Students across the country who survive massacres, like Sandy Hook and Parkland, are left with a myriad of mental health problems. Before the pandemic, 95-percent of American schools practiced some form of lockdown or active shooting drills. Research has shown these drills can have a severe impact on students’ mental health, including increasing feelings of stress, anxiety and depression. NBC’s Ayman Mohyeldin speaks to Doctor David Schonfeld, Director of the National Center for School Crisis