cola, my children's gifted program in elementary school consisted of pull-outs once per week where the kids worked on special projects outside the normal curriculum. I don't think my kids got much out of it, other than the opportunity to be with other gifted kids - which was huge for them! They loved that about the program, plus the projects were fun for them.

Elementary school (when we were in public) wasn't ever going to be a good fit for gifted kids in the schools my kids were in, and to be honest, I don't think my kids would have benefited from a grade skip, because grade skips just meant moving up, not picking up the pace or depth of instruction. Our private school worked much better, not because it was private, but because the focus was on meeting individual students where they were and challenging each student to reach for a lot more, not mass-producing good scores on state testing. FWIW, the options in middle school and high school open up quite a bit (here) over elementary - because you can start to subject accelerate more easily with multi-class schedules. OTOH, it's still not great. My ds is in HG classes in high school, but the pace and depth isn't what I would have expected, and we've been discouraged from allowing him to reach higher - the emphasis seems to be more on grades and SAT scores than learning for the sake of learning.

polarbear