I'm intrigued by the idea of students learning from each other. Most often, the audience for students' work is the teacher, but students have more motivation to perform for their peers. I teach two sections of 9th grade geometry, and I've been playing with this idea of audience by having each section create practice problems for the other section to complete. Here is my most recent exercise in student parallelism.
Update: I gave this assignment to my students as an in-class assignment. The students enjoyed getting to check and initial their friends' work. When a student would ask, "Is this right?" I just referred them to their neighbor. I incorporated the partner aspect of the assignment into the grading as well. Any points deducted were shared equally between the problem-writer and the problem-checker. The next step is to share these problems with the other section of Geometry.
I started this blog to share my transformation from math nerd to math nerd who loves to share math with young people. I teach high school in Philadelphia, Pennsylvania. Your comments are always welcome.