Most 9th graders at Milton take Geometry AFAIK. Even if you took geometry in 8th grade, you did not take the Milton version. Boarding school math classes are light years ahead of the equivalent named classes at local schools. You are very unlikely to be bored. Ditto for just about every subject. Trust me, I’ve seen enough kids complain, both here and IRL, that they were not placed “correctly” only to realize after a few classes how much they really did not know. Nothing, and I mean absolutely nothing, will change before you actually start classes. As I said, if you were placed too low (or too high),the teacher/adviser will rectify it quickly into the start of the term.