This study adopts a mixed-methods approach to explore the effectiveness of the Layered Curriculum (LC) on students' English grammar achievement. Quantitative data were gathered using the Solomon Four-Group Research Model, a robust experimental design, to assess the impact of the LC on grammar achievement scores. In both experimental groups, English grammar lessons were conducted with LC activities, while in the control groups, the methods and techniques in the textbook of the school's current curriculum were applied. In addition to quantitative findings, qualitative data revealed positive responses from students towards the various learning activities facilitated by the application, including visual materials, practical activities, and interactive grammar activities. The results indicate significantly higher grammar achievement scores among students exposed to the LC activities compared to control groups. Students highlighted the LC's encouraging features, emphasizing the right to control their own learning process, the freedom to choose activities, and the opportunity to present completed tasks orally. They identified the provision of adequate teaching materials, a student-centered learning environment, and opportunities for active participation as key factors contributing to their positive learning experiences. In addition, this study revealed that the responsibility for learning is assumed by the student and learning is accountable.