Lessons on how to use the internet safely should become compulsory in schools, university researchers say.
The Cyberspace Research Unit at the University of Central Lancashire (UCL) says learning about internet safety should be on the National Curriculum.
Pupils should be taught about the potential dangers posed, such as paedophiles using internet chatrooms to make contact with children.
The researchers say too few pupils are taught how to use the internet safely.
Director of the unit Dr Rachel O'Connell said that while up to 92% of nine to 19-year-olds were now accessing the internet at school, a third had not received lessons on its use.
Just over half had seen pornography on the web, but only four out of 10 said they would tell their parents if something on the net made them feel uncomfortable, she said.
Dr O'Connell said IT lessons currently taken in schools focussed on computing skills rather than using the internet with care and caution.
"Children are involved in a lot of social networking - they share whiteboards, write their blogs, post up pictures," she said.
"And there are extensive positive opportunities here and extensive benefits to understanding other people's viewpoints. But there are risks and children need to learn about issues like evaluating friendships online."
Dr O'Connell said the skills gap between young people and adults remained a problem in getting across the message of safe online usage.
"It's a very serious issue - we need to bridge that gap. Parents should be the first line of defence for children."
Dr O'Connell's call came as a new website - internetsafetyzone.com - offering internet safety tips for parents and children was launched.
'There isn't room'
A spokesperson for the Department for Education and Skills said the department took internet safety "very seriously".
"Almost all schools use a filtered or restricted internet service which helps protect children," the spokesperson said.
"The DfES and the British Educational Communications and Technology agency (Becta) have produced a detailed information pack for teachers and parents about pupils' safe use of the internet."
John Dunford, general secretary of the Association of School and College Leaders, said all children studied IT at school.
"It is an important part of people's education," he told the BBC News website.
"IT teachers would take safety as a part of their responsibility."
But Dr Dunford said he would not advocate adding internet safety as an extra module on the national curriculum.
"There isn't room," he said.