Rates of change on graphs
Pages
Speed from a distance–time graph
Speed as the gradient of each straight section; horizontal means stopped.
The gradient as a rate of change
Reading a straight-line gradient as a rate: vertical units per horizontal unit.
Average rate of change from a chord
The gradient of a chord joining two points on a curve as the average rate.
Instantaneous rate of change from a tangent
A tangent's gradient as the rate at that instant, an estimate by eye.