Assessing conceptual understanding in high school chemistry: particulate nature of gas concept test (PNGCT) with Rasch modeling

This study evaluates the combined analysis of a two-tier test and Rasch analysis on learning assessment. A quantitative exploratory design was conducted on the validated 10-item Particulate Nature of Gas Concept Test (PNGCT) to assess learning among Grade 11 learners (n = 235) and Rasch model analysis. Rasch's analysis revealed that all items fit well within the model, and learners' performance, expressed as a mean percentage, followed approximately a normal distribution based on cognitive levels: understand (26%), apply (52%), and analyze (22%). Conception analysis showed a complete understanding of some easy items at the understand and apply levels. However, items at the analyze level were difficult and alternative conceptions were detected. Conceptual Understanding Test (CUT) Evaluation model emerged from synthesizing the analysis of the PNGCT. The combined Rasch analysis and two-tier test provided a deeper insight into student conception and performance. This assessment strategy has a potential utility in other programs and fields of study beyond chemistry.