Development and Validation of a Critical Thinking Test Instrument on Acid-Base for Senior High School Students

Critical thinking is an essential competency in chemistry learning, yet its assessment requires valid and reliable instruments capable of measuring students’ reasoning beyond answer selection. This study aimed to develop and validate an evidence-based critical thinking test instrument for senior high school students on acid-base chemistry. The study employed a Research and Development design using the 4D model consisting of Define, Design, Develop, and Disseminate stages. The instrument was developed as a 20-item open-ended two-tier multiple-choice test integrating five critical thinking indicators: interpretation, analysis, inference, evaluation, and self-regulation. Content validity was evaluated by three expert validators, while empirical validation involved 86 senior high school students in Jayapura. Item characteristics were analyzed using the Item Response Theory approach with QUEST software. Expert validation resulted in an overall validity score of 96.11%, categorized as very valid. Empirical analysis showed that 12 of 20 items met the psychometric criteria, with INFIT MNSQ values ranging from 0.74 to 1.26 and person reliability of 0.87. Eight items produced zero scores and were excluded from calibration. The findings indicate that the developed instrument demonstrates strong psychometric quality and can be used to assess students’ critical thinking in acid-base chemistry.