Identifying Learning Gaps: A Diagnostic Chemistry Test for Secondary Students

Abstract

This study sought to develop and psychometrically validate a Grade 10 Chemistry achievement instrument intended for diagnostic assessment and to determine students’ least mastered Chemistry competencies. A researcher-constructed 50-item multiple-choice instrument was developed based on selected Grade 10 Chemistry learning competencies prescribed in the curriculum. The instrument underwent readability analysis and content validation by three experts in Chemistry education to establish content relevance, clarity, and alignment with intended learning outcomes. Following expert review, the instrument was pilot tested with 150 Grade 10 students to evaluate reliability and perform item analysis. Reliability estimation using Cronbach’s alpha yielded a coefficient of 0.846, indicating high internal consistency. Item difficulty and discrimination indices were examined, resulting in the retention of 30 items that satisfied acceptable psychometric standards. The validated 30-item achievement instrument was subsequently administered to 88 Grade 10 students from two purposively selected sections at MSU–University Training Center, Marawi City. Student performance was analyzed using a criterion-referenced framework to determine mastery levels across Chemistry learning competencies. Findings revealed differential levels of mastery, with Chemical Reactions emerging as the least mastered competency, while topics related to Solutions, Acids and Bases, and Gases and Gas Laws were moderately mastered. Overall, the results provide empirical evidence that the developed instrument demonstrates satisfactory validity and reliability and functions effectively as a diagnostic assessment tool. The study highlights the critical role of validated diagnostic assessments in identifying learning gaps and informing targeted instructional interventions to enhance the teaching and learning of Chemistry at the secondary level.