Unfortunately, through much of school "assertive" is interpreted as "aggressive" and punished. I would classify it as assertive if a student, after raising their hand without results for a minute, said they had to go to the bathroom & then got up & went to the bathroom.

The teacher on the other hand might decide it was time for a trip to the principal's office & call home to parents because the student caused a disruption to the class by leaving without permission.