It seems to be a staple of drama and film; a teacher with an unconventional method of teaching arrives in town, causing chaos in her or his wake. The students are inspired, but the parents and the rest of the teachers plot to remove the new teacher. Ultimately by the end of the film or episode, the teacher is run out of town, but the children Have Been Changed. Cue end credits.
Did anybody actually have a teacher like that? Is it more of an American culture difference? I have many teachers that I remember fondly, and yes, they were unconventional, but they stayed. The teachers that left after a term or so tended not to be very good. So I've never really understood film and television's obsession with this idea of a rogue teacher (okay, I understand to the point that it's a good way of creating conflict, and easy for a a TV show to cast the role for a one-off performance, rather than keeping the actor on the staff).
Happily, the episode in question did its best to make things as ambiguous as possible; the teacher turned out to have an outstanding arrest warrant for failure to pay alimony, and he ran away at the first hint of trouble. Hurrah for subtly subverting teen drama clichés!
(Oh, and the dance Claire Danes does in the middle of Why Can't Jordan Read? Simply magical.)