In this older but still very relevant piece, Time magazine provides a compelling look at the powerful impact of socioeconomic status on student and school performance, debunking the current trend of blaming poor teachers or curriculum.  From the article, a quote attributed to Diane Ravitch, "American schools in which fewer than 10% of the students were poor outperformed the schools of Finland, Japan and Korea.  Even when as many as 25% of the students were poor, American schools performed as well as the top-scoring nations.  As the proportion of poor students rises, the scores of U.S. schools drop.

http://ideas.time.com/2011/12/09/why-are-the-rich-so-interested-in-public-school-reform/#ixzz2Z7UjG5RV