There is a common attribute shared by the profession of acting and the practice of teaching: both require a high dosage of passion. We teach largely because we are in love with it. The difference between us and actors is that they seem to know better how to make that passion visible—through their voice, gestures, and body languages. We teachers, on the other hand, rarely make any conscious choice about the nonverbal messages that we convey, especially when we are in the classroom.
Sharon Guan, Instructional Design and Development Blog (DePaul University)