We would like to help future science teachers broaden their understanding of preparation process utilizing engineering tools at their classes. Currently, this field is barren of research although increasing interest. Therefore, this study researched about preservice science teachers (PST) who participated in engineering design project (EDP). We studied what they learned from this project. The results of the study can be summarized as follows. (1) we could not say whether the project is success or not with the success of problem solving. Learning was made although there were some failures of resolving questions. Thus, we think the project is succeed. PST could escape from a stereotype that there was no gain if they did not solve their assignments. (2) PST realized variety of possible solutions by doing EDP. The PST participating in the EDP produced fine dust measuring tools in various ways for each team. With this project, PST also could avoid from a stereotype that each problem has only one right answer. (3) PST understood students can learn concurrently science and learning, and science and engineering have similar problem-solving processes. Through this fact, PST were able to be free from another stereotype that students have to learn separately science and engineering. (4) Important discovery of this study is PST find their future prospect as teachers by themselves during EDP execution. We found PST use EDP as an opportunity of thinking their roles. To sum up, we expect EDP will promote to find identities of PST and teachers. The conclusion of this study is as follows. EDP should be further expanded in the provision of pre-service teachers in order to familiarize the PST with engineering and provide opportunities to form their identity as a teacher of the future.