The purpose of this study is to develop a history of science activity which can be used to improve middle school students' nature of science views. The activity was designed and implemented based on an explicit-reflective approach within the context of the circulatory system. The activity was designed for grade 6 students and implemented during the 3-hour class period. During the implementation, most of the students successfully participated in the whole class discussion and established a connection between historical material and the corresponding nature of science aspect. Since the history of science activities in teaching key aspects of nature of science are still insufficient, the activity might both contribute to filling this gap in the literature and provide an example for science teachers to teach nature of science.