Try trespass and interference with an officer.
She was a student at the school so she was not trespassing, just like you can not have your unruly child at your house arrested for trespassing either. You could not get a jury in the world to civic a child not suspended from school for trespass for being at their school during school hours.
She did not interfere with an officer either. She was sitting in a desk.
I guess you might argue she failed to obey an order. Though I am not sure how it is a lawful oder for a cop to order a child out of their assigned classroom. Also I have not heard that this “resource officer” was trying to arrest her. Had he done his job and stood her up and marched her to the office, he would have his job still.