Student Created Excel Models To Test
Environmental Claims
Richard Lahti
Minnesota State University Moorhead
There is a need for more math
in K-12 science:
 Math is the #1 barrier many college students face in
their chemistry and physics classes at MSUM, not science
content.
 In order to make high school science “accessible to all
students” , much of the math has been removed.
 There are attempts to reintegrate math into k-12.
 Dr. Neuhauser’s work.
 PKAL/QuIRK
 Other “numeracy” efforts.
Description
Proper tire inflation vs. offshore drilling was a
debate that could be easily modeled and tested.
Students in an environmental
chemistry course created from scratch models to
test other claims. Their models, and the broader
NOS implications to hypotheses and theories, will be
examined and discussed.
http://www.time.com/time/politics/article/0,8599,1829354,00.html
http://www.factcheck.org/elections-2008/the_truth_about_tire_pressure.html
http://blogs.abcnews.com/politicalpunch/2008/07/from-the-fact-1.html
Scientific models are an essential part
of science
 They are mentioned repeatedly in the Minnesota
math and science standards.
 They are mentioned repeatedly in national
standards.
 http://www.nap.edu/booksearch.php?term=models&isbn=0309053269
 http://www.project2061.org/publications/bsl/online/index.php?chapter=11#B0
 Grosslight et al. (1991) detail the most common
misconceptions students have about models.

Grosslight, L., Unger, C., Jay, E., & Smith, C. L. (1991). Understanding models and their use in science: Conceptions of middle and high school
students and experts. Journal of Research in Science Teaching, 28, 799–822.
Scientific models are not easily
understood by students
Scientific conception Misconception
Purpose of
scientific
models
Nature of
scientific
models
Multiple
scientific
models
Creating/ testing
hypotheses in
addition to 
Only to show, or at best,
to teach or communicate.
Theories/ideas made
tangible. Dynamic,
manipulable.
Convey different
aspects of behavior.
Simplification vs.
complexity. Specific
purpose.
Static, physical
representation. There is a
“right” model.
Learning styles, personal
preference, show different
perspectives/points of
view.
Overlap between models and theory
 Student’s understanding of models should be related to
their understanding of theories.
 Physicists use model and theory interchangeably. (i.e.
Standard Model).
 The purpose of a model or theory is to allow for
adequate predictions or explanations of phenomena.
 Both are supported by using the model/theory to create
a hypothesis and then testing it.
Regurgitation of Nature of Science
Concepts
 Hypothesis is an “educated guess”
– what does educated mean? (based off of theory)
 A theory is a “hypothesis that has been tested many times
and not been proven wrong”
 (unless it’s evolution, then it is “just what some people think”).
 But what does “tested many times” mean? The same test over and
over?
 Most of my students (MSUM) come to me:
 not knowing the difference between a theory and law
 and most think a theory can become a law
“Content-Free Inquiry”
 Windschitl and Thompson (2006).
 Science Fair:
 Stains and dyes. No one’s hypothesis referenced
solubility.
 Making a hypothesis with a model is a potential
“cure” for this idea of content free inquiry.

Windschitl, M. & Thompson, J. (2006) Transcending simple forms of school science investigation: The impact of preservice instruction on
teachers’ understandings of model-based inquiry. American Educational Research Journal, 43(4), 783-835
Closing the learning cycle
Model/theory
Hypothesis
Data
Testing
Differences between subjects,
teachers, creates problems
 Physicist have the best understanding
 many of their theories are still active and being tested.
 Unfortunately, most of this work is in modern physics and beyond the
high school level.
 Chemist’s tend to see their models of atoms as literal because
 Their theories have all been “proven” (atomic theory and kinetic molecular
theory)
 Biologist’s falls somewhere in between
 big theory (evolution) is too controversial to be useful in teaching NOS.
 Many of their models (cells, anatomy) are physical.
 Genetics and predator prey provide good opportunities for exploring
models and theories.
 Many biology theories (germ theory, cell theory) have also been “proven”.
Justi, R. and Gilbert, J. K. (2003) Teachers' views of the nature of models. Int. J. of Science Education, 25, 1369-1386.
To teach all of the important aspects of
models requires
 Having a model that can be manipulated
 Multiple valid models of the same phenomenon are
possible
 Using models to make predictions and testing those
predictions, with subsequent revision.
 Modeling the behavior of an object or phenomenon, not
the object itself.
 Draws on Lesh et al mathematical modeling.

Lesh, R., Cramer, K., Doerr, H., Post, T., & Zawojewski, J. (2003) Model development sequences. In R. Lesh & H Doerr (Eds.), Beyond constructivism:
Models and Modeling perspectives on mathematics problem solving, learning and teaching.
Mahwah, New Jersey: Lawrence Erlbaum Associates.
Some methods of model instruction
show little improvement.
 Ruebush et al in Jan/Feb JCST.
 The above “black box” study found many student’s
misconceptions about models were unfazed by
teaching. The researchers commented on the
desire of students to know the “right” model,
even months after the study.
 Problem: there was a “right” answer.

