That story is horrifying. One, on it's face, it's ridiculous. I believe she's entirely innocent. But who cares if she's not. If a sub teacher in a classroom is intentionally using a computer to surf the Internet for pornography -- no one has alleged it was illegal pornography; just that it was pornography -- fire her, never use her in you school system again, and flag her name for background checks in the state's education system. Because, you know, she was probably she bored and stupid, but there could be some risk there. But you fire her, you don't imprison her. None of those kids were harmed by what they saw, main reason being they've *seen it before* on their own home computers.
I have three kids, a girl and two boys, and I can guarantee you, really I can, that none of them would be permanently scarred, or even temporarily scarred for a period lasting longer than one second, from seeing some porn on the Internet. I'm against pornography for ethical reasons -- mainly having to do with abuse of women, attendant drug abuse in the industry, and the wholesale degradation of human sexuality -- and we forbid the children old enough to use the computer from accessing such things, but it's not going to warp them if they just glance at it, or seek it out once or twice from curiosity. They're not going to develop some depraved porn addiction.
Oh my stars. This is just crazy. These prosecutors are crazy. Scary crazy. It's worse for society to be a scary crazy person that it is to be an occasional consumer of legal pornography.