a speech or writing that is didactic is intended to teach people a lesson
Usually whenever I do something wrong, my mom gives me a super long didactic speech! It gets pretty annoying after a while.
1. Intended to instruct or inform or inclined to moralize excessively. (e.g., a didactic story)
2. A word that is overused by English majors as a pretense to sound intellectual when they are actually stating an obvious and trivial fact.
"I liked the story, but it was a little too didactic for my taste."