Resources in Understanding Electromagnetism: Building a Conceptual Bridge for Physics Learners and Teachers [email protected] Friday, May 2, 2008 University at

Resources in Understanding Resources in Understanding Electromagnetism: Building a Electromagnetism: Building a Conceptual Bridge for Physics Conceptual Bridge for Physics

Learners and Teachers Learners and Teachers

[email protected], May 2, 2008 University at Albany, SUNY

Carolann KoleciAssistant Professor of Physics

Worcester Polytechnic InstituteWorcester Polytechnic InstituteDepartment of PhysicsDepartment of Physics

Worcester Polytechnic Institute

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PRELUDE

Ask yourself a question

Is it what, where, or why?

Solving problems requires inquiry

So why not give it a try.


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Why is Physics Perceived as Difficult?

Fox Trot Cartoon Strip, by: Bill Amend


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HERE’S WHAT REALLY HAPPENED…


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Never Underestimate Creativity

lim [ 1/(t – 8) ] = ∞

t→8

Now what do you get for:

lim [1/(t – 4) ] =

t→4


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ORGANIZATION

• Theory/Statement of the Problem

• Learning Resources in EM

• Assessment Tools

• Pilot Study at WPI (Spring 2006)

• Current Results (some excerpts)

• Future Directions


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ACKNOWLEDGMENT

• Special thanks to Prof. John Belcher, Prof. Sen-Ben Liao, Prof. Peter Dourmashkin, Prof. Sahana Murthy, and the MIT Visualizations Team for their inspiration, collaboration, and support.

• We kindly acknowledge support from the Davis Foundation and the NSF.

• Thank you to UAlbany (Department of Physics) for the opportunity to share our work.


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STATEMENT OF THE PROBLEM

• “I read the book, take notes on the chapter, attend all lectures and recitations, do all of the sample problems from the book, and get ‘good’ grades on my homework, yet I still cannot do well on the exams.”—anonymous introductory physics student


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EM Road Blocks (excerpts)

• Electricity flows like water in a pipe to the receiver. Only needs one wire.

• Electrons flow at the speed of light.

• Electric companies supply electrons to your house.

• Magnets only attract.

• Magnets only attract to iron.

• Only magnets have magnetic fields.


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More Impediments

• The Three Principles of EM: V = IR,

I = V/R, R = V/I

• Coulomb Syndrome

• Students accept the existence of a cause only when they can imagine an effect (i.e. to calculate E, only need q(enc) )

• When the RHR becomes the LHR


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Learning Resources in EM

• Physlets; Belloni & Christian; Davidson College:

http://webphysics.davidson.edu/cise_qm/• PHysics Education Technology Project

(PHET); University of Colorado (Boulder): http://www.colorado.edu/physics/EducationIssues/research/research_projects.htm

• Technology Enabled Active Learning (TEAL); MIT: http://web.mit.edu/8.02t/www/802TEAL3D/visualizations/electrostatics/index.htm


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ON CREATING EXAMS…

What it is that a test item measures (that is, its content validity) depends not on what adult experts or critics think it measures nor on what item statistics suggest about the item but rather on how individual test-takers perceive and react to the test or item.... To delve into what it is that a test or test item measures for particular test-takers requires some kind of observation or communication with them on an individual basis (Haney & Scott).


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ON CREATING EXAMS…

Likewise, students' classroom experiences play into their perceptions and response to the fairness of testing. Reporting on her interviews with students, Thorkildsen (1999) found that their judgment of how much testing is fair had to do, in part, with the curriculum and instruction they experienced on a day-to-day basis. Consequently, those taking a test that differs radically in mode or content from their classroom learning may respond negatively to the test itself, especially if the test does not allow them to demonstrate what they know how to do.


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LEARNING AND TRANSFER

“Learning often cannot be translated into a generic form until there has been enough mastery of the specifics of the situation to permit the discovery of lower order regularities which can then be recombined into higher-order, more generic coding systems.”—Jerome Bruner, Going Beyond the Information Given (1973)


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LEARNING

• Thorndike, Woodworth, et al. were among the first to use transfer tests to examine assumptions about learning (1901)

• Initial learning is necessary for transfer• Knowledge that is overly contextualized

can reduce transfer• Transfer is an active, dynamic process All

new learning involves transfer based on previous learning

Mestre et al., Rebello et al., etc.


