Engaging in engineering tasks can help students learn science concepts. However, many engineering tasks lead students to focus more on the success of their construction than on learning science content, which can hurt students' ability to learn and transfer scientific principles from them. Two empirical studies investigate how content-focused learning goals and contrasting cases affect how students learn and transfer science concepts from engineering activities. High school students were given an engineering challenge, which involved understanding and applying center of mass concepts. In Study 1, 86 students were divided into four conditions where both goals (content learning vs. outcome) and instructional scaffolds (contrasting cases vs. no cases) were manipulated during the engineering task. Students with both content-focused learning goals and contrasting cases were better able to transfer scientific principles to a new task. Meanwhile, regardless of condition, students who noticed the deep structure in the cases demonstrated greater learning. A second study tried to replicate the goal manipulation findings, while addressing some limitations of Study 1. In Study 2, 78 students received the same engineering task with contrasting cases, while half the students received a learning goal, and half received an outcome goal. Students who were given content-focused learning goals valued science learning resources more and were better able to transfer scientific principles to novel situations on a test. Across conditions, the more students valued resources, the more they learned, and students who noticed the deep structure transferred more. This research underscores the importance of content-focused learning goals for supporting transfer of scientific principles from engineering tasks, when students have access to adequate instructional scaffolds.