The problem involved mathematical equivalence (i.e., 4+5+7=__+7), which is known to be critical to later algebraic learning. In the speech-only videos, the instructor simply explains the problem. In the other videos, the instructor uses two hand gestures while speaking, using different hands to refer to the two sides of the equation.
Students who learned from the gesture videos performed better on a test given immediately afterward than those who learned from the speech-only video.
Another test was given 24 hours later, and the gesture students actually showed improvement in their performance while the speech-only students did not.
Some advantages of flipped classrooms.
