Exercises for Bringing the Hypothetico-Deductive Method to Life

Abstract

This article explains four kinds of inquiry exercises, different in purpose, for teaching advanced-level high school and college students the hypothetico-deductive (H-D) method. The first uses a picture of a river system to convey the H-D methods logic. The second has teams of students use the H-D method: their teacher poses a hypothesis drawn from a research article the students have not seen and asks them to design an H-D test of it. Later they read the article and compare their designs with its. The third exercise extends this; when economically practical, the class may experimentally test the best of its designs. Finally, an Internet/library exercise lets students inquire into the history of the H-D method.

Full text

Ab s t r A c t
This article explains four kinds of inquiry exercises, different in purpose, for
teaching advanced-level high school and college students the hypothetico- deductive
(H-D) method. The first uses a picture of a river system to convey the H-D method’s
logic. The second has teams of students use the H-D method: their teacher poses
a hypothesis drawn from a research article the students have not seen and asks
them to design an H-D test of it. Later they read the article and compare their
designs with its. The third exercise extends this; when economically practical, the
class may experimentally test the best of its designs. Finally, an Internet/library
exercise lets students inquire into the history of the H-D method.
Key Words: Hypothetico-deductive method; inquiry-based learning;
case study method.
One aim of biology courses is to give students an understanding
of the hypothetico-deductive (H-D) method, widely used for testing
research hypotheses. Some students will become scientists, having
occasion to do research with the H-D method and to evaluate
research based on it; others will become science teachers, charged
with helping students learn it. And all will become adults who ought
to understand it, since much of the scientific knowledge that affects
them and society is discovered with it.
How well is this aim achieved? Consider that Niaz (2004), testing
83 university science graduates, found that approximately 60% could
not elaborate the difference between a hypothesis and a prediction,
key elements of the H-D method. Cortéz and Niaz (1999), testing 110
eleventh-grade science students, found that
only 37.3% adequately understood the H-D
method’s logic, and concluded: “school curri-
cula should include development of students’
hypothetico-deductive reasoning abilities.”
To this end, four kinds of inquiry exercises,
developed for and practiced in my under-
graduate teaching, are presented below. The
first uses a picture of a river system to convey
the H-D method’s logic. The second uses case
studies – widely acknowledged as effective in teaching business, law,
medicine, and science – to give students experience in designing
H-D tests of research hypotheses. The third exercise extends the
second, having students experimentally execute their designed tests.
The fourth is an Internet/library exercise through which students
explore the H-D method’s history. Besides teaching the H-D method,
the exercises stretch creative skills, allowing teachers to assess their
students’ ingenuity, factoring it into their grades.
Teaching the H-D Method’s Logic Using

a Picture
To begin, the teacher gives the students a picture of the river system
shown in Figure 1, asking them to imagine:
You are standing at place A on the main river, 10 miles down-
stream from a dam. Upstream, below the dam, out of sight of place A,
another river – call it the “shunt river” – flows into the main river.
Suddenly a distant rumble suggests to you this hypothesis:
H: The dam just broke.
Not being at the dam, you can’t look at it and know directly. You
must test H indirectly, that is, with the H-D method. To do this, from
H you deduce an observable prediction, P – say this one:
P: In minutes there will be a flood at place A.
The main river is a duct from the hypothesis to the prediction,
amounting to the deduction of P from H, logically embodying this
if–then idea: “If the dam just broke, then in minutes there will be
a flood at place A.” This is the design of the
H-D test.
Next, suppose you see that a flood occurs.
Thus the prediction is true, which corrobo-
rates the hypothesis. However, it does not
absolutely prove it, because the dam may
be intact (the hypothesis false) while some
unexpected event up the shunt river – call it
a “shunt cause” – possibly a great cloudburst,
caused the flood.
But instead suppose no flood occurs. That makes the prediction
false, and so the hypothesis must be false.
346 THE AMERICAN BIOLOGY TEACHER VOLUME 76, NO. 5, MAY 2014
How to do it Exercises for Bringing the
Hypothetico-Deductive Method
to Life
H. CHarles romesburg
The American Biology Teacher, Vol. 76, No. 5, pages 346–348. ISSN 0002-7685, electronic ISSN 1938-4211. ©2014 by National Association of Biology Teachers. All rights reserved.
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DOI: 10.1525/abt.2014.76.5.9
One aim of biology
courses is to give students
an understanding of the
hypothetico-deductive
(H-D) method.

