There's an unspoken reality not often mentioned about inner schools. They have to compete with the environment they're located in. Students see the hustler, gangsta or thugs on the street making bank -- sometimes a few feet away from the campus. They see them being feared and sometimes respected by the community. Some students see that power and see school as a joke that will not fulfill their immediate needs.
Also, many come from hard lives -- broken, dysfunctional families is a huge factor.