Schoolchildren as young as 10 should learn about pornography as part of the national curriculum, according to a teaching union.
The call comes at the same time as a report claimed it is now 'the norm' for teenagers – especially boys – to watch hard-core material online.
For one in three, their online activities cause problems in their real-world relationships by giving them a misguided view of sex or leaving them desensitised.
Researcher Prof Andy Phippen, from Plymouth University, said: "Some people are getting hooked on porn and then are not able to perform in the real world. It can be very damaging."
The findings come from a survey of 1,000 young people. Some of those questioned said they had first seen hard-core material from the age of 11 or 12. Often, they were introduced to pornography by an older sibling.
Separately, the National Association of Headteachers said primary school teachers needed to respond to the fact that children were now getting a large amount of their information about sex from the internet.
They said sex education guidelines are hopelessly out of date and cannot cope with the 'overtly sexualised world' in which children are now growing up.
Campaigners say the easy access of porn online is harming children, and the NSPCC says they have seen an upsurge in calls from teenagers upset by what they have seen.
In an interview with BBC Radio 1's Newsbeat programme, NAHT policy adviser Sion Humphreys said teachers should hold lessons on the 'impact of pornography'.
"Children are growing up in an overtly sexualised world," he said.
"That includes easy access to porn and they need the skills to deal with it.
"We would support children being taught in an age-appropriate way about the impact of pornography as part of a statutory Personal Social Health Education programme."
And Leonie Hodge, from the charity Family Lives, said it was vital children learned about porn. She said that at a time when 90 per cent of children own a smartphone, it is no longer relevant to talk about 'making a baby'.
"Teenagers are bombarded with pornography from a young age; you can't escape it. It's patronising to say they can't cope with the lesson because they can," she said.
However, another teaching union – the National Union of Teachers – said it was too early to start teaching children about porn at primary school. They said schools should only talk about it if asked by students.
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