My general workflow is to write notes by hand the first time I teach something. If I teach it again, I type up those notes— making changes as I do— and print them out. When I teach it the time after that, I pencil in revisions on the print out from the time before. For things I teach many times, I eventually incorporate the revisions into the file and print a fresh copy.
This means that I’m not just phoning in the same lecture every time, but I’m also not starting from scratch every time. Incremental refinement.
Today I’m teaching Peirce’s essay “The Fixation of Belief” in my Understanding Science class. I was preparing for class and realized that my marked printout was originally composed for Understanding Science in Fall 2012. Since it’s been almost ten years, I figure it’s time to revise the file and print a fresh one.