16.4 Reading charts and graphs · Unit 16 Interpreting and discussing results

1 · Teaching slidesuse ← → keys

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2 · Key words

bar chartA chart whose bar heights show frequencies.

line graphPoints joined in order, for data that changes over time.

pie chartA circle divided into sectors showing shares of a whole.

sectorOne slice of a pie chart.

scaleThe numbers on an axis, and what one unit stands for.

trendThe general direction data is moving in.

3 · Summary of the sectionrevise from this

A bar chart compares separate categories. Read the height against the scale.
A line graph shows how something changes over time. The joined points show the trend.
A pie chart shows shares of a whole. The sectors must total 360°.
In a pie chart of N people, one person is worth 360 ÷ N degrees.
To go the other way: people = angle ÷ (360 ÷ N).
A percentage becomes an angle by taking that percentage of 360°.
A bar chart's scale should start at zero. If it does not, the differences look bigger than they are.
A pie chart alone does not tell you how many people were asked — the total must be stated.
Always read the numbers from the scale, never judge by the picture alone.

PDFPrintable worksheet All 64 questions, space to work PDFWorked answers Full solutions, not just the answer

Video lessons2 videos

Reading Bar Charts

British corbettmaths

Reading heights off the scale, and the questions examiners ask about them.

Interpreting Pie Charts

British corbettmaths

Turning a sector angle into a frequency, and back again.

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Reading charts and graphs