I'm working on a project that involves assignment management for students. The basic functionality is that once the student completes an assignment, they check it off of the list. I'm wondering how to best show already completed tasks as students may need to access this information at a later date (i.e. exams, quizes, etc.).
One solution that was suggested is to just have two categories stacked on top of each other — completed tasks and tasks that need completing. The app, Wunderlist, was cited as an exemplar for this method. This seems like a weak solution to me but I'm having trouble giving a rational reason as to why it's not ideal because I can't find any related research. Can you suggest a solution or point me to a link where similar research has been done?