On April 20, 1999, two teens carried out an attack at Columbine High School in Littleton, Colorado. Twelve students and one teacher were killed during the assault and more than 20 others were wounded before the teen attackers committed suicide. This horrifying event shocked the nation and caused immeasurable grief for the survivors and the families of the deceased and wounded.Over the past 20 years, there have been many discussions about the best way to keep students safe, as well as new legislation at the state and federal levels. Although school entrances have been hardened, firearm laws have been tightened,...