An Example of a Deductive Approach to Scientific Inquiry
Tom Thompson
Philomath High School
Philomath, OR
In the November/December issue of TOST, Edith Gummer presents some issues
and solutions related to scientific inquiry in the classroom. I have had many discussions
with her about the process she presents. In this brief article I will share my observations
about trying to teach about scientific inquiry and teach using scientific inquiry. I will also
share some activities that I have used that mirror some of what Edith described.
I have been incorporating scientific inquiry into my classes for many years. This
includes extensive incorporation into a freshman science class. I was able to get students
to design investigations and document those designs. I also think I have been successful
in helping students put data into graphs or tables. I was also pleased with my attempts to
have students experience scientific inquiry in forms other than single variable controlled
experiments. What bothered me was how few students connected a question to a
conclusion by using the data they had collected. They seemed to have mechanics down,
but they were unable to develop any reasonable arguments to support their conclusions.
This really became obvious to me when a graduate student at Oregon State University
observed my classes and interviewed some of my students. To most students, inquiry was
just a series of things to do with the final goal being a lab report.
Over the years I have tried several ways of dealing with the issue of developing
scientific arguments. I developed a unit on scientific inquiry with five or six
investigations that were chosen because of their interest to students and the prior
knowledge that students had related to each investigation. I developed an instruction unit
on reaction rates with the learning cycle in mind. Students developed their understanding
of reaction rates through the activities and then conducted a more open-ended
investigation of a new reaction. The results were never spectacular in terms of students
producing scientific arguments.
More recently I have been trying some of the strategies described by Edith
Gummer. There are two major ideas that I incorporate into investigations. First is what I
would call deductive inquiry. Students start by looking for scientific claims in their text or
some other source of information. This helps them to focus on the specific content and
helps limit the investigations to more significant ideas in science. When I first started
doing that I was worried that students would ask why they should investigate something
that scientists already know. What I have found is that students are willing to be skeptical
consumers of scientific information and so they are willing to test claims made by others.
The other thing that concerned me is whether this approach to scientific inquiry would be
significantly different from what scientists actually do. However, a little reading and
discussion with others has convinced me that much of what scientists do is to test the
claims made by other scientists, replicate investigations, or apply claims to new settings.
The second big idea is the focus on claims. The purpose of scientific inquiry is to
develop evidenced-based arguments that can support or refute claims. When I focus on
claims I don’t worry about whether something is a hypothesis, theory, or inference. They
are all claims. The goal of the investigation is to collect evidence related to the claims.
Using the language of claims and evidence seems to be easier for students to understand.
It also avoids the issue of getting caught up in writing a proper hypothesis or some sort of
testable question. A deductive approach focused on claims and evidence seems to help
students keep track of the major purpose of an investigation. Whenever they get lost in
the process of inquiry, I can bring them back to the overall purpose by having them make
decisions about their investigation by thinking about the initial claim.
I have often used a simple table to help students organize their thinking around
claims and scientific inquiry. An example for two different activities can be found at the
end of this article. The first activity is a blend of scientific inquiry and design tied to
transfer of heat energy. The students are asked to read a small section of their text to
locate claims about how heat flow can be blocked. Previously I set up the issue by having
them compare the heat loss in a paper hot cup and a Styrofoam hot cup. The book
describes heat loss by convection, conduction, and radiation and describes methods that
are used to reduce each type of heat loss. In the case of radiation, the text makes the claim
that light colored surfaces reflect the radiant energy. Typically students will propose a test
of this claim by comparing heat loss in cups wrapped with reflective material to heat loss
in cups without. They also test the claim by darkening surfaces in a cup.
Previous to using a deductive approach centered on claims and evidence, students
would collect data, make some sort of statement about their hypothesis, and attribute
problems with their data to “human error.” Now, in terms of the hot cup investigation,
students are not so quick to state a conclusion. If the data seems to provide evidence that
does not support the claim, they start examining the method they used to collect that data.
Decisions about the procedure, how to display data, and arguments about the meaning of
the data are more closely tied to the original claim.
Another example of an activity that follows the techniques that I have described is
focused on rates or reactions. Most texts make claims about motion of molecules and
rates of reaction. I introduce students to a simple reaction between calcium carbonate
(marble chips) and hydrochloric acid. The students carry out the reaction and collect the
resulting gas so they have some experience with lab techniques. I then have the students
search in their text for claims about reactions that might help us figure out how to speed
up or slow down the reaction. The text claims that heating reactants makes the molecules
move faster and increases the chances that they will contact each other forming a product.
A simple test of that claim is to heat up or cool down the acid. In addition, the students
have to realize that the other claims made in the text may have an impact on their
investigation so they need to consider what size pieces of marble they will use and the
concentration of the acid.
At this point I am not sure why this particular technique seems to work better than
other techniques I have explored. I suspect one reason is the simplicity of condensing
scientific inquiry to a test of claims. Everything eventually goes back to the original
claim. Decisions about procedure, data manipulation, and communication can all be
brought back to the original claim. The other reason this method may work is that it helps
students focus on a small subset of the content. I recently read some articles about
cognitive load. They reminded me of the cartoon where the student wants to be excused
because his brain is full. Asking students to choose appropriate content and appropriate
investigation strategies at the same time may be more than can be handled well. In this
case the content is clearly stated in the text and the student can refer to it as frequently as
necessary while thinking about the complexities of the investigation.
Whatever the reasons, I am getting better arguments related to student
investigations. Students give specific evidence why the claim is supported or not
supported. They also discuss the strength of the evidence rather than canned responses
about human error or better technology. Perhaps what is most obvious is that students
seem to be learning important content while doing inquiry better than when I used more
inductive discovery approaches.
Example of a table to help students think about claims and evidence related to an
investigation.
Heat Transfer Example (What students would write is in italics)
What is the claim? How might I test
What evidence
the claim?
would I accept if the
claim were
supported?
Light colors reduce Wrap one cup in
The temperature of
heat loss by
aluminum foil and
the water in the cup
reflecting heat
keep the other one
with foil should not
energy.
normal.
drop as much in 5
minutes as the other
cup.
What evidence did I
actually find?
The temperature of
the water in the cup
with the foil dropped
10 degrees and the
water in the other
cup dropped 12
degrees.
Rates of Reaction Example (What students would write is in italics)
What is the claim?
How might I test
the claim?
Powdered solids
have more surface
area so particles
collide with it more
often.
Use different sized
pieces of marble
and measure how
fast the gas is
produced.
What evidence
would I accept if the
claim were
supported?
The bigger pieces of
marble should
produce gas slower
than the small chips.
What evidence did
I actually find?
The test tube filled
with gas in 1 minute
and 35 seconds for
the large chips.
For the small chips
it took only 20
seconds.
Biographical information
Tom Thompson is a science teacher at Philomath High School and a graduate student in
science education at Oregon State University. He has worked with ODE on professional
development related to scientific inquiry.