ANALYSIS OF VISUAL REPRESENTATION OF DECOMPOSITION REACTIONS IN NIGERIA SECONDARY SCHOOL CHEMISTRY TEXTBOOK

Visual representation in chemistry textbooks play a crucial role in enhancing student’ understanding of abstract concept, such as decomposition reactions. In Nigeria, secondary school chemistry education heavily relies on textbooks as primary instructional materials. However, the accuracy, clarity, and pedagogical quality of these visual representation remain underexplored, raising concerns about their effectiveness in supporting student’ conceptual learning. Therefore, this study analysed the visual representation of decomposition reaction in Nigeria secondary school chemistry textbooks. This study used a qualitative content analysis approach to examine the visual representation of decomposition reaction in Nigeria secondary chemistry textbooks. Employing a descriptive and interpretive framework based on Johnstone’s triangle (microscopic, submicroscopic and symbolic levels), the study assessed how visuals support conceptual understanding. Three widely used and officially approved textbook were purposively sampled, and a coding framework adapted from Chen et al. (2020) guided the analysis, focusing on representation levels, functions, text-visual relationships, and linkages. Data collection involved identifying and categorizing visuals related to decomposition reactions, while both qualitative and quantitative methods, including descriptive statistics and bar charts, were used for data analysis. Validity and reliability were ensured through expert reviews, inter-rater reliability checks. Senior secondary school chemistry textbooks mainly employ macro and symbolic visual representations to illustrate decomposition reactions. New School Chemistry and Comprehensive Chemistry use only this type, while Essential Chemistry includes some purely symbolic visuals. In New School Chemistry and Comprehensive Chemistry, these visuals serve interpretational purposes, whereas in Essential Chemistry, they are used solely for organizational functions. Across all three textbooks, the visual representations are entirely aligned with the accompany text, showing full relevance. Additionally, they all demonstrate complete and sufficient correlation across multiple level of representations, reflecting strong integration between visuals and textual content. The study concluded that senior secondary school chemistry textbooks consistently depict decomposition reactions using predominantly macroscopic and symbolic visual representations, with Essential Chemistry also including purely symbolic visuals and for organization clarity. All three textbooks show complete alignment between visuals and text and a strong correlation across multiple levels of representation, promoting coherent and effective learning of decomposition reactions. The study recommended that textbook authors should consider incorporating a balanced mix of macroscopic, submicroscopic, and symbolic representations to provide students with a more comprehensive and multi-level understanding of decomposition reaction