Step 10 Objective

Understand and use proportionality and calculate the result of any proportional change using multiplicative methods.

Examples of what pupils should know and be able to do

Compare ratios by changing them to the form m : 1 or 1 to m.
For example:

• The ratios of shots taken to goals scored by two hockey teams are 17 : 4 and 13 : 3 respectively. By changing each ratio to the form m : 1, say which is the more accurate team.

Interpret and use ratio in a range of contexts.

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?

What if pupils find this a barrier?

Refer back to Step 8 and the unitary method and then make links to multiplicative methods, i.e. instead of dividing by 5 and then multiplying by 7 you could multiply by 7/5.
See the Year 9 proportional reasoning mini-pack - Acrobat pdf document (137Kb).

ITP Enlargements - Zip file (456Kb)