It's a well crafted documentary but I'm concerned that it's too simplistic (and too biased) to ever fulfill it's ambition. According to the performance agenda this movie touts, many of my best teachers would have been fired for deviating from the sacred curriculum.
The film is obsessed with measurable performance, which often leads to disgruntled students and teachers that spend all their time prepping kids for the next exam. Not surprisingly, math is the subject given the most focus in this doc because it fits neatly into the narrative. One can easily measure performance in mathematics and there is a consensus about what ought to be taught. That's not the case with the humanities - there are radically conflicting ideas about what makes a good government, social studies, or English lit teacher.
I had a U.S. history teacher in middle school that spent an entire class reading letters from Union & Confederate soldiers from the Civil War. It may sound dumb but before that class I never really understood history. I'd never been exposed to the hopes and fears of common people from another era - just names, dates and exams.
What makes a good teacher? It's a tough question... a lot more complex and controversial than this film would suggest.