Using Rubric is an excellent tool for the student to use prior to finishing their assignment, it serves as a guide to improve their work. it also lets them know where they went wrong. For example, at the school, I work at if a student does not answer the initial discussion forum within 2 days and answer two classmates within 4 days they lose a lot of points. Having the Rubric lets them know they need to improve on that and motivates them to make sure they answer within the frame it tells them.
