The user contributions can also be tracked using the Education extension which you can get installed for your wiki. Students just enrol in the class using a special page like this:

https://cs.wikipedia.org/wiki/Education_Program:VO%C5%A0_soci%C3%A1ln%C4%9B_pedagogick%C3%A1_a_teologick%C3%A1/Z%C3%A1klady_pr%C3%A1va_%282013-2014%29

To get the statistics for each course, you just copy the list of usernames in each class and analyze them using Wikimetrics app.