It is no secret that disadvantaged children are more likely to struggle in school. For decades now, public policy has focused on how to reduce the achievement gap between poorer students and more-affluent students. Despite numerous reform efforts, these gaps remain virtually unchanged--a fact that is deeply frustrating and also a little confusing.…

Has the gap in average standardized test scores between students from high- and low-income families widened, narrowed, or remained stable over the last 3 decades? The question is important both because the achievement gap is measure of how (un)equally educational opportunities are distributed in the US, and because the disparity in educational…