Video: Using Equations and Bar Models to Represent Multiplicative Comparison Statements

James drew this to show that 36 is 4 times as many as 9. Write an equation which shows this.

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Video Transcript

James drew this to show that 36 is four times as many as nine. Write an equation which shows this.

Here, we can see what looks like a bar model that James has drawn. And the question tells us the number fact that James wants to show by drawing this bar model. He wants to show that 36 is four times as many as nine. If we look carefully at the bar model we can see how James has built it up. He started off by drawing four blocks all the same size. They’re all the same size because he wants them to be all worth the same amount. The bar underneath that James eventually draws is going to be four times as long as one of these bars.

So it’s important that each of his four bars are exactly the same size. James wants each one of the four bars that he’s drawn to be worth nine. And the total of all four bars is worth 36 because the whole point of James’s bar model is to show that the number 36 is worth four times as many as nine. There are four lots of nine that make 36. Now, we are asked to write an equation which shows this. Now remember, an equation is a statement that has an equal sign in it. Something this side of the equal sign is worth the same as something this side of the equal sign.

If we look back at the question, it gives us a hint as to where to write the equal sign. We could even replace the word “is” for an equal sign. James drew this to show that 36 equals four times as many as nine. So let’s start by writing the number 36. 36 equals what? Four times as many as nine or four lots of nine. We could write our equation like this. Four lots of nine is simply nine plus nine plus nine plus nine.

But is there a more efficient way to write four lots of nine? Yes, we can write four lots of nine as a multiplication. We could even imagine that we cross out some of the words in the question to get another hint. 36 equals four times nine. Bar models are a really good way of representing calculations, especially multiplication calculations. So this bar model shows our multiplication perfectly. The equation that shows that 36 is four times as many as nine is 36 equals four times nine.

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