Presently, sex education is limited to the biology classroom but RFSU is seeking for it to be added to maths, geography, home economics and English.
"The teaching needs to be more coordinated so that it's not that one student gets great sex education while another gets none at all," said Han Olsson, an expert on sex education with the RFSU, in a statement.
Sex education has been a compulsory subject in Swedish schools since 1955. In 2011 the government announced they were pumping an extra 10 million kronor ($1.5 million) to expand the subject into other lessons.
Getting sex education earlier is important, RFSU argue and Olsson added that it was "necessary" for students to be made aware of their own bodies earlier in life even if they aren't sexually active.
"Sex education needs to be professionalized. It needs to be seen as an area of knowledge much like other subjects," he said.
The national body are also keen for sex education to become a part of religious studies to counteract statements from religious leaders who criticize the use of condoms and homosexuality.
When the national TV network Sveriges Television (SVT) together with sexual educators RFSU showed a film called "Sex on the map" (Sex på kartan) in Swedish schools it met with strong reactions as a dark skinned boy was shown having sex with a lighter skinned girl, and because the film featured homo-, bi-, transsexual and queer issues.
Meanwhile, the Swedish evangelical alliance have said they want religious studies to be incorporated into other lessons, according to a report in the Christian Dagen daily.
Suggestions include 'how to walk on water' for physics, 'how to paint icons' for art and 'how to turn water into wine' for chemistry.
"We want the Swedish National Agency for Education (Skolverket) to make the scriptures a part of every school subject. According to the curriculum the school's fundamental values rest on the ethics of Christian tradition and western humanism," said Stefan Gustafsson of the Swedish evangelical alliance, to the newspaper.
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