Tell it to the parents at Columbine High.
Perhaps you could back your beliefs with some data.
Again, if you look at students killed in schools, there are the vast minority... These cases are known because of the media' thirst for "news", but they aren't the usual nor the normal...
I could then throw in your faces the much more numerous cases of children killed by their parents to "show" that parents are dangerous to their children, but this would be the same non-argument!