One of the powerful ways that classmates collaborate on Appropedia is through student peer review.
For example, Las Malvinas community center shade describes a student project to provide a community center in the Dominican Republic with durable shelter from sun and rain. Click the “discussion” tab and you arrive here, to see critical and constructive comments from two fellow students. Clearly they’ve followed useful steps they were given at well at using their own insights.
I don’t know which of our academic contributors began this practice, but I love the power of it. It gives students more chances to learn and to improve their work, to help each other to learn, while learning team skills of collaboration and constructive feedback.