For the Yale University course "History of Modern Science in Society" (HIST 236), taught by Ole Molvig, the students were assigned to research and write encyclopedia articles on history of science topics poorly covered in Wikipedia. I (Sage Ross, User:Ragesoss) was the teaching assistant; I designed and supervised the assignment and coordinated the the integration of the resulting material into Wikipedia. While students were not required to put their finished work into Wikipedia, 13 of 14 chose to do so, resulting in the creation or significant improvement of as many articles.
See also my general recommendations for Wikipedia assignments.