This study assessed the efficacy of the spaced learning method compared to the activity-oriented method in improving chemistry achievement among high school students, focusing on different cognitive domains. An experimental design involving pre and post-test control groups was employed, with 106 students from two schools participating. The experimental group, consisting of 53 students, was taught using the spaced learning method, while the control group, also comprising 53 students, received instruction through the activity-oriented method. Achievement tests conducted before and after the intervention provided data for evaluating the effectiveness of the methods. Statistical analysis revealed that the spaced learning method significantly enhanced chemistry achievement compared to the activity-oriented method. Specifically, the spaced learning method demonstrated superior results across all cognitive domains, including remembering, understanding, applying, analyzing, evaluating, and creating. These findings indicate that the spaced learning method, characterized by interval-focused study interspersed with breaks, promotes better retention and comprehension of chemistry concepts. The study underscores the effectiveness of the spaced learning method in improving academic performance and recommends its integration into chemistry instruction to support student learning outcomes. This research offers valuable insights into effective pedagogical practices by highlighting the necessity for innovative teaching strategies in science education. The results suggest that educators should consider adopting the spaced learning method to achieve a deeper understanding and long-term retention of chemistry content among high school students.