A modular crank toy includes a group of interchangeable elements which may be arranged creatively in multiple patterns. Rotary motion is transmitted from a drive unit with a crank handle to the other elements to provide entertaining and educational animated movements throughout various branches of the system assembled by the user. The movement is exhibited through a variety of different animated display-producing elements which rotate about their axes. Branches and circuits are created by joining such multiple, different animated display-producing elements together through a variety of junction units through which the rotational movement is transmitted.