Are pen and paper going the way of the buffalo? In universities and high schools across America, students—more than half a million of them—are using handheld mobile devices in class to register attendance, respond to opinion polls, take quizzes, and anonymously register confusion during lectures. “Clickers,” as they are commonly called, are in use on thousands of college campuses, including Harvard, the University of Arizona, Vanderbilt, and Northwestern. Many students report that the interactivity of the handheld device, which bears a notable resemblance to the ubiquitous cellphone, keeps students more engaged in class. Some students, professors say, have cheated the attendance-checking capability by having friends simply bring their clickers to class for them—but there “are other ways to count attendance,” one professor reminded his class.