I’m a big fan of this sentiment:
I try to keep Pegg’s axiom in mind when I’m teaching. Every winter, I teach the laboratory portion of a course in animal diversity, much of which consists of dissections. Every week during that course, my students dissect one or more specimens from selected animal phyla and observe without cutting preserved specimens of several more. Each week comes with a theme, such as convergent evolution, divergent evolution, or metamerism, and ideas such as the state of the body cavity pervade the entire course as well.
Every session of that class where the time is available, I spend the last 15 minutes or so showing videos, still images, and articles about the weirder and more wonderful aspects of the animals within that session. For many students, classes like these are their one and only encounter with creatures like ragworms and tarantulas. Augmenting the dry and often harried perspective offered by detailed dissection guides and midterm exams with the novelty and wonder of their living forms is one way that I try to keep this course interesting even for (gasp) pre-medical students who don’t necessarily enter the course brimming with enthusiasm about crayfish and sea stars.
Infectious enthusiasm is the best teaching aid there ever was, and I bring it to my classes even if I have to add my own material to an established course. This is that material.