The three ringleaders who were arrested are being treated as juveniles. It's serious. The whole class was going to be in on it but apparently some in the class weren't sure it was serious or not but the one student brought a knife to school who was supposed to stab the teacher and another brought the paper weight to hit her over the head in the first place to knock her out and the cleaner upper brought stuff, etc.

It is a special needs class and I read they may have thought it was like cartoons and that they'd do whatever and that the teacher would then jump up again and it would all be over, etc.

Kids have odd thougths about things, not as much logic and structure and experience as adults. I remember the story of when my cousin almost hit my brother over the head with a hammer when they were 2-4, that sort of thing. It's not really a "plot" they were angry (the teacher reprimanded some of them for standing on a chair) and it's the "next" step in their minds. They can't think it "through" or understand about consequences, etc.