Real-life graphs, speed and growth
Read a distance–time graph for stops and speeds, sketch the graph of a walk, match a filling bottle to its graph and compare doubling with steady growth.
- UK: Year 8
- France: grade 5
- Germany: grade 8
- Iran: grade 10
- Syria: grade 7
- Palestine: grade 9
- Ukraine: grade 6
- Russia: grade 7
Guide
On a distance–time graph the horizontal axis is time and the vertical axis is the distance from home. The graph is not a map of the road: when the graph goes up you are getting further from home, not climbing a hill.
A flat piece means the distance is not changing: you have stopped. The steeper a piece, the more distance in the same time, so the faster you are going. The speed on a piece = the distance of that piece ÷ the time of that piece.
In steady growth the same amount is added every hour and the graph is a straight line. In doubling growth the amount doubles every hour, 1, 2, 4, 8, …, and the graph gets steeper and steeper. That is an exponential function.