Lockdown is the knee jerk reaction to some threat
Well, whats your answer to what a school should do in the face of a threat? I disagree that it's a "knee-jerk reaction", in large part because of the nature of the beast. What do you think a principal should do if they are alerted by police? Let anywhere from 1 to 2500 kids, who don't have a great concept of danger and security, run pell-mell out of the school? Let every kid leave under the watch of a parent, despite the fact that in a large school it is just about impossible to account for the identities of all those people with anything even remotely resembling accuracy and efficiency? Would you just let the school stay open and hope for the best?
B.D. Turner said that the reason his daughters school was locked down was because
The bank across the street from the school had been robbed and the gunmen were on the loose
I am sorry if you disagree, but that is a perfectly valid reason to lock the school down. Now, you can argue that it might have been wise to let the kids who had phones call out, and to a certain degree I can understand that argument. Unfortunately, I think what you would end up with is a whole mess of freaked out and scared parents (and rightfully so) trying desperately to get information, which results in nothing more than a massive disruption that diverts resources away from where they need to be.
Here is an example. B. D. said he called the police, which is a perfectly logical thing to do after getting a call from his little girl, who sounded scared. Imagine that her school has 1000 students, and then imagine that maybe half of the kids called home in a similar fashion. That results in 500 parental calls to the police and/or school, a certain number of parents showing up at the school, and a lot of unneeded hysteria. If nothing else, it jams up phone lines that could be put to much better use, and in a worst case scenario, it gets someone killed.
The real problem here is that schools shoulder an ungodly amount of responsibility for your kids when they are at school or on a school activity. When I taught at a school larger than the one I am at now, I had anywhere from 35 to 45 kids at any given time that were directly under my supervision. Of those kids, there are special needs kids, english language learners, emotionally disturbed kids, "normal" kids, and so on. In an emergency situation, I must control this widely disparate group as a whole. Bluntly put, that means that I don't particularly care what your opinion is of how I should act in regards to your individual kid. My concern is the welfare of the class, period. Fact is, if something bad goes down and I get my class (or, from a different perspective, your kids) through it safely, you can scream at me all you want. I will sleep soundly at night knowing that while your angry at some injustice (real or percieved), your kid is safe.
The fact is that parental rights are ignored in some situations, and I believe rightfully so. In fact, there is even a legal term for it, "in loco parentus". There are plenty of "loopholes" to that concept, but suffice it to say the school makes plenty of decisions about your kids without your consent and without consulting your wishes. Heck, just the pure logistics of figuring out what the parents of 1000 kids would want done in a fashion acceptable to most in an emergency situation is impossible, let alone the implementation of those wishes. The simple fact is that if an armed robber is roaming around outside the school, they are going to lock down and ignore your pleas to come inside. It's not a function of some sort of Orwellian desire for control as much as it is concern for your kids safety. Unfortunately, our society has evolved such that litigation is also a concern. In any event, the school is going to manage the situation as best it sees fit, and in every school, particularly the large ones, it boils down to an "all or nothing" point of view. By that I mean that all the kids stay in one place where they can be supervised (and, if need be, protected to the best of the teachers ability), or none of them do.