We all(well most of us)went to public schools, that doesn’t mean a teacher did it. Besides the whole subject is BS, she was a teenager doing stupid sh** the way teenagers do.
Of course it doesn't. It was a tangential point. But the fact of teachers abusing their position and influence children in the wrong way is a subject that is well worth discussion. It has been said, for example, that there are more children sexually abused by teachers in the NYC public school system in one year than in the entire history of the priest abuse scandal. And yet, it never seems to be the time to discuss that.
And finally, teenagers don't do such "stupid things" unless someone shows them how to. You say, "another teenager did." Sure. And where did that other teenager see it. Somewhere along the line, an adult is involved - on that the teenager trusts.
Nowadays, they can find all manner of perverse influence on the net, on TV, whatever. Back in the day, it wasn't so.