CNN  —  They were pianists and painters, swimmers and dancers, budding readers, little brothers and big sisters. Then, in a flash of violence, their 20 bright smiles were snuffed out forever in a rampage at Sandy Hook Elementary that haunts the nation to this day. Also stolen that chilly Friday – just 11 days before Christmas – were six adults felled by the same gunman as they refused to abandon their sacred trust to safeguard the smallest among them. Seven years later, even those who have never set foot near Newtown, Connecticut, can conjure the scene painted by police of a first-grade classroom turned into a killing field. Can see…