Maybe it's no mistake that we talk about "grasping" new ideas. When we find our hands moving wildly as we try to explain something, maybe we shouldn't feel ridiculous. Research in math classrooms has found that kids learned better when a teacher used gestures—and their grip on the new material improved even more after the lesson ended.
Teachers who gesture more or less while they speak can have other differences too, of course: they might use different intonation or vocabulary, or have more or less energy. University of Iowa psychologist Susan Wagner Cook and her coauthors, though, were only interested in the effect of teachers' hand motions. To isolate this factor, they created a series of videos.
In the videos, aimed at elementary schoolers, a teacher taught a single scripted lesson. The subject of the lesson was equivalence, the idea that what's on one side of an "=" must be ...
