Teachers generally work on a mass-production model—if 30 kids are in the class,
the goal is to find a method that will allow the highest percentage of them to
succeed. A great teacher can employ secondary methods to get through to
laggards, but given the variables that individual students bring to the class, a
handful of kids will inevitably be shortchanged. Teaching each child at his or
her optimal level with the optimal technique has traditionally been left to
private schools and expensive tutors.