Science, technology, engineering, and mathematics (STEM) professional development for K–5 teachers often includes engineering design as a focus. Because engineering applications provide perspective to both teachers and their students in terms of how mathematic and scientific principles are employed to solve real-world problems (Baine, 2004; Roden, 1997), there is great interest in using engineering as a context for studying STEM education. Engineering as a context for learning mathematics and science is documented in the National Research Council’s review of K–12 engineering curricula (National Research Council, 2010). Further, engineering has become integrated into the Next Generation Science Standards (NGSS Lead States, 2013), which provide a mandate for the formal integration of engineering into the K–5 curriculum. Although it may suggest fluidity in curriculum and instruction among the four disciplines, “the STEM acronym is more often used as shorthand for science and mathematics education” ( Katehi, Pearson, & Feder , 2009, p. 12). The increased attention to engineering in elementary curriculum (e.g., the Next Generation Science Standards ), teacher preparation, and professional development provided the motivation for our research. Our project provided teachers with professional development opportunities designed to enhance their knowledge and preparation for teaching using engineering design. Following the professional development course, we observed how the teachers implemented engineering design lessons with students in their classrooms. In recognition of the limited preparation of elementary level teachers to teach engineering content and pedagogy, we created and implemented a professional development opportunity for grade K–5 teachers to enhance their knowledge of engineering and the design process. Specifically, our collaboration sought to enhance the participating teachers’ understanding of the work of engineers. We also explored the procedures for engineering design as approaches to solving problems and conducting research while recognizing the developmentally appropriate application and use of these approaches for teaching STEM to elementary level learners. Our STEM education intervention consisted of a three-day summer institute that combined presentations, workshops, hands-on activities, and curriculum planning and development. Our research was based on the anticipated influence of engineering-focused professional development on teacher practice and the subsequent increase in student engagement in engineering design-based learning activities (Fox-Turnbull, 2006). Specifically, we examined the elements of the design process that teachers emphasized in their instruction and the student- generated artifacts inspired by the lessons, and we classified the design assignments by the extent of responsibility taken by the teacher and student in terms of the structure of the elements in the design process. We gathered empirical data detailing teacher knowledge of the design process, their instructional use of engineering design, and student response to design assignments at the elementary, K–5 level. Our report presents a new level of design classification rubric developed for categorizing levels of responsibility of the students and teachers in the design process. The rubric was designed to classify design lessons based on the student and teacher (or instructional resource) responsibility for decision making in determining the structure of the elements of design.