If anyone is thinking "they cann't do that, it violates the Constitution" my money says you're wrong. My school district made everyone sign a waiver of liablity, and waive there Constitutional Rights. So, there is actually no way to violate there rights.
So specifically, what constitutional right is it that is being taken away?
There are many other places that operate the same way, we just think of schools differently because it is our kids and because they are there every day. But what do school do that isn't done in Airports?