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What is a line graph?

What is a line graph?
We explain what a line graph is and how children are taught to construct line graphs and answer questions on a line graph.
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What is a line graph?

A line graph is used to display information which changes over time. It is plotted on a graph as a series of points joined with straight lines.

Children start looking at line graphs in Years 4 and 5. They then need to be able to construct them in Year 6. Often this learning is linked with science, where children may carry out investigations which can then be presented as line graphs (for example, temperature changes over time).

How to draw a line graph

If a child was creating a graph like the one above, they would need to:

  • Remember that the general rule is that time goes along the horizontal axis.
  • Look at what their highest temperature was and make sure that the y axis (the vertical axis) went up as high as this number.
  • Make sure that there was an equal number of squares in between each number on the y axis.
  • Make sure that they started the y axis at 0.
  • Think about the x axis (horizontal axis) and how many minutes needed to be shown along here.
  • They would again need to make sure that there were an equal number of squares between each number.
  • The children would then look at the temperature taken after each minute and plot these points on the graph by marking them with an x.
  • They would then join all the xs with llines drawn with a ruler.

Children in Years 5 and 6 may be asked to answer questions on a line graph where the answer cannot be worked out exactly and an estimate needs to be made. This means they need to think carefully about the numbered points on the axes and what numbers might be in between them.