Of course you should question authority when it's appropriate (for example, if Congress or President declares that guns are illegal without getting second amendment properly ratified) but you don't question an officer when he gives you a lawful order to get up and leave class room. If the teacher has already tried to get student to leave and she refused then a cop tells her to leave (repeatedly, no less) and she still proclaims "No, I didn't do anything wrong so I don't have to do what you tell me. I'm right and you're wrong... wah, wah, wah" then yeah, force is necessary. She's disrupting that class and stopping the other students from learning. If the cop had just agreed with her and said "OK. You're right and I"m wrong. Since you refuse to leave you win and I"ll let you stay" what kind of impression would that leave on the other kids? That it's perfectly acceptable to disrespect those in authority and tell a cop who tells them to do something to kiss their asses?
That kind of attitude towards police officers is one of the major things wrong with this country. Certain group of people who think just because they have dark skin that they're entitled to disrespect cops all they like with no punishment for it whatsoever. That's not racist comment, btw. It's reality of the state of America today. You don't see this kind of thing happening to white people because most of them have been raised to RESPECT AUTHORITY. When a cop tells them to do something, they do it. IF they disagree with what a cop tells them to do then they take it up in court afterwards. That's the proper way to do it.