I would say that acceleratING solves the problem (though it causes some problems too). Acceleration, as in whole-grade, may only be a temporary patch. HG+ kids need to go either faster or deeper. A regular classroom (even one for older kids) may not do either. So you can bump them and it will seem good for a while (they missed stuff, they have to hustle to catch up, new things are exciting) but then the same issues can arise -- not fast enough, not deep enough.
I think there's this common misconception among schools and parents (and I used to think this too) that you just have to find the right LEVEL for the child and then everything will be OK. So once you bump them to where there's new stuff, now you're set and then can just march along with everyone else. Plus it can be so hard to even get an acceleration (we never could) that it becomes something like the holy grail of educational fixes.
Truth is that unless they have the opportunity to also go faster or deeper within that class (or both), they may have the same issue again in a year.
Which does not mean not to do it now. Because it will be better for a while. HK made the comment in another thread that no solution worked longer than about 18 months. That's been similar to our experience as well. So just be ready for that possibility.
