The school-to-prison pipeline -- or, the system of extreme disciplinary practices that push young people out of school and into the criminal justice system -- is often discussed from the angle of isolated incidents. In April, for example, a six-year-old Georgia girl named Salecia Johnson was, handcuffed and carted away from school in a squad car after throwing a temper tantrum in her kindergarten class. There's also the story of Mississippi high school senior Cedrico Green, who has spent his childhood in and out of juvenile detention for such infractions as wearing the wrong color socks and being a few minutes late for class. But these cases aren't just isolated incidents. Injustices like these happen with alarming regularity across the country.