Using Bar Models To Solve Complex KS2 Multiplicative Problems

Hi, my name is Ben. And in this video we're going to be looking at using the bar model to solve more complex multi step problems involving multiplication and division. Here's our question. Abigail is three times lighter than her brother Jamie. Their father is twice as heavy as Jamie. The total of their weight is 130kg. How much does each person weigh? So we've got three children, three people, and we've got 130kg. We know that Abigail has a weight, we don't know how much, And we know that Jamie is three times more than Abigail because here it says that Abigail is three times less. So, so if the children use their knowledge of the inverse, they can see that the inverse of three times less will be three times more. We also have the father, and the father is twice the weight of Jamie. So we can make the bar twice as long. Now, all these parts together weigh 130kg. And if we count up the parts of the whole, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, we see that the whole is made up of 10 parts. So we can look at the weight 130 kg and we can divide it by 10, which equals 13 kg. We therefore know that each part is worth 13 kg. So Abigail is 13 kg, Jamie will be 3 lots of 13, which is 39 kg, and father will be 6 lots of of 13, which is 78 kg. Children may also be aware that 39 doubled is 78 and they can use their knowledge of doubles too. And that's how you can use the bar model to solve more complex problems involving multiplication and division.