Comparing Student Reasoning on Graphical Problems in Chemical Kinetics and Physics Motion Using Eye-Tracking

Graphs are essential tools in introductory STEM courses, yet students often read them as pictures rather than quantitative representations of changing quantities. This study examined how 18 first-semester general chemistry students interpreted two structurally parallel, three-question graphs in chemistry and physics: a concentration-time graph of a chemical reaction and a position–time graph of a walking person. Using eye-tracking, written work, and accuracy data, we found high but asymmetric performance (82% in chemistry; 89% in physics), with rate calculations as the most challenging items in both domains. Students commonly conflated value with rate and sometimes averaged from the origin across discontinuities, with these difficulties more prevalent in chemistry. Trials resulting in correct answers typically followed a question → axes → curve pattern with brief returns to the prompt, whereas trials resulting in incorrect answers often showed early and repeated attention to salient non-target graph features without careful attention to axes. These findings support teaching graph comprehension as a discipline; it is a general but context-sensitive skill and has potential value in an axes-first, rise-over-run-based protocol for rate-of-change reasoning.