The union said the government offer did not go far enough.
He just kept saying no until the union said yes.
The union said it made the move in the hope of getting back pay for the workers.
The union has said its members had nothing to do with it.
The union said it would fight the plan in court.
For about 30 of them, the union says, the call came quickly.
The union has said it will ask for all information.
The union has not said how big a raise it wants.
But some classes have 45 students or more, the union said.
The union says it wants to help but has had no raise for nearly three years.