Retractable steel walls? Here are some other ideas to secure our schools

In terms of beefing up security in schools across the country, liberals have been quick to dismiss the idea of arming school officials in the wake of last week's deadly shooting in Newtown, Conn. That isn't to say, however, that they aren't offering up alternatives of their own.

Take, for instance, Rep. Sheila Jackson Lee's genius idea to install retractable steel walls in schools, designed to keep potential attackers out.  She didn't (but I'm assuming she meant to) mention how the security system will detect potential attackers and trigger the motorized steel walls to shut down the school before they can enter.  I'm imagining some sort of Minority Report-like system that predicts crimes before they happen.  Either that or a security device that will ask visitors whether they are at the school to a) attend a PTA meeting or b) to kill people.  If the intruder responds that they indeed intend to kill, a secret trap door will drop the perp down into a pool of alligators.  Or fire ants.

Speaking of alligators, wouldn't it be easier to just dig a moat around the school and fill it with the hungry crocodilians?  Surely this would be a more cost-effective solution than steel walls.  You could lower the draw bridge when non-violent visitors arrive and for routine fire drills.  They'd also be good fun for kids during recess:

We could also keep a litter of vicious attack dogs at each school and "release the hounds" whenever trouble arises.  Oooh, or how about man-eating lions?  I'm sure Sheila Jackson Lee failed to mention these options in error.

What are some other security measures you think could help keep our schools safe that a) don't involve arming any law-abiding citizens, and b) are as viable as the installation of giant retractable steel walls?  Be sure to let us know with a comment!