If you consider how a typical classroom is designed, the expectation is that students will largely fall within one standard deviation of the mean, ranging from the low end of average (about the 16th %ile) to the high end of average (about the 84th %ile). Functionally, this encompasses about a half grade level below nominal grade level, up to about a half grade above. A child above the 90th %ile (who is often probably a grade level above) thus falls outside of the differentiated instruction range for which standard textbooks plan, and will need more than the teacher normally provides--even though 98th %ile is where the GT classification formally kicks in in most places. So a nominally non-GT child may very well need GT-type planning.
I don't mean to hijack this thread but aeh, what you wrote is eye opening! Do you have any sources you could share? DS (99 %ile) is bored silly but the school keeps spitting out the line "the classroom teachers differentiate to each child's level ... so his needs are being met".
