Lynn, just as a little anecdote: We lived in the Bay Area when i was in 2nd - 5th grade. They started a new program (I've since heard a term for it, but I can't remember what it's called) that
failed miserably, but basically they allowed each
child to determine the pace at which we wanted to work in each subject. I loved reading and spelling, so I always did the maximum allowed work in that subject, and wound up finishing up the curriculum halfway through the school year. I was not fond of math, and did the minimum.
As a result, when we moved to Washington in 5th grade, I was a
full grade behind in math!

Dumb, dumb, dumb!