Data charts – bar, line, and pie from the same table

What it shows

The same small data table can be drawn in several ways, and each chart answers a different question. A bar chart compares the size of separate items by bar height; a line graph joins values in time order to show a rising or falling trend; a pie chart shows each value as a share of the total, with each central angle equal to the share × 360°. The sample sets make the choice visible: London's monthly temperatures suit a line graph but not a pie chart, because temperatures are not parts of a whole, while top students per class have no time order to connect.

How to use

Choose a Sample data set and a Number of data points, then switch between the Bar, Line and Pie buttons for the same table and read the comment below the chart. Drag a bar top or a point on the line to change a value and watch the total, average and pie percentages update. Ask students to justify which chart suits each data set, then try the Temperature, Top students and Revenue buttons in turn.

Parameters you can change

• Number of data points 3–12
• Initial chart type Bar chart, Line graph, Pie chart
• Sample data set Average monthly temperature (°C), Number of top students per class, Revenue by quarter
• Show values on chart
• Currency From the language, US dollar, Euro, Indian rupee, Indonesian rupiah, Saudi riyal

Questions to explore

1. Which chart type best shows how London's monthly temperature changes through the year, and why?
2. When is a pie chart a sensible way to display a data set?
3. If you increase one value, what happens to the angles of the other pie slices?