Development, Validation and Evaluation of Microlearning Materials for Grade 10 Learners in Chemistry and Biology

Addressing persistent learning difficulties in secondary science education requires instructional strategies that align with human cognitive architecture. This study investigated the development, validity, and instructional effectiveness of microlearning materials designed for Grade 10 Chemistry and Biology competencies. Employing mixed-methods, pretest-posttest research design in a public secondary school setting, the study evaluated the impact of targeted micro-modules on student conceptual understanding. The diagnostic phase established that core competencies in Chemistry (Chemical Reactions, Conservation of Mass, Balancing Equations, and Reaction Rates) and Biology (Homeostasis and Evolution) posed a high challenge to learners under conventional, lecture-heavy instruction. Evaluation by ten Science master teachers and instructional media experts using Department of Education quality assurance tools confirmed that the developed microlearning materials achieved High validity across Content, Format, Presentation, and Accuracy and Up-to-datedness. Following the instructional intervention, student academic performance demonstrated a dramatic progression, escalating from a low pretest baseline mean to a posttest mean representing a very high level. Inferential analysis using a paired-samples test confirmed a statistically significant performance gain, rejecting the null hypothesis. These findings prove that chunking complex scientific concepts into bite-sized, dual-coded modules effectively reduces working memory strain and accelerates conceptual mastery. The study provides strong empirical support for adopting modular microlearning frameworks in secondary science curricula, informing educational policy, instructional design, and classroom practice.