Comment by SoftTalker

I'm not sure when this changed, but in school for me in the 1970s and early '80s the teachers (at least the older ones) were all pretty much of the attitude that "what you get out of school depends on what you put into it" i.e. learning is mostly up to the student. Grades of "F" or zero for uncompleted or totally unsatisfactory work were not uncommon and students did get held back. Dropout age was 16 and those who really didn't care mostly did that. So at least the last two years of high school were mostly all kids who at least wanted to finish.