One circle for the whole set
Show on a big screenForty learners voted on their favourite game. Cut one circle into 40 equal parts called wedges. The circle can stand for all forty.
- A full circle — one whole turn.
- Cut into 40 equal wedges, one per voter.
- One wedge, on its own: 9°.
- 40 × 9° = 360°.
A pie chart is a circle that stands for a whole set. Here the set is all 40 voters. A slice is one group's part of the circle. The whole circle is one full turn, 360° (360 degrees).
Each voter is one member of the set. A member's share is that member's part of 360°.
Rule: One member's share is 360° ÷ the number in the set.
The equal shares fill the whole circle. So we divide 360° by the number in the set.
Try other sets. 24 learners give 360 ÷ 24 = 15° each. 200 learners give 360 ÷ 200 = 1.8° each. The circle stays the same size. Only each member's share changes.
Drag the slider. Watch one wedge change size.
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Try the lab to finish this lesson.