If you are teaching a course on social networks it is quite proper to ask small groups of students to investigate different social network systems based upon some sort of guidance on what to look for to evaluate the system. however, when their exists a whole set of course ware systems with better functionality for the course process such a moodle i am unclear why one would want to teach using any of the social network systems. Even a bulletin board system like WebBoard would be better to offer a class then all the social network systems i have seen. If you want a good student project to get students to be aware of problems on the web, set up trials of different online sellers and then get some students use accounts that have cookies from very cheap places like walmarts and other students to use accounts with cookies from places like niemen markus and what they will discover they will get different prices from the same sellers depending on the cookies they or you have. This is not illegal and was verified by some tests a few years back done out one of a business school in a professors class. It pays to clean up your cookies. Distinguished Professor Emeritus Information Systems, NJIT homepage: http://is.njit.edu/turoff