Addressing students' reasoning difficulties in thermal physics

Recent investigations into student learning of thermal physics at the undergraduate level have shown that most students in introductory courses face significant obstacles in mastering fundamental concepts in this area. [M. E. Loverude, C. H. Kautz, and P. R. L. Heron, Am. J. Phys. \textbf{70}, 137 (2002); D. E. Meltzer, Am. J. Phys. \textbf{72}, 1432 (2004).] Results from a variety of institutions indicate that up to 80{\%} or more of all students fail to complete introductory courses with an ability to use the first law of thermodynamics in problem solving, while related confusion with entropy and second-law concepts is also widespread. Our ongoing investigation of student learning of thermal physics at the advanced undergraduate (junior-senior) level is probing the evolution of students' reasoning as they attempt to integrate the macroscopic and microscopic /statistical viewpoints into a coherent understanding. This work confirms that difficulties with fundamental concepts persist for a majority of students at this level as well. Among the specific difficulties identified are a strong tendency to attribute state-function properties to process-dependent quantities such as heat and work, a complementary failure to recognize the state-function property of entropy in irreversible processes, and confusion regarding the application of the second law to entropy changes in non-isolated systems. I will present data that characterizes these learning difficulties in more detail and reflects their prevalence at different levels of instruction. We have been developing and testing a variety of pedagogical strategies aimed at addressing these difficulties at both the introductory and advanced undergraduate level. I will outline and discuss these strategies along with a preliminary assessment of their effectiveness, and show examples of the curricular materials that are under development.