Examining the Relationship Between Science Curriculum Coherence, Instructional Alignment, and Student Achievement Across Nigerian Geopolitical Zones: A Nationally Representative Study

This study examined the relationships among science curriculum coherence, instructional alignment, and student achievement across Nigerian secondary schools in all six geopolitical zones. Curriculum coherence, the degree to which curriculum standards, instructional content, and assessment are logically and sequentially connected, is a foundational driver of educational quality, yet its measurement and relationship to outcomes in Nigeria's diverse educational landscape has not been investigated at national scale. A nationally representative cross-sectional design was used. One hundred and twenty secondary schools stratified across all geopolitical zones participated. Data were gathered from 720 Science teachers using a Curriculum Coherence Rating Scale and an Instructional Alignment Observation Protocol, while student achievement was measured through a nationally standardised Science Competence Assessment. Reliability indices exceeded 0.82. Multilevel Structural Equation Modelling was used to test the proposed national model. Results revealed that curriculum coherence had the largest total effect on student achievement, with instructional alignment fully mediating the coherence-achievement relationship at the school level. Significant inter-zonal variation was found, with South West schools recording highest and North East schools lowest on both indicators. The study makes an original contribution to national science education policy by providing an evidence-based model for curriculum quality assurance. Keywords: curriculum coherence, instructional alignment, student achievement, Nigeria, nationally representative study.