As soon as I saw "locking the children in" I thought of The Triangle Shirtwaist Factory, where a fire killed many young women who had been locked into that sweatshop on The Lower East Side (where NYU now is) in Manhattan. It led to some of the reforms of The Progressive Era. I don't want to lock children in.
Oh Deb, I didn't mean locked in that way. I mean with doors that open from the inside, but not the outside. It was normal protocol when my kids were in elementary school in the 90's. There was one door you could go in that led directly to the office. You couldn't go beyond that point without a visitor's pass. You had to sign in. This is not a radical idea. I think it could be beefed up a bit. It only offers a bit of security, but as a parent, I'd want some basic things done at my child's school. This is not an answer to the problem by any means, just something that could be done without approval from the NRA.