A bargaining unit can’t go on strike without the consent of a majority of its members participating in a vote. All its members are eligible to participate, and they must be given at least 48 hours’ notice of the vote. And the vote must be held by secret ballot, not a show of hands ...
They’re closer to boycotts, although a boycott usually doesn’t mean refusing to accept a service for which you’ve already paid. And participation in a boycott is, and should remain, voluntary.
Students have the absolute right to boycott their classes, and to try to persuade others to do so. But nobody has the right, legal or moral, to interfere with anybody who wants to receive a public service to which he or she is entitled.