Weight is one of the basic concepts of physics. Its gravitational definition accommodates difficulties for students to understand the state of weightlessness. The aim of this study is to investigate the effect of materials based on 5E teaching model and related to weightlessness on science student teachers' learning. The sample of the study was 9 volunteer student teachers who were in their first grade in Science Teaching Program in Fatih Faculty of Education, Karadeniz Technical University. Both qualitative and quantitative data were gathered to find answers to the research questions. Findings revealed that all physics textbooks reviewed gave gravitational definition of weight. Also the concept of weightlessness hasn't been covered in high school and some university textbooks. It was determined that before the implementation student teachers had non-scientific explanations about weightlessness. The implementation of the 5E teaching model and materials developed are effective on learning the weightlessness. It is suggested that similar applications can also be used in other physics subjects or in other fields of science.