With the recent implementation of the K-12 curriculum in the Philippines, teachers are challenged to develop relevant, research-based, and responsive instructional materials. At present, few reference materials for use have been prepared for the required senior high school (SHS) competencies. This study developed a workbook in physical science for SHS based on the students' least learned concepts in a government-owned university in Central Luzon, the Philippines. Results revealed that the developed workbook was found to be very much acceptable (M = 3.90) by expert validators. In particular, the workbook was acceptable in terms of adequacy (M = 3.85), coherence (M = 3.90), appropriateness (M = 3.90), and usefulness (M = 3.95). Student-validators who were enrolled in a physical science course also rated the workbook acceptable (M = 3.79). The validated material is recommended for use as supplemental instructional tool in physical science course in the SHS. The material which was anchored to the analysis, design, development, implementation, and evaluation model may serve as a prototype for the development of workbooks for other courses in the K-12 SHS curriculum. Further review and evaluation of the workbook may be considered to make it more contextualized, localized, and indigenized in the Philippine setting.