Interaction and engagement are often limited by class size and human dynamics (a few students may dominate the conversation while most avoid interaction). Interaction and engagement, both important learning principles, can be facilitated with clickers. Clickers can also facilitate discipline-specific discussions, small work-group cooperation, and student-student interactions. Clickers—plus well-designed questions—provide an easy-to-implement mechanism for enhancing interaction. Clicker technology enables more effective, more efficient, and more engaging education.