Costa, I beg to differ. My research is only anecdotal - I've noticed that the kids at Mac.Rob who significantly lag behind the others end up becoming disengaged with their schoastic pursuits. In year 9, one of the girls remarked that she had no clue what was going on in English class - she couldn't follow the discussion and wasn't familiar with the lexicon being used by her peers.
This girl probably sits at the 80th percentile in comparison to the rest of the state. Now she feels like she's dumb and is reluctant to participate in class.
Look, I'm sure there are exceptions to the rule, but in my opinion, it's just not fair to put people into that position. She'd be better off in an environment where she'd be able to keep up to date and be engaged in what she does.