As U.S. Secretary of Education Arne Duncan works with other Obama administration officials on policy responses to the shootings at a Connecticut elementary school, he brings a personal and professional history that has acquainted him with the impact of gun violence. As schools chief in Chicago from 2001 to 2008, he was affected by the gun deaths…

President Barack Obama's announcement last week of a wide-ranging anti-violence plan in response to the Newtown, Connecticut, school shootings comes as many districts are adopting new and sometimes dramatic measures--including arming teachers and volunteers--intended to prevent similar tragedies in their own schools. School safety experts warn…