The New York Times published a piece at the end of April that revealed the variance in learning outcomes for students across the United States. The findings reported in the article were based on data and articles published by Stanford Center for Education Policy Analysis. Here is the key quote from the third paragraph, " Children in the school districts with the highest concentrations of poverty score an average of more than four grade levels below children in the richest districts." The next paragraph pointed to even more troubling finding, " Even more sobering, the analysis shows that the largest gaps between white children and their minority classmates emerge in some of the wealthiest communities." The researchers from Stanford further found that even in districts where students of different races came from similar economic backgrounds white students tended to perform better. One of the authors, Sean Reardon, noted that in these cases it might be that white children unconsciously are tracked into more rigorous courses or given more challenging work.
The NY Times article came with some great data displays. I have downloaded the data from Stanford and created a dashboard that allows users to select a single state and compare achievement (measured in grade-level equivalency) with various demographic factors of the district (e.g. median income, household in poverty). One of the things I learned by doing this is that not all states look the same. For example,. the correlation of income with achievement in Missouri is much smaller than in Connecticut or New York.