There are several variations of resonance laboratory activities used to determine the speed of sound. This is not one of them. This activity uses the resonance tube idea to teach resonance, not to verify the speed of sound. Prior to this activity, the speed of sound has already been measured using computer sound-sensors and timing echoes produced in long tubes like carpet tubes. There are other methods to determine the speed of sound. Some methods are referenced at the end of this article. The students already know the speed of sound when they are confronted with data that contradict their prior knowledge. Here, the mystery is something the students solve with the help of a series of demonstrations by the instructor.

1.
As mentioned above, students had already determined the speed of sound before doing this activity. There are simulations on the web that students can use to determine the speed of sound. The students could have found the speed of sound by measuring the time for a clapping sound to reach an observer using the website http://serc.carleton.edu/dmvideos/players/keep_time.html?hide_banner=true [
Dan
MacIsaac
, “
WebSights: Direct measurement videos
,”
Phys. Teach.
54
,
254
(
April
2016
)]. A typical laboratory activity used to verify the speed of sound is found at http://www.physics.smu.edu/∼olness/www/index.html. Once there, scroll down to Fall 2013: Physics 1320/3320 & MPSY 5340 Musical Acoustics. Then click on Link to the PreLab and Lab Assignments (in PDF format), and finally on 03resonance.pdf. Another approach often used to teach about resonance in tubes is that exampled by the lesson shown in “Sound waves in tubes” http://schoolphysics.org/age16-19/sound/index.html. Once there, download the experiment “Velocity of Sound Resonance Tube.” Another example of the use of resonance tubes to determine the speed of sound is found in
Wilton Pereira
da Silva
,
Jürgen
W. Precker
,
Diogo D. P. S.
e Silva
, and
Cleiton D. P. S.
e Silva
, “
The speed of sound in air: An at-home experiment
,”
Phys. Teach.
43
,
219
(
April
2005
). In some of these activities students use instructor-generated audio files that must be loaded into student computers. Others require long glass tubes and ask students to find the distance between two positions. Still others use sophisticated equipment like electronic circuits with speakers and detection systems.
2.
Richard
Hake
, “
Interactive-engagement versus traditional methods: A six-thousand-student survey of mechanics test data for introductory physics courses
,”
Am. J. Phys.
66
,
64
(
Jan.
1998
). Students learn more if they are required to engage in their own learning as evidenced by the success of the Modeling Program started at Arizona State University. That Hestenes and others confirm this can be seen in “Excerpt from a Draft of
Hestenes
,
D.
,
Megowan-Romanowicz
,
C.
,
Osborn Popp
,
S.
,
Jackson
,
J.
, &
Culbertson
,
R.
(
2011
)
A graduate program for high school physics and physical science teachers
,
Am. J. Phys.
79
(
9
), p.
971
979
,” found at URL http://modeling.asu.edu/R&E/ASU-FCI-stdtGraph-MNStchr.htm. It is certainly becoming clear that teachers must find instructional methods that fit today’s students’ learning styles if more students are expected to understand the physical laws of nature. This is made clear by the Committee on the Status, Contributions, Future Directions of Discipline-Based Education Research, Board on Science Education, Division of Behavioral, Social Sciences, Education, and National Research Council (2012), and shown in
Chapter 6: Instructional Strategies
” in
Discipline-Based Education Research: Understanding and Improving Learning in Undergraduate Science and Engineering
(
,
2012
). Available at http://www.nap.edu/openbook.php?record_id=13362.
3.
The PVC pipe should be about 0.75-in diameter and about 40 cm long.
4.
The frequency of the tuning forks should be between 256 and 1024 Hz. Alternately, students can use the free smartphone app Hz Function Generator rather than tuning forks.
5.
Modeling Instruction: An Effective Model for Science Education
,”
American Modeling Teacher’s Association
, http://www.nsela.org/images/stories/scienceeducator/17article7.pdf.
6.
The adjusted resonance length of the PVC pipe is found by adding a percentage of the diameter of the PVC pipe to the tube’s resonance length measurement. This corrects for the fact that the actual antinode is just outside the PVC pipe.
7.
See
Iqbal
and
Hudhaifa Mazin Abdull
Majeed
, “
End correction of a resonant standing wave in open pipes of different diameters
,”
J. Nat. Sci. Res.
3
(
4
),
21
25
(
2013
). The end correction for a resonance tube depends upon the diameter of the tube.
8.
Michael J.
Ruiz
, “
Boomwhackers and end-pipe corrections
,”
Phys. Teach.
52
,
73
(
Feb.
2014
).
9.
David R.
Lapp
, “
Harmonics in an aluminum rod. ‘A Golden Oldie,’
Phys. Teach.
35
,
314
315
(
May
1997
).
10.
Michael
Hirth
,
Sebastian
Gröber
,
Jochen
Kuhn
, and
Andreas
Müller
, “
Harmonic resonances in metal rods – Easy experimentation with a smartphone and tablet PC
,”
Phys. Teach.
54
,
163
(
March
2016
).
11.
B.
Lasby
,
J. M.
O’Meara
, and
M.
Williams
, “
The singing rod (in the modern age)
,”
Phys. Teach.
52
,
86
(
Feb.
2014
).
12.
A recently published explanation is found at
H.
Eshach
and
A.
Volfson
, “
Explanatory model for sound amplification in a stethoscope
,”
Phys. Educ.
50
(
1
),
75
(
2015
).