Perhaps 5 minutes for the principal to get there.
The thing is, the teacher isn't allow to use force on the student to make him leave. That could explain why the teacher evacuated the rest of the class. I haven't watched the video yet, so I don't know all the details of that incident.
A a former assistant principal in a school with 3200 students, let me ask these people a few questions about getting the principal to come get the student.
What if the principal is doing one of those teacher observations that education bashers claim do not ever happen?
What if their is another student involved in a fight?
What is another student got caught with drugs?
What if another student was suspected of having a gun in his backpack?
There are so many reasons why the teacher is expected to handle these minor disciplinary issues. The kid was being an asshole, but the teacher should not have called him one.