Prior to the fall of 2004, students did not have access to this particular model. Instead, they
had a light source on the optical bench and a wooden dowel with two different sized balls
attached to the ends of the stick, looking very much like a small irregular dumbbell. The
instruction directed the students to move this prop around in the path of the light source to
simulate phases and eclipses. Students in the spring of 2004 effectively had to build their own
3D model (See Appendix 2). The analysis of data looks into any changes in student knowledge
that may be attributable to the lesson modifications, particularly the use of the new three
dimensional Sun/Earth/Moon model, by looking at the pre/post test results and any changes in
percentage of correct answers on the quizzes between semesters.