Illustrations and supporting texts for sound standing waves of air columns in pipes in introductory physics textbooks

In our pilot studies, we found that many introductory physics textbook illustrations with supporting text for sound standing waves of air columns in open-open, open-closed, and closed-closed pipes inhibit student understanding of sound standing wave phenomena due to student misunderstanding of how air molecules move within these pipes. Based on the construct of meaningful learning from cognitive psychology and semiotics, a quasiexperimental study was conducted to investigate the comparative effectiveness of two alternative approaches to student understanding: a traditional textbook illustration approach versus a newly designed air molecule motion illustration approach. Thirty volunteer students from introductory physics classes were randomly assigned to two groups of 15 each. Both groups were administered a presurvey. Then, group A read the air molecule motion illustration handout, and group B read a traditional textbook illustration handout; both groups were administered postsurveys. Subsequently, the procedure was reversed: group B read the air molecule motion illustration handout and group A read the traditional textbook illustration handout. This was followed by a second postsurvey along with an exit research questionnaire. The study found that the majority of students experienced meaningful learning and stated that they understood sound standing wave phenomena significantly better using the air molecule motion illustration approach. This finding provides a method for physics education researchers to design illustrations for abstract sound standing wave concepts, for publishers to improve their illustrations with supporting text, and for instructors to facilitate deeper learning in their students on sound standing waves.

Figure 1

Typical illustrations of sound standing waves in air columns in a pipe in introductory physics textbooks.

Figure 2

First harmonic sound standing wave in an open-open pipe.

Figure 3

Flow chart of activities for groups A and B.

Figure 4

Boxplots of score distributions: Presurvey, Post Alt, and Post Text for groups A and B.

Figure 5

The percentage of students who chose either one, two, three, or four distractors in questions 9–14 in the Presurvey and in questions 10–15 in the Post Alt and Post Text surveys for group A and group B.

Figure 6

Percentages of students in group A and group B choosing options A through D in question 3 in the Presurvey and question 4 in the first and second postsurveys.

Figure 7

Number of correct answers in the Presurvey and postsurveys.

Figure 8

Excerpt from a textbook [11] that contains diagrams for sound standing waves represented by two intertwining sinusoidal curves. This excerpt is reproduced by permission: From SERWAY/FAUGHN/VUILLE. Enhanced College Physics (with PhysicsNOW), 7E. © 2006 Brooks/Cole, a part of Cengage Learning, Inc. Reproduced by permission. www.cengage.com/permissions.

Figure 9

First harmonic standing sound wave in an open-open pipe.

Figure 10

Second harmonic sound standing wave in an open-open pipe.

Figure 11

Third harmonic sound standing wave in an open-open pipe.

Figure 12

First harmonic sound standing wave in an open-closed pipe.

Figure 13

Third harmonic sound standing wave in an open-closed pipe.

Figure 14

Fifth harmonic sound standing wave in an open-closed pipe.