Teachers only really teach the middle third - the top third can be ignored because they can do it for themselves while being bored.
The bottom third can’t be helped because they won’t be helped without a huge amount of energy by the teacher (for little rewards), and so won’t do it for themselves while being bored.
The middle third is all that gets schooled because they can at least be bumped up a little higher towards where the under-achieving top third thus rests.
Teachers only really teach the middle third - the top third can be ignored because they can do it for themselves while being bored.
The bottom third can’t be helped because they won’t be helped without a huge amount of energy by the teacher (for little rewards), and so won’t do it for themselves while being bored.
The middle third is all that gets schooled because they can at least be bumped up a little higher towards where the under-achieving top third thus rests.