Goals for teacher learning about energy degradation and usefulness

Abstract

The Next Generation Science Standards (NGSS) require teachers to understand aspects of energy degradation and the second law of thermodynamics, including energy's availability and usefulness, changes in energy concentration, and the tendency of energy to spread uniformly. In an effort to develop learning goals that support teachers in building robust understandings of energy from their existing knowledge, we studied teachers' impromptu conversations about these topics during professional development courses about energy. Many of these teachers' ideas appear to align with statements from the NGSS, including the intuition that energy can be present but inaccessible, that energy can change in its usefulness as it transforms within a system, and that energy can lose its usefulness as it disperses, often ending up as thermal energy. Some teachers' ideas about energy degradation go beyond what is articulated in the NGSS, including the idea that thermal energy can be useful in some situations and the idea that energy's usefulness depends on the objects included in a scenario. Based on these observations, we introduce learning goals for energy degradation and the second law of thermodynamics that (1) represent a sophisticated physics understanding of these concepts, (2) originate in ideas that teachers already use, and (3) align with the NGSS.

Identifying content knowledge for teaching energy: Examples from high school physics

“…This time, she sees a difference in the end point of the two groups' Energy Theater representations, and infers a difference in the students' sense of energy concentration and spreading: some students show thermal energy accumulating in the box (and not transferring to the environment), whereas others show thermal energy transferring to the environment (and not accumulating in the box). Ms. Allen's attention to this issue suggests her content knowledge that in real, irreversible processes, energy spreads (within objects, to other objects, and through space, among other possibilities)-a statement of the second law of thermodynamics appropriate for secondary learners [35]. Our evidence of her content knowledge is in the questions she asks, which highlight a particular feature of students' ideas (their sense of energy concentration and spreading).…”

Productivity of “collisions generate heat” for reconciling an energy model with mechanistic reasoning: A case study

“…In the following days of the course, the teachers went on to analyze transformations of thermal energy to kinetic energy (e.g., in adiabatic expansion); recognize that some kinetic-to-thermal transformations are reversible (e.g., compression) but others are not (e.g., rubbing, deformation); realize that even when the energy of two similar systems is the same the transferability of the energy can be different; identify the conditions that determine energy transferability; and negotiate a working definition of free energy [20]. Their analysis of the energy dynamics of adiabatic compression was the basis for extended development of sophisticated concepts in thermodynamics.…”

“…Furthermore, within our own instructional context, we find many examples of ideas that are both canonically incorrect (or undeveloped) and productive [20,37,50,51]. Our informal sense is that it is not rare for such ideas to play a productive role in teachers' learning, moving them (and us) forward in understanding energy concepts.…”

“…Our informal sense is that it is not rare for such ideas to play a productive role in teachers' learning, moving them (and us) forward in understanding energy concepts. For example, Daane, Vokos, and Scherr found that teachers' sense of energy as being "used up" was not inconsistent with teachers' commitment to energy conservation; instead, it expressed an intuitive understanding of energy degradation [20]. On this basis, Daane, Vokos, and Scherr articulate learning goals for energy degradation and the second law of thermodynamics that incorporate teachers' intuitive ideas about energy, the relevant physics content being discussed, and the Next Generation Science Standards [34].…”

“…IVA. The themes of the course included (1) mechanisms of energy transfer and transformation and (2) energy degradation [20]. The data for this paper are from the first week of instruction, which focused on mechanisms of energy transfer and transformation.…”