The problem isn't really the practicality (although highly questionable) of books or ballistic rated backpacks; the problem is the favoring of knee jerk reactions built on paranoia and a lack of understanding of violent encounters over logical and practical solutions. This reminds me of the good ol' days of the cold war where kids would practice hiding under desks in case of a nuclear attack...
As Upnorth mentioned, the probability of a school shooting is very low; disproportionately low in comparison to other safety hazards. This does not mean, however, that you don't disaster plan. Every school, for example, has a disaster plan for tornadoes, even though the probability of a school building being ravaged by a tornado is also low.
But that is just it; most of us don't have irrational fears of tornadoes. The news, the media pundents, and the politicians aren't ranting and raving about he next possible tornado attack that is going to the destroy lives and families of all in its wake. So, people tend to not be irrationally afraid of tornadoes, or the weather in particular, even though it can be dangerous at times. We use our resources to understand the weather and the risks, and we take the proper precautions if something like a tornado does hit our schools or homes.
Why can't we do that with terrorists threats in the schools? [keep in mind, "terrorism" isn't isolated to islamo-facist driven violence; I consider any school shooting like Columbine a terrorist act.] It is very simple to put a disaster plan in place if there is a threat that involves either exiting the building or barracading a door and staying in a room per the teachers discretion. Really, a practical solution that is
PROPORTIONAL to the probability of the threat is very simple to put in place. And these simple, practical solutions are much more effective then the outrageous paranoia driven ideas that the news catches.
Ballistic backpacks are not practical or cost effective. Such an item will cost 100's of dollars, and the kid isn't going to be walking around with his backpack on all day for it to even be effective, and it won't cover most of the child's body. Granted, it up's the safety level a little, but only circumstantially. Considering that the child would have to have it on while running away and to only get shot in the back with a pistol (it will not stop a rifle round) and no where else, I just don't think it is a reasonable solution. Really, you might as well have your kid wear a vest to school if your going to go this route.
And yes, books can stop rounds to a degree. Nice article on the subject:
http://www.theboxotruth.com/docs/bot31.htm
But... practical? Not really. If someone is in a room shooting, a kids best bet is to get the hell out of that room, not waste valuable time trying to fish a book from under a desk or elseware. Teaching a kid to try to deflect a bullet with a textbook or backpack like something out of a poorly choreographed action film would be laughable if people weren't serious about it. That isn't going to be a natural reaction for a trained adult human being, let alone a scared child. If someone is shooting in a room, and if you can't shoot back or beat his *** right there, YOUR going to run, plain and simple. And you should. And so should a child.
What will work for children is a simple, effective disaster plan that should be in place, but like tornado plans, not really given much thought once the plan is understood. There are much more important things that kids and parents should be worrying about otherwise...
C.