The purpose of this study is to enable students to understand that electric current produces a magnetic field by knowing the occurrence of magnetic field in a whole wire where electric current flows, and explain the relationship between a number of turns in the coil and electromagnetic force from scientific perspective and ideas. A lesson was developed, conducted in the unit "Power Produced by Electric Current" in the fifth grade of elementary school, and then investigated the learning effect through a questionnaire. Alternatively, students managed to understand a magnetic field was generated in a whole wire where electric current flows and explain the relationship between a number of turns in the coil and electromagnetic force on the ground of a magnetic field produced in a wire. This result suggests that some students considered a greater number of turns in the coil made electric current stronger, and let electric current flow the iron core. Altogether, students were unable to understand that electric current produces a magnetic field.