A different perspective here. MUS was not a huge success for us. We are only using it right now for the pre-algebra level and the younger kids have switched to CLE. I think that MUS would have worked well for my oldest children who were more math-inclined and did better at working independently. For the younger children, the mastery approach doesn’t seem like a good fit. If they didn’t see a type of problem for awhile, they would forget how to do it and we’d have to relearn it. Ummm, wait, I thought we had “mastered” this!
CLE is more of a traditional program and is less time consuming for me to teach multiple levels (currently five). I like that all the explanations are right there in the student book, so they can read it for themselves, then if they understand it they can just keep going instead of having to wait for me to explain. Until the sixth level, there are built-in review drills every day and I don’t even have to think about it because it’s right there in their book. For example, it will say, “Count by 2’s from 20 to 100” or “Do speed drill #4”. Also, my kids like it that the curriculum comes in 10 smaller books and they have a great sense of accomplishment when they finish a book.
Ok, I know you were only asking about MUS and I’ve given you an advertisement for CLE. MUS is a strong program and many people like it. It just didn’t work that well for us.