Just read this from a 1973 WT:
"Boys and girls may start to play with their private parts during puberty and, not receiving any counsel against this, the first thing they know they are "hooked" on the habit. And if some know nothing about such self-abuse before entering high school, the chances are they will learn of it from either fellow students or the teachers themselves."Okay, seriously, how many of you actually learned how to Masturbate from one of your teachers, or from one of your peers at school? I know that there may actually be some experiences of this out there, but the chances are quite slim that a child will experience this at school.
I think the WT is picking on the parents' thoughts that "Things are so much different now than when I was in school" and are putting false thoughts into their heads that this is really a normal thing that happens in public schools, which is NOT the case.