The Juvie Three by Gordon Korman

Mr. Healy is a former juvenile delinquent; he knows what it's like. He hatches a plan to save three young criminals from rotting in jail. That's how Gecko, Terence, and Arjay suddenly spring from their juvenile detention centers to an experimental halfway house in New York, with Mr. Healy as their mentor. Their second chance explodes when Mr. Healy falls three stories during a fight. A head injury leaves him with no memory, of his identity or of his boys. What now for the "Juvie Three?"

Check out a New Tech Student website about The Juvie Three.