David Hestenes

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These slides were used in Daveid Hestenes
General Interest Seminar at Edinburgh
Universitys School of Physics and Astronomy on
28th April 2009. Slides 125 were presented
during the lecture. Slides 2641 are
supplemental. http//www.ph.ed.ac.uk/seminars
Naïve Beliefs about Physics and
Education
David Hestenes Arizona State University
UK 2009
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Why is physics so difficult?
Stock answer few have the talent for it!
Science Education Research has a different
answer, from thorough investigation of personal
beliefs about how the world works uninformed by
science (hence naïve!)
Definitive conclusions naïve beliefs dominate
student performance in introductory
physics! conventional instruction is almost
totally ineffective in changing them!
this result is independent of the instructor and
his/her mode of teaching!
How can this be? Cant we do better?
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Major result A detailed taxonomy of naïve
beliefs about mechanics the science of motion
very stable and expressed with confidence
deep seated!?
incompatible with Newtonian physics
misconceptions vs. alternative hypotheses
universal everyone has them!
independent of intelligence Aristotle ? Jean
Buridan ? Galileo ? Newton!
retrograde amnesia of physicists
implications for structure and development of
cognition perceiving the world as Newtonian!
reliable instruments to detect the presence
and change of naïve beliefs
large body of data for comparisons from
high school to grad school
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Naïve Physics ? a system of common sense beliefs
about the physical world
Research problem Develop simple and reliable
instruments to distinguish systematically
between naïve and Newtonian beliefs about
motion and force. Evaluate the effectiveness
of physics instruction in changing naïve
beliefs.
Will discuss instrument design, extensive data,
implications
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Effects of conventional instruction (gt 1,000
univ. students) small (lt 15 improvement)
independent of instructor mode of
instruction reproducible and universal (across
the U. S.) persistence to graduate school
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Discriminating power of the FCI from saliency
of its distractors
What the answers tell us
No passive forces table just gets in the
way!
_ under pressure
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Missed by 42 of junior senior science
majors in a physics class at Harvard (1991)
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How common are these naïve beliefs?
Clerk Maxwells commentary on Herbert Spensers
appearance before Section A of the British
association (Belfast 1874)
Mr. Spenser in the course of his remarks
regretted that so many members of the Section
were in the habit of employing the word Force in
a sense too limited and definite to be of any
use in a complete theory of evolution. He
had himself always been careful to preserve that
largeness of meaning which was too often lost
sight of in elementary works. This was best done
by using the word sometimes in one sense and
sometimes in another and in this way he
trusted that he made the word occupy a
sufficiently large field of thought.
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Implications
Since students ascribe different meanings to
basic terms like force, they systematically
misunderstand most of what they hear and
read in introductory physics!
S I understand the theory, I just cant work
the problems!
Why have physics teachers and professors so
long remained insensitive to this problem?
Because
They are satisfied with their own system of
naïve beliefs about education !!
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Conventional physics instruction
is tacitly based on a system of naïve beliefs
about knowing, thinking and learning.
These beliefs are implicit in the way the
subject is taught!
Thus, they are transferred tacitly to
students, influencing the way they study!
To examine and evaluate these beliefs they
must be explicated from their tacit state, and
compared with alternatives
To that end, we need to characterize and
compare the following Belief Systems
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A comparison of Belief Systems
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From naïve physics to naïve epistemology
Caloric Theory of heat heat is a substance
transferable from one body to another.
Caloric Theory of knowledge
knowledge (caloric) is substance-like
facts and ideas are things that can be
packaged in words and distributed to students
a fact is a hard thing! Ronald Reagan
Implication A Transmissionist Theory of
Instruction
to know is to possess knowledge stuff (caloric)
to learn is to collect knowledge
to think is to manipulate knowledge
to teach is to distribute knowledge
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Let us examine Transmissionist Theory in practice
Dedicated educational researchers have probed
beyond this crude model of transmissionist
instruction to discover the operative principles
of a deep-seated theory!
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Principles of Transmissionist Learning Theory
factons items emitted by teachers to
be recorded on exams!
factinos items of profound insight and
significance emitted by professors!
factinos (being of zero conceptual mass)
pass through with little detectible effect!
