For DD we did a whole grade acceleration (she skipped most of K and part of first grade)...math and reading were still a bit easy for her but there were many advanced kids in her particular class. Now she just finished third grade and I can see her skipping to 6th grade math but ONLY because I have been working with her a bit at home. She got almost no differentiation in school. For reading the same thing. She could probably skip 4th and 5th grade reading. Writing is a different story and she really struggles for whatever reason (Part of the reason why is that g/t kids do not necessarily have advanced fine motor ability).
DS just finished first grade and the first half of the year he got no differentiation (other than the little I did at home), and the second half of the year we switched schools and his teacher had him doing mainly 4th-5th grade math, but it was not a real "curriculum" and there was a lot of skipping around from grade to grade depending on the topic. Not sure what's going to happen next year. He's at about a 4th grade level for reading, although tests like an average 5th grader. Unfortunately the teachers don't really have appropriate level books in the classrooms and they hesitate a lot giving kids material that they consider too advanced. But it's easier to ability group and/or differentiate for reading than math. Each kid is given a "just right" level based on testing that is probably not accurate.
In terms of appropriate pace, I think they could have moved twice as fast and skipped kindergarten altogether. So they could have done 1st-2nd grade in one year, 3rd-4th in one year, etc. Unfortunately in real life it doesn't work that way although DD is headed to a g/t magnet for 4th grade that apparently does compacting/accelerating of material.
I have no idea what is going on with science. I just let the kids read what they are interested in at home.
