The data was taken at Iowa State University in the Fall of 2000, for an introductory astronomy class.
There were 414 students.
The answers to the question on the cause of the lunar phase were broken up into categories based on answers receive. The major categories were, blocking (something is blocking the light from the moon), Shadow, and Correct. There are other smaller categories.
Next, the drawings were measured. I measured the Earth diameters, Moon Diameters and distance. I then put these in terms of the Earth Diameters based on the drawing. So if a student had a 2 inch earth, then that was the diameter I used to get the Moon diameter in earth diameters.
On the preinstruction Survey
48% of students believe that the Earth and Moon were separate by less then 1 Earth Diameter
38% believed that the Earth and Moon were between 1 to 3 Earth Diameters apart.
Only 1% of students were able to get the Moon the correct distance from the earth,
The post instruction survey shows a trend towards larger distances.
16% of students taking the survey, placed the Earth and Moon less than an Earth diameter apart.
31% placed the Earth and Moon between 1 to 3 Earth Diameters apart,
28% had the Earth 3 to 10 Earth Diameters from the Moon
and 9% had the Moon and the Earth the correct distance apart.
The theory behind this thesis is that students get the cause of the moon phases wrong because they have no idea how far and how big the moon is.
What we found is that we could count on fingers the number of students who got both the explanation and the scale correct.
The idea was that instruction that emphasized the scale would increase understanding of the lunar phases.
I didn't really find that yet, still working on it. I need some more data to see for sure
Tina
Tina Fanetti
Physics Instructor
Western Iowa Technical Community College
4647 Stone Ave
Sioux City IA 51102
712-274-8733 ext 1429