.

We're then going to do some exploring on how to make 10, how to make 100, and then we're going to practise by giving change before we go off and do our independent task and some shopping, and then we're going to do the quiz.

So before we begin and as always, we need to make sure we have the correct resources.

So for this lesson you'll need a pencil, a piece of paper, and a ruler.

So please make sure you have those things before moving on with this lesson.

Here we have our star words.

The first star word is change.

We have number bond, inverse, make 10, check, difference, make one hundred, efficient, adding on.

Can you show me change? Can you show me make 10? Can you show me check? Can you show me difference? Super job.

Now remember we need to use these star words the entire time through this lesson.

It helps us to remember the key vocabulary.

If you've spotted the 'I've not used the star words', please whisper to your computer, and I'll be able to hear it through the screen.

Brilliant.

Let's get started.

Here I have the equation 40 subtract 33, but which number facts could help me to calculate this efficiently? Well with my number bonds, I know that 10 subtract three is equal to seven and the inverse of that is three add seven is equal to 10.

So I could use the number bond.

Seven add three is equal to 10.

Or I can use the inverse of 10 subtract three is equal to seven.

So if we know that 33 add seven is equal to 40 then what do we know about 40 subtract 33? And why? Well we can actually use the inverse, Because we know that subtraction is the inverse of addition.

So we can just move the equation around.

So if 33 add seven is equal to 40, then I know that 40 subtract 33 is going to be equal to seven.

Here we have a number, or bar model sorry.

And you can see, we have our two parts of 33 and seven.

You we also have a whole of 40 and here we have partitions 33, thank you for reminding me, partitioned 33 and seven.

So if 40 subtract 33 is equal to seven, what's a hundred takeaway 33? Can I use the same strategy of using my number bond of 10 to help me calculate this efficiency? Hmm, hmm.

I think we can.

Let's have a think.

Here is a lovely number line.

Which are my favourite things to use.

And we can do some jumping.

So I'm going to add seven to get to my nearest multiple of 10.

We need to make 10.

So 33 add seven is equal to 40.

And then I just need to make a really big jump all the way up to 100, because I need to make 100.

And I know my number bonds that if I know that four add six is equal to 10, then I know that 40 add 60 is equal to 100.

so my big gap is going to be 60.

And when I add them together, the answer is 67.

So 100 subtract 33 is equal to 67.

So let's do a little bit more exploring.

And today we're going to be looking at giving change.

So I want to buy a yoghourt cause I'm really, really hungry.

And I've been given one Pound, but how much change will I be given? So I can see this yoghourt.

It's 54 P.

There's my money.

I have a nice, shiny one Pound.

I know that one Pound is the same as 100.

So I can use this equation.

If I know that four add six is equal to 10, then I know that 54 P add six P is going to be equal to 60, because you remember first I need to make the nearest multiple of 10 and then if I know that six add four is equal to 10, then I know that 60 add 40 is equal to 100.

So when I look at these two numbers here, I know I need to add them together, I get 46 Pence change.

There's my change there.

So now it's your turn.

You're going to be doing a little bit of shopping.

Here we have the chocolate bar that's 45 P, a pencil that's 28 P, a banana which is 23 P, a bouncy ball which is 67 P, and a comic book which is 89 P, and you have one Pound.

So you are going to do a little bit of shopping.

You are going to have a think.

If I buy a banana at the 23 P how much change am I going to get from one Pound? If I buy a comic book for 89 P how much change would I get? And so on with the chocolate bar, the pencil and the bouncy ball.

So make sure you pause this video, and write down your answers before moving on.

So you and I have arrived at a toy shop, which I love going to toy shops.

We can see, we have a football, which is three Pounds and 99 Pence, a puppet which is six Pounds and 55 Pence, some yummy popcorn, love this popcorn, which is one Pound and 49 Pence.

We have a torch which is five Pounds and 38 Pence.

I really love the colouring book, which is two Pounds and 45 Pence, a toy robot which is actually quite expensive, for eight Pounds and 89 pence, a model car for eight Pounds and 20 Pence, and a set of radios, walkie talkies, for seven Pounds and 59 pence.

