Slightly off-topic, but I have a friend who does training for active shooter response (he goes around to schools and large businesses and teaches people what seems to work best for saving lives in these situations). When I see things like "they huddle under their desks in the dark" I cringe. His training is very different, and focused on evacuating the students and disrupting the shooter. First, barricade the doors, then seek immediate escape and RUN. If that's not possible, everyone picks up whatever they can throw and gets ready to pelt the shooter with it if the door is breached. While this is happening, people escape around the edges and others attempt to subdue the shooter (taking advantage of the fact that it's very hard to shoot accurately when you're being pelted with hard, heavy objects).

He has researched a number of these events, and he has some chilling stories. In one case, the shooter walked up and down the rows of desks where people were cowering in the dark and executed each person. I think he said there were only a couple of survivors, and even those were critically injured. In the same shooter incident (sorry I can't recall where he said this one happened), another classroom used the disrupt and escape method, and almost all of them survived.

Bringing it back to topic, I wonder how the psychological effect would change if the students and teachers were trained with active responses that have been shown to greatly improve their odds of survival, instead of being told to wait passively in the dark and hope they get skipped. Would the fear be reduced? I honestly don't know how it would be for kids, but in my own case I feel better when I'm prepared to act instead of having to wait around for something to happen to me.