Charts and graphs

Charts turn numbers into pictures so patterns jump out. Read the scale carefully: not every square is worth 1. Bar charts compare amounts, line graphs show change over time and pie charts show parts of a whole.

Key facts

  • Check what each square on the axis is worth.
  • Bar charts: gaps between the bars; the height shows the amount.
  • Pie charts: the whole circle is 360°, so each item gets (its amount ÷ total) × 360°.

Worked examples

Example 1

How many more books were borrowed on Wednesday than on Monday?

  1. Monday’s bar reaches 3. 3
  2. Wednesday’s bar reaches 7. 7
  3. Subtract. 7 − 3 = 4

Answer: 4

Example 2

In a class of 30, 12 walk to school. What angle does “walk” get in a pie chart?

  1. Each student is worth 360 ÷ 30. 12° each
  2. Twelve students. 12 × 12 = 144°

Answer: 144°