This study makes both theoretical and practical contributions to research on instructional quality in multilingual secondary science education.

First, it contributes to pedagogical research by providing empirical evidence on how structured, multilingual physics workbooks can function as an effective instructional intervention in upper secondary classrooms where subjects are taught through multiple languages. By integrating sequenced explanations, scaffolded problem-solving tasks, visual representations, and subject-specific academic vocabulary, the workbooks support students’ simultaneous development of conceptual understanding and disciplinary language. The findings extend existing research on CLIL and multilingual STEM education by demonstrating how carefully designed learning materials can reduce cognitive load and improve coherence between instruction, learning activities, and assessment.

Second, the study contributes to instructional quality research by highlighting the role of teacher-developed materials as a mechanism for improving lesson organization, pacing, and formative assessment practices. The workbooks provided a consistent instructional framework that supported alignment between curriculum objectives, classroom activities, and exam-oriented tasks. Teacher reflection data indicate that the structured design enabled systematic identification of instructional challenges and informed iterative improvements in teaching practice.

Third, the study offers a methodological contribution through the use of a classroom-based mixed-methods approach that combines learning outcome data with qualitative insights into instructional processes and student experience. This approach illustrates how practitioner-led research can generate robust evidence while remaining closely connected to classroom realities.

Finally, the study contributes practical value by demonstrating that low-cost, scalable instructional tools can meaningfully enhance teaching quality and student achievement in linguistically diverse contexts. The findings are relevant for teachers, school leaders, and education researchers seeking sustainable strategies to support high-quality physics instruction in multilingual education systems.

This study employed a classroom-based mixed-methods research design within a teacher-led pedagogical inquiry framework. The methodology was chosen to examine both measurable learning outcomes and qualitative aspects of instructional quality in a multilingual upper secondary physics classroom.The study was conducted with upper secondary students at Nazarbayev Intellectual School, where physics is taught in English as a third language. The intervention consisted of the systematic use of teacher-developed structured multilingual physics workbooks across selected instructional units.The workbooks functioned as the primary instructional intervention. They included sequenced conceptual explanations, scaffolded step-by-step problem-solving tasks, subject-specific academic vocabulary with diagrams, homework assignments, challenging problems, and exam-oriented tasks aligned with curriculum requirements. 1)Quantitative data were collected through: Pre- and post-intervention assessments, including diagnostic tests Summative examination results aligned with curriculum objectives These data were used to compare student performance before and after the implementation of the workbooks, with particular attention to multi-step reasoning and conceptual problem-solving tasks. 2)Qualitative data were gathered through: Classroom observations focusing on instructional coherence, lesson pacing, and student engagement Analysis of student written work, examining structure, use of physics terminology, and problem-solving approaches Student feedback questionnaires, capturing perceptions of clarity, support, and learning processes Teacher reflective notes, recorded after each instructional unit to document observed challenges, strengths, and areas for improvement. Quantitative data were analyzed descriptively to identify trends in student achievement. Qualitative data were analyzed thematically to identify recurring patterns related to instructional quality, student engagement, and language-related learning challenges. Triangulation of data sources was used to enhance the credibility of the findings.

The study indicates that the use of structured multilingual physics workbooks contributes positively to both student learning outcomes and instructional quality in upper secondary physics education. Quantitative analysis of pre- and post-intervention assessments shows measurable improvements in students’ exam performance, particularly in tasks requiring multi-step reasoning, conceptual understanding, and the application of physics principles. A reduction in language-related errors and greater consistency in problem-solving structure were also observed in student work. Qualitative findings suggest that the workbooks enhanced instructional coherence by providing a clear and consistent framework linking lesson objectives, classroom activities, and assessment tasks. The structured design supported more effective lesson pacing and facilitated formative assessment by enabling the teacher to identify learning difficulties more systematically and respond through targeted instructional adjustments. Students reported that the inclusion of step-by-step explanations, visual representations, and subject-specific vocabulary improved clarity and helped them engage more confidently with physics content taught through a third language. From a pedagogical perspective, the study demonstrates that teacher-developed instructional materials can function as a practical mechanism for reflective practice and continuous improvement. The process of reviewing student responses and documenting areas for improvement after each unit informed subsequent teaching decisions and material refinement, strengthening the relationship between knowing and acting in classroom practice. Overall, the findings highlight the potential of low-cost, scalable instructional tools to support equitable access to high-quality physics education in multilingual school contexts. The study contributes evidence that structured workbooks can enhance both student achievement and instructional effectiveness, offering practical implications for teachers and school leaders seeking sustainable strategies to improve science teaching under changing linguistic and educational conditions.

Abrahams, I., & Millar, R. (2008). Does practical work really work? A study of the effectiveness of practical work as a teaching and learning method in school science. International Journal of Science Education, 30(14), 1945–1969. Coyle, D., Hood, P., & Marsh, D. (2010). CLIL: Content and language integrated learning. Cambridge University Press. De Jong, T. (2010). Cognitive load theory, educational research, and instructional design: Some food for thought. Instructional Science, 38(2), 105–134. Johnstone, A. H. (2006). Chemical education research in Glasgow in perspective. Chemistry Education Research and Practice, 7(2), 49–63. Shulman, L. S. (1986). Those who understand: Knowledge growth in teaching. Educational Researcher, 15(2), 4–14. Sweller, J., Ayres, P., & Kalyuga, S. (2011). Cognitive load theory. Springer. Wellington, J., & Osborne, J. (2001). Language and literacy in science education. Open University Press.