your query appears to be the exact opposite to what I am posing here.
you want a sequence and I want a course which can be completed in any order. I reply not only to get attention to my post but also as it could well be that the solution to my 'problem' could be adapted to solve yours (e.g. in place of the complete/incomplete conditions it could look more like
if complete then
but also the first reply to my post mentions the "gradebook" which could be what you are after for a global view of progress.