And the evidence is strong that low-income students thrive in higher-income schools -- in fact, after the socioeconomic status of a student's family, the biggest predictor of academic success is the socioeconomic level of the school. In the 2005 National Assessment of Educational Progress given to fourth-graders in math, low-income students attending more affluent schools scored 20 points higher -- the equivalent of almost two years' learning -- than low-income students in high-poverty schools. Low-income students in middle-class schools did better than middle-class students in high-poverty schools.
First, "thrive" is a poor choice of words. Low-income students do not thrive in higher-income schools. The fact is that they fail in unconscionably large numbers even in higher-income schools.
Second, there aren't enough higher-income schools to place all the poor kids into so that the "magic aura" of the rich kids can rub off on the poor kids and magically boost their performance.
And third, the classification of low -income for purposes of NAEP includes income levels up to something like $40,000 which includes kids who are decidedly not all that poor. The WaPo editors also don't seem to realize that the poor kids in the higher-income schools aren't as poor on average as the kids in the poor schools. It is this differential that is attributable the tiny 20 point difference the WaPo Editors allegedly found in 4th grade NAEP math scores.
It is this kind of misreading of data which leads to silly education policies like that propounded by the WaPo editors. It's not like we don't have decades of busing data showing that this kind of racial balancing doesn't lead to increased achievement.