My 8 yr old son is in grade 4 in a combined 4th/5th class, having skipped a grade earlier. The teacher does a great job of ability grouping within the class, and he is with the 5th graders for most subjects including math. This is the first time these classes have been combined, and it's really working out beautifully for our son.

Usually the teacher moves the 5th graders with math averages >95% at the end of the first trimester to the next math book up (algebra 1/2 I think). She is changing the cut off this year to make it higher because she only used to give 1/2 credit back for corrections on homework but this year she's giving full credit. She'll either raise the average necessary or make the cut-off on tests only (where kids can't do corrections).

Our son really wants to be in the group that moves up. His current average is 96%, with a 94% on tests. So we're not sure at this point whether he'll qualify --could go either way. Walking into parent-teacher conferences my husband and I were split on whether or not it is a good idea. I am concerned about workload, but my husband thought he should be able to go for it if he wants to.
In conferences, the teacher expressed a desire not to have him move up even if he does make the cut. Her rationale was that while he'd be fine THIS year, next year (when he'd be in algebra) the concepts start getting very abstract, and since his chronological age will be so young that his brain won't be ready to handle it.

So, two questions I'd love some thoughts on:
1) can parents of kids who've been through this validate her logic? Do young kids do fine accelerated in math until the concepts get abstract, and then hit a wall until their brains mature a bit more?
2) how should we handle this with our son? He wants this very badly (he talked about it again yesterday) and he's done everything right in order to earn it. If he doesn't make the cut off that'd be an easy conversation. But if he does...

Thanks for your help!

Our son really wants to be in the group that moves up.