On May 24, it will be two years since 19 children and two teachers were killed in the shooting at Robb Elementary School in Uvalde, Texas. Photojournalist Tamir Kalifa has spent much of the last year and a half documenting the lives of the victims’ families and friends in the wake of the tragedy. Last week he was awarded the American Mosaic Journalism Prize for that work. He told Marketplace’s Lily Jamali about how social media is helping the community deal with its grief and bolstering its push for gun control.