It's a shame that there aren't more half-courses. Running both a course on filters and "a tiny course on the stuff about filters you need to you for other courses" (that could maybe be as little as a few optional classes + a test) shouldn't be beyond our organizational skills.

Maybe what I want is more tests as pre-requisites rather than only full fledged courses (my alma mater had an English test that could be taken in lieu of one mandatory course)