Abstract: A chaos waterwheel teaching device is provided for demonstrating and illustrating to students that random appearing phenomena occurring in natural systems such as biological, chemical, physical, and mathematical may actually reflect the action of simple underlying non-random processes or deterministic systems that illustrate basic concepts of dynamics and chaos theory. A dual wheel device is provided in which one wheel is driven by a stream of water and the other wheel acts as a brake, resisting the rotation created by the first wheel by dragging a series of vanes through a water bath. The operation of the device can be varied and controlled by varying one or the other of the parameters, including the water level in the braking compartment to cause different states of operation, namely periodic or chaotic.