I think the key advantage of this kind of method is that rather than proceeding at a single pace, the students can stay on a topic until they master it, and the

I think the key advantage of this kind of method is that rather than proceeding at a single pace, the students can stay on a topic until they master it, and then move on. It's kind of a way of ensuring every student gets at least a 90% in a course, but the amount of time it takes them to get there can vary. While this is obviously a little more difficult in a classroom format, I have seen it done in the 80s completely offline for math where the whole grade of students take a bunch of pretests at the beginning of the year (including the tests for the prior year material) and then are assigned to two week groups or classes for the topics they need. After two weeks, they get a post test. If they haven't passed at 90%, they stay in that topic until they complete it. If they have, they move on to the next topic. It got a little complicated as a few people were in groups that went down to one person after a while, and they were just giving me worksheets and then I would ask if I had a question, but I was able to proceed at more than 2x the normal pace for a few glorious years. So, maybe doing the Khan Academy thing in the building, where you have a supervisor there to keep kids on task and prevent cheating, as well as ample people to whom one can ask questions, could be a net improvement.