When I was a kid, one of my parents told me diff eq was a course they had not even gone to class for and passed, which set me up for disappointment in diff eq pedagogy for sure. It didn't help when I read this article, and then took sophomore diff eq and it was exactly as described. Later in grad school I'd actually teach the course to my complete chagrin. I think I mentioned this essay to my students, because how could I not? Of course I did not try to redo the diff eq pedagogy, but I did put a lot of emphasis on linearity.