Developing Problem-Based Learning (PBL) Biology Science Learning Devices to Improve Cognitive Learning Outcomes. Preliminary research at Islamic Middle School 1, Ternate City, North Maluku, revealed that no biology learning tools based on the PBL learning model had ever been developed and implemented. In addition, cognitive learning outcomes for environmental pollution material are still relatively low. The aims of the research are to find out (1) the validity of the PBL model-based learning device; (2) the effectiveness of learning tools based on the PBL model. This type of research is research and development. A limited trial was conducted on Class VII-1 biology students at the Islamic Middle School 1 Ternate City, North Maluku, totaling 28 students. The results of the study show that (1) the learning tools developed have fulfilled the validity aspect; (2) learning tools developed are effective in completing students' cognitive learning outcomes.