Read and interpret pie charts

What you will learn

• Read and interpret pie charts

Models used: number sentences, stories, diagrams.

Before you start

• Read and interpret line graphs

The whole circle means everybody

The class has 20 pupils. This entire circle stands for all 20.

1. The class has 20 pupils. This entire circle stands for all 20.

   Each share belongs to one common total. The pieces together must account for the whole.

2. Each strip is one whole of the same size. Count all the equal parts, then count the shaded parts.

   The walking sector covers half the circle. It represents half the pupils.

   1/2 of 20 = 10

   The size of a fraction depends on both numbers: how many equal parts make the whole, and how many of those parts we take.

3. Each strip is one whole of the same size. Count all the equal parts, then count the shaded parts.

   The bus sector covers one quarter. One quarter of the 20 pupils is 5.

   1/4 of 20 = 5

   The size of a fraction depends on both numbers: how many equal parts make the whole, and how many of those parts we take.

Worked example: A new example, together

What is the difference between the votes for Apples and Pears?

1. Read the total and category labels before turning a sector share into a count.

   Sector fractions encode shares of a common total.

2. The fraction printed on each sector refers to all 34 votes.

   What is the difference between the votes for Apples and Pears?

   2

3. The fraction printed on each sector refers to all 34 votes.

4. Apples has 12/34 of 34, or 12 votes.

5. Read the requested count or compare the specified categories: 2.

6. Check the result against the question we started with.

   The sector counts sum to 34.

   We found 2. Sector fractions encode shares of a common total.

Common mistakes to discuss

• A bigger slice always means more. A slice is a share of its own whole. Thirty per cent of 200 beats forty per cent of 100.

Check your understanding

• Read and interpret pie charts
• interpret a pie-chart share using its common total
• check the answer against the original quantities and units

Explain your reasoning to an adult, then try a fresh question in the interactive lesson. A result from one attempt is not proof of lasting mastery.