A three-dimensional demonstration of eclipses may be constructed inexpensively and easily using balls
and hoops of different sizes to represent the Earth and Moon, and their orbits. This demonstration
illustrates the conditions necessary for eclipses to occur. Pitfalls and related exercises have been described,
and sample test questions have been given. Over the past few years, while the demonstration was being
refined, assessments of the effectiveness of the demonstration were qualitative; now that the demonstration
has been fine-tuned, concrete assessment data will be obtained and evaluated beginning this fall.