So we have 10 Pounds to spend.

What are we going to buy with 10 Pounds? So I've decided that I want to buy the puppet and I know the puppet is six Pounds and 55 Pence.

So on my number line I'm going to write six Pounds and 55 Pence.

Now I know to make my life much easier, I want to make, I want to round six Pounds and 55 Pence up to the nearest Pound.

And I can do that by adding 45 Pence.

So that becomes seven Pounds.

And then I just need to do my jump up to 10 Pounds, which is three Pounds.

Excuse me.

So I will receive three Pounds and 45 Pence change when I've bought this puppet.

So for your independent task today, you're going to be doing the same.

You're going to be doing a little bit of shopping.

You are going to have 10 Pounds and you're going to work out the change for each object bought.

For example, if I buy a football for three Pounds and 99 Pence how much change will I get from my 10 Pound note? You'll be doing the same with the popcorn, the colouring book, the puppets, the torch, the robot, the radio, and the model car.

So you have 10 Pounds to spend and you're going to be telling me the change for each object.

So you need to make sure to draw your number line.

You're going to round each number up to the nearest Pound then make your big jump up to 10 Pounds and add the two numbers together.

Remember to pause this video and get started.

See you on the other side.

Lovely job everybody.

Well done.

Let's go through the answers together.

So here we have our football, our popcorn, and our colouring book.

Let's have a look at football together first.

So we know that we need to round up three Pounds and 99 Pence to the nearest Pound, which means you'll be adding one Pence to get to four Pounds.

And then we can make our lovely big jump up to 10 Pounds, which is six Pounds difference.

When we add the two together, it will tell us that we will get six Pounds and one Pence change.

Remember to tick and fix as we go through the answers.

Our next object was the popcorn, my absolute favourite.

And we need to round up to the nearest Pound and we know that the nearest Pound is going to be two Pounds.

So we need to jump up 51 P, that will take us to two Pounds, and then we need to make a really big jump all the way up to 10 Pounds.

And the difference between two Pounds and eight Pounds or 10 Pounds, I gave away the answer, so the difference between two pounds and 10 Pounds is eight Pounds.

So we will receive eight Pounds and 51 Pence change.

For our colouring book which is two Pounds and 45 Pence, we need to round up to three Pounds, which is a 55 Pence difference.

We then need to make our big step up to 10 Pounds, which is a seven Pounds difference.

Therefore we will receive seven Pounds and 55 Pence change.

For our puppet we need to round up to seven Pounds, so the difference is 45 Pence, and then from seven Pounds to 10 Pounds is three Pounds.

So we will receive three Pounds and 45 Pence change.

For our robot which is eight Pounds and 89 Pence, we need to round up to our nine Pounds.

And we can see that's 11 Pence difference.

We then need to round up from nine Pounds, sorry we need to find the difference, between nine Pounds and 10 Pounds, which is one Pound.

So we will receive one Pound and 11 Pence change.

For our final two objects, our radios, now the radios are seven Pounds and 59 Pence change, and we need to make sure we round up to eight Pounds, and the difference is 41 Pence.

The difference between eight Pounds and 10 Pounds is two Pounds.

So we know we need to receive two Pounds and 41 pence change.

For our model car which is eight Pounds and 20 Pence, we need to round up to our nearest Pound, We need to make it, which means we will have 80 Pence.

And then the difference between nine Pounds and 10 Pounds is one Pound.

So we will receive one Pound and 80 P change.

Super job today everybody.

I really hoped you enjoyed some shopping with me today.

If you'd like to share your work, please ask your parent or Cara to share your work on Instagram, Facebook or Twitter, tagging @OakNational and #LearnwithOak.

It's been so wonderful learning with you today.

I really hope you've given yourself a one, two, three, well done me! Super.

Well, have a lovely rest of your day and make sure that you complete the quiz before you go anywhere.

Take care and see you again soon.

Bye!.