I've got a better idea than arguing this argument for the 10th time. How about we find what's causing people to do this. What makes someone think it's a good idea? Last I checked it didn't happen a few decades ago. Is it because of the media's obsession with violence? Is it because there seems to be little other way to solve some problems other than violence? What's changed since the 1980s? It isn't gun laws, those have gotten stricter.
Brother, sorry to burst your bubble, but people have been senselessly killing one another with various weapons since the dawn of humanity, this is by no means anything even remotely in the same universe as a recent development in aberrant human behaviour.
As for attacks on schools, I direct you to the
Bath School massacre, which occurred in 1927;
the earliest marketed TV sets hit shelves in the UK in 1928. Modern media didn't exist, then, so there's little cause to claim that the two are somehow linked. Its not that it just started happening suddenly around the 80s, its just that we're exposed to more of it due to the immense breadth of information to which we have access in our times.