If you grade improvement rather than mastery, you incentivize feigning incompetence at the start of the course to game the system. The closest thing I ever saw

If you grade improvement rather than mastery, you incentivize feigning incompetence at the start of the course to game the system. The closest thing I ever saw to this was my high school weightlifting class. Your bench press single rep max was a high percentage of your overall grade, and was tested several times over the course of the semester. You were graded on improvement. The teacher made sure not to mention this before the first test, to keep people from cheating, but a few kids were in the know and faked a low max. From a philosophical/values point of view- what is more important for education- incentivize all students to try to achieve the mastery level expected, or incentivize all students that as long as it looks like they're making progress, that is enough? I'd go with mastery. The appearance of progress is too easy to game, too subjective, and not easily applicable to varying courseloads.