To prove the credibility of empirical and theoretical claims about the ties between problem-based learning (PBL) and educational outcomes, this study investigates the role of PBL as a teaching model to enhance students’ learning activities and outcomes in South Sulawesi located in rural Indonesia. The study subjects included first graders at a junior high school who achieved lower levels academically than pupils in other regions. This study involved classroom activities conducted in two cycles, each comprising routine of planning, action, observation, and reflection. Observation sheets and evaluation tests were used to measure students’ learning activities and outcomes. The data were subjected to qualitative and quantitative analyses. The results showed that the students’ learning activities and outcomes in biology class were improved from the first to the second cycle, suggesting successful resolution of students’ difficulties and enhanced performance. In addition, teachers improved their effectiveness by implementing PBL, even though they lacked prior knowledge. Therefore, this study may be useful for practitioners especially teachers administering PBL. PBL is an effective approach that may be incorporated into teaching curriculum by science teachers.