"Well, Mississippi has lower scores, but when you account for the fact that the people having those scores are black people the Mississippi comes out ahead!"
You don't see the issue?
You don't see the issue?
When you're measuring schools you're trying to measure the impact of the actual school, not all the other factors, and to do that you have to separate out socioeconomics. Higher income parents are more involved in their children's education and can make up for a bad school in ways that lower income parents can't. It's pointless to compare schools to each other unless you adjust for demographics.
The correct approach is to adjust for demographics but do so carefully, rigorously, and consistently.