Stages of
Experimental Inquiry
Carl J. Wenning, Coordinator
Physics Teacher Education
Illinois State University
Five Stages of Experimental Inquiry
1. Observation & Identification
2. Experimentation:
a) Observational
b) Testing
c) Application
3. Generalization
4. Verification
5. Communication
1. Observation & Identification
 Systematic observations lead to different
types of questions to be resolved:
 Why?
 How?
 What if?
 A well-formulated research question is
derived from current knowledge
2a. Experimentation
 Plan the experiment
 Gather evidence from observations
 Create an evidence-based relationship, test
and explanation, or find an application
2b. Experiment Types
 Observational (experiment to investigate
a new phenomenon.)
 Testing (experiment to test a hypothesis
or model.)
 Application (experiment to solve a
practical problem or determine a physical
quantity in two independent ways.)
2b1. Observational Experiment
 “You have a sealed hollow metal sphere
with an unknown gas inside. You also have
a thermometer, a pressure gauge, a hot
plate, some ice and a container holding
water. Design and conduct an experiment
to determine if there is a relationship
between pressure and temperature of the
unknown gas when its volume is kept
constant.” (PAER Group, Rutgers U.)
2b2. Testing Experiment
 “Design and conduct an experiment to test
the following rule: an object always moves
in the direction of the net force exerted on
it. You have a dynamics cart, dynamics
track, a spring scale, masking tape, a
bowling ball, a mallet, a small ball and
cushion to use. You may also use any other
common equipment available in the lab.
Feel free to use your lab partner as an
object!” (PAER Group, Rutgers University)
2b3. Application Experiment
 “Design and conduct at least two
independent experiments to determine the
coefficient of static friction between your
shoe and the sample of carpet/linoleum
provided. Equipment: spring scale, ruler,
protractor, carpet or wood surface, tape.”
(PAER Group, Rutgers University)
3. Generalization
 Depends upon type of experiment
 Observational - typically a relationship is
derived from a graph; a hypothesis or model
might be generated for further experimentation
 Testing - typically evidence is determined to
support or disconfirm a model or hypothesis;
data never “proves” a model or hypothesis
 Application - either it works or it doesn’t
 Be careful not to overextend generalization
4. Verification
 Depends on type of experiment
 Observational - Use new formulation to make
predictions for verification
 Testing - Use hypothesis or model to deduce
predictions for verification
 Application - Either it works or it doesn’t
 Consider statistical probability
 Consider other explanations if hypothesis
or model is basis of prediction
5. Communication
 Recall that science is a social compact, and that
there are accepted avenues and processes for
communicating results
 Recall that evidence only supports of disconfirms,
never “proves”
 Your credibility is on line
 Remember to limit your generalizations
 Communication provides evidence as well as
procedures so that others can replicate your
findings
Generic Experimental Design
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Identify the system to be studied
Identify and distinguish system variables
Identify general procedures to follow
Identify the model if possible
Choose range of the independent variable
Collect and interpret data
Consider overall precision of experiment
References
 For types of experiments including
additional procedures, visit PAER Group at
Rutgers University:
 http://paer.rutgers.edu/ScientificAbilities/For
mative+Assessment+Tasks/default.aspx
 ISU Student Lab Handbook:
 http://www.phy.ilstu.edu/slh/