Lesson video

Hello everybody.

Welcome back to another math lesson with me, Mrs. Pochciol.

As always, I'm hoping that we're gonna have lots of fun and also learn lots of new things.

So, let's get started.

This lesson is called "Record Doubles Within 10," and it's from the unit, "Secure Fluency of Addition and Subtraction Facts Within 10." By the end of this lesson, you should be confident to record doubles within 10.

Let's have a look at this lesson's keywords, "double," "doubling," "half," and "halving." Let's practise them! My turn, "double," your turn.

My turn, "doubling," your turn.

My turn, "half," your turn.

My turn, 'halving," your turn.

Well done! Now that we can say them, let's use them.

In today's lesson, you are going to meet Izzy and Sam.

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

Let's have a look at our lesson outline.

So, the first part of our lesson, we are going to represent and use doubles within 10.

And, the second part of our lesson, we are going to represent and use halves within 10.

Let's get started.

"Izzy and Alex are looking at their table reward chart.

How many stars do Alex and Izzy have altogether?" Alex has noticed that they both have three stars.

They have equal numbers.

So, to work out how many they have altogether, Alex will calculate three plus three.

Izzy has noticed that because they are two equal add-ins, Izzy can say, "double three," because when we add two equal add-ins, we can say we are doubling.

Alex uses a bar model to help him work out how many stars they have altogether, his three stars, and Izzy's three stars.

Alex notices that three plus three is equal to six, that's six stars in total.

So, three plus three is equal to six.

Izzy then explains that we could say that double three is equal to six because we know that when we add two equal numbers we can call this doubling.

So, three plus three is equal to six, or we could say double three is equal to six.

So, let's have a look at these.

So, which of my equations involve doubling? Remember, we can say that we are doubling when we add two equal numbers together.

So, which of those are doubling equations? Pause this video and come on back once you've had a go.

Welcome back.

So, let's have a look.

Which of these equations involve doubling? Remember, we are looking for two equal add-ins that are being added to find the sum.

I can see that B and C both have equal add-[Instructor].

In B, both of the add ends are one.

So, we could say double one is two, and in C, both my add ends are? Five.

So, what could we say? Instead of five plus five is equal to 10, We could say, "double five is 10." Well done if you spotted those, and well done if you were able to explain it using doubling.

So, let's have a look at this one, then.

So, here's a bar model that's been completed.

What equation, and what doubling fact is shown using this bar model? Have a think, and come on back when you are ready.

Okay, let's have a look then.

So, we can see that we have got two equal parts in our bar model, and they are both worth four stars.

Our whole is eight, so we can say that four plus four is equal to eight.

So, what doubling fact can we see using this bar model? I can see that both my add-ins are equal.

So, what are I doubling? That's right, we are doubling four, and we know that double four is eight.

Well done if you spotted the equation, and well done if you are able to work out the doubling fact.

So, let's explore doubling a little bit further.

We are going to use a number frame here to help us visualise doubling.

So, let's have a look.

If I have one on this side of my number frame, what will be the other add-in if I'm doubling? That's right, one, because it has to be equal, and we can see that one plus one is equal to two.

That's our first doubling fact.

So, let's have a look at the next one.

Oh, two plus two.

I know that two plus two is equal to four.

Well done.

Let's pop that over there.

Let's have a look at the next one.

Three.

So, if three is one of my add-ins, what's the other add-in going to be? That's right, three, because when we double we add two equal add-ins.

So, what is three plus three? I can see that there are six on my number frame.

So, three plus three is equal to six.

Four, what's my other add-in going to be? Four.

And, four plus four is equal to eight.

Well done.

And, finally, we have five.

Five are our equal add-ins, and we know that five plus five is equal to 10.

Well done.

So, you can see we've now created our equations of adding two equal add-ins.

But, what would the doubling facts be for these equations? I can see in the first one that I am adding one plus one is equal to two.

So, I can say that I am doubling one.

"Double one is two," is my doubling fact.

Let's practise that.

My turn, "double one is two," your turn.

So, what doubling fact is shown with the equation, "two plus two is equal to four?" That's right, double two is four.

My turn, "double two is four." Your turn.

And, three plus three is equal to six.

What doubling factor we have here? "Double three is six," your turn.

And, four plus four.

I can see that my add-ins are four and four, so I must be doubling four.

My turn, "double four is eight." Your turn.

And, finally, five plus five, we must be doubling five.

So, my turn, "double five is 10." Izzy has noticed something in our doubling facts.

All of the sums are even, let's have a look.

2, 4, 6, 8 and 10.

They're all even, Izzy.

