When gesture does and does not promote learning.

Speakers move their hands when they talk--they gesture. These gestures can signal whether the speaker is ready to learn a particular task and, in this sense, provide a window onto the speaker's knowledge. But gesture can do more than reflect knowledge. It can play a role in changing knowledge in at least two ways: indirectly through its effects on communication with the learner, and directly through its effects on the learner's cognition. Gesturing is, however, not limited to learners. Speakers who are proficient in a task also gesture. Their gestures have a different relation to speech than the gestures that novices produce, and seem to support cognition rather than change it. Gesturing can thus serve as a tool for thinking and for learning.