1. Models and Modeling
in the High School
Larry Dukerich Brenda Royce
Dobson HS University HS
Mesa, AZ Fresno, CA
Arizona State University
2. The Problem with Traditional
Presumes two kinds of knowledge:
Facts and ideas - things packaged
into words and distributed to
Know-how - skills packaged as rules
Assumes students will see the
underlying structure in the content.
3. “Teaching by Telling” is Ineffective
Systematically miss the point of what we
do not have the same “schema” associated
with key ideas/words that we have.
do not improve their problem-solving skills
by watching the teacher solve problems
4. Algorithms vs Understanding
What does it mean when students can
solve stoichiometry problems, but
cannot answer the following?
Nitrogen gas and hydrogen gas react to form
ammonia gas by the reaction =H
N2 + 3 H2 → 2 NH3 =N
The box at right shows a mixture of nitrogen and
hydrogen molecules before the reaction begins.
Which of the boxes below correctly shows what the
reaction mixture would look like after the reaction
A B C D
5. How Do You Know?
All students know the
formula for water is H2O.
Very few are able to cite
any evidence for why we
believe this to be the
6. Do They Really Have an
Atomic View of Matter?
Before we investigate the inner workings of
the atom, let’s first make sure they really
believe in atoms.
Students can state the Law of Conservation of
Mass, but then will claim that mass is “lost” in
When asked to represent matter at sub-
microscopic level, many sketch matter using a
Where’s The Air?
Model of Matter
9. Where’s the Evidence?
Why teach a model of the inner workings of
the atom without examining any of the
Students “know” the atom has a nucleus
surrounded by electrons, but cannot use this
model to account for electrical interactions.
What’s gained by telling a Cliff’s Notes version of
the story of how our current model of the atom
10. Instructional Objectives
Construct and use scientific models to
describe, to explain, to predict and to control
Model physical objects and processes using
diagrammatic, graphical and algebraic
Recognize a small set of particle models as
the content core of chemistry.
Evaluate scientific models through
comparison with empirical data.
View modeling as the procedural core of
scientific knowledge 10
11. What Do We Mean by Model?
Models are representations of structure in a physical
system or process
12. Why Models?
Models are basic units of knowledge
A few basic models are used again and
again with only minor modifications.
Models help students connect
13. Why modeling?!
To help students see science as a way of
viewing the world rather than as a collection of
To make the coherence of scientific knowledge
more evident to students by making it more
Models and Systems are explicitly recognized
as major unifying ideas for all the sciences by
the AAAS Project 2061 for the reform of US
14. Uncovering Chemistry
Examine matter from outside-in instead
of from inside-out
Observable Phenomena → Model
Students learn to trust scientific thinking,
not just teacher/textbook authority
Organize content around a meaningful
‘Story of Matter’
15. Particle Models of Gradually
Begin with phenomena that can be
accounted for by simple BB’s
Conservation of mass
Behavior of gases - KMT
Recognize that particles DO attract one
“Sticky BB’s” account for behavior of
16. Models Evolve as Need Arises
Develop model of atom that can acquire
charge after you examine behavior of
Atom with + core and mobile electrons
Conductivity of solutions
Properties of ionic solids
17. Energy - Early and Often
Make energy an integral part of the
Help students develop a coherent
picture of the role of energy in changes
Energy storage modes within system
Transfer mechanisms between system and
18. Reconnect Eth and Ech
Particles in system exchange Ek for Ech to
181 kJ + N2 + O2 ––> 2 NO
Representation consistent with fact that an
endothermic reaction absorbs energy, yet the system
19. How to Teach it?
constructivist vs transmissionist
cooperative inquiry vs lecture/demonstration
student-centered vs teacher-centered
active engagement vs passive reception
student activity vs teacher demonstration
student articulation vs teacher presentation
lab-based vs textbook-based
20. Be the “Guide on the Side”
Don’t be the dispenser of knowledge
Help students develop tools to explain
behavior of matter in a coherent way
Let the students do the talking
Ask, “How do you know that?”
Require particle diagrams when applicable
We’re here to tell you about the application of the Modeling Method of instruction (first developed for use in high school physics) to the high school chemistry course.
First some background on what is the problem with conventional instruction. Bullet-1 David Hestenes refers to the first as “factons”, what students record and try to reproduce on tests. The 2nd category he calls “factinos”, stuff that passes unimpeded through students’ heads.
Our students don't share our background, so key words, which conjure up complex relationships between diagrams, strategies, mathematical models mean little to them. To us, the phrase inclined plane conjures up a complex set of pictures, diagrams, and problem-solving strategies. To the students, it's a board, and it makes a difference which way it is tilted. All my careful solutions of problems at the board simply made ME a better problem-solver.
There is a big difference between the mathematical ‘game’ of stoichiometry and being able to describe what is going on in a reaction vessel. Ideally, students would do both simultaneously.
What does it mean to be ‘2 parts hydrogen and 1 part oxygen’? There can be a very real gap between their words and how they perceive matter at the microscopic level (for more than just water!!)
The real roadblock to many students is not which atomic model they use, but whether they have ANY sufficiently developed atomic model that is consistently applied. SAMPLE STUDENT WORK NEXT
The steel wool turns color when heated. Some think that some part of the gas from the burner flame in now trapped in the wool, but few actually drew atoms that combined to form new substances.
This is why I have a problem with texts that ruin the story by going to the end of the book right away. If we want students to see science as more than a collection of facts, then we have to connect our models to the evidence that lead to them.
What should we teach? Our students should learn to do the following: They should see that physics involves learning to use a small set of models, rather than mastering an endless string of seemingly unrelated topics.
This word is used in many ways. The physical system is objective; i.e., open to inspection by everyone. Each one of us attempts to make sense of it through the use of metaphors. Unfortunately, there is no way to peek into another’s mind to view their physical intuition. Instead, we are forced to make external symbolic representations; we can reach consensus on the way to do this, and judge the fidelity of one’s mental picture by the kinds of representations they make. So the structure of a model is distributed over these various representations; later we’ll provide some specific examples.
Students WILL work from a model of matter** - the question is which model and is it a rigorous, scientifically supported model applied consistently to all situations **refer to storyboards
Emphasis on points 1 and 2.
Reference: “The Story So Far” doc
Reference: Energy Paper
Here are the key ways in which the modeling method differs from conventional instruction. Students present solutions to problems which they have to defend, rather than listen to clear presentations from the instructor. The instructor, by paying attention to student’s reasoning, can judge the level of student understanding.