Heat Maps can be displayed or printed for each pair of pupils. Each heat map increases in difficulty indicated by the hotness, the redder/hotter the more difficult the question. Pupils choose a cell to start at and perform the given operation with the corresponding element of the question from the x and y axis.
This heat map requires pupils to evaluate different functions in the form f(x), g(x). This resource is part of the Heat Map Bundle, check it out.