As someone who skipped what my school called “6th grade math” and went straight to prealgebra and has continued along that path up to doubling up on calculus BC and Statistics in senior year (BC is a one semester course offered to seniors who got an A in AB as a junior at my school), I’d like to add that I really shouldn’t have taken the advanced course. I have a weak foundation in basic math now because I spent most of middle school playing catchup and my math ACT is noticeably lower than my other subscores (28 vs. 35-36). Acceleration in order to take more APs could potentially backfire. Anyways, on the track your kids are on they can still complete Calc AB, as well as Stats if they like math and want to double up.