Conservation of energy: An analytical tool for student accounts of carbon-transforming processes

Energy and energy conservation are powerful concepts for understanding biological systems, but helping students use these concepts as tools for analysis of these complex systems poses special challenges. This chapter focuses on three issues that arise in teaching about energy in biological systems: 1. Understanding the purpose of the concept of energy. Students often use energy in cause-effect stories related to vitality or animation (“energy is what makes things happen”), rather than treating energy as an enduring entity that can be used as a tool for analysis. In instruction, we treat the principles of energy conservation as “rules to be followed.” Students use these rules to trace energy through processes and observe how energy constrains these processes. 2. Identifying forms of energy in living systems. Students often associate energy with cause, vitality, or growth in ways that do not align with scientific conceptions of energy. In our instruction, we make simplifications we feel are important for helping students develop a working discourse about energy in science classrooms: we describe energy in different forms, one of which is chemical energy that is associated with bonds of molecules. 3. Tracing energy separately from matter. Students often lack a sense of necessity for distinguishing between matter and energy (“glucose is energy”). We use physical representations of energy (twist ties) and a framework for scaffolding distinct accounts of matter and energy to help students focus on explaining matter and energy as separate entities.