It is not just studentss in poor school districts whose performance has declined. ALL students in all school districts know less today then their counterparts who graduated from High School in the mid-1950's. This is a verifiable, objective fact. Just review the subject matter changes made to the SAT's to make sure the dumbing down of the curriculum was not highlighted.
People keep blaming poverty. Is that why single parenthood of black families went from seven percent (7%) of all births in 1964 to over 70% of all births today in that community (all black births, not just the poor). And by the way, Slavery did not yeild this percentage of out of wed lock births. They only occurred after the civil rights bill was passed.