Reading Charts and Graphs

Understanding the concept

Charts turn numbers into pictures. Read the title, axes, labels, units and scale before comparing values or drawing conclusions.

Start by identifying the quantities and units. Use a small example to understand the idea before attempting larger calculations.

Step-by-step method

Identify the chart type and the quantity on each axis. Check whether the vertical axis begins at zero and how large each tick interval is.

1. Read the question and underline what you must find.
2. Write down the given values and check their units.
3. Apply the relevant method one step at a time.
4. Estimate or reverse-check your answer before presenting it.

Quick-reference table

Use this reference to recognise common situations.

Four worked examples

Compare the different types of questions and the steps used to answer them.

Example 1: Bar values

Question or method: Apples 12, oranges 8, pears 5.

Example 2: Line change

Question or method: Rainfall rises from 10 mm to 16 mm.

Example 3: Percentage share

Question or method: A category has 25 out of 100 responses.

Example 4: Axis scale

Question or method: Ticks go 0, 5, 10, 15; a point is at the third tick after zero.

Common mistakes

These errors are easy to make. Read each one and check your working.

• Ignoring whether the axis starts at zero.
• Confusing percentages with absolute counts.
• Assuming a trend continues beyond the shown data.

Always ask whether your answer is reasonable for the original situation.

Practice questions

Try each question on paper before revealing the answer.

Review checklist

• Can you explain the key idea in your own words?
• Can you complete a worked example without looking at the solution?
• Can you identify a common mistake and correct it?
• Can you estimate whether your result is sensible?

Related lessons and tools

Continue with Everyday Maths lessons, or browse the CS17 Learning Centre. Where helpful, check calculations with the CS17 Calculator Workshop.