As Corey Witherspoon cradled a senior who had just been stabbed in the heart at Baltimore's Renaissance Academy High School, the boy's mentor tried to stop the bleeding with his hands. He screamed: "Fight. You can make it. You'd better keep breathing!" Those words became the unofficial mantra for Renaissance's Class of 2016, a group that endured so much trauma last year, perhaps the toughest year ever for the school, or any school.