Graphs and charts Cambridge IGCSE Information & Communication Technology revision
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In plain words
A chart turns a column of numbers into a shape that can be understood at a glance. Choosing the right kind of chart, and labelling it fully, is most of the marks.
7 things to know
- A bar or column chart compares separate items. A pie chart shows how a whole is divided into parts. A line graph shows how something changes over time.
- The data for a chart can be contiguous, with the cells next to each other, or non-contiguous, with the cells apart.
- Labels a chart may need: a chart title, a legend (the key that identifies each data series), a category axis title and a value axis title, and data labels showing values or percentages. A pie chart needs sector labels.
- A second data series can be added to compare two sets of values. If the two have very different sizes or units, the second is plotted against a second axis.
- The scale of an axis can be set: its minimum value, its maximum value and the size of its steps.
- Values can be formatted to a number of decimal places or as currency.
- A sector of a pie chart can be pulled out to emphasise it. Colours or fill patterns should be chosen so that the parts can be told apart, even when printed in black and white.
Worked example
A shop wants to show what share of its total sales came from each of five departments. Which chart should it use, and what labels are needed?
- Shares of a whole are shown by a pie chart.
- It needs a title, and each sector labelled with the department's name.
- Percentages on the sectors show each share exactly.
Tips and tricks
- Pie: parts of a whole. Bar: comparing items. Line: change over time. Match the chart to what the data is showing.
- A pie chart has no axes, so it does not have axis titles. A legend is not needed if every sector is labelled.
It lands in your notebook with its questions as flashcards.
Graphs and charts: 5 questions and answers
These are the quiz’s questions. Do the quiz first, then come back here for the ones that got you.
Which chart is best for showing parts of a whole?
Each sector is a share of the total.
Which chart is best for showing a change over time?
The line shows the trend.
What is a legend on a chart?
It matches colours to series.
What is non-contiguous data?
Two separate ranges can be selected for one chart.
Why might a sector of a pie chart be pulled out from the rest?
It draws the reader's eye.
Quiz
5 questions
Tap an answer and you’ll see straight away whether it’s right, and why.
Worksheet
2 questions, 4 marks. Write your answers on paper, then check them.
Graphs and charts
Cambridge IGCSE Information & Communication Technology 0417 · 4 marks · papermunch.org
Name ______________________________ Date ______________
State the most suitable type of chart to show the temperature in a town for each month of a year, and give a reason.[2]
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A line graph, because it shows how a value changes over time.
Explain why a second axis may be needed when a chart shows two data series.[2]
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The two series may have very different values or units. On one scale, the smaller series would be too small to read.
Answers: Graphs and charts
- 1. A line graph, because it shows how a value changes over time.
- 2. The two series may have very different values or units. On one scale, the smaller series would be too small to read.