British teachers are using graphic books and cartoon images to teach children as young as five years old about sexual positions, prostitution, and "how mommy and daddy fit together," according to a report released by the Christian Institute.

The report details what conservatives across Great Britain are calling a disturbing collection of books and online educational programs that contain explicit references to sex.

Listen to Todd's report for Fox News Radio:

Play Audio Clip Listen to audio clip.

The book "How Did I Begin?" was especially troublesome for the Christian Institute. The book featured an image of a couple in bed along with an explanation about what was happening:

"As they cuddled, your dad's penis moved gently inside your mum's vagina and the sperms flowed out," the book read.

The children's book, "Mummy Laid an Egg," also drew complaints from the group. It featured a cartoon drawing of a man and woman having sex on a skateboard. That book was award the British Illustrated Children's Book of the Year.

Other publications encouraged primary-aged children to learn about anal intercourse, oral sex and prostitution. One book compared sex to skipping - something they can do all day long.

"Parents don't want their children to be exposed to material which sexualizes them and most would be deeply upset if these materials were used with their primary-aged child," Mike Judge, of the Christian Institute told The Daily Mail. "If public bodies believe these resources are suitable for young children, there is clearly a problem with their judgment and more control needs to be given to parents."

Justin Hancock, the editor of a website devoted to sex and relationship education for young people, defended the materials - but said he understood how parents could be upset.

"Age and cultural appropriateness is the key," he wrote in an editorial published by The Guardian. "There is no way on earth I would want my materials to be used for primary school kids. No sex educator wants to upset parents, teachers or children. And there is simply no point in teaching stuff that is going over kids' heads."

Hancock suggested the Christian Institute "cherry picks" examples that refer to sexual body parts and sexual acts.

"Children need to know how their bodies work; that touching, for example, the clitoris can feel nice; that some touching is appropriate and some isn't; that adults have sex and what that means; that some people love people of the same sex," he wrote.

The Department of Education told The Telegraph that the books were not recommended by the government. A spokesman said teaching materials are determined by local schools.

"It's down to teachers themselves to use their professional judgment in deciding this - and its common sense to involve parents closely in this," the spokesman told The Telegraph.

The spokesman also said parents have the right to pull their children out of any sex education class - so long as the class is not mandated by law.