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FACTORS THAT INFLUENCE TRANSFER

• Time on Task (e.g. Garner 1974)• Motivation to Learn (e.g. Schwartz et

al., 1999)• Context (e.g. Lave, 1988)• Problem Representations (e.g. Spiro

et al., 1991)• Relationship between Learning and

Transfer Conditions (e.g. Brown 1986)


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Assessment Tools in E&M

• CSEM: Conceptual Survey in Electricity and Magnetism; Hieggelke, Maloney, O’Kuma, Van Heuvelen

• DEEM: Diagnostic Exam in Electricity and Magnetism; Marx

• DIRECT: Determining and Interpreting Resistive Electric Circuits Concepts Test ; Engelhardt and Beichner

• BEMA: Brief Electricity and Magnetism Assessment; Ding, Chabay, Sherwood, Beichner


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DEEM

To fill the need for a tool testing introductory, undergraduates' knowledge of basic concepts in electricity and magnetism (EM), the investigator has developed a sixty-six item, multiple-choice diagnostic exam (DEEM). The exam is intended to provide physics instructors with a psychometrically sound instrument that serves three general purposes: (1) gauge students' pre-instructional knowledge (baseline assessment), assess students' post-instructional achievement, and provide scores to determine students' conceptual learning gains; (2) yield results that are maximally diagnostic to instructors by highlighting students' most common misconceptions and reveling patterns of responses which are easily interpreted by physics instructors; and (3) provide the physics education research community with a tool to measure the relative effectiveness of various curricula.

The exam covers the following basic concepts of EM: forces on charged particles in electric or magnetic fields; properties of electric fields and magnetic fields; properties of electrostatic potential and potential energy; Maxwell's Equations; and induction, with Lenz's Law. Items comprising the DEEM do not require calculus, explicit calculations, or memorization of fundamental constants; are pictorially based; and generally explore high-symmetry scenarios.

Reference: http://www.compadre.org/per/items/detail.cfm?ID=3786


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BEMA

Evaluating an electricity and magnetism assessment tool: Brief electricity and magnetism assessment

written by Lin Ding, Ruth Chabay, Bruce Sherwood, and Robert J. Beichner

The Brief Electricity and Magnetism Assessment (BEMA), developed by Chabay and Sherwood, was designed to assess student understanding of basic electricity and magnetism concepts covered in college-level calculus-based introductory physics courses. To evaluate the reliability and discriminatory power of this assessment tool, we performed statistical tests focusing both on item analyses (item difficulty index, item discrimination index, and item point biserial coefficient) and on the entire test (test reliability and Ferguson's delta). The results indicate that BEMA is a reliable assessment tool.

Physical Review Special Topics - Physics Education Research: Volume 2, Issue 1, Pages 7

Reference: http://prst-per.aps.org/abstract/PRSTPER/v2/i1/e010105


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Pilot Study at WPI (Spring 06)

• Sophomore/Junior Level Course in Electricity and Magnetism at the level of Griffiths (N = 26: Frsh=4, Soph=18, Jr=2, Sr=2)

• 85% class = PH majors; 15% = ECE majors

• Female = 5 (19%), male = 21 (81%)


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Course Background

• Vector/Tensor Analysis is a prerequisite for the course

• Material Discussed: Griffiths, Chapters 1,2,3,5

• 2/3 of HW is traditional, 1/3 are visualizations in the MasteringPhysics framework (MP problems done in special classroom)


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Hint for Question One


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Problem One (35 points): As shown in the diagram below, a rod of length L consists of a uniform line charge λ. (a) With V = 0 at infinity, what is V at P? (10 points) (b) On the diagram below, for the situation described in part (a), sketch the direction of the net electric field at point P (5 points). (c) Determine the electric potential, V, at point P, if the linear charge density is non-uniform and obeys the relationship λ = cx, where c is a constant having units of charge per length squared (15 points). (d) Set up, but do not evaluate, an expression for the electric field at Point P, for the situation described in part (c). (5 points)

