Astronomy clicker question: lunar phases

Astronomy 10, Summer Session 2007
Cuesta College, San Luis Obispo, CA

Astronomy 10 learning goal Q2.1

Students were asked the following clicker question (Classroom Performance System, einstruction.com) at the start of their learning cycle:

[0.3 points.] Shown below are eight different Moon phases.


What causes these different phases of the Moon?
(A) Different amounts of the far and near sides of the Moon as seen from the Earth.
(B) Different amounts of the day and night sides of the Moon as seen from the Earth.
(C) The Earth blocks light from the Sun, casting a shadow on the Moon.
(D) The slow, gradual rotation of the Moon about its own axis.

Correct answer: (B).

The border between the sides of the Moon that are illuminated or non-illuminated by the Sun is the terminator. As the Moon orbits the Earth (in approximately 28 days), the terminator moves across the face of the Moon. Students are instructed to diagram this, in order to construct a mental model of this phenomenon.

Student responses
Section 8027
(A) : 1 student
(B) : 4 students
(C) : 7 students
(D) : 1 student