The teacher uses a story to establish how ‘one’ and ‘negative one’ together make zero, and reinforces this with Anthony as demonstrator.
We follow Blue’s group for ‘3 subtract negative 2’. They use their knowledge that zero has the same value but difference appearance when it’s shown as 1 and negative 1 together.
Anthony makes a confident start in his head, but gets some calculations wrong, revealing frequent misconceptions. The teacher encourages him to use cards and he is successful, but he tells us of his upset at not being able to do the calculations mentally.
Blue and Anthony’s honest reflections will help many teachers understand what goes through children’s heads as they introduce this confusing area of maths.