Pie charts

Hello, and welcome to Myriora Maths! A pie chart shows how a whole is shared out, like slices of a pizza. Let's learn to read one, using fractions, percentages and angles.

The whole circle is everyone. Here, a class of twenty-four children chose their favourite sport. The biggest slice is football.

Football is exactly half the circle. Half of twenty-four is twelve. So twelve children chose football. Swimming is a quarter: a quarter of twenty-four is six.

A pie chart can also show percentages. The whole circle is a hundred per cent. Half is fifty per cent, and a quarter is twenty-five per cent.

Or angles. The whole circle is three hundred and sixty degrees. Each child gets three hundred and sixty divided by twenty-four: fifteen degrees. So the six swimmers make ninety degrees: a right angle.

Let's try one together. Tennis is an eighth of the circle. How many of the twenty-four children chose tennis? Say it out loud!

Twenty-four divided by eight is three. Three children chose tennis!

Here's a question that catches lots of people. Two pie charts both have half for football. Does that mean the same number of children chose football? Some people say yes. But one chart is for twenty-four children, and the other is for a hundred! Half of twenty-four is twelve. Half of a hundred is fifty.

Your turn! In a pie chart of forty people, a slice is a quarter of the circle. How many people is that? Pick the right card. You've got twenty seconds, or pause the video. Go!

Time's up! A quarter of forty is ten people!

Quick review. A pie chart shows how a whole is shared. Read the slices as fractions, percentages or angles. The whole circle is a hundred per cent, or three hundred and sixty degrees. And always check how many the whole circle stands for. See you next time!