Astronomy clicker question: very young star cluster

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 end of their learning cycle, during a review session before a midterm:

__________ will be found in an extremely young star cluster.
(A) Supergiants.
(B) White dwarfs.
(C) Red dwarfs.
(D) (More than one of the above choices.)
(E) (I'm lost, and don't know how to answer this.)

Section 70160
(A) : 17 students
(B) : 2 students
(C) : 1 student
(D) : 6 students
(E) : 0 students

This question was asked again after displaying the tallied results with the lack of consensus, with the following results.

Section 70160
(A) : 15 students
(B) : 0 students
(C) : 0 students
(D) : 10 students
(E) : 0 students

Correct answer: (A)

Low-mass protostars take a very long time to become a main sequence star; while massive protostars will take a very short time to reach a main sequence, live out its main sequence lifetime, and then become a supergiant. In-between are medium mass main sequence stars, which become giants, planetary nebulae, and then white dwarfs.

During the instructor-facilitated discussion following the second round of clickers, students who selected (D) said that a very young star cluster would have both supergiants and white dwarfs--which was then immediately shouted down by their fellow students.

Pre- to post- peer-interaction gains:
pre-interaction correct = 65%
post-interaction correct = 60%
Hake (normalized) gain = -16%