Education is the most essential part in every aspect of providing the quality of human resources. Thus, one of the learning innovations to improve quality, especially for children, is the engineering design process. The engineering design process (EDP) is a set of processes that engineers use to solve an issue. The purpose of this study is to find out the of EDP on design prototypes of the elementary school. The application of knowledge and capability through EDP were also able to develop critical and creative thinking skills so that they can solve problems, collaborate, and communicate. The method adopted in this research is case study. Seventeen elementary students from four different schools in three different cities in province Riau, Indonesia, are selected as participants. Data are collected through interviews and analyzed using a grounded approach. Finding of this study EDP became an ability that could involve students in the learning space and students were also challenged to work collaboratively in groups that were guided by researchers. From the designs made by students, the level of ability to design student prototypes was dominated by the level of the developing stage even to the level of the continuous stage. The findings indicated that the activities using EDP were able to help students to experience real learning and find components that can be used to compound a tool and solve real problems. The findings also indicate the need to reform curriculum for teacher training programs through EDP to include matters like design prototypes.