A new federal study shows that black and white students at schools with a high density of black students perform worse than those at schools with a lower density of black students

The report by the National Center for Education Statistics, the research arm of the U.S. Department of Education, sheds new light on the achievement gap between white and black students. The report found that, on average, white students attended schools that were 9% black while black students attended schools that were 48% black. Achievement was lower for both black and white students in schools where black students accounted for more than 40% of the student body, compared to schools where black students accounted for less than 20% of the student body. The study was conducted using data from the results of the 2011 eighth-grade math test given as part of the National Assessment of Educational Progress, an assessment that’s given to U.S. students in various subjects in grades four, eight and 12.