This paper describes an instructional design for introductory physics that integrates previous research results of physics problem-solving and the use of external representation into direct instruction (DI). The research is a part of research in obtaining an established instructional design to support mental-modeling ability. By integrating with the previous research results of problem-solving and external representation with the characteristics of DI, we obtained stages of a hypothetical design. The hypothetical design has been developed by implementing phases of formative research to obtain a final model of enhanced direct instruction (EDI). Results of experimental phase showed that EDI can support the students' mental-modeling ability.