Effective communication depends on mastering English grammar, yet numerous Grade 7 students face challenges with its concept. Using the ADDIE instructional design tool, this study aimed to create and evaluate a grammar workbook specifically for Grade 7 students. Pre-test and Post-test evaluations were conducted in this design-based approach to measure students’ grasp of parts of speech, morphology, and syntax. The research was conducted at Guadalupe National High School with 52 Grade 7 students selected randomly. The result showed that students have low proficiency levels in morphology and syntax; nonetheless, they demonstrate a significant difference between the pre-test and post-test results (p<0.001), highlighting the value of the workbook. Additionally, both experts and students rated the workbook as “highly acceptable” in content, presentation, and organization. These findings suggest the research to integrate the workbook into the Grade 7 English curriculum and enhance it with more interactive features and digital tools.