DIAGNOSTIC ASSESSMENT OF SENIOR SECONDARY SCHOOL STUDENTS' MASTERY AND NON-MASTERY OF SELECTED CHEMISTRY CONCEPTS IN EDE FEDERAL CONSTITUENCY, OSUN STATE, NIGERIA

Abstract

This study assessed Senior Secondary School Three (SSS III) students’ mastery and non-mastery of thermodynamics, qualitative analysis, electrolysis, and hydrocarbons in Ede Federal Constituency, Osun State, Nigeria. A descriptive cross-sectional survey with a diagnostic assessment component was adopted. From a population of 6,850 SSS III Chemistry students, 1,624 students (655 males and 969 females) were selected from 40 public and private schools using proportionate stratified and simple random sampling. Data were collected using a researcher-developed Chemistry Diagnostic Test comprising 60 multiple-choice items and three essay items scored across 18 rubric attributes. Content validity and Q-matrix alignment were evaluated by five experts, with Kendall’s W = .72. Reliability coefficients were KR-20 = .99 and Cohen’s kappa = .70. Students were classified as having mastered a concept when they demonstrated at least 50% of the mapped items or attributes. Results showed high non-mastery in thermodynamics (74%), qualitative analysis (80%), electrolysis (86%), hydrocarbons (59%), and essay items (78–88%). Comprehension, sequencing, and computation were the weakest skills. Gender was not significantly associated with essay mastery, χ²(1, N = 1,624) = 0.436, p = .509. The study recommends regular diagnostic assessment, targeted remediation, and strengthened instructional support for difficult Chemistry concepts and skills.