Supporting submicroscopic reasoning in students’ explanations of absorption phenomena using a simulation-based activity†

The Beer–Lambert law is a fundamental relationship in chemistry that helps connect macroscopic experimental observations (i.e., the amount of light exiting a solution sample) to a symbolic model composed of system-level parameters (e.g., concentration values). Despite the wide use of the Beer–Lambert law in the undergraduate chemistry curriculum and its applicability to analytical techniques, students’ use of the model is not commonly investigated. Specifically, no previous work has explored how students connect the Beer–Lambert law to absorption phenomena using submicroscopic-level reasoning, which is important for understanding light absorption at the particle level. The incorporation of visual-conceptual tools (such as animations and simulations) into instruction has been shown to be effective in conveying key points about particle-level reasoning and facilitating connections among the macroscopic, submicroscopic, and symbolic domains. This study evaluates the extent to which a previously reported simulation-based virtual laboratory activity (BLSim) is associated with students’ use of particle-level models when explaining absorption phenomena. Two groups of analytical chemistry students completed a series of tasks that prompted them to construct explanations of absorption phenomena, with one group having completed the simulation-based activity prior to the assessment tasks. Student responses were coded using Johnstone's triad. When comparing work from the two student groups, chi-square tests revealed statistically significant associations (with approximately medium to large effect sizes) between students using the simulation and employing particle-level reasoning. That said, submicroscopic-level reasoning did not always provide more explanatory power to students’ answers. Additionally, we observed the productive use of a variety of submicroscopic light–matter interaction models. We conjecture that engaging with BLSim provided new submicroscopic-level resources for students to leverage in explanations and predictions of absorption phenomena.