Chapter 5: Ratio and proportion
The chapter problem: the model garden
A school is drawing a model of a garden. The path is 18 m long, and a scale drawing must show it accurately. Before learning the method, predict: would the path fit on a 30 cm page if 1 cm represented 1 m? Estimation is enough for now.
By the end of this chapter you will be able to
- Write, simplify and use ratios to share amounts.
- Connect ratios with fractions, tables and straight-line relationships.
- Model direct and inverse proportion.
- Use scale drawings and compare lengths, areas and volumes of similar shapes.
Roadmap
- 5.1 Ratio notation, simplifying and sharing
- 5.2 Ratio, fractions and linear functions
- 5.3 Direct proportion
- 5.4 Inverse proportion
- 5.5 Scale factors, scale diagrams and maps
- 5.6 Comparing lengths, areas and volumes — Higher only
At each progress check, return to the garden path. By the end, you can choose and use its scale accurately.
Your connection
Ratios compare quantities in many settings. Write one place where you or someone you know compares quantities, such as a recipe, journey or model. What quantities are compared?