Assessment and Practice in Educational Sciences 3092-717X In Press 2026 11 01 The Analysis of the Role of Integrated Critical Thinking Instruction in Improving Mathematics Performance among Secondary School Students: A Mixed-Methods Study in Tehran Schools The Analysis of the Role of Integrated Critical Thinking Instruction in Improving Mathematics Performance among Secondary School Students: A Mixed-Methods Study in Tehran Schools 1 15 10.61838/japes.263 EN Journal Article 2026 01 16 <p>The present study aimed to analyze the role of integrated critical thinking instruction in improving mathematics performance and critical thinking skills among secondary school students in Tehran using an exploratory sequential mixed-methods approach. This study employed an applied mixed-methods design with an exploratory sequential approach. In the qualitative phase, data were collected through semi-structured interviews with 20 mathematics education experts and experienced secondary school teachers, classroom observations, and document analysis. The qualitative findings were analyzed using thematic analysis in MAXQDA software to identify the major components of critical thinking in mathematics education. In the quantitative phase, a quasi-experimental pretest-posttest design with control and experimental groups was implemented. The participants included 120 tenth-grade students selected from four secondary school classes in Tehran, with two classes assigned to the experimental group and two classes to the control group. The intervention consisted of eight 90-minute instructional sessions integrating critical thinking strategies into mathematics teaching. Data collection instruments included a researcher-made mathematics performance test. Quantitative data were analyzed using descriptive statistics and analysis of covariance (ANCOVA) in SPSS software. The qualitative findings identified major themes including analytical reasoning, reflective thinking, conceptual understanding, inquiry-based learning, collaborative reasoning, and real-life application of mathematics. Quantitative findings demonstrated that integrated critical thinking instruction had a statistically significant effect on students’ mathematics performance and critical thinking abilities. ANCOVA results revealed significant differences between the experimental and control groups in mathematics performance, F(1,117)=73.92, p&lt;0.001, η²=0.39, after controlling for pretest differences. The findings indicated that integrating critical thinking strategies into mathematics instruction significantly enhances students’ mathematics achievement, analytical reasoning, conceptual understanding, and reflective thinking abilities. The study supports the effectiveness of learner-centered and inquiry-based instructional approaches in improving mathematics education and highlights the importance of incorporating critical thinking components into secondary school curricula and classroom practices.</p> https://www.journalapes.com/index.php/apes/article/download/263/283