Tooth Truth with Harv and Marv is one, and I'm watching the MST3K Reunion show and the very first short in that one is one I remember. The one about teaching kids to be careful crossing streets, etc.
I'm gonna be 34 in a couple months, so I'm JUST old enough that they were still showing these kinds of messed up films to use when I was really, really little, like kindergarten/first grade.
I also find it amazing how something that obscure can just lay dormant in your brain for decades and you see it again and it's like a ! appears over your head and you get that Metal Gear Solid alert sound.