588 ©Authors This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND 4.0). International Journal of Learning, Teaching and Educational Research Vol. 24, No. 6, pp. 588-608, June 2025 https://doi.org/10.26803/ijlter.24.6.27 Received Apr 4, 2025; Revised May 29, 2025; Accepted May 31, 2025 Development and Evaluation of a Collaborative Lesson Planning Model for Science Teacher Internships Everlita Ebillo-Canalita * Mindanao State University – Iligan Institute of Technology Iligan City, Philippines University of San Carlos, Talamban Campus Cebu City, Philippines Richard Ramos Jugar University of San Carlos, Talamban Campus Cebu City, Philippines Abstract. Preservice science teachers often struggle with lesson planning due to limited pedagogical knowledge, insufficient collaboration, and a lack of structured reflective practice—challenges that are especially evident during internships. To address these issues, this study developed, validated, and evaluated a collaborative lesson planning (CLP) model to support both preservice and in-service teachers. Using a concurrent nested mixed-methods design, the study prioritized qualitative data while incorporating quantitative insights, all collected during the second semester of the internship. The model was implemented with 31 preservice and 17 in-service basic science education teachers. Informed by theoretical and empirical foundations, the CLP model addresses lesson planning challenges, fosters social interaction, and cultivates a community of practice. Validation by science education experts confirmed its feasibility, contextual relevance, and alignment with the Philippine teacher education curriculum. Evaluations by the implementing teachers revealed key themes and sub-themes, categorized as follows: strengths, including improved teacher preparation, enhanced lesson quality, and strengthened teamwork; weaknesses, such as time constraints, limited autonomy, and conflicting ideas; opportunities, including professional growth, deeper reflective practice, and addressing misconceptions; and threats, notably teachers’ fixed mindsets and unequal involvement. Findings show that the model enhances pedagogical knowledge, promotes reflective practice, and strengthens collaboration, contributing to professional learning communities and improved science teaching. Its innovation lies in providing a structured, * Corresponding author: Everlita E. Canalita, everlita.canalita@g.msuiit.edu.ph