Rapid changes and developments in education have also changed the content and the scope of the activities carried out in schools. Learning and teaching through experiencing and practicing process carried out after the transition to the constructivist approach in recent years has started and expedited the performance of new activities in several institutions and organizations including both Ministry of National Education and TUBITAK, as the leading, in Turkey. Holding science fests during the educational process has led the observation of the developments in students' cognitive academic competence and psycho-motor levels and encouragement of students' participation into the activities especially with TUBITAK's starting to support. This research especially aimed to determine the situations of the students on project-based thinking skills related to science fests and science fest process supported by TUBITAK within the scope of the history lesson in recent years. The answer was sought to the question of "Do the science fests held in high school history lessons affect project-based thinking of the students?" The research was a descriptive study revealing the contribution of science fests activities performed in history lessons upon the project-based learning of high school students. Qualitative and quantitative data were obtained in the research. This study was limited with 66 participants from the 10th and 11th grade of three different high schools in central districts of Mersin province in 2014-2015 academic year. According to the data obtained at the end of the study, science fests were noticed to provide a clear contribution. In project-based studies, the students were determined to express themselves more easily and get rid of memorizing. Furthermore, it was also noted that visual materials, tools and equipment and three-dimensional materials were expected to be exhibited in science fests. In this study, it was determined that the projects students carried out within the scope of science fests held in the high school history lessons had effect upon the learning awareness of the students.