Many educators have found that models can add a lot to the understanding of astronomical concepts. Attractive commercial models of the solar system and celestial globes are readily available. Many models can be constructed of common materials — I found in my doctoral dissertation work that models made and manipulated by students increased retention of concepts of the celestial sphere and rotation, the seasons, lunar phases, and planet motions.

But there is another type of model which I have found very successful. I call it the “dynamic human model.” Actually, the concept is not new. I know that many good teachers have a favorite demonstration in which one or more students represent the Earth, sun, or moon. Also, the Elementary-School Science Project of the University of Illinois contained activities for student models to distinguish between Ptolemaic and Copernican systems. However, I do not think the idea has been extended as far as it should be. I would like to suggest ideas for dynamic human models beyond what I have seen elsewhere.