Didactic Strategy for the Teaching of Isotope Mixing Models for Stable Isotopes Relevant to Biogeochemistry Based on the Analogy with Color Composition

The continuous advances in mass spectrometry techniques have pushed forward the frontiers of all branches of the isotope biogeochemistry field. In environmental studies, different isotope ratios as determined in different reservoirs offer the opportunity, for example, to identify pollution sources and to trace metal fluxes within the trophic web and in dietary studies. Despite its relevance, trace metal isotope biogeochemistry is infrequently taught in undergraduate courses because it demands a rather high level of complexity of teaching strategies and abstraction capacity from students. Additionally, available didactic material for introducing mixing source modeling with stable isotopes relevant to biogeochemistry is scarce. In this context, the present study applies a visually appealing didactic strategy based on the analogy between colors (analog domain) and isotopic compositions (target domain), in order to encourage and assist the teaching–learning processes of this new subject in environmental science and chemistry classes. We demonstrate how familiar and simple concepts can be applied for introducing challenging subjects. In a setting that restricts in-person academic activities such as during a pandemic, the development of appealing visual approaches is imperative to engage students during online classes. The didactic strategy proposed herein was put to the test during remotely taught classes on the topic of “Environmental Impact Assessment Methodology” (winter 2021, 18 students) and “Environmental Contamination” (summer 2020, 18 students, and winter 2021, 20 students) of the Postgraduate Program in Geochemistry at the Fluminense Federal University (Rio de Janeiro, Brazil). Students’ feedback was very positive; they found our approach stimulating, and it helped them to better visualize, understand, and interpret the targeted learning outcomes.