Interview Results
Interviews can be categorized as “Consistent,” meaning that a student appeared confident in his or her responses
and consistently applied similar reasoning strategies, or “Inconsistent,” meaning that a student was very unsure
of his/her responses and changed reasoning throughout the interview. Appendix B summarizes student interview
results, including examples of possible working mental models (explained in Section 6).
Question 1A proved to be an excellent starting place to probe students’ mental models. The majority of students
answered that astronauts appear to float in their spacecraft because there is no gravity in space. These students
were then asked related questions to bring up contradictions in their reasoning. This is demonstrated in the
following transcript between a student (S) and interviewer (I):
S: “Why do astronauts appear to float in their spacecraft?” My response is “there is no gravity in space.”
I: Okay, and do you still agree with that?
S: Yes, I do.
I: Okay, and what do you define as “space”?
S: Anything outside of our gravitational pull.
I: So is there a boundary where something is in our gravitational pull and then not?
S: I think it gradually decreases from Earth’s surface to nothing at some elevation above earth.
I: Astronauts orbit Earth just outside our atmosphere, so I guess I’m asking if it [gravity] decreases fast enough to
get to be zero just outside our atmosphere.
S: Yes.
I: So then is the gravity from the Earth zero at the Moon? Does the Moon feel Earth’s gravity at its location?
S: No, the Moon has its own gravity.
I: But the Moon orbits the earth, right?
S: True.
I: So why does it orbit the earth?
S: Because of the gravitational pull between the two masses.
I: Okay, so it seems that you’re saying that the Moon does feel the Earth’s gravity.
S: Yes.
I: So why can the Moon feel Earth’s gravity, but the space station can’t?
S: Because the space station isn’t a big enough mass.
This example reveals how misconceptions are often intertwined—th