AS PUPILS file into their classroom at Kipp Renaissance, a high school in a battered corner of north-east New Orleans, each one stops to shake the hand of a history teacher. “Changes”, a rap song by Tupac about the struggles of being poor and black in America, plays quietly in the background. Within a minute or two, the dozen teenagers—all black—are busily filling in test papers. Soon afterwards, Mr Kullman, the teacher, begins rapping himself—hopping around the room demanding quick-fire answers to questions about the civil war. Pupils shout back answers in chorus.

Kipp Renaissance is one of New Orleans’s newer high schools. Since Hurricane Katrina hit in 2005, only six traditional public schools, directly run by the city, remain. Instead 94% of pupils now attend charter schools, which are publicly funded but run by independent non-profit organisations such as Kipp (in full, the “Knowledge is Power Programme”).