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.