Ruebush, L., Sulikowski, M. & North, S. (2009) A Simple Exercise Reveals the Way Students Think About Scientific Modeling. Journal of College Science
Teaching.
The study
 Setting : Liberal studies environmental chemistry
class at MSU Moorhead.
 Pretest on Nature of Science and Modeling
 Series of activities using/critiquing models
 Final Excel activity building model
 Posttest on Nature of Science and Modeling
The following scaffolding projects
preceded the Excel project:
1. Using/critiquing a teacher provided food and water use
model in Excel
2. Comparing several carbon footprint models
3. The Java Climate change model
http://www.astr.ucl.ac.be/users/matthews/jcm/
4. PHET Greenhouse Effect model
http://phet.colorado.edu/simulations/sims.php?sim=The_Greenhouse_Effect
After each stage, an explicit reflective
approach (Abd-El-Khalick) was used to get
students reevaluating their thinking about models.
Where to go for ideas?
 Ask Pablo does “back of the envelope” calculations
regarding environmental issues. Often, the replies in the
blogs that follow are as interesting and show large and
small revisions to the models. http://askpablo.org/ bottled water for instance?
 Several sites give information about the energy
(embodied, embedded) or CO2 needed to make a
product, “cradle to grave” or “lifecycle analyses” of
various products.
 Foods: http://www.scribd.com/doc/24163/CO2-Emissions-of-Foods-and-Diets
 Materials: http://www.victoria.ac.nz/cbpr/documents/pdfs/ee-coefficients.pdf
 Fuel: http://www.transportation.anl.gov/pdfs/TA/339.pdf
Some student models built
 Which is better for the environment:
 Driving or flying?
 Shipping fresh produce, canning, or freezing?
 Range fed or feedlot beef?
 Burning or burying garbage?
 Incandescent or fluorescent light bulbs?
 Disposable or cloth diapers?
 Hybrid vehicles or regular gas vehicles?
 Refillable glass bottles, plastic bottles or aluminum cans?
Another type of question
 How long does it take:
 For a new, better mileage car
 For a new, Energy Star appliance
 For new insulation
 For a new, natural gas furnace
… to pay the carbon/energy debt needed to build it, in
reduced emissions per year?
Misconceptions
 The goal of this exercise is primarily in understanding
models, and indirectly theory and other NOS concepts.
The purpose is NOT to understand content.
 The goal of this exercise is also not to get the “correct
answer”. The correct answer may not be known.
 The purpose is to understand how a system behaves and
get a reasonable answer.
 If both students and teacher understand the above, the
experience will go better.
Advantages of building their own Excel
model.
 The focus is on behavior of the system, there is no physical
component
 Dispels the misconception that a model must be physical
 Increases the focus that a model must “act like” rather than “look
like” its target.
 “create explanations and/or models” is a 9th grade standard.
What does this mean?
 “Cookbook” model?
 “Inquiry” model?
We all(?) agree inquiry labs are better than cookbook labs,
inquiry modeling is likewise better than cookbook modeling.
Advantages of building their own Excel
model.
 After the model is built, they test it against others who have
done similar analyses (either other classmates or the web).
 If their model does not work, they reexamine and revise and
try again, just like a scientists would do with a theory.
Students showed gain in understanding the extent to which
and the conditions necessary for theory revision.
Advantages of building their own Excel
model.
 Most importantly, the last step is to form a far transfer
hypothesis.
 Gas laws can be explained with kinetic molecular theory.
But, if air is made of little balls in random motion…
 Hypothesis about diffusion
 Hypothesis about thermal expansion in solids
 Confirmation of these kinds of tests are what strengthen
theories.
Examples of far transfer hypotheses:
 After building a flying vs. driving model, use it to predict
the number of passengers where the “answer” changes.
 After building a coal vs. nuclear electricity model,
determine what carbon tax ($/ton) is necessary to force
the advantage in favor of nuclear.
 After making a predator and prey model, adjust it to see
how sustainable “harvest” of deer can be calculated by
DNR.
Other content areas:
 Chemistry: Kinetics
 Biology: Predator prey, Harvey-Weinberg Equilibrium
 Geoscience: Half-life
 Physics: collisions, conservation of energy systems, etc.
Physics is easy because everything is mathematical…
Limitations of the method
 Students need to be able to manipulate equations, so some
algebra skills (Algebra I?) would be a minimum pre-requisite.
 Students need to have some Excel skills. My experience was
many students get some of this in middle and high school,
and enough can be taught in a day or two.
 On the other hand, opportunity to team-teach with math
and/or computer science?
Further limitation
 Part of my study was looking at a possible relationship
between students Cognitive Level (Piaget – concrete vs.
formal) and their ability to learn from models.
 It is possible that students stuck in the concrete level could
not make a model.
 Specifically, they could not conceive of a variable, and instead
used brute force.
Further research
 I will be interested in trying this kind of an approach in
grades 8-12.
 I am seeking collaborators and have ideas for many subjects
especially chemistry.
 Please contact me lahtiri@mnstate.edu if you are interested
in anything I have said today.
 web.mnstate.edu/lahtiri