Development of a Measurement Instrument to Assess Students’ Conceptual Understanding in Three Levels of Chemical Representation of Galvanic Cells by Using the Rasch Model

This study aimed to develop a Rasch-model-based assessment tool to assess students’ conceptual understanding on three levels of chemical representation within the context of galvanic cells. The conceptual understanding framework for developing a test was structured into three levels according to the content complexity presented in the Thai high school chemistry curriculum. Level 1 focused on identifying and recalling basic knowledge of the galvanic cells using only one representation level, Level 2 involved understanding cell reactions and explaining galvanic cell operations through multiple representations, and Level 3 required the analysis of principles and application of the galvanic cells in complex problems using multiple representations. A two-tier multiplechoice test comprising 11 items was developed, aligned with the defined levels of conceptual understanding. The instrument was administered to 293 Grade 11 students in Thailand. The results indicated strong measurement properties, including construct validity, acceptable person reliability (0.71), and excellent item reliability (0.97).