Video: Using Number Lines to Model Multiplication within 100

Look at how Victoria used a number line to multiply. I start at 0 and make 4 jumps of 5. I land on 20. So, 4 × 5 = 20. What calculation has Liam shown on this number line? What is 3 × 6?

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Video Transcript

Look at how Victoria used a number line to multiply. I start at zero and make four jumps of five. I land on 20. So four times five equals 20. What calculation has Liam shown on this number line? And what is three times six?

This problem is all about using number lines to model multiplication facts. We’ve given an example to start with. And the first part of the problem actually tells us to look at how Victoria used a number line to multiply. So let’s start of by doing that. The clue to how she uses her number line is in the speech bubble. Victoria says that she starts at zero. And then she makes four jumps of five. One, two, three, four. For each jump she can count in five. Five, 10, 15, 20. She starts on zero, makes four jumps of five, and ends up on the number 20. So she knows that four lots of five are 20 or four times five equals 20. And this is the multiplication fact that she shows using her number line. Four is the number of jumps, and five is the number that is being jumped each time, four jumps of five.

Now we can use Victoria’s method to solve some multiplication of our own. Firstly we’re shown a number line. It already has some jumps marked on it. The question asks us which calculation has Liam shown on the number line? Well, firstly, we know that it’s going to be a multiplication. Something multiplied by something equals something. Let’s imagine Liam says the same sort of thing as Victoria. What do you say? I start at zero and make how many jumps? One, two, three. I start at zero and make three jumps of- of how many? We can see all the plus eights underneath the arrows. This tells us that Liam has added eight each time. He starts at zero and makes three jumps of eight. Where does he land? Eight, 16, 24. He lands on 24. Three jumps of eight takes him to 24. So we can complete Liam’s multiplication as three times eight equals 24.

In the last question we need to solve, we’ve been given a multiplication. And now we need to use the number line for ourselves. What is three times six? Well, to model three times six on the number line in the same ways we’ve done already, we need to make three jumps of six. And we can see that one jump of six has been made already. So we only need to make another two jumps of six. What’s six plus six? Well, if we add another six to six, we get 12.

We’ve now made two jumps of six, one more to go. Where do we end up if we make a jump of six from 12? Well, 12 add six equals 18. We’ve made three jumps of six. We started at zero six, 12, 18. If we start at zero and make three jumps of six, we land on 18. So three times six equals 18. The calculation that Liam shows on his number line is three times eight equals 24. And we’ve also used a number line to show that three times six equals 18.

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