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Traditional vs. Problem Based Approaches to Teaching Introductory Physics 2001 Science Educators’ Conference

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Traditional vs. Problem Based Approaches to Teaching Introductory Physics2001 Science Educators’ Conference

David P. Wick

Clarkson University

Acknowledgements: Michael W. Ramsdell

Joseph Hruska

- A strong program should emphasize experiential learning, open-ended problem solving and development of analytic and collaborative learning skills.
- Students should have the opportunity to experience all aspects of scientific analysis including the design, development and executionof a successful experimental investigation.

- Students should have access to experiences that encourage the development of verbal and mathematical models used to mimic the natural world.
- A strong program should provide exposure to experimental, theoretical and numericaldevelopment, allowing students to truly master a variety of basic skills in problem solving and data analysis.
[i]American Association of Physic Teachers, "Goals of the Introductory

Physics Laboratory," Am. J. Phys. 66, 483-485 (1998).

Outstanding challenges for the scientific community are to:

- Find innovative methods for achieving these goals.
- Develop tools for assessing the performance of our students and the effectiveness of our methods.

- PER has logged over three decades worth of scientific investigation with attention given to:
- Identification of student misconceptions.

- Development of pedagogical strategies to provide a

more effective learning experience for students.

- Assessment of educational approaches.

- Student minds are not blank slates.
- Many students defend their beliefs from the high seat of experience.
Student difficulties are not reflections of “stupidity”, but rather deeply rooted and seemingly logical consequences of perception reinforced with personal experience.

[2]Aarons, A. B.,Teaching Introductory Physics, John Wiley & Sons (1997).

- Examples are well documented.

Ball A

Ball B

Question: Do these two balls ever have the same speed?

Study: 300 student interviews at University of Washington

(calculus-based physics course).

Misconception: The balls have the same speed at the moment one

40% passes or is next to the other. Students associate

“same speed” with “passing” or “same position.”

[3]McDermott, L. C.,“Research on Conceptual Understanding in Mechanics,” Phys.

Today, 37, 24-32 (1984).

Question: A ball is thrown vertically upward from ground level

with an initial speed vo. The ball reaches a maximum

height d and returns to ground level. Which statement

is TRUE?

43% A) The initial velocity is equal to the final velocity;

32% B)The average velocity for the entire flight is zero;

9% C) The acceleration on the way down is greater than the

acceleration on the way up;

16% D) The average acceleration for the entire flight is zero.

Study: 500 student responses at Clarkson University – Exam I

(calculus-based physics course).

Misconceptions: “Velocity” and “Speed” are interchangeable.

Acceleration depends on direction of motion.

- They understand the concept.
- It is believable.
- It is useful.
- It conflicts with their current beliefs.
“Understanding the way students and scientists think is the key to developing more effective methods of science teaching and is itself an intellectual challenge.”

[4]Reif, F.,“Scientific Approaches to Science Education,” Phys. Today, 39, 48-53 (1986).

- Lecture-based (Peer instruction, Interactive Lectures, …)
- Recitation-based (Tutorials, Cooperative Problem Solving, …)
- Lab-based (Projects, Problems, Simulations, …)
- Combination (Physics by Inquiry, Workshop Physics, Physics Studio …)
[5]Redish, E.,“New Models of Learning and Teaching,” Conference of Physics Department Chairs (1997).

A typical first-exam grade distribution in Physics I at Clarkson University:

The bi-modal nature is indicative

of a well prepared and an ill

prepared group.

Typical Laboratory Manual Contains:

Title

Apparatus – Description of equipment

Introduction – Theory, figures, equations

Procedure – Step 1, Step 2, …

Tables and Graphs, etc.

- Modification of the traditional laboratory / recitationto incorporate a problem based learning experience with an emphasis on open-ended problem solving.
- Provide students with the opportunity to:
- Formulate verbal models

- Develop mathematical models (theoretical and numerical)

- Design experimental procedures

- Test the predictive capability of their models.

- Current Participation: 10-15 % of class
- Lecture Component – Traditional
- Lab/Recitation Component – Problem Based
“Modeling is the name of the game in the Newtonian

World”

[6]Hestenes, David,“Modeling Games in the Newtonian World,”

Am. J. Phys. 60, 732-748 (1992).

- Physics I – Modeling the Motion of a
Matchbox Car

- Physics II – Modeling the Motion of an
Electric Train

- David Hestenes (Arizona State University) and others have developed a quantitativeassessment tool for checking a student's understanding of basic concepts in physics.
- FCI topics cover the fundamental issues and concepts in Newtonian dynamics.
- FCI distractors (wrong answers) are “malicious” -- they are based on research that exploits students' most common misconceptions.

- Richard Hake (Indiana University) conducted a study of 62 classes (6542 students) from around the country. He showed that for a wide range of initial pre-test scores, the fractional gain is similar for classes of similar instructional method.
- For Traditionalclasses: h ~ 0.23 +/- 0.04
- For IE classes: h ~ 0.48 +/-0.14
[7]Hake, Richard,“Interactive Engagement vs. Traditional Methods,”

Am. J. Phys. 65, (1995).

Problem Statement:

Develop a theoretical model describing the motion of a MatchboxTM car racing down an arbitrarily shaped track. Your model should describe the velocity of the car at any point along the track. (Identify the most important effects that should be included in this model).

Design an experimental procedure to evaluate the predictive capability of your model.

Facts:A typical MatchboxTM car has a die-cast body, two axles, and four hard plastic wheels, with a total mass (m) of approx. 50 g. The combined mass of the wheels is less than 3 % of the total mass of the car.

The plastic wheels rotate on the axle through direct contact with a sliding type motion. Air resistance can be accentuated by mounting a shield of varying area.

- Consider the forces acting on the car:
Frictional Model

Drag Force Model

- Applying Newton’s Second Law will allow us to develop a model for the velocity of the car.

Case by Case Assumptions

Case Agravitational potential andkinetic energies

Case Bsliding friction

Case Ctrack shape

Case Dair resistance

This multi-level approach illustrates how each successive stage in model development provides a correction to the previous one.

Measuring friction and air drag

We can extract values for and kby measuring

the velocity of the car at different points along a flat,

horizontal track using a series of photogates.

0.049 (No Shield)

k=1.48 x 10-4(kg/m) (No Shield)

Goal:Predict where your car will first come momentarily to rest.