A short instructional YouTube video (presented by Ellie) for Year 6 pupils showing how to solve a pie-chart problem to develop greater depth in statistics. It demonstrates converting 20% of a pie chart to an angle (72°), finding 3/4 of that angle for another sector (54°), recognizing a labeled right angle (90°), and calculating the remaining sector as 144° by subtraction from 360°. The focus is on applying percentages, fractions and angle knowledge and suggesting pupil strategies.
Questions this video answers
72°
54°
90°
144°
Chapters
Hi, I'm Ellie and in this video we're going to look at a really good question for getting your pupils working at greater depth when they're looking at statistics. This would be perfect for year six as it gets them practicing lots of different skills, working out fractions, percentages and using their knowledge of angles. So let's look at the question. This pie chart shows the different colours of cars in a survey. 20% of the cars are red. The number of white cars is 3/4 of the red cars. And it's asking us to find out the size and degrees of each part of this pie chart. So we're going to begin by looking at what we know about pie charts. Circles. We know that the whole thing is 360 degrees. It's really important that your pupils know that. We're then going to look at the information that we're given in the question to start with. So 20% of the cars were red. So we're going to start by working out this angle here. So 20% of 360. Pupils could start to find 10% by dividing by 10, which will give them 36. And to find 20%, then they just multiply that by two, so you can label that straight away as 72 degrees. And that's our red cars there. We're then going to look at the next bit. It tells us the white cars are three quarters of the red cars, so we know the red cars are 72. You then want to make sure your pupils remember how to find fractions of an amount. So if they're finding a quarter, they're going to divide by four. They could do this in lots of different ways, but one quick way would be to half it and then to half it again. 72. Half is 36, half again is 18, but it's not 1/4 of this amount, it's 3/4. So the last thing we need to do is multiply that by 3 and 18 multiplied by 3 gives you 54 degrees. So that's our white cars there. Is there anything else on the pie chart which can help our class? Hopefully they've spotted that our right angle is labeled and they should all know straight away that a right angle is 90 degrees, which just leaves this section here. And all they need to do for that they should be able to spot this is take away the total of these three angles from the whole thing, which is 360. So they'll need to add 90 and 72 and 54 together. They might want to do that in written methods or using their informal methods mentally, and that will give them 360. Take away the total of all of those together, which is 216, which leaves you with 144 degrees. So now we know that our green cars are represented by a section of this pie chart, which is 144 degrees. And that's how we can use our knowledge of fractions, percentages and pie charts to really extend the learning for our pupils.
