I typed half a post on this thread the other day and deleted it because it wasn't coming out right and I didn't have time to make it so. Let me try again. If the tone is off, please read that I didn't mean it so; I am just trying to express that the common way of thinking seems odd to me, because that may be useful input.
I get that in many school situations, subject acceleration is what you have to do because there's no better alternative. But if you're homeschooling (freely, not tied to school courses in any way), it seems odd to me even to ask the question that way.
Part of my hesitation is that, perhaps, this may just be evidence that DS isn't actually gifted. But [expletive deleted] it, I don't actually believe that. So it is relevant to say: in a good school, the best way to meet his needs (granted that they aren't all going to be perfectly met) has been not to use acceleration. If I were homeschooling him, I would simply abandon all notion of what grade he was in for each subject (just as I have for maths, the subject where he is treated differently at school). There is no age of students such that he is just like the average student of that age, even if you take writing out of the equation.
For basic skills:
- Reading: DS started to read by 2 (before he could talk, hence, I don't know exactly when) and for some years, a useful rule of thumb was that doubling his age gave a safe underestimate of what he could read. By the time he went to school at 4 he could read anything that interested him with ease, which included much science material aimed at adults (though I don't mean Nature; that used to be a bit hard, though he did happily try). Reading isn't a school subject after age 8 at school - it is assumed that all children can read by then, and the focus moves on to studying literature - so I don't really know what people mean by "grade 6 reading" etc. At 10 he often reads "light" adult literature (Asimov, Douglas Adams, Agatha Christie being recent favourites), but as he's generally quite happy reading what other children his age read, we haven't given him Proust.
- Maths:
-- he started school at 4 doing only simple addition and subtraction, took off that year...
-- completed ALEKS grade 3 and 4 maths aged 5,
-- and grades 5 and 6 aged 6 (all this very fast, it wasn't that that was what he did that year, just that it's a convenient label for something he spend a few weeks on that you may recognise)
-- aged 7 he completed the GCSE course aimed at 16yos here, and learned to problem-solve independently, and did ALEKS Algebra 1 (again, in a week or two, knowing almost all of it already)
-- aged 8 he did ALEKS high school geometry and Algebra 2, and a lot more problem solving;
-- aged 9 he did ALEKS Precalculus, yet more problem solving, and most of AOPS Geometry (which overlapped his tenth birthday)
-- aged 10 his maths teacher says "he could obviously do university maths" and I guess that's so, though he hasn't covered the whole school syllabus yet and we're in no hurry; he has competition honours that very few 18yo students planning to make maths their career reach.
(By the way, aeh, if there's really no maths in elementary school other than the four operations, you need better elementary schools!)
So actually, in both, "twice his age as a safe underestimate" works not badly for both of those basic skill sets.
But in other subjects, the challenges aren't basic-skill related, nor are they limited by what the subject matter is. He's at liberty to make more sophisticated interpretations of sources, use a more interesting vocabulary, come up with weirder hypothetical questions, than his age peers if he wishes. Perhaps if he were an unusually fluent writer for his age or unusually social-chameleon, I might feel there was benefit in putting him up a lot of years to get peers who were more likely to be doing the same (I think HK has found this, in particular), but as he isn't, the few years that would be practical doesn't feel like a benefit worth having. And "what grade level is he working at in history" say, feels like a non-question.
