Active participation in project-based learning (PBL) could develop students` knowledge and crucial learning skills across various disciplines. However, the implementation of PBL in the K-12 classroom is usually impeded by the stepby-step PBL cycle. Micro project-based learning (MPBL), which advocates and adheres to the learning principles and mechanisms of PBL with constraining the learning cycle in shorter periods, has been considered as a lightweight alternative to PBL process. As an exploration, this study explored the impact of MPBL on the conceptual understanding of sodium bicarbonate and the crucial learning skills in chemistry class at upper-secondary schools. The quasi-experimental research was implemented for 125 students, with an experimental group receiving MPBL teaching and a control group receiving conventional teaching. In the study, data including knowledge tests, crucial learning skills survey, and student interview were collected and analysed. The results indicated that MPBL was effective in the development of students' conceptual understanding and crucial learning skills (i.e., communication and collaboration, information integration, independent learning, and problem-solving). The study will inform the pedagogical innovation in chemistry education and teaching practices in chemistry class.