This study aimed to develop and use teacher-made instructional materials otherwise known as Strategic Intervention Materials (SIMs), and investigated the impact of these intervention materials in teaching the identified least learned concepts in Science VI namely: Circulatory System, Nervous System and Respiratory System. The study was a mixed method research which utilized an explanatory sequential design where quantitative data collection and analysis occurs first, followed by a qualitative data collection and analysis. It was revealed that there was a significant difference between the pre-test and post-test performance of the students. The utilization of the SIMs is an effective intervention that made students obtained better scores in the posttest
