It isn't money that is the problem - some of the worst performing school districts have the highest spending per capita.
The problems are:
* teacher unions that don't let you fire bad teachers
* children from fatherless households drop out of school and get held back at 3-4 times the rate of married two parent households - and our current welfare system punishes those who marry so the poor are the most likely to never marry, nearly guaranteeing bad life outcomes for the next generation in the ghetto or poor rural area; our schools don't emphasize the importance of marriage and actually support girls to keep the baby and go to school instead of pushing her to put the baby up for adoption
* not implementing discipline in mostly poor schools out of fear of being called racist, so black and some hispanic kids can run wild and act out in class or assault others with minimal consequences - so there are so many disruptions in inner city schools that 12th graders have the equivalent of an 8th or 9th grade education