includes bibliographical references.

This study investigated the effect of differentiated instruction on the numeracy skills of Grade 11 students at San Agustin (Stand-Alone) Senior High School, lriga City, during the School Year 2024-2025. Utilizing a quasi- experimental research design, the study employed pre-test and post-test assessment using the Albay Numeracy Assessment Tool (ALNAT) to evaluate the performance of two intact class sections: one experimental group exposed to differentiated instruction, and one control group taught using traditional methods. A total of 38 Grade 11 STEM students participated in this study. Findings revealed a significant in the experimental group, with their performance progressing from the "Needs Major Support" level to the " Emerging" level. The control group, while showing some improvement, remained within the lower proficiency bracket. Statistical analysis using paired and independent sample t-tests confirmed that the improvement in the experimental group was significantly greater than that of the control group (p < 0.00001). Additionally, a post-intervention survey indicated high student acceptability and positive perceptions of differentiated instruction. The results affirm the effectiveness of differentiated instruction in enhancing numeracy skills and suggest its potential as an inclusive and impactful teaching strategy for senior high school mathematics education. The study recommends its broader adoption and further exploration of related pedagogical innovations to support diverse learners in developing foundational math competencies.