This study aimed to investigate the effect of project-based learning strategies on the metacognitive skills of Grade 5 students at Sumagonsong Elementary School during the School Year 2021-2022. This is an experimental research design that utilized the pre-test and post-test assessments. Sixty (60) grade 5 students were used as a respondent from two heterogeneous sections which were selected through matched-pairing using their second-quarter grades as a basis. The first group received case-based instruction, while the second group received just-in-time instruction. In this study, a 45-item validated metacognitive test was employed to assess whether there was a significant difference between the pre-test and post-test scores of the two groups. The study revealed that the pre-test scores of the respondents in the two experimental groups as to their metacognitive skills in terms of planning, monitoring, and evaluating were in the beginning and developing levels, indicating that students possessed poor metacognitive skills. The post-test results of the respondents in both groups revealed that they performed better after the treatment, which indicated that they had acquired enhanced metacognitive skills. Likewise, a significant difference was found between the pre-test and post-test scores of both groups exposed to project-based strategies. However, there’s no significant difference in the effectiveness of case-based teaching and just-in-time teaching in enhancing metacognitive skills such as planning, monitoring, and evaluating. Keywords: Project-Based Learning Strategies, Metacognitive Skills, T-test, Philippines