Purpose: Implementing STEM education in the early grades is a more effective way to encourage creativity, problem-solving, and innovation. There is a need for elementary teachers to implement STEM education to integrate and contextualize science, technology, engineering, and mathematics (STEM) in their teaching. This research aims to examine the prerequisites for elementary teachers before practicing STEM education with students. Research Method: This study is a case study and implementations were undertaken with six teachers over 13 weeks and were delivered in theoretical and practical ways. Open-ended pre-test and post-test, interviews, diaries of both researcher and participants, worksheets, lesson plans, assessment tools and engineering design process (EDP) reports were used as multiple data sources to triangulate findings. Thematic analysis was utilized using open coding and cross coding of data. Results: Several codes emerged from the analysis that were grouped under five salient themes as follows: understanding STEM, instructional gains of STEM education for teachers and benefits of STEM education for students, instructional prerequisites for teachers and conditions of schools to perform effective STEM education. Implications for Research and Practice: Theoretical and practical integrated STEM education can be planned in a long-term manner for the education program of elementary school teachers consisting of problem-based, inquiry-based and project-based learning enriched with content knowledge integrated STEM practices.