Newton's Cradle is a series of bifilar pendulums used in physics classrooms to demonstrate the role of the principles of conservation of momentum and kinetic energy in elastic collisions. The paper reviews the way in which textbooks use Newton's Cradle and points out the unsatisfactory nature of these treatments in almost all cases. The literature which attempts to explain how the apparatus works is discussed and alternative strategies which make it possible to teach about the nature of models in science as well as to teach physics through use of the apparatus are suggested.