Lecturing is not simply a matter of standing in front of a class and reciting what you know The classroom lecture is a special form of communication in which voice, gesture, movement, facial expression, and eye contact can either complement or detract from the content. No matter what your topic, your delivery and manner of speaking immeasurably influence your students' attentiveness and learning. Use the following suggestions, based on teaching practices of faculty and on research studies in speech communication, to help you capture and hold students' interest and increase their retention.
(http://teaching.berkeley.edu/bgd/delivering.html )