Engineering design activities are a common way for teachers to incorporate engineering into their science classrooms, as called for by current science policy documents in the United States. However, little is known about how teachers prioritize different learning objectives during engineering design lessons. Understanding teachers' thinking on this subject is important for teacher educators because teachers' beliefs about learning goals influence their teaching practices. This study presents elementary teachers' views on what their students learned during engineering instruction, most of which was in the form of design activities, over the course of a semester. The teachers were participants in a teacher education and professional development project aimed at supporting elementary science and engineering instruction. The results indicate that most teachers described student learning in terms of developing design skills and practices, whereas very few discussed their students' learning of engineering concepts. Interestingly, teachers also frequently discussed students' learning of the nature of engineering, suggesting that they highly prioritized this outcome.