Among the many deep implications of this theory
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Critique (essential to science)
Socrates the unexamined _______ is not worth
_____!
Transmissionism
Reifies concepts into things (concrete thing
metaphor)
Transmits concepts as messages (conduit
metaphor)
Communication involves more than transmission!
One _____s message is another _____s noise!
foreign language
Messages must be reconstructed from signals with
a codebook!
? a scientific alternative
CONSTRUCTIVIST Learning Theory
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Constructivist Learning Theory (one version)
Facts exist only as part of a conceptual system.
Information is meaningful only to the extent
that it can be represented within the system.
Radically new information can be incorporated
only by restructuring the conceptual system.
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Implications of Constructivist Theory
recapitulates one of the great scientific
revolutions rewriting the codebook of the
students experience!
The wonder is ______?
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Instructional implications of transmissionist
theory
Clear lectures
Impressive demonstrations
Worked examples
Lots of homework
Passive students
Hidden knowledge
Conceptual filtering
Example formula-centered problem solving
see the answer comes from a formula.
homework practice confirms this.
discount as irrelevant if not required on
exams
theory as not practical diagrams as
not essential
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Consequences of conventional problem-solving
instruction
According to Don Woods Editor, Problem-solving
News
We at McMaster University found that our
students solved over 3000 homework problems over
a four year engineering program they saw
professors solve on the board over 1000 example
problems. We could detect no improvement in
problem-solving ability . . . Students still
made the same mistakes. Something needs to be
done!
Clue ? 20 elect to draw free-body diagrams on
exams!
Constructivist moral Drill and practice is
not effective at eliminating misconceptions
and developing understanding. Practice makes
permanent!!
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Implications for instructional design
Constructivist Implementation
The teacher creates and maintains a learning
environment
No quick fixes no substitute for technical
knowhow skill
The devil is in the details Malcolm Wells,
a documented existence proof!
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Richard Feynman A Teachers Responsibility
Each generation that discovers something from
its experience must pass that on, but it must
pass that on with a delicate balance of
respect and disrespect, so that it does not
inflict is errors too rigidly on its youth, but
it does pass on the accumulated wisdom, plus the
wisdom that it may not be wisdom. It is
necessary to teach both to accept and to reject
the past with a kind of balance that takes
considerable skill. Science alone of all the
subjects contains within itself the lesson of the
danger of belief in the infallibility of the
greatest teachers of the preceding
generation. What is Science? Physics Teacher
7, 313-320 (1969)
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Summary
Student initial beliefs
about the physical world,
about knowing and learning,
are major determinants of what they learn in
intro physics
Conventional physics instruction is highly
inefficient, because
it fails to take student beliefs into account,
and
it is itself based on naïve beliefs about
learning!
This problem cannot be resolved without
a strong program of educational research and
curriculum development,
together with continued development of
scientific learning theory, broadly based in
cognitive science!
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The bottom line!
It aint what you dont know that hurts you,
Its what you know that aint so!
Mark Twain
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Brief taxonomy of (naïve) alternatives to
Newtonian force laws
(2) Motive power (impetus) ? called force
(a) Imparted by contact (b) ? mv
(c) may wear out or build up like an applied force
(3) Resistance opposes or consumes force
(4) Obstacles just get in the way!
(5) Gravity Heavier objects fall faster
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Conceptual Calibration of the FCI
3 Stages of Conceptual Evolution in Newtonian
mechanics
I. Develop universal force concept ? Recognize
agents of force (active passive) ?
Differentiated concept of motion velocity vs.
acceleration
II. Develop (vectorial) dynamical
concepts Discriminate 1st and 2nd Laws
III. Develop complete interaction concept ?
universal, reciprocal, binary Essential to the
3rd Law conservation laws
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What is a typical FCI score? ? comparative
statistics
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FCI has high validity and reliability on every
measure ? False negatives rare (these
questions too trivial for my students!)
? Misses are highly informative!
strong correlation with problem solving (?
Graduate Record Exam)
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Elements of Modeling Instruction
Impediments to learning physics (a)
Misconceptions about common physical phenomena.
