A lesbian mother has started a campaign urging her school district to ban teachers from promoting political causes in the classroom.

Washington parent Cynthia Deford is demanding an apology after her daughter’s eighth grade math teacher wore an anti-gay marriage button in class.

The Peninsula Daily News reports the badge’s message said: ‘No on 74: one man + one woman = marriage.’

Deford said her child came home after school and told her about the button worn by the teacher, saying she was ‘surprised and offended.’