What learning progressions on carbon-transforming processes tell us about how students learn to use the laws of conservation of matter and energy

AbstractWe report on learning progression research that tracks how students develop an understanding of matter and energy conservation as they pertain to the carbon-transforming processes of combustion, photosynthesis, cellular respiration, digestion, and biosynthesis. We find that typically only 10% of students in American high schools develop scientific explanations of these processes where they successfully conserve matter and energy (atoms in the inputs match those in the outputs and chemical energy is accurately associated with changes in chemical bonds). Students with confused explanations do not use the conservation laws to monitor their ideas. We present data that indicate that explicit instruction and consistent assessment on the use of the conservation laws as tools for understanding the carbon-transforming processes can advance students’ understanding