CHICAGO (AP) — A cellphone video showed the attack in grainy but gruesome detail: A mob overwhelmed a South Side teen shortly after he left school, mercilessly kicking and stomping on him, then hitting him in the head with a wooden plank.

Long before Chicago's latest spasm of gun violence claimed 15-year-old Hadiya Pendleton, the honors student who was killed not far from President Barack Obama's home, there was Derrion Albert, another honors student slain in 2009. His killing came to symbolize the dangers facing young people in the nation's third-largest city.

But if the 16-year-old's death illustrates how little things have changed since then, it also helps tell a different story — how one of America's most notorious schools succeeded in restoring calm and defusing many confrontations. As other districts across the country grapple with security issues, Fenger High School shows how determined school officials curbed violence by deploying "peace circles" and in-school suspensions as much as police and armed guards.