Biology courses in senior high school can play an important role in the effort to improve the student critical thinking skill. This study has been carried out to develope the instructional sets called PPBI and to evaluate its implementation effects on the critical thinking skill of the tenth grade student. The PPBI was developed according to the Dick & Carey model’s. The quasi experimental research was conducted as a factorial design and the data analysed using Anacova. The results show that student who learn using PPBI obtained better scores on critical thinking skills, student who learn through STAD cooperative strategy has higher scores of critical thinking skill than the TGTs student, and there were no significant effects of the interaction of the instructional sets with the type of cooperative strategies on student critical thinking skills. In conclusion, the implementation of PPBI gave significant contribution to the developement of student critical thinking skills. |