This Pi Day, March 14, in an upstairs workspace in Caltech's W. M. Keck Engineering Laboratories building, eight robotic arms were showing off their stuff. Under the watchful eye of the undergraduate students who built and programmed them, each robot performed a unique task. One arm picked up and arranged toy train tracks and another arm built tangram puzzles, while a third played backgammon, and yet another arm flicked disks across a board in a game of carrom. Meanwhile, none of the stud...