Draw and interpret statistical charts
Choose and construct bar, pie, pictogram, stem-and-leaf and frequency displays, including stacked and side-by-side bars.
Use this pathway for Cambridge IGCSE International Mathematics 0607, 2028–2030. Core and Extended objectives are labelled in each lesson; Extended adds requirements beyond Core. Paper 1 and Paper 2 are non-calculator. Papers 3–6 require a graphic display calculator (GDC). These original lessons use self-checked practice; they are not a Cambridge grade, full timed paper or teacher review.
Before you begin
- Check whether your school has entered you for Core or Extended. Core and Extended share most Number ideas, but some notation and methods are Extended only.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
Which display compares categories as parts of a whole?
What you will learn
- Select a chart that fits the data and comparison
- Calculate sector angles and use a consistent scale
- Order stem-and-leaf values and include a key
Match the display to the question
Bar charts compare categories; stacked or side-by-side bars compare category counts across groups. Pictograms need a clear key. A pie chart shows parts of a whole; a sector angle is frequency ÷ total × 360°.
A stem-and-leaf display preserves individual values. Order leaves and state a key such as 2|5 = 25. A simple frequency distribution groups or lists how often each value occurs.
Label scales and protect the meaning
Give axes, units, category labels and a sensible even scale. The bar heights or sector sizes must represent the frequencies; do not truncate an axis in a way that exaggerates a small difference without making it clear.
Read the chart back against its source totals. In a pie chart, all sectors sum to 360°; in a frequency chart, all counts sum to the total number of observations.
Pause and explain
What must a stem-and-leaf diagram include to show how to read each entry?
Worked example
In a class of 40 students, 10 choose drama. Find the pie-chart sector angle for drama.
Show the worked solution
- Drama is 10/40 = 1/4 of the class.
- Sector angle = 1/4 × 360°.
- The angle is 90°.
Answer 90°.
Try a topic test
Choose Easy, Normal or Difficult. Save your answers and open worked review after finishing.
Test this topic →From guided practice to a new situation
Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.
A survey has 20 responses: 5 prefer tea, 9 coffee and 6 water. Find each pie-chart sector angle.
Give me a hint
Multiply each fraction of 20 by 360°.
Compare my reasoning
- Tea: 5/20 × 360° = 90°.
- Coffee: 9/20 × 360° = 162°.
- Water: 6/20 × 360° = 108°; the angles sum to 360°.
Tea 90°, coffee 162°, water 108°.
Look for these in your work
- Each category uses the total 20
- Angles calculated
- Total checked
Write the ordered stem-and-leaf display for 14, 17, 21, 22, 26, 31, 34, and give a key.
Give me a hint
Use tens as stems and order the units as leaves.
Compare my reasoning
- Stem 1 has leaves 4, 7.
- Stem 2 has leaves 1, 2, 6; stem 3 has leaves 1, 4.
- Key: 2|6 = 26.
1 | 4 7; 2 | 1 2 6; 3 | 1 4. Key: 2|6 = 26.
Look for these in your work
- Stems identify tens
- Leaves ordered
- Key interpretable
A school compares club participation for Year 9 and Year 10 across art, music and sport. Which display is appropriate, and what should its bars show?
Give me a hint
The question compares the same categories across two groups.
Compare my reasoning
- Use a side-by-side bar chart to compare each category between year groups.
- Show the count for each year group within art, music and sport using a common vertical scale.
- Label the axes and include a legend; stacked bars would show totals and within-category composition instead.
A side-by-side bar chart with paired year-group counts for each club category, shared scale and legend.
Look for these in your work
- Comparison purpose matched
- Counts encoded consistently
- Labels and legend included
Common mistakes
- Forgetting a stem-and-leaf key
- Using inconsistent class widths or scales
- Drawing pie sectors from raw counts instead of proportions
- Treating a bar chart as continuous data
What can you explain now?
If 15 of 60 responses fall in a category, what pie-sector angle represents it?
Compare with the explanation
90°
15/60 × 360° = 90°.
After trying it yourself, choose your next review. This is your self-assessment.
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Make it stick
How do the data type and comparison goal help you select a suitable statistical chart?
If you needed the solution, close it and solve the problem again from a blank page. A correct answer is stronger when you can explain the reason for each step.