3.  REACHING STUDENTS. In Ramsey Musallam’s A.P. Chemistry class at Sacred Heart Cathedral Preparatory in San Francisco, cell phones are a natural extension of the way he communicates with his students. As soon as kids walk in, Musallam sends out a text blast through Remind101, asking them a challenge question that’s related to the day’s lesson. “First person to tell me the units on K for a second order reaction gets chocolate,” he types and sends off. His students know he does this regularly, so they’re constantly anticipating the question during the day, in and out of class.