A physics laboratory instructor used action research to effectively implement a 5E instructional approach, which incorporated scientific practices. The instructor explored how to integrate the instructional approach into practice, challenges present in the implementation, and students' learning experiences. The data were collected during three consecutive semesters through instructor and student reflections, weekly lesson plans, and lesson artifacts. These qualitative data sources were analyzed for emergent codes to develop categories. The results indicated that the instructor's reflections helped to appropriate the existing physics laboratory curriculum into the 5E model and support the curriculum with additional formative assessment tasks. The instructor also explored students' experiences in engaging in scientific practices. Students' reflections and lesson artifacts revealed their challenges in scientific explanations, experimental design, use of models, and measurements, which guided the instructor to modify the instruction.