California parents are complaining that a new sex-education book for ninth-graders has way too much hot, naked sex in it.

The Fremont school board voted to replace a 10-year-old sex-ed book with a new book, titled Your Health Today, which includes details about things like foreplay, masturbation and bondage.

Some parents are not happy about it. Almost 2,000 of them have signed a petition to remove the book from schools, but the school district says it has no intention of pulling it.

“There’s a section that tells you how to talk to your prospective partners about your sexual history,” parent Asfia Ahmed told the San Jose Mercury News. “I am a very liberal person, and, in spite of that, I still find the book shocking.” Other parents were appalled to find mentions of ropes, handcuffs and sex toys.

School-board president Lara Calvert-York said that despite parental objections, it’s better to educate teens early, before they become sexually active. “Ninth grade is the last time when we have an opportunity to help educate our students on how to be physically and emotionally safe,” she told the Mercury News.

[San Jose Mercury News]

Write to Charlotte Alter at charlotte.alter@time.com.