Gesturing helps you think

Talking with your hands as you speak helps you get your point across to the people you're talking to. But new research suggests gesturing can help you think too. For example, students who gestured while discussing math problems were better at learning how to solve the problems. (And no, they weren't counting on their fingers.) Now, researchers from the University of Chicago and University of Iowa are trying to figure out the relationship between gestures and abstract mental processes. From Scientific American:
The new study... focused on third and fourth graders solving a problem that required grouping. Students who are coached to make the "v" gesture when solving a math problem like 3+2+8 = ___+8 learn how to solve the problem better. But students also do a better job even if they were coached to make the "v" shape under the wrong pair of numbers. The very act of making the "v" shape introduces the concept of "grouping" to the student, through the body itself.

But what, exactly, was the process that made this possible? During the study, all of the students memorized the sentence "I want to make one side equal to the other side." They were then asked to say the sentence out loud when they were give a problem to solve. The authors suggest that students who also gestured attempted to make sense of both the speech and gesture in a way that brought the two meanings together. This process, they suggest, could crystallize the new concept of "grouping" in the student's mind.

The same process could occur in any situation where the person who is speaking and gesturing is also trying to understand - be it remembering details of a past event, or figuring out how to put together an Ikea shelf.
With a wave of the hand