So reports Annie Murphy Paul, among other things in her MindShift blog on gesturing and its importance in education. This doesn't surprise me, except for the fact that it's algebra and it's hard for me to visualize what they were gesturing.
Then again, abstractions and gesturing go hand in hand, so to speak. Public speakers have long been onto this, as in this Toastmasters video. Murphy Paul may be interested to know that not only does gesturing improve communication, it was inherent in the development of language. The which-came-first debate is still an active file in cognitive science, though I think the evidence weighs highly in favour of gesture. The evolutionary process is mimicked by the developmental process: looking at things gives way to pointing at things (something only humans and perhaps Pointers do, Disney movies notwithstanding), followed by grunting and pointing, followed by signing. Desmond Morris wrote about this in the 70's in The Naked Ape, and consulted on the proto-language hijinks in Jean-Jacques Annaud's 1981 feature, Quest For Fire.
Gestures have acquired a whole new meaning in the 21st Century. Apple opened the door with its iPhone, Wii and Kinect brought the whole body into play with its camera based systems, Samsung has added non-contact gestures to its phones, and in this Sixth Sense TED talk, the body practically morphs into a walking computer.
Not so much a secret code as a universal language (with colourful cultural variations, of course). So if there any teachers out there not gesturing, the question is, what's stopping you?