Joplin remembers deadly tornado, 1 year later

President Barack Obama observes a moment of silence for tornado victims during commencement ceremonies for the Class of 2012 at Joplin High School Monday, May 21, 2012, in Joplin, Mo. Seniors at the school finished their high school education in a converted big-box store after the old high school was destroyed by an EF-5 tornado that killed 161 people on graduation day a year ago. (AP Photo/Charlie Riedel)