This study aimed to develop a Strategic Intervention Material (SIM) addressing the Least Learned Competencies of Grade 7 students in a public secondary school in Agusan del Sur, specifically focused on solving problems involving algebraic expressions during the 2021-2022 academic year. The research employed an educational design approach to systematically design, develop, and evaluate the intervention. The study identified the most preferred activities by student evaluators across the six facets of understanding, which included "Concept Map," "Represent Me," "My Facemask," "Tiles," "You Are X Years Old," and "Synthesis Journal." Furthermore, teacher validators rated the instructional quality of the SIM in terms of content, format, presentation, organization, and accuracy as very satisfactory, with an overall weighted mean of 3.63. These results highlighted extension activity and implementation of the SIM to address student’s difficulties in the least learned areas, contributing valuable insights for enhancing instructional materials in Mathematics education.