Astronomy clicker question: "exact change required"

Astronomy 210, Fall Semester 2008
Cuesta College, San Luis Obispo, CA

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

A photon with slightly more energy than is required for an electron to move between energy levels 1 to 2 would:
(A) be absorbed, causing the electron to move between energy levels 1 to 2.
(B) not be absorbed, such that the electron stays in energy level 1.
(C) (Not enough information is given to answer this.)
(D) (I'm lost, and don't know how to answer this.)

Section 70160
(A) : 21 students
(B) : 4 students
(C) : 0 students
(D) : 0 students

This question was asked again after displaying the tallied results with the lack of consensus, with the following results. No comments were made by the instructor, in order to see if students were going to be able to discuss and determine the correct answer among themselves.

Section 70160
(A) : 16 students
(B) : 9 students
(C) : 1 student
(D) : 0 students

Correct answer: (B)

Some students latched on to the key phrase from the textbook: "exact change required." Most students had assumed (incorrectly) that the electron could "make change" and jump up to the higher orbital, and somehow dispose of the excess energy.

Pre- to post- peer-interaction gains:
pre-interaction correct = 16%
post-interaction correct = 35%
Hake (normalized) gain <g> = 22%