Comparison of mathematics textbooks between Indonesia and Singapore is one way to assess the educational process. This article provides insight into how mathematical concepts are taught and applied in problem-solving in each country. The study provides knowledge about how mathematical concepts are constructed by teachers and students and implemented in problem-solving between countries. This study aims to compare task designs in high school mathematics textbooks between Indonesia and Singapore based on the type of task, technique, technology, and theory used, with a focus on cubes and cuboids. The comparative analysis of the two books uses praxeological theory, the main construction of Didactic Anthropology Theory, with reference to epistemological model (REM) model analysis. The research results show that there are differences in the approaches, methods, and habits used in task design in the two countries. The techniques, technology and theories found in the two task designs show that Indonesian mathematics textbooks use more verification and drawing up conclusions which are influenced by perceptual techniques. Meanwhile, the task of designing Singapore's mathematics textbooks involves more direct investigations into forming students' knowledge through physical and operational techniques. The techniques, technology, and theories used in both designs influence the number of learning obstacles. Epistemological constraints occur in Indonesian textbooks and only a few in Singapore textbooks. These findings provide insight into how to build mathematical knowledge for students through good assignment design based on a country's educational character.

In this study, a topic-based analysis of students’ academic performance in mathematics across specific topic areas in selected lower secondary schools in Rwanda was conducted. The research examined third-term exam scripts (2022-2023 and 2023-2024) of 267 Senior One (S1) and Senior Two (S2) students at Groupe Scolaire Rushara, Groupe Scolaire Sheli, and Groupe Scolaire Nyarugugu, along with data from their eight mathematics teachers. A quantitative approach was employed using ANOVA to compare students’ performance across five key mathematics topics: algebra, metric measurement, proportional reasoning, geometry, and statistics and probability. The findings revealed significant improvement in statistics and probability (p =.000, η² = 0.293) and geometry (p =.000, η² = 0.178) between S1 and S2 students. In contrast, metric measurement showed no significant difference (p =.234, η² = 0.003), while algebra demonstrated minimal improvement (p =.050, η² = 0.007). Proportional reasoning showed moderate progress (p =.000, η² = 0.057), although students continued to struggle with applying proportional relationships. These results indicate that while notable gains were made in some areas, others require targeted pedagogical interventions to improve students’ conceptual understanding and performance in mathematics. The study underscores the importance of adaptive teaching strategies, enhanced instructional materials, and a more student-centered approach to mathematics education in lower secondary schools in Rwanda.