Tracking Student Learning Across a Conceptual Landscape: Transitions and Differential Changes in Conceptual Modes During a Unit on Chemical Kinetics and Equilibrium

Abstract

Understanding chemical reactions (CR) is central to both disciplinary learning and informed en-gagement with societal issues in which content knowledge about CR is relevant. While prior re-search has mapped students’ conceptual development in CR during lower secondary education, little is known about students’ progression during upper secondary levels, particularly in response to targeted instruction. This study investigates how students’ conceptual modes – specific reasoning patterns about the start, progress, and end of chemical reactions – develop following instruction on chemical kinetics and chemical equilibrium. Drawing on a pre-post study conducted over an extend-ed instructional period, we assessed N = 183 German upper secondary students conceptual under-standing using open-ended tasks before and after participation in a digitally implemented teaching unit. Conceptual modes were analyzed both descriptively and inferentially, incorporating difference-in-differences estimation and ordinal logistic regression to examine instructional effects and the role of prior knowledge. We included subject-related interest as an exploratory covariate. Results show significant transitions towards more sophisticated mechanistic reasoning, particularly among stu-dents who received instruction on both kinetics and equilibrium. Prior conceptual modes emerged as a strong predictor of post-instruction understanding, highlighting the cumulative nature of con-ceptual development as well as the diagnostic potential associated with this approach. We discuss implications for designing learning environments that scaffold mechanistic reasoning in chemistry and support the continuity of learning progressions across educational stages.