Year 8 - Maths
Interpreting pie charts
Graphical representations of data
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This pupil-friendly study guide includes a unit summary, clear notes, common mistakes, and quick questions with answers.
Unit Summary
In this unit pupils will interpret and construct a range of representations of data including bar charts, pie charts and scatter graphs.
Lesson Summary
You will learn to interpret pie charts.
Key Notes
- Knowing the angle size for a sector allows calculation of the frequency.
- By knowing the total, statements can be made comparing the data.
- Different pie charts may have different totals even though proportions are the same.
Vocabulary To Learn
- Pie chart: A pie chart (pie graph) is a circular graph where sectors represent different groups proportionally.
- Frequency: The frequency is the number of times an event occurs; or the number of individuals (people, animals etc.) with some specific property.
- Sector: A sector is the region formed between two radii and their connecting arc.
- Proportion: Proportion is a part to whole (sometimes part to part) comparison. If two things are proportional, the ratio of part to whole is maintained
- Degrees: Degrees are the most common unit of measurement for angle. One whole turn is equal to 360 degrees, written 360°.
Common Mistakes To Avoid
- Two sectors on two different pie charts that have the same angle represent the same frequency.
3 Quick Questions (With Answers)
1. Solve this in steps: explain the method from this lesson and why each step matters.
Knowing the angle size for a sector allows calculation of the frequency. By knowing the total, statements can be made comparing the data.
2. Use this key word in a maths sentence and explain it clearly. 'Pie chart'
A pie chart (pie graph) is a circular graph where sectors represent different groups proportionally. Use this word when showing your method, then check your final answer is reasonable.
3. Spot and fix this common maths mistake.
Mistake: Two sectors on two different pie charts that have the same angle represent the same frequency. Correction: 90° of a pie chart of 4 data points represents less frequency (frequency of 1) than 90° of a pie chart of 200 data points (frequency of 50).
More Lessons In This Unit
- Checking understanding of pictograms and bar charts Study Guide
- Constructing bar charts by utilising technology Study Guide
- Constructing pie charts Study Guide
- Constructing pie charts by utilising technology Study Guide
- Constructing scatter graphs Study Guide
- Constructing scatter graphs by utilising technology Study Guide
- Interpreting scatter graphs Study Guide
- Problem solving with graphical representations of data Study Guide
- Securing constructing bar charts by hand Study Guide
- Securing constructing pictograms Study Guide
Browse all guides in the Year 8 Maths guide library.