Lesson video

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Hello mathematicians, Ms. Charleton here, and Hedwig my talk partner back for some more learning.

Now we are very excited about this lesson aren't we Hedwig because we think that it's something that you will be able to spot quite soon when you go shopping.

So when we talk about it and when we have a little think when you next go shopping to see if you recognise any of the things that we've been talking about today.

Should we find out what we're going to do? We are going to find double and half of a number within 20.

We're going to find double any number to 10 by adding the same number to itself.

Then we are going to half even numbers to 20 by sharing between 2 groups.

Then you'll do your independent task and an end of lesson quiz.

Today you're going to need a pencil and some paper and if you want to use some counting objects to help you count, you might like to use coins, or buttons, or counters, or pasta, or raisins, or any objects that you want or you can just use the pictures on the screen that are provided anyway for you.

Are you ready to through our star words? Get your hands ready! Hands up star words! Double! Half! Equal! Those are the words we'll need in today's lesson.

Right.

Now it gets exciting.

We get to go to the sweet shop.

Ooh! Look at that sweet shop.

Look how many sweets there are and chocolates.

It's making me so hungry.

Is it making anyone else hungry? Which one do you think you'd like? I quite like the look of the jelly beans or maybe flying saucer in the bottom there, the pink flying saucer.

I like those.

They make your tongue tingle.

Who would fancy a biscuit on the top instead? Lots of things.

Is your mouth watering now thinking about it? My certainly is.

Now the exciting thing about this shop is that today we've got a sale on.

All of the sweets are buy one get one free.

Now has anyone ever been shopping where they have seen a sign saying 'Buy one get one free?' Normally people go a bit wild for those and they get really excited.

This is how we do it.

In the sweet shop, if we buy one, just like that blue one there, we get one free.

We've ended up with 2 sweets but we have only paid for one.

Can you see how I've split the grid into paid for and free? What about if we got another one? We paid for, we got one free.

We paid for, we got one free.

Having a look at that, how many sweets have we paid for? We've paid for 1, 2, 3, 4 and how many have we got free? We've got 4 free.

How many sweets did we get all together? 4, 5, 6, 7, 8.

We got 8 sweets altogether but we only paid for 4.

Does anyone else think that sounds like a pretty good deal? I definitely do.

And this is what is called doubling.

This is doubling.

Let's go through.

Let's say that as a full sentence together! Adding the same number to itself.

Doubling is adding the same number to itself.

So here, double 4 is 8.

I paid for 4 but I got 8 sweets altogether.

Doubling is adding the same number to itself.

4 plus 4 is equal to 8.

Let's imagine that you were paying for these items. You paid for 8 sweets.

Let's have a look in the grid that says paid for.

How many sweets? We got 8.

1, 2, 3, 4, 5, 6, 7, 8.

If you paid for 8 sweets, how many sweets would you get free? You would get another 1, 2, 3, 4, 5, 6, 7, 8.

Oh, I had just added the same number together.

We paid for 8 and you got 8 free.

This is doubling.

Adding the same number to itself.

Doubling is adding the same number to itself.

Great full sentences everyone.

So double 8 is equal to, hmm.

I paid for 8 sweets but how many did I get altogether? Let's count.

8, 9, 10, 11, 12, 13, 14, 15, 16.

So that would have cost me 16 pence.

Double 8 is 16.

Good.

I paid for 8 sweets so that cost me 8 pence but I got 16 sweets.

So it was almost like paying for 16 but we didn't.

Let's have a look at this in a different way.

It is getting a bit trickier now.

Now this is Kim.

Kim went to the shop and she came out of the shop with 10 sweets.

Now we know this shop has got a half price sale on.

If we has come out with 10 sweets, did she pay for all 10 of those sweets? Have a think.

No, she didn't pay for all 10 because we know that there is a half price sale on.

So how much did she pay? Let's have a look.

For every one sweet that she bought, she got one free and she came out with 10 sweets.

So let's count out 10 sweets and figure out which ones she paid for and which ones she got free.

Remember every sweet she bought she got one free.

She paid for 1, she got 1 free.

Keep going.

So that is 1, 2, 3, 4, 5, 6, 7, 8.

1, 2, 3, 4, 5, 6, 7, 8, 9, 10.

Those are the 10 sweets that she went shopping for but did she pay for all of them? No she didn't, let's look carefully.

Those are the 10 sweets altogether but she paid for 1, 2, 3, 4, 5.

She only paid for 5.

Double 5 is equal to 10.

5 plus 5 is 10.

That's doubling, adding the same number to itself.

5 plus 5 is 10.

Can you say that? Well done.

So she paid for 5 sweets but she came out of the shop with 10 sweets.

5 pence, 5 pence.

Now it's your go.

Are you ready? We've got a grid here and you get to go to the same shop.

Your independent task is to have a look at the number of the sweets.

Count out the total number of sweets and then use the table on the next page to work out how much it cost.

So for example you've got the number of sweets in the column but I want to know how much it actually cost you.

So if you bought 10 sweets would you pay for 10 sweets? No, you would only pay for 5.

Let's have a look at that more clearly.

10 sweets.

If you paid for 10, let's count her out.

1, 2, 3, 4, 5, 6, 7, 8, 9, 10.

Those are my 10 sweets and I've put them into a grid for paid for and free.

Those are my 10 sweets but how many did I actually pay for? 1, 2, 3, 4, 5.

In the paid for section there are only 5.

I only paid for 5.

5 plus 5 is equal to 10.

Double 5 is 10.

That's doubling.

I added the same amount to itself.

Using the grid and using the table provided or you can draw your own one out, you can either draw dots depending on how many the numbers are, or you can use objects to help you count.

When you've done that, come back and we'll have a look at the answers together.

How did everybody get on? Let's see.

So if you bought 20 sweets, it would have cost you 10 because 10 plus 10 is equal to 20.

Double 10 is 20.

If you bought a 18 sweets it would have cost you 9.

Double 9 is 18.

16 sweets would cost you 8 pence.

Double 8 is 16.

If the number of sweets was 14 it would have cost you 7 pence because double 7 is equal to 14.

If you bought 12 sweets, it would cost you 6 pence.

Double 6 is 12.

Double 5 is 10.

Double 4 is 8.

Double 3 is 6.

Double 2 is 4.

And double 1 is 2.

So those are the costs of all of the different sweets.

I think it sounds like a sweetie shop that I would really want to go to.

Can you spot the pattern there? Can you use the pattern going along? 20, 10.

Ooh.

Half of 20 is equal to 10.

That's a bit tricky.

We've just been talking about doubling today but some of you might have noticed that doubling is linked to halving.

But don't worry, we're going to talk about that another time.

I hope you had a really great time shopping at our sweetie shop with all the special deals on.

Should we wake Hedwig up? Come on Hedwig, say wakey wakey.

Wakey wakey Hedwig.

Hedwig do you think you would have liked to have gone shopping in our sweetie shop? No I don't think Hedwig eats sweets.

That's okay isn't it because it is more sweets for us.

Now Hedwig, first of all we learned about the word doubling.

We know now that doubling is when you add the same number to itself.

For example, 5 plus 5.

That's doubling.

We know that half means sharing equally between 2 equal groups.

And we did that by sharing the amount we had.

We had a look at the sweetie shop and we had a look at how many sweets we would have come out with and we realised that we would only spend half the amount.

But we will talk about that another time.

Do you think you understand doubling and halving Hedwig? I think she does.

Well then everybody you can go and do your quiz now and I'll see you again soon.

Bye bye.

I've finished the video