Hazel shows no workings, Mabel makes errors. Each gets marks (or not as the case may be) for questions but Mabel gets more even when Hazel is correct. This idea was from a colleague who wanted to emphasise the importance of showing a clear method and the potential to get more marks even with an incorrect answer. The intention is to get students to discuss where marks are gained and where they are lost as well as them correcting Mabel.