I go to the parent side and look on the scores page. I hover over the progress bar, which tells me how many tasks there are in the course. Then, I divide that by the number of weeks he and I have decided that he's going to work on the course. I then round up to the next even number to set the weekly goals (video and quiz or review and test are two separate steps, but really the same lesson, so I try to keep them paired up).