Understanding undergraduate student conceptions about biogeochemical cycles and the earth system

Abstract

Research has shown the highest level of understanding in the geosciences to be the ability to think about the Earth as a dynamic system. The Earth system contains four spheres: the geosphere, the hydrosphere, the biosphere, and the atmosphere. These spheres are linked through the biogeochemical cycles that move matter and energy through the various parts of the Earth system. This study aims to fill a gap in the literature by examining how undergraduate students perceive fluxes and reservoirs of important elements within the Earth system: namely carbon, nitrogen, and phosphorus. Through interviews, concept drawings, and surveys, undergraduate students’ conceptions and alternate conceptions about the Earth System and biogeochemical cycles were collected. This study revealed that undergraduate students in both STEM and non-STEM fields tend to hold a “bio-centric” view of the carbon cycle and have more limited conceptions in terms of detail and breadth of the nitrogen and phosphorous cycles. Students who took more STEM courses and were in more interdisciplinary fields tended to have more nuanced (though not necessarily complete) conceptions of these cycles. Implications for this study involve the improvement of teaching biogeochemical concepts across disciplines, but also inform our knowledge about using these cycles in the context of systems thinking. This work also provides a baseline for future work on developing learning progressions for biogeochemical cycles and complex Earth systems and in assessing systems thinking abilities through student knowledge of biogeochemical cycles.