(Chiara Xie for NPR)As students across the country head back to class, one thing won’t be coming with many of them: their cell phones. In Texas, every public and charter school student will be without their phones during the school day this fall. Some 31 states and the District of Columbia now restrict students’ use of cell phones in schools, according to Education Week. Their old policy had each teacher at Lincoln High School collect phones at the start of class in a lock box. This year students’ phones will be locked away for the entire day, not just class time.