A Comparative Study of Upper Secondary Biology Textbooks in Iran and Finland through the Lens of PISA 2015 Scientific Literacy Framework

Background and Objectives: : Scientific literacy, as defined by the PISA 2015 framework, framework (Program for International Student Assessment) encompasses not only content knowledge but also scientific competencies, contextual understanding, and attitudes toward science. This study compares the twelfth-grade biology textbooks of Iran and Finland to evaluate how each aligns with this multidimensional construct. Methods: A mixed-methods content analysis was conducted on the complete texts of both official textbooks using a validated five-dimension checklist aligned with PISA 2015. Two independent raters coded all content (κ = 0.76). Quantitative data were analyzed via independent t-tests and two-proportion Z-tests (α = 0.05). Findings: The Iranian textbook demonstrated significantly stronger coverage and conceptual depth in core topics; especially genetics and biotechnology, and higher-quality visual representations (mean = 4.1 vs. 2.8, p < 0.001). Conversely, the Finnish textbook excelled in scientific competencies: it featured more critical-thinking activities (3.7 vs. 1.9, p < 0.001), collaborative learning tasks (3.2 vs. 1.5, p < 0.001), and application-oriented exercises (53% vs. 29%, p = 0.0006). Finland also adopted a more balanced global perspective, integrating crisis-aware and solution-focused narratives. Conclusion: Neither textbook fully realizes all PISA 2015 dimensions in isolation. Iran prioritizes content accuracy; Finland emphasizes process-oriented learning. An integrative model—combining Iran’s rigorous content design with Finland’s active-learning pedagogy—could serve as a robust framework for 21st-century biology education. Limitations include the exclusive focus on textbooks; future research should examine classroom enactment.