(b) Misconceptions about scientific method.
(c) A view of science as a fragmented
collection of facts, rules and formulas.
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Managing Classroom Discourse (talk is not enough!)
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Empirical Design and conduct experiments to
investigate structure in physical
systems and processes.
Theoretical Construct, analyze and apply
scientific models and theories.
Technical Use scientific instruments and
modeling tools to sharpen scientific
investigation and inference.
Social Scientific discourse and
argumentation to negotiate mutual
understanding of models and
implications of experimental results.
? Teachers guide student inquiry by
organizing activities and discourse around
scientific models informed by research on
student conceptual learning
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Assessing the energy concept

• All energy is stored in some physical system.
• Energy can be transferred from one thing to
  another.
• This causes changes.
• The amount of energy in the universe is
  constant.
• Energy cannot be made, nor can it be destroyed.
• Energy tends to disperse to more and more
  objects.
• Entropy can be made, but it cannot be destroyed.

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You have a can of soda that you would like to
keep cold and a sandwich to keep warm. You have
woolen blankets and some aluminum foil. What
combination of materials would work best?
9th HS UNIV
57 42 32
6 16 23
26 30 31
3 5 9
5 6 4
a. Aluminum foil wrapped around the soda and a
woolen blanket wrapped around the sandwich. b. A
woolen blanket wrapped around the soda and
aluminum foil wrapped around the sandwich c.
Aluminum foil wrapped around each
individually. d. A woolen blanket wrapped around
each individually. e. Wrapping each separately
with either material would work equally well.
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A steel ball rolls along a smooth, hard, level
surface with a certain speed. It then smoothly
rolls up and over the hill shown below. How
does its speed at point B after it rolls over the
hill compare to its speed at point A before it
rolls over the hill?
9th HS UNIV
4 6 6
10 30 44
23 24 20
56 35 26
4 4 4
a. Its speed is significantly less at point B
than at point A. b. Its speed is very nearly the
same at point B as at point A. c. Its speed is
slightly greater at point B than at point A. d.
Its speed is much greater at point B than at
point A. e. The information is insufficient to
answer the question.
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Which of the following statements describe the
difference between a strong chemical bond and a
weak chemical bond between two atoms?
i. The strong chemical bond stores more energy
than the weak chemical bond. ii. More energy is
needed to separate strongly bonded atoms than
weakly bonded atoms. iii. More energy is
released to the environment when two atoms become
strongly bonded than when two atoms become
weakly bonded.
HS UNIV
4 1
27 36
4 5
19 20
44 38
a. i only b. ii only c. iii only d. ii and
iii only e. i, ii, and iii
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When a candle burns the energy released
9th HS UNIV
20 14 14
27 25 37
33 45 41
9 6 3
8 9 5
a. comes mainly from the wax and air b. comes
mainly from the burning wick c. is produced
mainly by the fire d. comes from the match that
lighted the candle e. Comes mainly from the wax
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A living tree in its environment
9th HS UNIV
2 1 1
28 28 24
47 56 59
4 4 7
16 7 4
a. does not possess energy b. possesses energy
that it has received from the sun c. possesses
energy that it has made as well as energy that
it has received from the sun d. possesses only
energy that it has made e. possesses energy that
it received from the sun and the energy of its
life force.
A dead tree in its environment
9th HS UNIV
59 29 21
12 27 31
7 13 13
9 19 25
10 9 9
a. does not possess energy b. possesses energy
that it has received from the sun c. possesses
energy that it has made as well as energy that
it has received from the sun d. possesses energy
that it has made e. possesses energy that it
received from the sun and still a little energy
of its life force.
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• Students have an incoherent view of energy.
• Potential energy is often ignored.
• Just a number
• An invented quantity
• Potential energy is not actual energy.
• It often is thought to have nowhere to exist,
• so it cannot really exist.

• Energy can be produced.
• Energy conservation only weakly constrains
  student
• thinking. It does not force inferences.
• Energy is not useful to students in describing
  and
• explaining natural phenomena.
• They often have to be prompted even to invoke
  it!