Basing their tests on the idea that the nervous system makes internal representations of movements - that then inform the other senses, researchers found that doing hand movements made it easier to discriminate them later.
What does this mean? In some cases, it may help students learn if they do at the same time. Doing helps may them sharper about what they see. Sports trainers probably already know this. What's the flipside? It might also remind us that the eyes and movement systems are tightly controlled. Fine motor control problems might make it harder for students to "see" when their being shown how to write, and undiagnosed visual problems could behind other students' problems with motor tasks.
Your Hands Help You See