Using equivalent ratios and the unitary method students learn how to calculate amounts that are in direct proportion, such as exchange rates and cooking recipes. During the lesson students progress from working proportions in the form 1 : n to finding conversion factors from a real-life graph.

The start of the lesson recaps working with equivalent ratios through mile to km conversions. The plenary challenges students to perform calculations using a conversion graph.

**Differentiated Learning Objectives**

- All students should be able to calculate proportionate amounts in the form 1 : n.
- Most students should be able to calculate proportionate amounts using equivalent ratios.
- Some students should be able to solve problems involving equivalent ratios in context.