Lesson video

Hello, everybody! Mrs. Vachell here with your maths learning today.

I can't wait to learn lots of new things and hopefully have lots of fun.

So let's get started.

Today's lesson is called Double numbers and explain what doubling means, and it comes from the unit Addition and subtraction facts within 10.

By the end of this lesson, you should be able to double numbers and explain what doubling means.

Here are this lesson's keywords.

Double, doubling, addends, and equal.

Let's practise saying these words.

My turn, double, your turn.

My turn, doubling, your turn.

My turn, addends, your turn.

My turn, equal, your turn.

Well done! Now that we know how to say them, let's start using them.

Let's have a look at our lesson outline.

You can see that this lesson has two parts.

The first part of the lesson, we will be adding two equal addends.

And the second part, we will be using doubling to solve number problems. Let's get started with the first part of our learning, adding two equal addends.

In this lesson, you will meet Sam and Jacob.

They're going to help us with our learning today.

Sam and Jacob are explaining what they can see.

Sam looks at this picture and says that she can see 1 cube on each side of the seesaw.

She notices that this seesaw is equal.

There are 2 cubes in total.

Jacob explains this representation as 1 cube plus 1 cube is equal to 2 cubes.

He writes it as 1 + 1 = 2.

Now let's look at this seesaw.

What can you see? How would you describe this seesaw? How is this seesaw different to the one that we've just seen? Let's see what the children think.

Sam says that she can see 2 cubes on each side of the seesaw.

Both sides are equal.

There are 4 cubes in total.

Jacob writes his equation again.

2 cubes plus 2 cubes is equal to 4 cubes.

So he has written that as 2 + 2 = 4.

Was yours similar to either of those children? Let's have a go at this.

So how many cubes would need to be on the other side of the seesaw to make it equal? Have a think.

Can you remember what equal means? I know that equal means it's the same as.

So if there are 4 cubes on the left-hand side of our seesaw, how many do you think should be on the other side? Sam thinks that there are 4 cubes on the side of the seesaw.

The seesaw is balanced, so to make it equal, there should be the same on the other side.

4 cubes.

Well done if you got that correct.

There will need to be 4 cubes on the other side to make it equal.

Sam and Jacob noticed that each side of the seesaw has the same amounts of cubes.

1 and 1, 2 and 2, 4 cubes and 4 cubes.

Each side of the seesaw is equal.

They also notice that when they find the sum of the cubes on each seesaw, it is always even.

1 plus 1 is equal to 2, 2 plus 2 is equal to 4, and 4 plus 4 is equal to 8.

2, 4, and 8 are all even numbers.

When we add together two addends that are equal, we can say that we are doubling.

3 cubes on each side, so that is 3 + 3, and we know that that is equal to 6.

But we can also say that we are doubling.

We can say we are doubling 3.

Double 3 is 6.

Let's check that.

So what is being shown here? Is my representation showing double 3, double 5, or double 4? Remember, doubling is when we add two equal addends together.

I can see that there are 5 cubes on the left and 5 cubes on the right, so I know that we must be doubling 5.

Sam can see 5 and 5.

She knows that she is doubling 5.

So the answer is double 5.

Well done, Sam.

Double 5 is 10.

5 plus 5 is equal to 10.

Let's explore this a little bit further.

1 plus 1 is equal to 2.

That is our first doubling fact.

So if my first addend is 2, if I'm doubling 2, what must the second addend be? That's right, 2.

2 plus 2, or double 2, is equal to 4, another even number.

3 plus 3 is equal to 6.

4 plus 4, double 4, is equal to 8.

And finally, 5 plus 5, or double 5, is equal to 10.

Sam and Jacob's idea was correct.

The sum in each doubling equation is always even.

I wonder if you can see why.

Jacob's noticed that he can see that this is because a counter always has another counter to pair up with.

All doubles are made from groups of 2, or those pairs of counters, so they have to be even, because we know that even numbers are made from groups of 2.

2, 4, 6, 8, and 10, all made from pairs of counters.

We can say that doubling a whole number always gives an even number.

Let's practise that.

My turn, doubling a whole number always gives an even number, your turn.

Well done.

Let's remember that because that's gonna help us with our learning today.

Let's have a look.

So what is being shown on this ten frame here? I can see that I've got two red counters and two blue counters.

Could this be showing me double 2 is 4? Could this be showing me 2 plus 2 is equal to 4? Or could this be showing me 2 + 2 = 4? Hmm.

Let's have a look.

They're all correct.

This representation is showing all of them because double 2 is 4 is the same as saying 2 plus 2 is equal to 4.

And at the bottom, we have said the same thing but we have written it as an equation.

Well done if you spotted that.

Well done, Sam.

We can say it in lots of different ways, but we are still doubling 2 and the sum is always 4.

