Teacher guidance

Check that pupils understand the context before they begin, for example, by saying:

• There are ‘problem pages’ in many magazines and newspapers where readers ask for advice; you are asked to provide advice to two readers of ‘Help Online’.
• The two readers ask for advice on age difference between them and their partner.
• There is a graph which shows what some people think is an acceptable age difference between people in a relationship.
• You need to use this graph to provide the advice.

The task requires an understanding of linear graphs.

During the work, the following probing questions may be helpful:

• Are there any important differences between Jenny’s information and Tim’s?
• Is there a way you can work out an acceptable age gap for any age?
• Are there are any other issues you need to consider?
• Would people use this rule in the real world? Why - or why not?

There are three key aspects to this task:

1. Interpret the graph: what the lines and the green area represent.
2. Define the equations of the lines for the ‘acceptable’ age limits for any given age.
3. Apply this to Jenny and Tim’s questions, giving them informed and relevant advice.

Pupils should also reflect on the rule of the ‘half the older one and add seven’ in the real world: is it an appropriate rule to judge the success (or otherwise) of a relationship?