Maybe we can make a clear and logical argument in preparation for the next time a school says they do not allow acceleration.

School: We do not do grade acceleration.
Parent: Is it because of the difference in ages?
School: Yes.
Parent: Oh! But I don't understand. Tommy is in kindy, and he just turned 7. Isn't there a problem with the 2-year range of ages?

(of course, my argument needs work! i never said I was logical and clear...)

In my town, redshirting is very common because of sports. grrrr.