The topic speaks for itself, so let me indulge a pessimistic angle here.
The teacher probably had it out for the child. At work, if you suddenly notice yourself getting talked to about seemingly insignificant flubs, you are on the way to getting fired. You can't quantify laziness, but if your register is off by a dime, there is a record of it. They don't need to care about a dime, but they do care about your general work ethic. Crimes require hard evidence... perhaps this child finally did *something* that could be used against her. It was something insignificant, but still something.
Otherwise it's too stupid. Funny how my rose colored glasses would prefer a 12 year old be a bad child just so that the world makes sense.
I can believe that, though I'm thinking its probably the principal who's out to get the child since I doubt that the teacher has the power to actually get a child arrested.
It might not even be directed at the child itself. A school that has been pretty inefficient at controlling problem behaviors will easily do a complete 180 if enough administrators and parents complain. Kids just unfortunately get caught in a zealous crossfire to save face. And yeah...sadly I've seen this, though no where NEAR to this extent. This is just hardcore stupid.