Step 8 Objective

Use proportional reasoning to solve a problem, choosing the correct numbers to take as 100%, or as a whole.

Examples of what pupils should know and be able to do

There was a 25% discount in a sale. A boy paid £30 for a pair of jeans in the sale. What was the original price of the jeans?
When heated, a metal bar increases in length from 1.25 m to 1.262 m. Calculate the percentage increase correct to one decimal place.
Pupils should be able to use unitary methods and multiplicative methods

Probing questions

Which are the key words in this problem? How do these words help you to decide what to do?
What are the important numbers? What are the important links that might help you solve the problem?
How do you decide which number represents 100% or a whole when working on problems?
Do you expect the answer to be larger or smaller? Why?
What would you estimate the answer to be? Why?

What if pupils find this a barrier?

Use a spreadsheet to explore real-life examples of proportion.
Use a graph plotter to look at proportional relationships.
The Year 9 proportional reasoning mini-pack - Acrobat pdf document (137Kb) is the sequel to the Year 8 pack referenced in Step 7 and provides many resources and teaching ideas to develop proportional reasoning.
Securing level 5 lesson 9N4.3 - Acrobat pdf document (53Kb)