Problem One (35 points): As shown in the diagram below, a rod of length L consists of a uniform line charge λ. (a) With V = 0 at infinity, what is V at P? (10 points) (b) On the diagram below, for the situation described in part (a), sketch the direction of the net electric field at point P (5 points). (c) Determine the electric potential, V, at point P, if the linear charge density is non-uniform and obeys the relationship λ = cx, where c is a constant having units of charge per length squared (15 points). (d) Set up, but do not evaluate, an expression for the electric field at Point P, for the situation described in part (c). (5 points)


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Problem Three: Short Answer Questions: Please answer the following possibly unrelated questions, using a minimum of mathematics (5 points each, 30 points total).

a. We give below three possible expressions for the z (vertical) component of the electric field at point P, Ez. Which one of

these is correct? The circular loop has radius r and carries a uniform line charge λ.

i.) Ez = (2πr)(λ/(4πεo)) [z/(z2 + r2 )5/2 ]

ii.) Ez = (πr)(λ/(4πεo)) [1/(z2 + r2 ) ]

iii.) Ez = (2πr)(λ/(4πεo)) [z/(z2 + r2 )3/2 ]


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Preliminary Data Average (%)

Standard Deviation

Mastering Physics Assignment 80 14

Traditional Homework Assignment 86 8

Exam Two 85 13

Exam Two, Question One 89 17

Exam Two, Question Three, Part A 99 0.39

Student Ranked Degree of Helpfulness*** 2.96 0.87

***Likert Scale: 1-5


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Correlation Matrix****

Variables(1) (2) (3) (4)

(1) MasteringPhysics Assignment 1.00 0.41 0.37 0.26

(2) Traditional Homework Assignment 0.41 1.00 0.21 0.01

(3) Exam Two 0.37 0.21 1.00 0.81

(4) Exam Two, Question One 0.26 0.01 0.81 1.00

****Product Moment Correlation


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Grades Factored According to Student Rank of MasteringPhysics Helpfulness

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10

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30

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50

60

70

80

90

100

rank 1 rank 2 rank 3 rank 4 rank 5

Likert Scale (Rank of Helpfulness)

MP

Exam 2

HW

Exam 2, Q1


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MasteringPhysics Assignment Average versus Student Perceived Degree of Helpfulness

0

10

20

30

40

50

60

70

80

90

100

0 1 2 3 4 5

Likert Scale (Helpfulness)


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Exam Two Grade versus MasteringPhysics Assignment Grade

y = 0.4475x + 41.717

R2 = 0.1681

0

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20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120

MasteringPhysics Assignment Grade (%)


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Student Feedback

“The Java applets were moderately interesting, as were many of the visuals. However, many of the better ones were hidden in the hints, which the grade system encourages users to not view.”—WPI Student

“It was a good summary of the concepts we learned, but some of the visualizations were a little ambiguous.”—Another WPI Student


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FUTURE DIRECTIONS

MasteringPhysics and Visualizations Pilot Study is currently ongoing at MIT. Findings?

Run more Comparison Tests: Academic Major, Gender, Class Year, CSEM gains

Interview students at both WPI and MIT to learn specific misconceptions and revise curricular materials as needed

Should the MasteringPhysics assignment be more difficult than the traditional homework assignment (addressing the context morphology issue)?


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EPILOGUE

“We talk about transfer of learning when learning is displayed in a situation somewhat different from that in which the original learning occurred. If the transfer situation is so different that the use of learning encounters some barrier or difficulty, we speak of problem solving. When the situation is greatly different and the distance of transfer needed is greater still, we speak of creativity.”—Wilbert McKeachie, Teaching and Learning in the College Classroom (1986).

Documents

Resources in Understanding Electromagnetism: Building a Conceptual Bridge for Physics Learners and Teachers [email protected] Friday, May 2, 2008 University at