Walk slowly, then sit, then run, then sit again. While you do, sketch a distance-vs-time graph of your motion. Each phase has its own shape.
Reading the graph
- Slope up — moving forward
- Flat — sitting still
- Slope down — walking back
- Steeper slope — moving faster
The slope of a distance-time graph IS the speed. That's the seed of calculus: a derivative is just a slope.