Using Bar Models For Simple Subtraction Problems

Hi, I'm Ellie, and in this video, we're going to look at how you can use a bar model to help support your pupils with simple subtraction problems. So let's look at the example that we have here. Hannah bakes 145 cakes. She sells 98 at the school fair, and how many cupcakes does she have left? So in this problem, what we're going to do is make use of the bar model to help pupils understand the process they need to go through to find their answer. So I want to underline, first of all, 145 cupcakes. This is the total number that we start with and we're going to represent that using our bar. So let's put an H for Hannah, and then we're going to draw a whole bar to represent that 145. You then want to ask the pupils how many she sold, and they should be able to spot from the question. It was 98. So we want to mark this on the bar. So I'm going to put roughly here, we're going to say that Hannah so sold 98, and then you can label these parts so that pupils understand what's happening. So this is a whole 145 that she had to begin with. And this is the 98 that was sold. The question asked, how many does she have left? And the good thing about a bar model with this kind of example is it's really making it very clear to the pupils that they need to find this part and that the idea of it really is to help reinforce that they're doing subtraction. So you start with 145 and you take away 98 to give you your answer, and that will tell you how many she had left. Now, pupils could do this in different ways. They might want to use column subtraction. I'd recommend just doing a really quick mental method. Take away 100 to give you 45, and add on the other two to give you 47. So that your answer here is 47 cupcakes left. And that's how you can use the bar model to solve simple subtraction problems.