This chapter presents the first part of the dissertation’s theoretical framework by unfolding the principle of deep cognitive engagement, which has been examined in three areas of research: learning science, digital media education, and mathematics education. These areas are connected by integrating the ICAP framework with the content-related CoDiL framework to make students’ cognitive engagement empirically accessible during the learning process and characterize how the students use the provided learning opportunities in a content-specific way. Regarding the dissertation’s design features, the chapter explains why interactive video features should be considered as scaffolds for initiating and maintaining deep cognitive engagement. The chapter concludes by refining the principle of deep cognitive engagement into three mid-level design principles: embedding video in a learning environment, supporting cognitive processing through media design, and focusing on relevant content.