Clark, Thompson, and Mountcastle on PV diagrams in physics and engineering

J. W. Clark, J. R. Thompson, and D. B. Mountcastle
Investigating Student Conceptual Difficulties in Thermodynamics Across Multiple Disciplines: The First Law and P-V Diagrams
Proceedings of 121st ASEE (American Society for Engineering Education) Annual Conference and Exposition (2014).

Thermodynamics is a core part of the curriculum in physics and many engineering fields. While individual courses in each discipline appear to cover many of the same topics at some level, the emphasis, applications, and many representations are idiosyncratic to the field. Education researchers in both disciplines have studied thermodynamics learning and teaching. Physics education researchers have identified student difficulties with foundational concepts such as heat, temperature, and entropy as well as with larger grain-sized ideas such as state variables, path-dependent processes, etc.  Engineering education research shows analogous findings and has identified additional difficulties unique to engineering contexts, such as confusion between steady-state and equilibrium processes.
     An open question is the extent to which discipline-specific research findings apply across disciplines.  Previous work by us and our colleagues in physics education research has explored student difficulties with thermodynamics and statistical mechanics in upper-division physics courses.  We have recently broadened the scope of our own investigation to include mechanical and chemical engineering courses, to see whether similar difficulties are present in these disciplines and how certain instructional pedagogies may affect student learning.  At our institution, thermodynamics is not covered in the introductory physics course sequence, so for most students this is their first formal encounter with the topic.
     Our initial focus is on the First Law of Thermodynamics and its constituent elements, as this topic is fundamental to all the courses of interest.  We have administered hand-written, free- response questions to students at various points before and/or after instruction.  The questions discussed here require interpretation of graphical information about thermodynamic processes. We have coded responses according to student reasoning (e.g., area under the curve, time- related) provided in the data so as not to confine our understanding of student ideas  We find that most reasoning patterns are present in all disciplines although the frequency varies by discipline. Initial answering patterns are similar across disciplines with a high proportion of students responding with incorrect ideas.  The post-instruction patterns are improved but show persistence of some specific difficulties (e.g. work is path-independent).  These outcomes vary between courses and are consistent with disciplinary emphasis and individual instructional practice.