No school district can be all charismatic leaders and super-teachers. It can't start from scratch, and it can't fire all its teachers and principals when students do poorly. Great charter schools can only serve a tiny minority of students. Whether we like it or not, most of our youngsters will continue to be educated in mainstream public schools. The good news, as David L. Kirp reveals in Improbable Scholars, is that there's a sensible way...