This study aimed to improve science teaching in a practical way by activating teachers’ potential teaching expertise or professional knowledge. We developed an alternative in-service approach, the Practical On-site Cooperation Model (POCoM), according to the following principles: (1) the “bottom-up” approach, where observed problems in science classes are improved practically and immediately without any pre-determined teaching plan or materials; (2) “cooperation” between researchers and teachers to improve teaching; (3) “naturalistic settings” where various real problems occur in actual teaching and learning situations; and (4) “gradual improvement” rather than revolutionary change. The POCoM was applied with three science teachers, and 24 classes were observed. We found about 65%–96% teaching improvement. The analysis of the cooperation processes and science teaching in classrooms identified seven types of successful improvements and five types of unsatisfactory cases, including their reasons and features.
Key words: cooperative model, in-service teacher, observational protocol, professional development, science teaching.