Development, Implementation and Iterative Refinement of a Three-Dimensional Assessment Framework for a Research-Integrated Chemistry Laboratory Course

Assessment of research-integrated chemistry laboratory courses requires approaches that capture both team outcomes and individual contributions. This study reports the development, implementation and iterative refinement of a three-dimensional assessment framework integrating teacher assessment, group peer assessment, and individual contribution ratios. A preliminary version was piloted in a surfactant chemistry elective course, and the refined framework was implemented across three cohorts (2021 to 2023, N = 73) in a research-integrated experiment involving the synthesis of sodium dodecyl sulfate and the determination of its critical micelle concentration. Grade records and questionnaire responses were analyzed. Teacher and group peer assessments were strongly correlated, although peer scores were systematically higher than teacher scores in the two earlier cohorts. Course grades were higher in later cohorts; however, because cohort membership is confounded with changes in implementation, this pattern is reported descriptively and not interpreted as evidence of improved performance. Students reported highly positive perceptions of innovativeness, helpfulness, and fairness, together with high self-ratings of ability development. These perception measures are exploratory single-item indicators and exhibit ceiling effects, so they reflect student experiences rather than verified gains in ability. Implementation revealed limitations, including leniency effects in peer assessment and negotiation bias in contribution ratios, which motivated implemented refinements such as calibration training, anonymized review, and behaviorally anchored descriptors, together with proposed future improvements such as process-based records and teacher-moderated arbitration. This study provides an evidence-informed account of how the framework functions in authentic teaching and offers a transferable basis for assessment design in research-integrated laboratory courses.