A line graph shows how something changes over time. We join the points with a line, so we can see it going up or down.
Why this matters: Line graphs show change. Weather forecasters use them for temperature, and a gardener can watch a plant grow taller week by week.
Reading a line graph
Time goes along the bottom. The thing we are measuring goes up the side. To read a point, go up from the time until you reach the line, then look across. Here is the temperature during one day.
| Time | Temperature (°C) |
|---|---|
| 8 am | 10 |
| 10 am | 14 |
| 12 noon | 18 |
| 2 pm | 20 |
| 4 pm | 15 |
Biggest rise and biggest fall
The line climbs as the day warms up, then drops in the afternoon. To find the biggest change, look at how much the line goes up or down between two times. From 8 am to 10 am it rose 4°C (10 to 14). From 2 pm to 4 pm it fell 5°C (20 to 15), the biggest fall of the day.
A plant growing
A line graph can also show a sunflower getting taller. If it is 2 cm in week 1 and 5 cm in week 2, it grew 3 cm that week.
Put these temperatures in order, coolest first:
- 10°C (8 am)
- 14°C (10 am)
- 15°C (4 pm)
- 20°C (2 pm)