While explaining the picture, the teacher encourages inqui-
ries. Suppose a student asks, “What is the purpose of the shunt?”
Responding with Socratic questioning, the teacher guides the class to
realize that without the shunt, a hypothesis would be definitely true
if its prediction were true, which is logically unrealistic.
Or suppose a student asks, “Are there good H-D test designs and
poor ones?”
Responding, the teacher Socratically guides the class to realize
that a design that admits only a few kinds of shunt causes, and/or
allows them to be controlled and made inoperative, is generally supe-
rior to a design that does not. For instance, with an actual flood at
point A, the corroboration of the hypothesis would be more reliable
if a check with the weather bureau revealed that a cloudburst hadn’t
occurred in the shunt river’s watershed.
For further examples that relate the logic inherent in Figure 1 to
H-D testing, see Romesburg (2009).
Case Studies in Designing H-D Tests

For a given case study, the teacher does the following. With several
students in each group, (1) pose a research hypothesis, telling them it
comes from a published report of H-D research (typically a journal),
but not disclosing its source. (2) Ask them to design an H-D test of
it (i.e., deduce from the hypothesis a prediction or predictions), and
state how to experimentally determine whether it is true or false.
(3) From information in the report, list for them the equipment and
facilities to assume they would have at their disposal, and the kinds
of experimental manipulations possible. (4) If they get stuck during
the exercise, Socratically facilitate their discovering how to advance.
(5) When they have finished their designs, for homework have them
read the published report, learning its design and rationale, details of
the experiment, and whether the prediction was true, corroborating
the hypothesis, or false, disproving it. (6) In class, have the teams
compare their designs with the published design and discuss respec-
tive merits and/or shortcomings.
Several such case studies, testing different hypotheses, will give
the students a good working understanding of the H-D method.
An Illustrative Example about Bee Communication
The teacher selects and explains, say, the hypothesis from Nieh and
Roubik’s (1995) article:
H: Bees feeding on sugar syrup located on
top of a 120-foot tower in a forest can, on
return to their distant hive, communicate
the food’s location to foragers there that are
unaware of its location.
From information in the article, the teacher lists the equipment
the teams should assume they would have available to carry out an
H-D test of H, and tells them what manipulations are feasible (e.g.,
capturing bees as they emerge from the hive and marking them by
pasting identification numbers on the thorax).
They are to design on paper a test of H, that is, deduce from H a
prediction, P; plan an experiment that would show whether P is true
or false; and identify any shunt causes and ways of ruling them out
with auxiliary experiments.
For this case study, there is only one realistic prediction, the one
the original researchers thought of, and the students will come to it:
P: Bees recruited in the hive by foragers just
returned from the feeder, and then captured
and numbered as they leave the hive, should
soon appear at the feeder after release.
After the students present their designs in class for comment and
critique, they read the source article, comparing its H-D design to
theirs, learning that the hypothesis was corroborated.
The exercise can be capped off (as I do in teaching this case
study) with the class watching the short, free online video “Bee
Lines,” featuring actor Alan Alda (2003). His enthusiasm is catching
as he interviews bee researchers in Panama while they recreate the
article’s H-D test, explaining its rationale, such as how they experi-
mentally eliminated the possibility that H was false but shunt causes
were making the prediction true (e.g., bees from the hive learning the
food’s location by following a scent trail left by returned foragers).
Case Studies in Designing & Executing

