Identifying Conceptual Gaps in Senior High School Chemistry Through a PISA-Aligned Assessment Framework

Scientific literacy–oriented assessment has become a central goal of contemporary science education; however, Chemistry assessment practices in many senior high school contexts remain largely recall-based and offer limited diagnostic value for identifying students’ conceptual learning gaps. Within the Philippine setting, locally developed assessment tools aligned with the Programme for International Student Assessment (PISA) Science Framework remain scarce. This study examined the Chemistry mastery levels of Grade 12 students using a PISAaligned assessment instrument and identified least mastered content areas to inform instructional planning. Using a descriptive research design, data were gathered from Grade 12 students through a researcher-developed, PISAaligned Chemistry questionnaire. Analysis of students’ performance revealed that a majority did not meet expected proficiency levels, indicating substantial learning gaps. Topic-level results showed that Nuclear Chemistry, Chemical Reactions, and Atomic Structure were the least mastered areas, while performance was comparatively stronger in Chemistry in Everyday Life, suggesting greater understanding in applied and contextualized content. The findings highlight the value of PISA-aligned assessments as diagnostic tools for revealing topic-specific learning gaps and supporting evidence-informed instructional decisions. The study underscores the need for targeted instructional interventions and assessment practices that prioritize conceptual understanding and scientific literacy, particularly in abstract and conceptually demanding areas of Chemistry