Hi! I don't know if this will help or not.
My DD8 is HG+ and was given early entrance to kindergarten and then last year was in 3rd grade in the mornings (math, reading, writing, p.e., art) and then 2nd grade in the afternoons. The afternoons were pretty much useless academically but allowed her to eat and play with her same-age friends. This year she's in 4th full-time and it is working out really well.
I have a few suggestions of things that worked with my daughter and might help a little bit to differentiate with your son without too much work for his teacher.
1. If your school has the AR program, maybe his teacher could allow him to read level-appropriate books on his own during reading instruction time and then take AR tests on what he reads. I know that you've said that your DS has great computer skills so he would probably be able to take the tests on his own without it having to take up any of his teacher's time. That way, too, you can document for the school just how he's reading and comprehending. My kids have always liked AR tests and they didn't take away any joy of reading. My DD8 started taking them in K when no one else did until 2nd grade.
2. Also, during reading instruction, maybe your son could use the time to write about the books he's reading that are on his level. I know my DD was a very good reader, and her writing skills were above grade level, too. But, in comparison, her writing was not as good as her reading and this gave her a chance to practice composing as well as the handwriting itself.
3. I don't know how well your DS does at self-direction, but it sounds like if the material is interesting that he does self-direct his learning. Perhaps it could be as simple as requesting that he be given the math materials (book, workbook, homework) for him to use during math time in his regular classroom. If he has trouble understanding something, maybe his teacher could arrange for him to meet with a more appropriate teacher once a week after school for a short time to answer all his questions for the week.
Also, I know that you're hoping not to single him out from the class in any way if possible, but I wanted to reassure you that these days all kinds of kids are pulled out from the class at varying times during the day (reading, behavior, speech, pt, ld, etc.) and the kids notice, but don't really care. Maybe when they get older (4th or 5th grade) they start to care more, but at young ages they just don't. They probably will notice that your son is smart, they just won't assign a value judgement to it. To kids at that age, it's really just like noting that his hair is blonde or that he's tall or short.
HTH! Good luck and I'm rooting for your DS!
