Well, here is a quick disclaimer: as a (current first-year) PhD student, I have not yet had the chance to teach/lecture an actual course. But I have some code repositories on my GitHub that (in my opinion) qualify as teaching material.
Contains textbook-style notes and explanations of several topics in physics.
Contains visualizations and explanations related to Minkowski diagrams in special relativity. (I am especially proud of the little rocket icon that comes with it.)
Contains code to generate plots visualizing gravitational-waveforms and their properties.