The schools provide free medical, dental and mental-health services (students are screened upon entry and receive regular check-ups), student incentives for achievement (money, trips to France, e.g.), high-quality, nutritious, cafeteria meals, support for parents in the form of food baskets, meals, bus fare, and so forth, and less tangible benefits such as the support of a committed staff. The schools also make a concerted effort to change the culture of achievement, surrounding students with the importance of hard work in achieving success. These types of school policies are consistent with those that argue high-quality schools are enough to close the achievement gap.
I think of this is the "drip irrigation" method of providing social services. Wouldn't want them to spread uncontrolled to the general population, would you?