There has been a lot of research on effective multimedia design for teaching and learning, with a particular focus on how to design effective slides. Much of this research has informed Mayer's Cognitive Theory of Multimedia Learning. His book Multimedia Learning outlines his theory as well as his applied design principles (available from KPU library online). The following video presents a brief introduction to Mayer's principles.
Video produced by Dr. Kacz and retrieved from YouTube on January 7, 2020
The KPU library also carries a copy Slide:ology by Nancy Duarte, and Presentation Zen by Garr Reynolds. Both of these books provide examples exceptional slide design. However, be aware that these authors are writing for business audiences, so they are design presentations for engagement and persuasion rather than engagement and learning.