Proportion, Graphs and Equations

Level: Year 9

Author: Marcus Garrett

Description:

In this unit you’ll identify and describe everyday examples of direct proportion such as when as the number of hours worked increases, earnings also increase. You’ll explore everyday examples of inverse (indirect) proportion, such as when as speed increases, the time taken to travel a particular distance decreases.

The unit will help you to recognise direct and inverse proportion from graphs, distinguish between positive and negative gradients when using a graph and to use the equation y = kx to model direct linear proportion (where k is the ‘constant of proportionality’).

This unit includes a GeoGebra graphing file to model tables of values and to graph equations representing linear direct proportion.

Australian Curriculum (Mathematics) Outcome:

• Solve problems involving direct proportion. Explore the relationship between graphs and equations corresponding to simple rate problems (ACMNA208)