Physics Education Research: Some Themes

Overview

• History of PER

• Some results

• Ideas for teaching

• Your experiences?

Physics Education Research

• Almost 30 years old

• Physics PhDs available in this area

• Active group at tOSU

• Application of scientific techniques to determine what does and does not work in physics instruction

Tabula Rasa?

• Students come to physics with pre-conceptions, about mechanics in particular

• Hard to dislodge!• Conventional instructional modes can be

ineffective• Students can hold contradictory ideas, one

they “believe” and another for the tests

Example

• Compare brightnesses of A, B, and C• Only 15% correct in calculus-based university

intro physics• Unaffected by conventional instruction!

What’s “Conventional”?

• Verbal explanation or textbook presentations of correct concepts or principles

• Problem solving that doesn’t emphasize conceptual understanding

• (Also “cookbook” labs…)

Other Common Misconceptions

• Motion implies force

• Electric current is “used up” in a circuit

• Gravity is stronger near the ground, which is why objects speed up as they fall

• Many Aristotelian ideas!

Implication

• It is necessary to discover and explicitly address student misconceptions– Not enough to just show the right way– Wrong modes of thought must be

unlearned

• Misconceptions may not stop students from doing well on conventional exams

Active Learning

• Encourage students to construct their own knowledge structures

• Exercises (could be in groups)

• Demonstrations

• Peer Instruction

Peer Instruction

• Developed by Eric Mazur (Harvard)

• Focus on conceptual questions

• Multiple choice

• Students choose answers, poll class

• Discuss with neighbors

• Re-poll and discuss

Example

• The balloonA. leans to the leftB. leans to the rightC. stays vertical

a

Air-filled box

Basic Ideas

• Force students to explain and defend their ideas to peers

• Improve conceptual understanding

• Eavesdropping on discussions can give insight into misconceptions, confusions– Can address these in discussion

Effect on Problem Solving

• Improved conceptual understanding leads to better problem solving

• Doesn’t work the other way!

• Should test conceptual understanding too, though

Problem Solving Strategies

• Students’ procedural knowledge is generally fragmented, unorganized– Look at physics as a collection of mostly

unrelated formulas– Formula-hunting style of problem solving– All knowledge equally important (x =

(1/2)at2 vs. F = ma)

Problem Solving Strategies

• Can require students to use a structured problem-solving strategy– Many physics texts describe these– Others available (see references)– Students write up solutions in a standard

format

• Designed to help them build more coherent patterns of knowledge

More on Problems…

• Some should be “context rich”– Force students away from formula hunting

• Typically best in group work– Ideally mixtures of stronger and weaker

students– All of them benefit!

• These can be created from “context poor” textbook problems

Sample C-R ProblemWhile visiting a friend in San Francisco, you decide to drive around the city. You turn a corner and find yourself going up a steep hill. Suddenly a small boy runs out on the street chasing a ball. You slam on the brakes and skid to a stop, leaving a skid mark 50 ft long on the street. The boy calmly walks away, but a policeman watching from the sidewalk comes over and gives you a ticket for speeding. You are still shaking from the experience when he points out that the speed limit on this street is 25 mph. After you recover your wits, you examine the situation more closely. You determine that the street makes an angle of 20° with the horizontal and that the coefficient of static friction between your tires and the street is 0.80. You also find that the coefficient of kinetic friction between your tires and the street is 0.60. Your car's information book tells you that the mass of your car is 1570 kg. You weigh 130 lb, and a witness tells you that the boy had a weight of about 60 lbs and took 3.0s to cross the 15-ft wide street. Will you fight the ticket in court?

Focus

• On phenomena rather than abstractions

• Ask questions like “How do we know…?” and “Why do we believe…?”

• Demos!

• Require qualitative explanations

The Zeroth Law of Education

• If you don’t test for it, they won’t do it!

• Homework and exams should include conceptual questions– Must go beyond pattern-matching and

symbol manipulation

Your thoughts…?

References

• A. B. Arons, Teaching Introductory Physics (Wiley, 1997)• E. Mazur, Peer Instruction, A User’s Manual (Prentice Hall,

1997). Project Galileo website:http://galileo.harvard.edu/home.html

• R. Knight, Five Easy Lessons: Strategies for Successful Physics Teaching (Addison Wesley, 2004)

• UMN (Context-rich and cooperative problem solving):http://groups.physics.umn.edu/physed/index.html

• tOSU PERG:http://perg.mps.ohio-state.edu/main/

• UW PERG:http://www.phys.washington.edu/groups/peg/

References, ctd.

• UMD PERG:

http://www.physics.umd.edu/rgroups/ripe/perg/• R. Felder’s collection of educational resources at NCSU (focus

on chemical engineering):

http://www.ncsu.edu/felder-public/RMF.html