Students are embracing gadgets with relish. At St. Petersburg High School in Florida, where a new policy allows cellphones, organizers and some other devices to be used only with permission, Mark Boyle, a 17-year-old senior, uses his phone as a daily planner, as a memo pad and, furtively, as a video game when he is bored in class. Even his locker combination is stored in his phone. ''It's easier to get at than pulling out a notebook and paper,'' he said.