You know the plot. Young, idealistic teacher goes to inner-city high school. Said idealistic teacher is shocked by students who don't know the basics and who are too preoccupied with the burdens of violence, poverty and indifference to want to learn. But the hero perseveres and at great personal sacrifice wins over the students using innovative teaching methods and heart. The kids go on to win the state spelling/chess/mathematics championship. c.f. Stand and Deliver, Freedom Writers, Dangerous Minds etc.
As he says, the problem is that it's just not realistic to build an entire system composed of teachers like that. What you need are methods, structures, and institutions that can work for disadvantaged kids that don't rely on Stakhanovite efforts by the teachers. He recommends Direct Instruction (see here and here) as something that's both workable and scaleable.