H-D Tests
Occasionally a hypothesis can be found in a research report for which
the students can design an H-D test of it, as above, then decide on the
best of their designs, and for a class or club project carry out the test,
the experiment taking moderate amounts of time and money.
An Illustrative Example about Plant Movement
Suppose the students are given this hypothesis:
H: The tip of Phalaris detects the direction of
a light source and transmits the information
to its lower parts, causing it to bend toward
the source.
After the teams have their designs, they present them in class.
If any are faulty (e.g., contain an illogical deduction of a predic-
tion from the hypothesis and/or fail to close off apparent shunt
causes), the teacher encourages the students to rethink the designs
until they reach a sound one. Such a design has four test predic-
tions: (1) untreated (control) plants will bend toward a light source;
(2) treated plants with tips removed will not; (3) treated plants with
tips covered with opaque caps will not; and (4) treated plants with
tips covered with transparent caps will.
Next, the class decides the experimental protocol for getting the
facts with which to compare these predictions and, over some weeks,
does the experiments. They discover that the four predictions are
true, corroborating the hypothesis.
Then they are let in on a secret. They have redone research that
Charles Darwin did on movement in plants. Have them critique
Figure 1. The logic of the hypothetico-deductive method, cast as
a river system. Arrows in the rivers indicate the direction of flow.
THE AMERICAN BIOLOGY TEACHER HYPOTHETICO-DEDUCTIVE METHOD 347

Darwin’s thought processes by reading his report of his research
(Darwin, 1880).
Internet/Library Exercises

Students’ understanding of the H-D method is incomplete unless they
know its history. Thus, along with doing case studies, I recommend
they do Internet/library exercises, like those suggested in Figure 2.
Conclusions

The chief merit of the river-system exercise is that it lends the H-D
method’s logic a pictorial comprehensibility. Case studies with
hypotheses drawn from the literature exercise students’ thinking
in ways close to doing actual research; I regularly see students who
have trouble memorizing excel in doing case studies. Yet which are
pedagogically preferable: case studies where students design H-D
tests but do not experimentally execute their designs, or those where
they also execute their designs? In answering this, we should keep in
mind that hypothetico-deduction is a logical method, not an experi-
mental method, and that students learn its logic mostly through prac-
tice in designing H-D tests, not from experimentally doing the tests.
Six or so hours of class time, say, allows for doing several case studies
where students design but do not execute H-D tests, whereas the
same time spent on a case of creating a design and executing it would
ordinarily far exceed six hours.
Finally, case-study learning of the H-D method can also promote
students’ appreciation of science as a wondrous thing: wonder at
the knowledge generated by applications of the H-D method, and
sometimes wonder at the scientists’ creative skills in designing H-D
tests. Statistically speaking, might students who through case studies
sense such wonder and become better at creating and thinking con-
sequently become more serious students?
References
Alda, A. (2003). Bee Lines. Scientific American Frontiers. Episode: Calls of the
Wild. Available at http://www.pbs.org/saf/1308/video/watchonline.htm.
Cortéz, R. & Niaz, M. (1999). Adolescents’ understanding of observation,
prediction, and hypothesis in everyday and educational contexts.
Journal of Genetic Psychology, 160, 125–141.
Darwin, C. (1880). The Power of Movement in Plants. Darwin Online.
Available at http://darwin-online.org.uk/EditorialIntroductions/
Freeman_ThePowerofMovementinPlants.html.
Niaz, M. (2004). Did Columbus hypothesize or predict that if he sailed
due west, he would arrive at the Indies? Journal of Genetic Psychology,
165, 149–156.
Nieh, J.C. & Roubik, D.W. (1995). A stingless bee (Melipona panamica)
indicates food location without using a scent trail. Behavioral Ecology
and Sociobiology, 37, 63–70.
Romesburg, H.C. (2009). Best Research Practices: Gaining Reliable Knowledge.
Morrisville, NC: Lulu Enterprises.
H. CHARLES ROMESBURG is Professor of Environment and Society at Utah
State University, Logan, UT 84322-5215. E-mail: charles.romesburg@usu.edu.
Figure 2. Internet/library student activity on the background
of the H-D method.
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he American Biology Teacher VOLUME 69
NUMBER 2
FEBRUARY 2007
The American
Biology
Teacher
VOLUME 70
NUMBER 8
OCTOBER 2008
You are invited to submit manuscripts to The American Biology Teacher that align with the focus issues
listed below. Manuscripts can be for any of the article types regularly featured in the ABT, and more
information can be found at www.NABT.org/publications.
All manuscripts will be peer-reviewed by experts in their respective fields, and ABT Author Guidelines
will be maintained. All ABT authors must be current members of NABT.
Questions should directed to Dr. William McComas at ABTeditor@nabt.org.
FOCUS TOPIC AND ISSUE D AT E NEED TO SUBMIT BY
Evolution: February 2015 July 2014
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