Good spot! I wonder why that is.

That is because each counter has a counter to match on each side.

So, every counter on our number frame has a matching partner on the other side.

So, that means that all doubles are made from groups of two.

So, they have to be even.

So, we now know that doubling a whole number always gives an even number.

Well done, Izzy.

So, let's check this learning.

What is being shown on this number frame here? Is it "double one is two," "double two is four" or is it "one plus one is equal to two?" Pause this video and have a think.

Come on back once you've got your answer.

Let's have a look then.

Alex has ticked C.

He has explained that he can see one red counter and one blue counter, and that there are two counters altogether.

So, this must show one plus one is equal to two.

Well done, Alex, but I think there might be another one that can explain this number frame, also.

That's right.

Double one is two.

We know that when we add two equal add-ins, we can call this doubling.

So, this number frame also shows double one is two.

Well done if you've got both of those correct.

Alex and Izzy now play a doubling game using dice to practise recalling the doubling facts that they have just learned.

Alex rolls a four, so he's now going to double this.

Double four is nine.

Hmm.

Izzy has realised that Alex cannot be correct.

Nine cannot be because it is an odd number, and we know that when we double a whole number, it must be an even number.

Alex, I think you need to check your working.

Well done, that's a good idea.

So, Alex is now going to use his number frame to check.

He's going to put four on this side, and to double, he knows that he needs to add the equal number on the other side.

So, how many counters will he need on the right side? That's right, he'll need four.

He can now see that there are eight counters all together.

So, double four must be eight, not nine.

Well done, Alex, and well done Izzy for spotting that Alex was incorrect.

On Izzy's turn, she rolls a five.

Can you help Izzy and find which of these double facts are correct? Double five is eight, double five is nine, or double five is 10.

Have a think which one is correct? C is correct, double five is 10.

Izzy can see this doubling fact as five plus five is equal to something, and she knows that five and five is equal to 10.

So, double five is 10.

Well done.

Okay then, over to you.

Task A is to play your own version of Alex and Izzy's dice game.

Roll a dice and double the number that you land on.

Use the number frame to represent the double, on this table below, and then record the addition equation and the doubling fact.

Remember though, if you roll a six, roll again, as this is in our future learning.

So, just focus on the numbers one to five.

Part two is to complete the missing parts of Alex's grid.

So, he's completed his grid below, but there are missing parts.

Can you complete it for him? Pause this video, have a play of the game, and have a go at helping Alex to complete his grid, and come on back when you are ready to continue with your learning.

Welcome back.

I hope you enjoyed playing our game, and helping Alex complete his table.

Let's have a look at what Izzy did.

Izzy rolled a three, so she knew that double three is six.

We could write this as "three plus three is equal to six." And, finally, she represented this on her number frame with her three red and three blue counters.

Well done, Izzy.

Now, let's have a look how you got on with Alex's grid.

We can see that in first part double one is two, and one plus one is equal to two.

So, we need to show what the number frame would look like.

We know that there would be one on the left hand side, and one on the right hand side.

So, well done if you've got that one.

Now, the next one, we can see that we've got our number frame, but that's the only piece of information that Alex has managed to fill in.

So, let's have a look.

We can see that double two is equal to four, so well done if you've got that one.

But, what's the equation? We know that we are adding two equal add-ins, so two plus two is equal to four.

Let's have a look at this next one.

What information do we know? We know that our equation is, four plus four is equal to eight.

So, we can show this on our number frame.

Four red counters and four blue counters.

So, we also know, from this, we can now complete our doubling fact.

"Double four is eight." And, finally, we've got our number frame filled in there.

I can see that there are five red counters and five blue counters.

So, I must be completing five plus five is equal to 10.

So, we can now complete our doubling fact, which is, "double five is 10." Well done if you manage to complete all of those problems. Let's move on to the second part of our learning, which is representing and using halves within 10.

Sam and Jun now explain that they also have the same number of stars on the table reward chart.

They have four stars all together.

So, how many stars does Jun have? Alex knows that Sam and Jun have got four stars all together and they have an equal number each.

Izzy's not sure.

So she's suggested that we show it in a bar model, to help us make sense of this problem.

So, let's have a look.

We know that Sam and Jun have four stars altogether.

So, Sam puts this onto the bar model.

We also know that they have an equal number.

So, four is the double.

Alex thinks about his doubling facts, and he knows that double two is four.

So, there must be two in each part of the bar model.

Two plus two is equal to four, or double two is four.

Well done guys, that's correct.

Now, if we subtract one of the equal parts, we will be able to see how many stars Jun has.

