In addition to information about how to put condoms on properly, the class was also advised that the anus is the next most sensitive part of a man’s body after the penis, online news website Le Matin reported.
Such information, according to Fleury, can push kids to engage in impure practices.
"If you tell them the anus is an erogenous zone, don't you think they're going to try it?" he asked.
Instead of discussing the mechanics of sex, Fleury wants schools to focus more on the emotional and moral aspects, as well as on safety issues such as how to prevent the transmission of AIDS.
His comments in the newspaper of the Federal Democratic Union of Switzerland, a small Christian party, have kicked off a vibrant debate on Swiss web forums this week.
But his son's school said it was only following the curriculum and had no plans to change its approach, newspaper Le Matin reported.
Eva Fernandez, from the association Ciao that advises adolescents on a number of issues, believes young people need concrete facts about sex, however unpalatable these may be to some parents.
“In two clicks, young people have access to thousands of porn sites on the internet. Good luck then, after that, trying to explain to them about the birds and the bees,” she said.
The FDU however insists that sex education should be the domain of parents rather than schools.
Plans by a teacher training centre in entral Switzerland to teach on topics such as anal sex, oral sex and sex with a same-sex partner are considered particularly outrageous.
It'ss all too close to pornography, the FDU says.
“Are there actually paedophiles or porn-addicted sex-educators at work here?” the organisation asks.