CRANSTON, R.I. — The members of the parent-teacher organization at Stadium Elementary School had no idea that the father-daughter dance they were planning last spring was, in fact, against the law.

But a complaint from a single mother about the event led to a renewal of a ban on such dances here, a move that has, in recent weeks, become a fiercely debated political flash point.

The Cranston Public Schools Committee met Monday night to ask the state to create a special exception to a law it has cited in banning the dances. The law prohibits sex discrimination in “any and all other school functions and activities.”

By last spring, district officials say, a decade of turnover since the law was passed meant that administrators at Stadium Elementary were unaware of it, and the P.T.O. set out to plan the “Me and My Guy” dance, as well as a mother-son baseball game.