The aim of this exploratory study was to learn about the misconceptions that may arise for elementary and high school science teachers in their reflections on science and engineering practice. Using readings and videos of real science and engineering work, teachers' reflections were used to uncover the underpinnings of their understandings. This knowledge ultimately provides information about supporting professional development (PD) for science teachers' knowledge of engineering. Six science teachers (two elementary and four high school teachers) participated in the study as part of an online PD experience. Cunningham and Carlsen's ("Journal of Science Teacher Education" 25:197-210, 2014) relative emphases of science and engineering practices were used to frame the design of PD activities and the analyses of teachers' views. Analyses suggest misconceptions within the eight practices of science and engineering from the US Next Generation Science Standards in four areas. These are that: (1) the nature of the practices in both science and engineering research is determined by the long-term implications of the research regardless of the nature of the immediate work, (2) engineering and science are hierarchical, (3) creativity is inappropriate, and (4) research outcomes cannot be processes. We discuss the nature of these understandings among participants and the implications for engineering education PD for science teachers.