Abigail R. Daane

Conserving energy in physics and society: Creating an integrated model of energy and the second law of thermodynamics

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 present the beginnings of a conceptual model of the second law as it relates to energy, with the aim of creating models and representations that link energy degradation, the second law, and entropy in a meaningful way for learners analyzing real-life energy scenarios. Our goal is to develop tools for use with elementary and secondary teachers and secondary and university students.

Energy Tracking Diagrams.

Energy is a crosscutting concept in science and features prominently in national science education documents. In the Next Generation Science Standards, the primary conceptual learning goal is for learners to conserve energy as they track the transfers and transformations of energy within, into, or out of the system of interest in complex physical processes. As part of tracking energy transfers among objects, learners should (i) distinguish energy from matter, including recognizing that energy flow does not uniformly align with the movement of matter, and should (ii) identify specific mechanisms by which energy is transferred among objects, such as mechanical work and thermal conduction. As part of tracking energy transformations within objects, learners should (iii) associate specific forms with specific models and indicators (e.g., kinetic energy with speed and/or coordinated motion of molecules, thermal energy with random molecular motion and/or temperature) and (iv) identify specific mechanisms by whic...

Energy Conservation in Dissipative Processes: Teacher Expectations and Strategies Associated with Imperceptible Thermal Energy.

American Association of Physics Teachers, College Park, Maryland 20740, USA(Received 1 October 2014; published 12 March 2015)Research has demonstrated that many students and some teachers do not consistently apply theconservation of energy principle when analyzing mechanical scenarios. In observing elementary andsecondary teachers engaged in learning activities that require tracking and conserving energy, we find thatchallenges to energy conservation often arise in dissipative scenarios in which kinetic energy transformsinto thermal energy (e.g., a ball rolls to a stop). We find that teachers expect that when they can see themotion associated with kinetic energy, they should be able to perceive the warmth associated with thermalenergy.Theirexpectationsareviolatedwhenthewarmthproducedisimperceptible.Inthesecases,teachersreject the idea that the kinetic energy transforms to thermal energy. Our observations suggest that apparentdifficulties with energy conservation may have their roots in a strong and appropriate association betweenforms of energy and their perceptible indicators. We see teachers resolve these challenges by relating theoriginal scenario to an exaggerated version in which the dissipated thermal energy is associated withperceptible warmth. Using these exaggerations, teachers infer that thermal energy is present to a lesserdegree in the original scenario. They use this exaggeration strategy to track and conserve energy indissipative scenarios.

Teaching About Racial Equity in Introductory Physics Courses

Even after you have decided to tackle a problem like racial equity, it may seem daunting to broach the subject in a physics classroom. After all, the idea of a (typically White) instructor in power tackling a sensitive topic such as social justice can be scary in any (mostly White) classroom. Not only that, but physics is typically viewed as a “culture with no culture.” The physicist’s quest for objectivity, along with a general focus on a fixed set of laws and formulae, support the treatment of this subject as untouched by people. Sometimes it is easier to ignore the problem and just focus on the Conservation of Energy Principle. However, ignoring the striking underrepresentation of ethnic/racial minorities and women in both the physics classroom and the field at large is a great disservice to all our students. We take the position that the persistence of representation disparities in physics is evidence that culture plays a role in who and what is involved in physics. Instructors have an opportunity to explicitly address the absence of equitable circumstances in classrooms and highlight the obstacles that contribute to the disparity (e.g., varied access to learning opportunities and support structures, dominant cultural norms, stereotype threat, implicit bias, hidden curricula, etc.). We acknowledge that incorporating these discussions in a physics classroom is fraught with difficulty, but we also believe that trying to lead these discussions is better than ignoring the problem. Furthermore, a set of resources for teachers interested in leading these discussions has been developing in the physics teacher community. Rifkin offers resources for leading a two-week unit on equity designed for secondary science classrooms. Here we describe another possible pathway for integrating a shorter equity unit into the traditional content of a (predominantly White) university physics classroom, addressing racial inequity and sharing common student responses that may arise.