Physics

The second law of thermodynamics is typically not a central focus either in introductory university physics textbooks or in national standards for secondary education. However, the second law is a key part of a strong conceptual model of energy, especially for connecting energy conservation to energy degradation and the irreversibility of processes. We are developing a conceptual model of the second law as it relates to energy, with the goal of creating models and representations that link energy, the second law, and entropy in a meaningful way for learners analyzing real-life energy scenarios. We expect this model to help learners better understand how their everyday experiences relate to formal physics analyses. Our goal is to develop tools for use with elementary and secondary teachers and secondary and university students.

The nature of energy is not typically an explicit topic of physics instruction. Nonetheless, verbal and graphical representations of energy articulate models in which energy is conceptualized as a quasimaterial substance, a stimulus, or a vertical location. We argue that a substance ontology for energy is particularly productive in developing understanding of energy transfers and transformations. We analyze classic representations of energy—bar charts, pie charts, and others—to determine the energy ontologies that are implicit in those representations, and thus their affordances for energy learning. We find that while existing representations partially support a substance ontology for energy and thus the learning goal of energy conservation, they have limited utility for tracking the flow of energy among objects.