So let's have a go at this.

Double 5 is.

Is it 9, is it 10, or is it 7? Have a think.

What is doubling, and what do we know about the sum when we double numbers? 10.

Double 5 is 10.

Well done, Sam.

5 plus 5 is the same as doubling 5, so we know that double 5 is equal to 10.

We also know that A and C could not possibly be correct because we know that when we double a whole number, it always sums to an even number, and 9 and 7 are odd numbers.

Well done if you also spotted that.

Okay then, over to you.

So Task A, question one is to explore doubles in the world around you.

We can see doubles everywhere.

So draw any that you find and record what it shows.

Here's an example.

I can see, using my fingers, that I have 3 fingers on one hand and 3 fingers on the other.

So what double is that showing me? That's right.

Double 3 is 6.

You can see I have 3 fingers and 3 fingers, so 3 plus 3 is the same as double 3, and I know that the sum is 6.

Have a look to see what doubles you can find in the world around you.

Task two is to play a game of snap.

You will turn over a doubling fact card.

If an expression is placed next to its correct sum, you can shout "snap," and the first person to do so will win that pair.

The winner will then describe what they can see.

So they may say, "5 plus 5 is equal to 10," or they may say, "Double 5 is 10." The winner is the person who collects the most pairs.

Pause this video and have a go at those two tasks.

Come on back when you're ready to continue with this lesson.

Welcome back.

Let's have a look at some of the doubling examples that Sam and Jacob found.

First up, they found a spider.

Hmm.

What doubles do you think that they spotted on a spider? Its legs.

They can see that double 4 is 8.

A spider has 4 legs on either side.

4 plus 4 is equal to 8.

Let's have a look at the bear.

What have they spotted on this bear? What might you see that is two equal addends? Hmm.

They've looked at his paws.

He has 2 paws on the left and 2 paws on the right.

Double 2 is 4.

You may have spotted some dominoes with equal addends on either side.

What does this one show? Double 1 is 2.

Well done if you got that one.

Ooh, a carton of eggs.

I can see double 3 is 6.

I can see two rows of 3.

And also looking down, you might have spotted your feet.

You may have spotted some toes.

Let's have a look at this picture.

I can see 5 toes on each foot.

So this representation must be showing me 5 plus 5 is equal to 10, or double 5 is 10.

Well done for finding doubles in the world around you.

Let's have a look at question two.

Your game may have looked like this.

1 plus 1 is equal to 4.

Hmm, nobody's shouting snap.

That must be incorrect.

5 plus 5 is equal to 10.

Snap! Well done, Sam.

Double 5 is 10.

So Sam wins that pair.

Let's have another go.

2 plus 2 is equal to 6.

Hmm, not correct.

4 plus 4 is equal to 8.

Snap! Well done, Jacob.

Double 4 is 8.

They both win a pair.

Let's have a look at the second part of our lesson.

So we've added two equal addends together.

Now we're going to look at using doubling to solve some number problems. Let's get started.

Have a look at our first problem involving doubling.

Jacob has 1 sweet.

Sam has double Jacob's amount of sweets.

So how many sweets does Sam have? Hmm.

Let's write an equation to help us solve this problem.

We know that when we double a number, we add together two equal addends.

So if we want to double Jacob's amount of sweets, we need to double 1.

Double 1 is the same as 1 plus 1.

Well done, Jacob.

Let's write that.

1 plus 1 is equal to 2, or double 1 is 2.

Well done, Jacob.

That means that Sam must have 2 sweets.

Well done if you got that.

Sam now creates a ten frame and gives Jacob a missing number problem to solve.

Can you help Jacob to complete her equation? Something plus 4 is equal to 8.

Hmm.

What is the missing addend in this problem? We can see our representation and we can see our equation.

Sam gives Jacob a hand.

She explains that her ten frame is made up of 4 red counters and 4 blue counters.

We can see that the amounts are the same.

So that must mean that our addends must be the same.

4 must be the missing number because 4 plus 4 is equal to 8.

We have doubled 4.

When the addends are equal, we are doubling.

Well done if you spotted that.

Jacob wants to use a bar model to represent some of these ideas.

What numbers could he use to complete it? Jacob has noticed that his bar model has two equal parts.

So this must be a doubling fact.

When both addends are equal, we are doubling.

So Jacob fills in the bar model.

What numbers is he missing? We can see that the whole is 10.

So what two equal parts would be equal to 10? 5! Well done, Jacob.

Jacob knows that 5 add 5, or double 5, is equal to 10, so they must be the missing parts.

Can you think of any more facts that could complete this bar model? You may have found 8 as the whole and 4 as the parts! Double 4 is equal to 8.

You may also have found double 3 is 6.

6 is the whole and 3 are the equal parts.

