The study was conducted to investigate the effectiveness of Predict-Explain-Observe-Explain (PEOE) approach to student's performance in chemistry. This study also determined the correlation of metacognition to student achievement. Specifically, it sought to find out: (1)if there is a significant difference between the pretest and posttest scores of the metacognitive group (MG); (2) if there is a significant difference between the pretest and posttest scores of the comparison group (CG); (3 ) if there is a significant difference between the posttest scores of the MG and CG; (4) if there is a significant relationship between the metacognitive awareness and achievement in chemistry; (5) the domains of metacognitive awareness should be that are evident among MG and CG; and (6) the learning strategies that the students utilized during the accomplishment of the PEOE tasks. This quasi-experimental study used seven (7) developed tasks employing PEOE approach to promote metacognition. Instruments such as Metacognitive Awareness Inventory (MAI) to measure students' metacognitive awareness, and teacher-made summative test in Chemistry were used. Students' journal entries were also culled to validate the data and looked for unique responses that would arise from the comparison (CG) or experimental (MG) group. Results showed that both groups had significantly improved posttest scores, with MG gaining significantly higher posttest scores. For metacognition awareness, while both groups preferred procedural knowledge in the knowledge of cognition domain, they differ in the regulation domain where CG preferred comprehension monitoring while MG favored using debugging strategies. Other learning strategies identified by MG are cooperation, communication and focus on their goal.