A short instructional video (presented by Ellie) demonstrating how to use bar modelling to solve a percentage word problem. The problem: Birmingham FC and Nottingham FC played 135 matches in total; Nottingham played 25% more than Birmingham (i.e., Nottingham = 125% of Birmingham). Ellie builds a bar model (Birmingham = 100% divided into four 25% parts; Nottingham = Birmingham + one 25% part), shows the combined model has nine equal parts, divides 135 by 9 to find each part = 15, and concludes Birmingham must play 15 more games to equal Nottingham.
Chapters
Hi, I'm Ellie and in this video, we're going to be looking at using bar modelling to solve some really quite complex problems. So let's look at what we've got on the board. It's an example involving football. We've got Birmingham FC and Nottingham FC and they played a total of 135 matches, but Nottingham played 25% more than Birmingham. And it asks us, how many more games do Birmingham need to play to equal the number of games that Nottingham have played? There's quite a few different steps in this. Let's begin with our bar. That represents the number of games that Birmingham has played. It tells us that Nottingham have played 25% more than them. So we want pupils to think about how they'd represent this effectively. This bar here represents 100% of the games that Birmingham have played, but we don't know how many that is at the moment. We do know it's 100% of the games they've played. Nottingham have played 25% more than them. So we know that Nottingham's bar is going to be bigger than Birmingham's. But how much bigger? Well, we want pupils to think about how they'd represent 25% on here. And they should know by this point that 25% is the same as dividing it into four equal parts. So we can divide our bar into four equal parts. Each of those is 25%. So then Nottingham, the number of games they played can just be represented by the same size bar as Birmingham, but then another 25% added on here, so that overall they've played 125% of the number of games that Birmingham played. We can break these parts up as well. And these are equal parts. So Overall we've got 1, 2, 3, 4, 5, 6, 7, 8, 9 equal parts. Now, that's really important because when we look at the information that we have in the question, that will help us to find our answer, they played 135 matches altogether. So let's label that 135. And at this point, you'd ask your pupils if this represents 135 and I've got nine equal parts, how do I find out what each part is? And they should hopefully be able to see that. You just need to do 135 divided by nine, and that will give you 15. So each of these parts here is 15. Now, you need at this point to point them back to the question and ask what has it asked us to find out? It doesn't say. How many games did Nottingham play? It doesn't say, how many games did Birmingham play. It says, how many more games did Birmingham have to play to equal Nottingham? So if you were asking your pupils to point out to you on here where the bit is that they're trying to calculate it, this part, it's that remaining part here. And the pupil should therefore easily be able to see that that remaining part is another 15. So the answer to the question is that Birmingham have to play another 15 games to equal the number of games that Nottingham have played. And that's how we can use a bar model to solve a more complex percentage problem.
