I Apologize that this doesn't fit the Forum topic but this one seems the most active and they appropriate Forum Topic last had an answer weeks ago.
My question is what are the truancy laws surrounding skipping a class, and would it be illegal to leave in the middle of a class to protest on school grounds even if the protest was peaceful and not a disturbance?
I've looked everywhere and cannot find an answer to these questions, though I'd assume that a school could punish you for cutting a class but unable to put you through court for protesting as it's covered in the first Amendment?

Editor's Response
I would not recommend following your proposed course of action. In addition to facing school discipline for your actions, you could face whatever criminal charges the arresting officers can think of (trespassing, etc.)