DES MOINES — A bill presented as an opportunity for parents to make an informed decision on whether they want their kids to participate in sensitive subject matter met with opposition Tuesday from labor unions, associations representing schools and groups providing human sexuality education.

Rep. Greg Heartsill, R-Columbia, told more than 50 people at a House Government Oversight subcommittee hearing that House Study Bill 647 would require parents to sign a permission slip before their children could participate in curriculum — at school or off-campus — dealing with human growth and development.

“If we’re talking an anti-bullying conference, it doesn’t apply,” Heartsill said. Same with suicide prevention, forming gay-straight alliances and preventing substance and domestic abuse, he said.

However, it would apply to the Iowa Governor's Conference on LGBTQ (Lesbian, Gay, Bisexual, Transgender, and Questioning) Youth where students last spring allegedly were provided with instructions on “safe” sexual bondage and how to find orgies.

Several speakers representing teachers and schools warned that an “opt-in” law requiring parents to sign permissions slips for their children would be onerous and prevent many students from participating. Most schools, according to Margaret Buckton of the Urban Education Network representing 17 of the state’s largest districts, have “opt-out” policies that allow parents to hold their children out of field trips and classroom curriculum they judge inappropriate.

Heartsill said HSB 647 stemmed from a situation where parents, teachers and administrator “didn’t realize their kids were going to be taught subject matter beyond what the parents were comfortable with.”

The April 2015 conference, which despite its title has nothing to do with the Governor’s Office, attracted about 1,000 students, 400 parents, school personnel and faith communities, according to organizers. In the past, they’ve said the legislation is being brought by lawmakers obsessed with the LGBTQ lifestyle. Students at the conferences were given sexual health information not widely available in school health classes, they’ve said.

Rep. Ruth Ann Gaines, D-Des Moines, split the difference. She called HSB 647 an overreaction to what one teacher “who thought what she heard was inappropriate.”

“We’re going on hearsay,” said Gaines, a teacher. “We’re overreacting to something that happened one time.”

Then she spoke to the organizers of the conference, telling them “get rid of those speakers … who insult students and teachers. Don’t invite them back.”

The third subcommittee member, House Government Oversight Committee Chairman Bobby Kaufmann, R-Wilton, is considering narrowing the focus of the bill to only off-campus events, such as the privately sponsored LGBTQ youth conference.

He expects the full committee will discuss the bill Wednesday.