IN A small classroom four teenage boys laugh and roll their eyes at each other’s wisecracks. The instructor, sometimes speaking in Spanish, encourages them to think about their futures. For his family, one says, “I want to buy a big-ass house.” Another wants to work with cars. A third thinks a family reunion would be great. The classroom is on Rikers Island, New York City’s biggest jail. The teens are participating in the Adolescent Behavioral Learning Experience (ABLE) programme, which helps them focus on personal responsibility through cognitive behaviour therapy. The programme’s goal is to cut the re-incarceration rate among the youngsters, and it is funded using social impact bonds (SIB).