Project-based learning is a modern teaching method aimed at students, connecting students' experiences with school life and stimulating serious thinking as students gain new knowledge. So that, this study aimed at investigating the impact of a teaching strategy adopting project-based learning on improving the critical thinking among upper basic Stage Students from male and female Science teachers' perspectives. The researcher used the descriptive-analytical method, through a questionnaire which applied to (111) male and female Science teachers teaching upper basic schools in Al-Kourah District, Irbid, Jordan. The results show that there is a significant statistical difference (a= 0.05) attributed between the conventional method and the project-based learning strategy. Thus, the differences came in favor of the project-based learning strategy. In addition, it is recommended that the project-based learning strategy should be adopted, and the textbook content and activities should be organized to commensurate with the project-based learning. In other words, this action requires the rehabilitation of the teachers to prepare learning situations by using a project-based learning strategy. Moreover, conducting further studies on other subjects in the method of learning thinking skills, such as creative thinking, reflective thinking, communication, and cooperation skills.