Ah yes, the humble fire extinguisher. They surround us, we only notice them when there's an actual fire, or, when the guy comes to check them once per year. Ever picked one up just to familiarize yourself with it? I highly recommend it, yes, even you little kids out there. 

Is this more Hollywood BS? Think about it, when these things are discharged, they make an attention getting hissing noise. You cannot ignore it. The powder that is ejected moves at considerable speed, and it can, depending upon the size, move very far. It creates an inert cloud that spreads. If you aim low it has a low spread. But just imagine, how many precious seconds it can give you, to run away, from the likes of Adam Lanza. You take away his sight, even slightly, you distract, and you run. Or you may even be able to tackle. You could even throw it at him, these are very blunt objects. Don't even begin to say to me that a child or a small woman could not hurl this thing at someone. Adrenaline has a proven track record in any emergency situation. 

I would like one of these under every teachers desk. You could even load it with tear gas or even just a substance designed to completely black out an area. You distract, you take away the sight of these cowards...you begin to level the playing field. And there's probably one of these somewhere near you right now. Think about it, are you going to be willing to pay for a heavily armed cop in every school? What's this thing cost? $200 max? And if you pull that pin and don't actually discharge it? So what? No harm done. That can be fixed, cheaply and easily. 

Start thinking outside the box, you have the power right nearby. Start using your brains people.