Step 5 Objective

Add and subtract positive and negative numbers in context.

Examples of what pupils should know and be able to do

The temperature is at freezing point. It falls by 10 degrees, then rises by 7 degrees. What is the temperature now?

Probing questions

The answer is −8. Give me three possible questions.

The result of subtracting one integer from another is −2. What might the two integers be?

What if pupils find this a barrier?

The suggested lesson develops pupils' understanding of adding and subtracting integers through the image of a number line. As a follow-up, pupils should be encouraged to visualise relevant sections of number lines in their heads when working out additions and subtractions of integers.