I remember the ABC Afterschool Specials. That show started in 1972, the year I turned 4, so I pretty much grew up with it. Only a few episodes really stick in my mind, though.
I don't remember the NBC one--but, considering when it started, I probably watched at least a few of them.
CBS Schoolbreak Specials started in 1984, while I was in high school. During my high school years, I was either chasing girls or doing outdoorsy things with my buddies. I had little interest in TV during that period.