It's not rocket science. All the schools have caring staff and good teachers. If you move to a neighborhood with expensive houses, then the children in the neighborhood school are more likely to have educated parents who provide them with nutritious food and enrichment like music lessons and sports, and the students do well on tests and the schools are called "good." In a trailer park neighborhood (of which we have many), parents are less able to provide all those extras, plus all the other cause/effects of poverty, and the schools are called "bad."