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Dehui Hu, Rochester Institute of Technology

Noah Finkelstein, H. J. Lewandowski. University of Colorado Boulder

Assumptions and idealizations play a significant role in developing and

applying models to real-world situations. Assumptions make models more

tractable, but also impact the design of experiments (through the introduc-

tion of possible sources of systematic error) and limit the range of validity

of predictions. In this investigation, students conducted a think-aloud

laboratory activity using LEDs. Videos were coded and analyzed using

a framework developed for model-based reasoning designed for upper-

division physics laboratory classes. The analysis focuses on multiple roles

of assumptions within the activity: making, recognizing, and justifying as-

sumptions; linking assumptions to limitations of the validity of theoretical

predictions and measured results; and using knowledge of assumptions to

iteratively improve experimental results.

PST1C22: 9:15-10 p.m. Spanning Student Reasoning about P-V

Diagrams in Physics and Engineering*

Poster – Jessica W. Clark, University of Maine, Orono, ME 04468;

John R. Thompson, Donald B. Mountcastle

As part of a new effort to investigate the learning and teaching of concepts

in thermodynamics and electronics in both physics and engineering, we

have been examining student learning of thermodynamics in mechani-

cal and chemical engineering and physics courses. In thermodynamics,

students must grapple with multivariable dependence between state

properties. They are also taught to use simplified models of real substances

(e.g., ideal gas). By varying a task we have previously studied which probes

students’ understanding of the First Law, its constituent elements, and

graphical representations, we access additional specific knowledge of the

univariant temperature dependence of the internal energy of an ideal gas.

Our results show that use of this concept varies across disciplines despite

being covered in all. Additionally, the task alteration suppresses the most

common previously identified difficulty and elicits others to give a more

complete understanding of student reasoning.

*The work described has been supported in part by the National Science Foundation

under Grant Nos. DUE-0817282 and DUE-1323426.

PST1C23: 8:30-9:15 p.m. Exploring a Logical Approach to

Promoting Conceptual Understanding

Poster – David Maloney, Indiana University Purdue University, Fort Wayne,

IN 46805;

An important aspect of scientific understanding is the use of sequential,

inferential reasoning. One school of psychology argues that humans reason

through models. This project is exploring the presentation and use of ex-

plicit models of conditional and bi-conditional statements as a mechanism

for promoting conceptual understanding. Students in a calculus-based

introductory physics course were given a conditional and a bi-conditional

statement involving everyday content. The truth status of each of the seven

possible rearrangements of the original statements was identified for each

case. Students then had a weekly homework assignment that required

explicit use of these models. In addition, there was a test item of the same

format on each of the four tests during the semester. This presentation

will present the struggles the students had with using the logic involved,

with the physics concepts and with connecting the physics with the logical

reasoning.

PST1C24: 9:15-10 p.m. Causal Effects of Reasoning Skills and

Epistemologies on Content Learning

Poster – Lin Ding, The Ohio State University, Department of Teaching and

Learning, Columbus, OH 43210;

Multiple factors can affect content learning. Research in physics education

has tapped into some key factors that are postulated to be causal agents of

learning gains. These include student pre-instructional levels of scientific

reasoning and epistemological sophistication. Previous work in this mat-

ter has largely relied on qualitative case studies or correlation analysis to

demonstrate, separately, the positive relation of reasoning and epistemol-

ogy with content learning. However, the postulated causality has not been

than males when the test was given both as a pre-test and post-test in tradi-

tionally taught calculus-based introductory physics courses. In the algebra-

based courses, the performance of females was significantly worse in the

post-test but there was no statistical difference in the pre-test performance

of males and females. These trends persisted regardsless of the instructors.

We discuss possible reasons for these differences. We thank the National

Science Foundation for support.

PST1C18: 9:15-10 p.m. Investigating Student Difficulties with

Dirac Notation

Poster – Emily M. Marshman, University of Pittsburgh, Pittsburgh, PA 15260;

Chandralekha Singh, University of Pittsburgh

Quantum mechanics is challenging even for advanced undergraduate and

graduate students. Dirac notation is a convenient notation used extensively

in quantum mechanics. We have been investigating the difficulties that the

advanced undergraduate and graduate students have with Dirac notation.

We administered written free response and multiple-choice questions to

students and also conducted semi-structured individual interviews with 23

students using a think-aloud protocol to obtain a better understanding of

the rationale behind their responses. We find that many students struggle

with Dirac notation and they are not consistent in using this notation

across various questions in a given test. In particular, whether they answer

questions involving Dirac notation correctly or not is context dependent.

PST1C19: 8:30-9:15 p.m. Investigating Student Difficulties with

Time Dependence of Expectation Values in Quantum

Mechanics

Poster – Emily M. Marshman, University of Pittsburgh, Pittsburgh, PA 15260;

Chandralekha Singh, University of Pittsburgh

Quantum mechanics is challenging even for advanced undergraduate and

graduate students. In the Schrödinger representation, the wave function

evolves in time according to the time dependent Schrödinger equation. The

time dependence of the wave function gives rise to time dependence of the

expectation value of observables. We have been exploring the difficulties

that advanced undergraduate and graduate students have with time depen-

dence of expectation values in quantum mechanics. We have developed

and administered conceptual free response and multiple-choice questions

to students to investigate these difficulties. We also interviewed 23 students

individually using a think-aloud protocol to obtain a better understanding

of the rationale behind students’ written responses. We find that many stu-

dents struggle with time dependence of expectation values of observables.

We discuss some findings.

PST1C20: 9:15-10 p.m. Analogous Patterns of Student Reason-

ing Difficulties in Introductory Physics and Upper-Level

Quantum Mechanics

Poster – Emily M. Marshman, University of Pittsburgh, Pittsburgh, PA 15260;

Chandralekha Singh, University of Pittsburgh

Very little is known about how the nature of expertise in introductory and

advanced courses compares in knowledge-rich domains such as physics.

We develop a framework to compare the similarities and differences be-

tween learning and patterns of student difficulties in introductory physics

and quantum mechanics. Based upon our framework, we argue that the

qualitative patterns of student reasoning difficulties in introductory phys-

ics bear a striking resemblance to those found for upper-level quantum

mechanics. The framework can guide the design of teaching and learning

tools.

PST1C21: 8:30-9:15 p.m. Assumptions and Idealizations in

Students’ Reasoning During Laboratory Activities

Poster – Benjamin M. Zwickl, Rochester Institute of Technology, Rochester,

NY 14623-5603;

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