Mondays are 'review and quiz' day. We started out with each person who was notetaker last week giving a summary of what was covered, so that we had about 15 minutes of review of last week's material. Then they wrote a 20 minute quiz, on that same material. There were three questions, so after the quiz I got them to divide into three groups, an allocated one question to each group. While they put together teacher's solutions for their question, and decided on a grading scheme, I dashed upstairs and photocopied all the quizzes, and then anonymized them by cutting off the names. Each group got the 10 solutions to 'their' question, and had to grade them, as a group. Wow! They really loved this! They said they'd never thought about things from the teacher's perspective, and realised just how many different ways there were to answer a problem. Also, quite a few mentioned that they'd assumed that it would be obvious how to grade a maths question - but when there are a bunch of different ways, or someone makes a mistake half-way through, suddenly it's not clear at all. The group who was grading the 'find the angle' problem got into a pretty intense argument; it was great!