VANCOUVER—The more popular Wikipedia seemed to get, the more Monica Freudenreich was told by her professors at the University of British Columbia to stay as far away from it as possible. The ever-growing online encyclopedia’s strategy of letting anyone with an Internet connection edit and revise, the argument usually goes, makes it unreliable, unacademic—and off limits. But then Freudenreich, 21, was given a surprising assignment by her Latin American literature professor: instead of writing term papers, the class would be writing Wikipedia articles.