Chapter 11: Straight-line graphs and rates of change
The chapter problem
A route planner shows that a walker is 2 km from home after 30 minutes. The walker continues at the same rate. Predict the distance from home after one hour. What information would help you draw a graph of the journey?
Make an estimate first. You can revise it as you learn about coordinates, gradient and real-life graphs.
By the end of this chapter
- plot coordinates and draw straight-line graphs from tables and equations;
- find and interpret the gradient and intercept of a straight line;
- find equations of lines, including parallel and perpendicular lines;
- interpret distance-time graphs and other real-life linear graphs;
- use gradient and area to describe rates and totals on graphs.
Where might this help you?
Graphs can describe travel, phone costs, water filling a container, or changing temperatures. Which situation have you seen, and what could a graph help you compare or predict? Write your own example.