Warren M. Christensen

Student ideas regarding entropy and the second law of thermodynamics in an introductory physics course

We report on students’ thinking regarding entropy in an introductory calculus-based physics course. We analyzed students’ responses to a variety of questions on entropy changes of an arbitrarily defined system and its surroundings. In four offerings of the same course we found that before instruction, no more than 6% of all students could give completely correct responses to relevant questions posed in both general and concrete contexts. Nearly two-thirds of the students showed clear evidence of conservation-type reasoning regarding entropy. These outcomes were little changed even after instruction. Targeted instruction that guided students to recognize that entropy is not a conserved quantity appears to yield improved performance on qualitative questions related to this concept.

Stereotyped: Investigating Gender in Introductory Science Courses

This study investigated the performance of women and men across introductory science courses, stereotype threat endorsement, and the utility of a values-affirmation writing task in reducing achievement gaps. Data analysis revealed no achievement gap, little stereotype threat endorsement, and no impact of the values-affirmation writing task on performance.

Addressing Student Difficulties with Concepts Related to Entropy, Heat Engines and the Carnot Cycle

We report the rationale behind and preliminary results from a guided‐inquiry conceptual worksheet (a.k.a. tutorial) dealing with Carnot’s efficiency and the Carnot cycle. The tutorial was administered in an upper‐level thermodynamics course at the University of Maine. The tutorial was implemented as the third in a three‐tutorial sequence designed to improve students’ understanding of entropy and its applications. Initial pre‐ and post‐tutorial assessment data suggest that student understanding of heat engines and the Carnot cycle improved as a result of tutorial instruction.

Student understanding of calorimetry in introductory calculus-based physics

We report on students’ thinking regarding calorimetry concepts in an introductory calculus-based physics course. We found that despite overall good performance, only about half of the students were able to provide correct answers with satisfactory explanations. A number of persistent student difficulties were found to affect approximately 40% of the students even after instruction, including apparent confusion about the meaning of specific heat and misunderstanding of the nature of thermal energy exchange. Student response patterns varied significantly depending on the context of the question and often reasoning did not appear to be consistent among contexts, instead favoring “rule-based” reasoning. Interviews with students suggest that difficulty with algebraic manipulations is a significant contributor to incorrect responses on calorimetry questions.

A comparison of student evaluations of instruction vs. students' conceptual learning gains

For decades, Student Evaluations of Instruction (or Teaching) have been used to evaluate the quality of teaching at universities and colleges nationwide. Often, student evaluations are the sole measurement of teaching quality in higher education, and as a result have been the subject of extensive study. While many of these investigations make claims about the correlations between student evaluations of instruction and student learning, the validity and reliability of both the methodologies and measurement tools in these studies is not clear. The study reported here uses research-based conceptual inventories, such as the Force Concept Inventory (FCI), to make the more rigorous claim that Student Evaluations of Instruction do not correlate with conceptual learning gains on the FCI. In addition, grading leniency by an instructor (i.e., giving easy A grades) does not correlate with increased student evaluations of instruction.