Despite their central role in many issues of importance to modern society, complex topics such as carbon cycling remain difficult for many students to reason about, in part because of the large spatial and temporal scales involved. Partly due to the confusion engendered by carbon cycling, public discussion of related topics, such as the potential role of biofuels in our society, is highly subject to slogan-dominated and often polarized discourse. Thus, providing students with the tools to reason critically through complex topics is one of the more valuable contributions formal education can make to public life. In particular, helping students to see the rootedness of the wide variety of ecological details in a small number of fundamental principles can help them to reason effectively, even when confronted with particular situations different from those they learned in school. We designed assessment items for use with students from grades 4-10, centered around the major components of the global carbon cycle, and investigated differences in their reasoning pre- and post-instruction. The instruction utilized materials that we had designed to highlight the conservation of matter and energy (with energy degradation) throughout the processes comprising the carbon cycle, such as photosynthesis, respiration and combustion.

Results/Conclusions

The students in our study demonstrated many of the same difficulties in understanding carbon cycling processes as our own and other researchers’ work has shown, such as a simplified gas-gas exchange between animals and plants, and a tendency to convert matter to energy when a gaseous product occurs. The key features of the materials we designed appeared to improve student performance in many areas, though. In particular, students were better able to trace matter and energy through processes by the end of the instructional sequence, although their ability to utilize scientific terminology often outstripped their capacity to explain phenomena in a scientifically principled way. As a result, their ability to articulate the application of scientific concepts to topics like biofuels remained limited, despite improvement from their pre-tested reasoning patterns. Still, results from one year of using these materials in instruction are promising, and it seems likely that continued exposure to models that foreground key ecological principles will further enhance students’ ability to integrate those principles into their decision-making as citizens.