How to see it
Before reading any chart, read three things: the title, the key or scale, the axis labels. A pictogram's key says what one symbol stands for. A bar chart's scale may count in twos or fives, so a bar between two lines needs care. A pie chart shows parts of 360 degrees. A line graph shows change over time.
A worked example
If each face is 4 people, three and a half faces is 14. For a pie: 60 pupils, and a sector of 120 degrees. 120 out of 360 is a third. A third of 60 is 20.
The common mistake: ignoring the key or the scale
The trap is counting the symbols, and saying three and a half. The key changes everything. In the pie, writing 120 as the number of pupils confuses degrees with people.
Try one
A pie chart of 60 pupils has a sector of 90 degrees. How many pupils?
- A90
- B15
- C30
- D4
Show the answerHide the answer
Right: B, 15
90 is a quarter of 360.