I disagree. Armed guards at the gate (which further implies a fence with gates), again at the door (which presupposes a number of doors few enough to maintain such staffing), and yet again throughout? That's very much a prison.
My high school had no such fence, and had far too many exterior doors to reasonably guard. You just couldn't have that many people moving (~2400 students--plus staff--twenty years ago) in and out in the necessary period of time without that many doors. And those armed guards would have to be supplanted by metal detectors, or they'd just be window dressing. Fence it all in? Okay, but again, you're talking probably ~500-600 cars, mostly entering and leaving in the space of, say, an hour...unless you plan for putting parking outside the wall, which just creates another choke point (as well as being untenable in the winter).
And, if you think this is a good idea...who's going to pay or it? A high school, a middle school or two (we had three), a handful of elementary schools...aren't our schools in poor enough financial shape as it is?
Allowing teachers to arm themselves is one thing, and I think a very good idea; having multiple layers of armed checkpoint security is more than most military bases get (which typically just have a gate guard, with a few buildings perhaps having further security). It is, in short, a description of a prison.