If we subtract two from four, that leaves us with two.

So, we know that Jun will have two stars.

Halving is the inverse of doubling.

So, we can also say that half of four is two.

Sam and Jun have half of the stars each.

So, they each have two stars.

Izzy and Alex create another bar model using stars.

What doubling fact can you see here? And, then could you use that to find the halving fact shown in this bar model? Pause this video, have a think, and then come on back once you've got an answer.

Welcome back, let's see how you've got on.

So, Alex noticed that there are two equal parts, four other parts, and eight is the whole.

So, he can see using this bar model that four plus four is equal to eight, or we can say double four is eight.

So, what would be our halving fact? We know that halving is the inverse of doubling.

If we know that double four is eight, we can also say that half of eight is four.

Well done if you manage to work that one out.

Izzy now wants to put her doubling and halving facts onto a bar model.

So, what would the bar model look like to represent these facts? Double three is six, and half of six is three.

Draw this bar model in front of you, and then come on back to see if you've got it correct.

Welcome back, let's see how you've got on.

Let's see if your bar model is correct.

Izzy is explaining that if double three is six, that means that three must be both parts, because we know that doubling is adding two equal add-ins.

So, three and three.

So, how is she gonna work out what the whole is? We know that half of six is three.

So, six must be the whole that we are working with.

Well done, if you've got that bar model correct.

Okay then, let's explore halving a little further, and we are going to use our stem sentence, "If I know, (hums) then I know.

(hums) My turn, if I know, (hums) then I know.

(hums) Your turn.

Let's have a look, then.

So, double one is two.

If I know that double one is two, then I know that half of two is one.

I've taken away one of those equal parts, which has left me with one.

So, if I know that double two is four, then what else do I know? Let's take away one of those equal parts.

We know that half of four is two, well done.

If I know double three is six, then I know half of six is three.

Well done.

And, if I know double four is eight, then I know half of eight is four.

And, finally, if I know double five is 10, what's going to be the halving fact? Half of 10 is five, well done.

We can use our doubling facts to help us work out what the halving facts would be.

So, let's have a go at this.

What doubling and halving fact is shown on this number frame, here? Pause this video and complete the facts, and come on back to see how you've got on.

Let's have a look then.

So, I can see on my number frame that I have four red counters and four blue counters.

So, I can see that I am doubling four.

So, my doubling fact is "double four is eight," because I have eight counters altogether.

I now know that double four is eight.

So, what is the halving fact that I can now work out from this? We know that the whole is eight, so half of eight must be four.

Well done, if you've got those two facts correct.

Well done, Izzy.

She used our stem sentence.

If I know four plus four is equal to eight, or double four is eight, I know half of eight is four.

Well done.

Okay then, let's practise this.

So, you can see that Alex has created a new grid.

He is representing his doubling facts, and his halving facts and using the number frame in the middle to represent this.

But, he's not filled in all of the parts.

Can you complete the missing parts of Alex's grid using your knowledge of doubling and halving? Remember you might want to use our stem sentence, "if I know, (hums) then I know." (hums) Pause this video, have a go at completing the grid, and then come on back to see how you've got on.

Welcome back, let's see what those missing parts are.

I can see that double one is two, and I need to represent this on my number frame, 'cause Alex didn't fill that bit in.

So, I know that one counter must be on each side.

So, if I know double one is two, then I know that half of two, because that's my whole, is one because that's one of the equal parts.

Well done if you've got that one.

So, let's look.

Now I've got my number frame completed, but I haven't got any facts.

I can see that both sides of my number frame, have got two counters.

So, I can see this as double two is four.

Now, if I know double two is four, I know that half of four is two, well done.

And, again, I've got my number frame completed.

This time I can see that there are four counters on each side.

So, this number frame is showing double four is eight.

If I know that double four is eight, I also know that half of eight must be four.

Well done.

And, finally, I've been given my doubling fact, which is double five is 10.

Let's show this on our number frame.

So, if it's double five, I know that there must be five counters on each side of my number frame, five red counters and five blue counters.

And, I also know that if double five is 10, then half of 10 is five, one of those equal parts.

Well done if you got those correct.

Well done for all of your hard work today.

I hope you're feel so much more confident with doubling and halving.

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

When we double, we add two equal add-ins.

When we halve, we subtract one of those equal parts from its double.

Halving is the inverse of doubling, and we use this stem sentence to help us.

"If I know, (hums) then I know." (hums) So, here's an example.

"If I know double four is eight, then I know half of eight is four." Thank you for joining me with your learning today, and I hope to see you again soon.

Goodbye!.