Development of Active-Learning Curricular Materials in Thermodynamics for Physics and Chemistry

David E. Meltzer Department of Physics and Astronomy

And

Thomas J. Greenbowe Department of Chemistry

Miller Faculty Fellows 1999-2000

Our Goal: Produce effective new curricular materials on

thermodynamics • Carry out research to identify introductory students’

learning difficulties with thermodynamics;

• Devise methods for directly addressing these learning difficulties;

• Develop curricular materials for both introductory physics and introductory chemistry courses;

• Test materials with students in both courses; use insights gained in one field to inform instruction in the other.

Nature of the Materials

• “Guided-Inquiry” Worksheets: Carefully sequenced printed worksheets which guide students step-by-step through reasoning process. Primarily qualitative questions.

• “University of Washington” Model: Elicit, Confront, Resolve. Aim to deliberately trigger common learning difficulties, then guide students to confront and resolve them directly

• Heavy use of multiple representations (diagrams, graphs, charts, sketches, etc.)

Development and Testing: An Iterative Process

• Initial draft of materials subject to review and discussion by both physics and chemistry education research groups;

• Revised draft tested in lab or recitation section;

• New draft prepared based on problems identified during initial test;

• Additional rounds of testing in lab/recitation sections; further revisions;

• Analysis of student exam performance (“treated” vs. “untreated” groups);

• Entire cycle repeats.

Initial Hurdle: Different approaches to thermodynamics

in physics and chemistry

• For physicists:– Primary (?) unifying concept is transformation of internal

energy E of a system through heat absorbed and work done;

– Second Law analysis focuses on entropy concept, and analysis of cyclical processes.

• For chemists:– Primary (?) unifying concept is enthalpy H [H = E + PV]

(H = heat absorbed in constant-pressure process)– Second law analysis focuses on free energy (e.g., Gibbs

free energy G = H – TS)

Learning Difficulty: Weak Understanding of “State Function” Concept

Instructional Strategy: Examine two different processes leading from state “A” to state “B”:– What is the same about the two processes?– What is different about the two processes?

• Elicit common misconception that different heat absorption must lead to different final temperatures (i.e., ignoring work done)

• Guide students to identify temperature as a prototypical state function

• Strengthen conceptual distinction between changes in state functions (same for any processes connecting states A and B), and process-dependent quantities (e.g., heat and work)

Learning Difficulty: Failure to recognize that entropy increase of “universe” (not system) determines

whether process occurs spontaneously

Instructional Strategy: Present several different processes with varying signs of Ssystem and Ssurroundings

(Present Ssurroundings information both explicitly, and in form of G or H data)

Ask students to decide:

• Which processes lead to increasing disorder of system?

• Which processes occur spontaneously?

Etc.

Learning Difficulty:Not distinguishing clearly between heat and temperature

Instructional Strategy I: Confront students with objects that have equal temperature changes but different values of energy loss.

Instructional Strategy II: Guide students through analysis of equilibration in systems with objects of same initial temperature but different heat capacities.

Question Types Incorporated in the Worksheets

I. “Expository” Material (Lecture Notes/Text Material designed in highly interactive format to guide students toward development of concepts.)

II. Multiple-Choice Questions for Peer Instruction in Large Classes (Structured sequences of multiple-choice questions stressing qualitative, conceptual understanding: for use with classroom communication systems [e.g., “flash cards” or “Classtalk”] in which instantaneous feedback is obtained from the whole class simultaneously.)

III. Material to Elicit Learning Difficulties (Questions designed to elicit well-known learning difficulties, and to lead students to confront these difficulties directly.)

IV. Material to Deepen Comprehension (Questions designed to deepen students’ understanding of a concept, by presenting concepts in a wide variety of contexts using multiple representations [verbal, mathematical, graphical, diagrammatic, pictorial, etc.])

V. Material to Improve Quantitative Problem-Solving Ability (Questions designed to improve students’ problem-solving abilities by “conceptually dissecting” quantitative problems and breaking them up into conceptual elements.)

Summary

• We have initiated a long-term project to develop improved thermodynamics curricula:

– for both physics and chemistry

– for both introductory and advanced courses

– which will be usable in both large and small classes

• New curricular materials will be based on extensive research on student learning (employing written diagnostics, student interviews, etc.)

• New materials will be continually tested and revised, and their effectiveness assessed.