Using student drawings of biogeochemical cycles to explore earth systems thinking abilities

Biogeochemical cycles are the fundamental construct connecting all parts of the Earth system. Cycling of elements like carbon, nitrogen, and phosphorus involves multiple fluxes and reservoirs through all components of the broader Earth system, making them an excellent gateway to examining systems thinking. One tool to try to understand student conceptions of these cycles is their drawings of various biogeochemical cycles. Specifically, the way that students depict reservoirs and fluxes in their drawings can give us valuable insight into their basic systems thinking abilities. In this exploratory study, we analyzed undergraduate student sketches of the carbon, nitrogen, and phosphorus cycles to determine the number of fluxes and reservoirs depicted in each one and the types of reservoirs pictured. We performed statistical analyses to explore if there were differences between the number of fluxes and reservoirs shown between students in STEM and non-STEM fields. We also performed correlation analysis to explore if the number of courses in various scientific disciplines was related to the number of fluxes and reservoirs shown. Results showed that students from STEM disciplines draw cycles with significantly more fluxes and reservoirs than their non-STEM peers. Additional analysis also showed that the number of chemistry and biology courses is most correlated to the number of fluxes and reservoirs depicted. Principal components analysis of carbon cycle drawings found that carbon cycle drawings tended to fall into “geo-centric” and “bio-centric” archetypes, with “bio-centric” drawings being more common and non-STEM majors consistently creating “bio-centric” drawings. This suggests that interdisciplinary training may be important in the development of systems thinking in undergraduate STEM students. It also suggests that more work is needed to integrate systems thinking skills into introductory courses, particularly those that serve non-STEM students.