People raise their arms while chanting, "Hands up. Don't shoot," near where St. Louis police say officers shot and killed a 23-year-old man who was wielding a knife and refused to drop it on Tuesday. Joe Raedle/Getty Images hide caption

itoggle caption Joe Raedle/Getty Images

Onaja Waki (left) is about to start college in California, but she and her mother, Oneida Cordova, have been talking openly for years about the dangers of sexual assault. Teresa Chin/Youth Radio hide caption

itoggle caption Teresa Chin/Youth Radio