It began with a trip to the cinema to see Cameron Diaz in her new comedy, "Bad Teacher." It was a bad choice. Not a great flick, but as a parody of bad employees, in terms of things that can get one fired--drugs, alcohol , cheating, foul language, inappropriate sexual behavior--Diaz slams pedal to the metal. She nips out of airline booze bottles hidden in her desk, smokes a bong in the parking lot, hands her bra to a seriously uncool kid to improve his street cred, and steals answers to state tests. Firing offenses? Sure, but "bad" teacher? Not quite. A bad teacher is different than a lousy role model. Thinking about other teacher movies the author has seen, she began to wonder about Hollywood's portrayal of teachers: were they quirky or idealized, sentimental or critical? And how did Tinsel Town depict "good" teachers? A cursory review of the teacher film canon showed that nearly all were biopics--"To Sir with Love," "Freedom Writers," "Goodbye Mr. Chips," "Dangerous Minds," "Conrack," "Mr. Holland's Opus," "Friday Night Lights," "Lean on Me," "The Prime of Miss Jean Brodie," "Up the Down Staircase," "Take the Lead," "Dead Poets Society," "Music of the Heart," "Stand and Deliver" (to name some)--all based on memoirs by educators or novels about teachers. What's challenging for moviemakers is that the kind of great teaching going on in classrooms today generally happens offstage, in lesson prep. The best teaching does not showcase a heroic protagonist, because the best teachers are generally not entertainers yammering away at the front of the room, but are more often found, almost invisible, coaching from the back. Truly great teaching is less about the performing teacher and more about the performing student.