In this context, Gaussian is a pretty useless assumption without fixing a variance. Proposed alternatives range from "already implemented" to "totally infeasible" depending on variance.
> which tests seem to verify
Not really. For each individual subject area, maybe, and again, Gaussian is pretty uninformative.
But the odds of a student being "average" in every subject area != the odds of a student being "average" in a given subject area.
> whose level there are ways to accommodate anyway in most school systems
Except the whole point is that there are not currently ways to accommodate this in most school systems! From GP:
>> Schools (at least around here) do not hold kids back anymore. No matter what.
Also notice that holding back a student in math is possibly net detrimental if the student is not also behind in English and Science.
> but also about sharing the same teenager and adult-making experiences as other kids of your age, which is probably even more important that what's actually taught
Again, the prepubescent/tween/teen division is much less granular/restrictive than the competency-by-age-X division.
That doesn't really help us to know if the top achievers are being held back, for example. Perhaps we can speculate that lower achievers are being pulled up?
Outside school you're almost always going to be in age diverse groups; I think a larger element of that in public schools would be better. IMO it helps to emphasise that children are there to make their own education and not simply to be part of an age defined peer group where it appears you're doing something just because of your age, not because of the educational opportunity.
Sounds quite logical to me. If we assume a gaussian distribution (which tests seem to verify), most kids of the same age will have the same skills/level.
So at worse you mismatch what's taught to some kids towards the edges, whose level there are ways to accommodate anyway in most school systems (skipping a class or two for extra smart kids, or staying behind/supplementary teaching for less than average smarts).
And it's not just about learning and who can cram more into one's head (akin to e.g. preparation for the Olympics), but also about sharing the same teenager and adult-making experiences as other kids of your age, which is probably even more important that what's actually taught (the majority of which most people will forget anyway).