School reformers have focused on evidence showing that high-quality teachers and schools also help close achievement gaps, although so far efforts to improve the teaching force and the quality of schools through opening more charter schools and putting teachers under the scrutiny of more intensive evaluations have had mixed results. A national study of charter schools has shown that a minority perform better than regular public schools, and many do worse, although students living in poverty tend to learn more in charters. And early adopters of new teacher evaluations, including Pittsburgh and Washington, D.C., have seen both drops and gains in test scores.
Most of these efforts have come far short of closing the gap completely, and they don't address how to deal with the growing divide between the middle and the top. "It's not that you can't do anything," Murnane says. "But I think we way underestimate the magnitude of the problem."
This story was produced by The Hechinger Report, a nonprofit, nonpartisan education-news outlet affiliated with Teachers College, Columbia University.