A study by the University of Chicago shows that children (and probably your audiences) learn when gestures and speech are both used in teaching.
In the study, “Children Learn when Their Teacher’s Gestures and Speech Differ” (Singer and Goldwin-Meadow), 160 third and fourth graders were taught math skills in different ways. One group of teachers used gestures to help explain concepts like grouping numbers, and one group did not. The group that used gestures got better results.
This may seem obvious, but it makes an important point: the gestures used were not simply the normal gestures used when speaking. They were conscious, descriptivegestures that sometimes contained different (but not contradictory) information than what the teacher was saying orally.
Careful attention to the gestures used gave the students both oral and visual cues, increasing the amount of information stored and retained.
How well are you conveying your message in more than one way?