As elementary schools across the U.S. continue to adopt new science education reform, attention is needed to understand how teachers make sense of using engineering design to teach science in their classroom settings. This study examined fourth-grade teachers' sense-making with learning to integrate engineering design-based science instruction and the impact their instruction had on student learning. Participants included four grade 4 classroom school teachers and 93 students. Using a mixed-methods approach, data collection entailed semi-structured interviews with teachers prior to and after implementation of multiple design tasks and daily classroom observations of each implementation. Student data collection included identical pre- and post-science content assessments. Interview and observation data were analyzed using open coding. Basic descriptive statistics were calculated for the content assessments for the overall sample and by classroom. Results indicated that elementary teachers in this study who demonstrated relatively high fidelity of implementation of design-based instructional strategies had students who performed well on corresponding knowledge assessments. Additional interpretation of data suggested that teachers' experiences with teaching design, attentiveness to student engagement, and perception of the nature of design tasks may have influenced how and what instructional moves teachers prioritized and how students performed. Implications for examining the adaptive nature of engineering design-based science instruction, continuous teacher sense-making, and student learning are discussed.