Lesson video

Hi everyone, Mrs. Barr here.

I'm really pleased to be back with you.

I'm going to start today's session by looking through the practise activity that you were left.

So here's your ratio chart, I expect you're coming quite familiar with now.

We're going to go through by chanting our times table to see if we can work out what the missing numbers where.

Are you ready? Zero twos are zero, one two is two.

Two twos are four, three twos are? Six, well done.

Four twos are eight, five twos are 10, six twos are 12, seven twos are 14, eight twos are 16, nine twos are 18, 10 twos are 20, 11 twos are 22 and 12 twos are 24.

Well done if you found those missing numbers.

We can also just skip count through the products of the multiples of two.

So we have to go back and see how we get on this might be how you did it.

Zero, two, four, six, eight, 10, 12, 14, 16, 18, 20, 22, 24.

Some of you might be getting pretty good at these facts now.

So you might have just known what the facts were.

That's what we're trying to get to and that's what we're going to carry on working on today.

So now we're going to carry on using the ratio chart but we're going to workout the missing numbers without tapping to chant through all the way through our times tables.

We're going to use the relationships.

And what we know about adjacent numbers, adjacent numbers are numbers that are next to each other, the higher and lower numbers.

What we know about adjacent numbers and the facts in our two times table to help us work out the missing numbers.

So, we're going to start with the missing product from three twos.

But we've already got the product from the factor two and two.

So, two twos are four, we already know that.

But now we need to find out what three twos are.

So the factor is increasing by one.

There's one more group of two.

So we're going to have a bit of help with this.

Here's our number line.

And we're starting on that fact that we've already got.

We already know that two twos are four, so we've got our circle around our four there.

And now we need one more group of two because we have three groups of two not two groups of two.

So, here we go.

Here's our rabbit, he's doing one more jump of two.

He's added on two, so we now have six which is two more, one group of two more than our two groups of two.

So, three twos are equal to two twos and another group of two.

So one more group of two.

So two is added on to two twos to give us three twos.

This time with our ratio chart we're looking to find the missing number to go in the box.

And it's seven twos that we're looking to find.

This time we're going to use the information that comes below the seven twos.

We're going to use eight twos to help us find that out.

So we know that eight twos are 16 but we want to find seven twos.

So, can you have a little think to yourself maybe pause and have a think about how we're going to get from eight twos to seven twos.

What operation might we do? Have you had a little think? Let's look at the animation now then.

So we've got our number line and the information we're starting with is eight twos are 16.

So there's our circle.

Let's have a look what our rabbit does.

What do you think it might be about to do? So for those of you who said it was going to jump back, it was going to take away two because we don't need eight twos, we only need seven twos.

So we have one less two and our answer of course is 14.

So let's have a look how we write that as an equation.

So we know that we've got seven twos are equal to eight twos take away two.

We have to take away that two otherwise we're just left with eight twos and that is not equal to seven twos.

So we can see that seven twos are equal to eight twos minus one of the groups of two.

So we're going to use the same chart and we're going to find the same missing number now but we're going to use different information to help us do that.

Last time we used eight twos are 16 to help us find what seven twos are.

But this time we're going to use six twos are 12 to help us find seven twos.

So what I want you to think about first is the relationship between those factors, seven groups of two and six groups of two.

So we need to look at the relationship between those to work out what we're going to do.

So we start with seven twos.

And we know that we need to do something to the six twos to make it equal.

So we've got six twos.

Do you think we need to add a group of two to get to seven twos or take away a group to get to seven twos? You're right, six twos aren't enough, are they? We need one more two.

So we're adding on one more two.

And we know that six times two, six twos are 12.

So we're just adding two to get to it, to get to seven twos.

So six twos are 12, seven twos are 12 add two which we know makes it seven twos are 14.

Now we're going to go back and look again at the missing number that went with our factor three.

So we did work this out but we used two, lots of two to work it out.

And this time we're going to use four twos are eight to help us work it out.

So we're going from the other adjacent factor.

We're going to be looking at four twos.

So we're going to do exactly the same thing as we did before, but we need to think about the relationship.

We know what four groups are but we don't know what three groups are.

So let's have a think what we're going to have to do to our four groups of two to get two or three groups of two.

Should we have a think? So three groups of two are equal to four groups of two but it's not as it four groups of two is one group too many.

So we're going to have to take it to one group of two away.

We're going to have to take one two away to make sure they balance, to make sure that they are equal.

So let's carry on looking at that.

So four twos are equal to eight, three twos are equal to eight but taking away a two.

So we know that three twos are equal to six, well done.

So here we have a different image which shows exactly the same thing.

This is an image that shows us the factors and it also shows us, it has counters in which are called an array model, which you're going to come across more and more as you do more multiplication and division.

So we have here, we can see that we have our factor here, one, two, three, four, five, there's our factors or group, how many groups we have.

And here is our other factor, how many is in each group? Which is two.

So we're going to cap through in twos to see how many we've got.

And they're going to flash up.

So we've got five twos, let's see what the product is.

Two, four, six, eight, 10.

So our skip counting tells us that five times two is 10.

But now we want to find out what six twos are.

So what I want you to do quickly is have a little think.

How do you think our model is going to change? What's going to look different on our screen when we have six twos? Can you imagine where those counters are going to go and where that number six is going to go on our model? There's six and we need those two more counters because it's exactly the same if we have a look at our equation here, six twos is the same as five twos add two.

We've just added that row of two here.

There's our six group of two.

So we know that six twos are equal to 10, add another two.

And we know that six twos are equal to 12.

And there's our model.

So we're going to have a go to task now, we're going to do this one together.

You're going to do a bit and then I'm going to help you.

And then the next one is going to be for you to do on your own after we finish this session.

So we've got a different missing number now.

We've got the product that goes with the factor four is missing.

So the product of four and two is missing.

And we're going to use the adjacent numbers to help us.

We're going to use what we know about three times two and five times two to help us.

And I want you to use them both this time.

We've just done one at a time before but now we're going to use both to really prove that we understand that.

So we're looking for the missing product from four twos.

We're going to use four times two is equal to three times two and something else.

We need to do something to the three times two.

And we're going to use four times two is equal to five times two, but we have to do something else to it.

So I want you to pause the video now and have a go on a whiteboard or a piece of paper to see if you can work out what should go in that missing box.

Four twos are equal to three twos, and what you've got to do.

And four twos are equal to five twos but we've got to do something to the five twos.

So pause and have a go at that now.

Okay, I hope you come back.

Let's have a look, shall we? I hope you've got plus two there, four twos are equal to three twos and one more because we need one more group, don't we? To get us to the four groups.

So if you've got that one right then hopefully maybe you knew what you had to do with the five twos to get it to be equal to the four twos.

That's right, you had to take one group away.

Well done.

So here's your practise activity.

It's exactly the same as the slide before but this time the product to go with the factor eight is missing.

So you're going to use the adjacent factors.

That's seven twos are 14 and that nine twos are 18 to give me two equations to show me how you're going to use those other facts to work out what's your answer is the eight twos.

And we'll go over that in the next session.

Okay, see you soon.