In the wake of tragic Sandy Hook, many Americans are desperate to prevent further school shootings. Thus do we find ourselves debating two very divisive ideas: gun control and armed guards in schools. But there is another idea, one both simple and acceptable to virtually all: lockable, bulletproof doors for classrooms and school entrances.

This is a commonsense suggestion that has precedent. After 9/11, we had similar debates to those raging now. Today we're divided over the idea of arming some teachers; back then there was rancor over the idea of arming pilots. Of course, we did finally appoint air marshals, the equivalent of armed guards in schools. Yet no one had to debate what was universally self-evident: the need to reinforce cockpit doors.

The cockpit door was a weak link that the 9/11 hijackers exploited to gain easy access to the pilots and airplane controls. Likewise, Sandy Hook Elementary's doors were a weak link; they were locked at 9:30 a.m., and video identification was conditional for entry, but murderer Adam Lanza was able to shoot his way in. Yet school doors are a weak link that is easily remedied.

There are many variations on the solution, each requiring different degrees of expense and offering different levels of security. The most secure option involves fitting all school entrances, as well as all relevant rooms within a school, with bulletproof doors that automatically lock upon closure. Here's how it would work: all school personnel and students would enter and exit the premises at one location, which would be manned when students arrived at, and departed from, school. It would be closed at other times, during which anyone who requested entry would have to be identified and buzzed in.

A secure entry door alone would greatly reduce the likelihood of another school shooting, but the inner locked doors would add another security layer. They also would lock upon closure and could be opened only manually from the inside. To ensure that one couldn't be locked out accidentally or by a mischievous student, entry would also be possible via electronic key cards -- the kind common in modern hotels -- which would be available only to school administration and would never leave the premises. The key cards and their receiver units would also be reprogrammed periodically. If this is deemed too restrictive, school personnel could be issued key cards allowing entry to the school and some or all inner rooms, but this reduces security, as it places the cards in wider circulation, increasing the chances that they'd fall into the wrong hands (not the likeliest scenario, though).

Many may view this maximum-security option as overkill, and it would be expensive. But it would reduce the chances of future school shootings drastically.

Another option involves lower-technology doors that could be opened only from the inside, or from the outside with keys. This may involve lower initial costs but require a sacrifice of security or a periodic change of locks to take the place of electronic-system reprogramming.

Another slightly less secure option involves installing doors that, while not necessarily billed as bulletproof, are for all intents and purposes impenetrable. As an example, consider the standard entry doors of homes and apartments in Poland, a nation I've visited. They often look like something befitting Fort Knox -- Chuck Norris couldn't kick them down. In fact, I was present when firemen broke into the apartment of a person believed to be in distress; they had to use various tools, including a hydraulic device, and it still took these professionals 10 to 12 minutes to gain entry. A lone maniac with a gun wouldn't have stood a chance.

Also note that Poles are poor by American standards, yet they all seem to have such doors. So the cost for us shouldn't be prohibitive. These "Polish doors," along with top-notch entry-door security, are probably the most realistic option.

Less expensive still is to rely solely on the aforementioned bulletproof entry-door security. After all, if you can control who and what enters a school, what happens within it is of little concern. However, there would be a problem if this one layer of security were breached. Thus, whatever we do, there is no reason why schoolroom doors should be unlocked during class -- or be unlockable (a student could still go to the restroom and be allowed re-entry).

I'll also mention that there already is an effort to address this weak-link door (WLD) problem. It's called the JAMBLOCK, a lightweight piece of steel that can quickly be secured under a classroom door, effectively locking it and greatly slowing the progress of anyone bent on breaking in. The problem, however, is that it's a half-measure. It doesn't create the virtually impenetrable barrier my preferred solutions would, and a teacher must become aware of a threat before it can be applied. And, well, using a play on that old saying, I wouldn't want mine to be the first door a bad guy came through.

Of course, nothing can completely eliminate the risk of school shootings or any other danger. There would be vulnerabilities even if the WLD solution were effected, such as periods when children file in and out of school, schoolyard recesses, and the possibility that a student has a weapon hidden on his person. Yet other measures could augment the WLD solution. For example, having metal detectors at the secure entrance, having the recess area within view of that entrance, and stationing one armed guard there would address all three of those problems. All these measures taken together would perhaps reduce the probability of another school shooting to near zero.

But this article's purpose is to focus on the WLD solution. And I'd like to make an appeal to those who would place emphasis elsewhere. Whether or not armed guards are a good idea, they cannot be everywhere at once; thus, advocating such without addressing WLD is like having air marshals but not reinforcing cockpit doors. If your preference is gun control, please consider that advocating such without addressing WLD is like outlawing box cutters (the 9/11 hijackers' weapons) but not reinforcing cockpit doors. Neither option is a realistic substitute for a WLD solution.

Of course, mindful that the chance of dying in a school shooting approximates that of being struck by lightning, one could question the need for sweeping policy changes of any kind. Yet given how these rare events traumatize the nation, how they become politicized and used to advocate counterproductive policy, and the fact that there is clamor for a solution, finding one isn't unreasonable.

And if we safeguard our money in bulletproof trucks and vaults, can we justify a lower standard for our children? All of us, left, right, and center, should be able to come together in support of the WLD solution. It's common sense, it can be common ground, and, most importantly, it would work.

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