Double 2 is 4.

2 plus 2 is equal to 4.

And finally, you may have found 1 plus 1, or double 1, is equal to 2.

Well done if you remembered any of those facts to complete those bar models.

Now let's have a look at a worded problem.

Jacob has collected 6 stickers.

He sticks 3 of them into his book.

How many stickers does he have left? Hmm.

Where would that information go onto my part-part-whole? Let's have a think.

Jacob has 6 stickers altogether, so we know that that must be the whole.

Where is the whole? Where would my number 6 have to go? There, well done.

He sticks 3 of them into his book, so we know that 3 of them must be our part.

So let's pop 3 into our part.

3 plus something is equal to 6.

We know that 6 is double 3, so 3 must be the missing part.

3 plus 3 is equal to 6.

Well done if you spotted that.

You may have also solved this a different way.

You may have used subtraction to find the missing part.

6 subtract 3 is equal to 3.

Jacob will have 3 stickers left.

I wonder what he's gonna do with those.

Right, over to you.

See if you can use what we've just learned to find out what the missing parts are in these part-part-whole models.

Pause this video and have a little go.

Come on back to see how you've got on.

I can see in A that I'm looking for the whole.

My two parts are 4 and 4, so I know that double 4 is equal to 8.

Well done if you got that one.

B, I can see that 1 is a part and 1 is a part.

So to find the whole, I must do 1 plus 1, or double 1, which is 2.

Well done.

Now, C, I already have my whole and I already have a part.

I know that 6 is a double.

So 3 plus 3 is equal to 6.

Well done if you got those.

How did you find those missing parts? Jacob noticed that in A, he doubled 4.

And in B, he doubled 1 because he needed to find the whole.

But in C, he knew that double 3 was 6, so he already knew that fact, which really helped him to fill in that missing part.

Did you use some similar knowledge to help you solve them? Let's get on to Task B then.

So Task B, Part 1 is to solve some worded problems. You might want to write an equation to help you solve each of them.

And Part 2, we have some missing number problems. So we have some equations and also some part-part-whole models.

Use what you have learned to help you to fill in the missing numbers.

Remember, doubling means adding two addends that are equal.

Pause this video, have a go at Part 1 and Part 2, and come on back to see how you've got on.

Welcome back.

Let's get started with those worded problems. So, let's look at what information we do know already.

Pencils are sold in a box of 4.

You can get double the amount in a larger box.

So how many pencils are in the larger box? So you know that doubling means adding together two equal addends.

So if I'm doubling the pencils in the smaller box, I'm doing 4 plus 4 because I'm doubling 4.

So that must mean that there are 8 pencils in the larger box.

Well done if you got that one.

Jacob explains how he solved it.

Double 4 is 8.

So he knew that there were 8 in the larger box.

Well done, Jacob, some great work there.

B, Jacob eats 3 slices of pizza.

Sam eats double the amount.

How many slices of pizza did Sam eat? Hmm, we know that Jacob has eaten 3.

Sam has eaten double that.

So double 3 is equal to 6.

Sam has eaten 6 slices of pizza.

Sam explains that double 3 is 6, or 3 plus 3 is equal to 6, so that must mean that she ate 6 slices of pizza.

Well done if you got that one.

Let's have a look at these missing number problems. 3 plus 3, or double 3, is equal to 6.

2 plus 2 is equal to 4.

1 plus 1 is equal to 2.

Oh, let's have a look.

We swapped the equals round there with question D, but does that change anything? No.

5 plus 5, or double 5, is equal to 10.

Well done.

Let's have a look at this part-part-whole then.

We can see that 2 is a part and 2 is a part.

So if we add together 2 plus 2, or double 2, we know that our whole will be 4.

Well done.

And F, I can see that 8 is my whole.

Hmm.

Do we know a doubling fact that would equal to 8? We do.

4 plus 4, or double 4, is equal to 8.

Well done if you remembered that fact.

Now that you've answered F, you should easily answer G.

4 plus 4 is equal to 8.

Now, I know what my sum is and I know what one of the parts is, so what must be that missing part? 5 plus 5 is equal to 10, well done.

We know that when we double, we are adding two equal addends.

Something plus 1 is equal to 2.

2 is a double number.

We know that 1 plus 1 is equal to 2.

And finally, something plus 2 is equal to 4.

We know that it's 2 plus 2, or double 2, is equal to 4.

Well done if you got those correct.

Well done for completing those tasks, and well done if you got them correct.

Well done for your hard work in today's lesson.

Let's have a look at what we've learnt today.

When both addends are equal, we are doubling.

Doubling means adding two equal addends.

And doubling a whole number always gives an even number.

Well done for all of your hard work today, and thank you for joining me.

I can't wait to see you again for another maths lesson.

Bye!.