There’s been quite a bit of debate on the forums for the Brown University MOOC I’m doing regarding the approach to scoring student assignments. The course uses a peer review system whereby your assignments are rated and reviewed by other students and you receive a score derived from the overall scores given by 5 of your peers.
Some folk have felt this is a case of the blind leading the blind but my own view is that this is working well. The reviews I got for my first assignment had obviously been well considered and from discussion in the forums its clear that students take the process seriously and see the chance to review other students work as helpful to developing their own understanding.
My only quibble is that student assignments can’t be flagged up for the staff to review except for fairly extreme things (such as plagiarism or concern over a student’s well-being) but I guess that’s a consequence of having so many students enrolled.