Energy is an important crosscutting concept in all science disciplines, and energy conservation is widely regarded as one of the most important principles in physics.1–3 Over the years, numerous graphical representations have been proposed that allow learners of physics to visualize energy states and dynamics in a particular situation.3–7 Each diagram highlights different aspects of energy and therefore may represent different conceptualizations of energy. Bar charts,8 for example, foreground the idea of multiple categories of energy to account for the distribution of energy in a system across those energy types. Similarly, pie charts5 highlight relative distribution of energy among different energy types. While bar charts are able to represent negative energy, pie charts emphasize that there is a certain, total amount of energy available that is distributed over different types. Various energy tracking diagrams (e.g., PET energy source-receiver diagrams,9 Energy Tracking Diagrams3) foreground the localization of energy along a chain of energy transfer processes and within the involved objects.10In this paper, we present the Energy-Interaction Diagram, a representation for energy dynamics in a physical system that highlights energy conservation and guides users to derive a mathematical model for energy changes in a system during a process of interest. The Energy-Interaction Diagram was originally developed by the late Wendell Potter (formerly of the University of California, Davis) for use in the Collaborative Learning through Active Sense-making in Physics (CLASP) curriculum.11 In our adaptation of the CLASP curriculum at San José State University (SJSU) over several semesters, we have formalized some of the ways the diagram has been used in practice at UC Davis and at SJSU. Our intent here is to provide the reader with the necessary resources to adopt and/or adapt Energy-Interaction Diagrams for instructional use beyond the CLASP curriculum because we think that they are powerful representations for modeling energy dynamics and versatile tools for answering many interesting questions about physical phenomena.A cornerstone of CLASP is its focus on the scientific practice of modeling: creating specific models for the energy dynamics in a particular physical system. For the original developers, the term model refers to “the collection of ideas and the relationships among those ideas that, when grouped together, prove useful to [the] students as they make sense of, develop explanations of, and make predictions of phenomena relevant to their needs.”11 We adopt this view of models that takes them as the malleable, ever-changing objects of scientific activity that scientists create and modify to understand the physical world.When engaging in the process of modeling a physical system in CLASP, students have to make a number of conscious decisions: They have to (1) choose a physical system, (2) choose an appropriate time interval to inspect the process of interest, (3) identify changes in certain properties of the system throughout the process, and (4) recognize whether any interactions occur between a system and its environment, or (5) between objects within system boundaries. The Energy-Interaction Diagram provides a productive scaffold for students to make those decisions when modeling the energetics of a system and to derive a quantitative model for the energy dynamics in a particular physical system that undergoes a specific physical process.
Benedikt Harrer and Cassandra Paul. "Modeling Energy Dynamics with the Energy-Interaction Diagram" The Physics Teacher (2019). doi:10.1119/1.5126824