Reed definitely takes an unconventional attitude towards grades (also other things, like sports or the USNews rankings). It’s true that you won’t know your grades unless you ask (or are failing).
But to my knowledge, Bryn Mawr and Haverford follow the conventional model. You take tests, you write papers, you get grades on them. A final grade for the course is posted after the end of the term (after final exams are over and all papers have been turned in). Same as other schools.