The paper reports on an empirical study on adopting an innovative pedagogical design in project-based learning to improve upper primary students' problem solving skills in science learning. A Grade 6 class in a Hong Kong primary school was involved in this study. The findings show that the students produced high group artifacts/projects in problem-solving quality and were positive in facing challenges in their project-based learning process. This indicates that project-based learning with PF instructional design can be an effective way to develop students' problem solving skills. Copyright © 2018 authors.