Two-thirds of around 2,500 school and university students in the UK who were questioned by the National Union of Students rated their sex and relationships education as 'fair, poor or terrible'.
More than half felt they weren't taught the issues they needed to know. Three-quarters admit they found out about sex and relationships through friends.
Clive Ireson, Association of Christian Teachers has blamed a lack of investment in sex education on the latest statistics.
He also believes the church and families should be working together on the issue, speaking to Premier, he said: "For a Christian family it's a partnership between school, the family and the church; and usually there are two bits of that missing. Often the family and often the church don't play their part in that.
"Because to get a full rounded sex and relationships education you need really to discover all about consent, relationships and all those sorts of things; but it's being done often in a clinical way."
The NUS is calling for sex and relationship education to be statutory in schools. Of the survey respondents, 90% agree that it should be made compulsory.
Colum McGuire, vice president of NUS, says: "Sex and relationship education is failing millions. People are being left with gaps in their education and [this] puts young people at risk.
"I find it alarming that sexual partners are listed as a top SRE source. Consider this in light of the fact that consent was never raised for two thirds of respondents [and that] the current system almost completely ignores LGBT relationships.
"We urge all political parties to commit to statutory SRE in their general election manifestos, and to accept that simple biology just won't cut it."
Clive Ireson, Association of Christian Teachers:
