Sex and relationship lessons in school would make all children safer, according to a survey of young people.
Three-quarters of 11 to 15 year olds in England believe that age-appropriate classes would improve child safety, the poll of almost 1,000 children, carried out by the charity Barnardo's has found.
Seven in 10 want the government to ensure that all young people have such lessons, while 25 per cent said either that they had not been taught about sex and relationships in school, or that the classes were bad.
The research showed that 96 per cent of children thought it was important to understand the dangers of being online, and 94 per cent wanted to know the risks of sharing images of themselves with a stranger online.
'Time to listen to children'
Javed Khan, Barnardo's chief executive, said that children had spoken "loud and clear", and that the government must not ignore them.
"It's time to listen to children who are clearly telling us that they need help in understanding the digital dangers and the risks of sharing images of themselves with strangers,” he said.
"Online grooming is a very real danger facing all children and nearly half of the girls polled said they were worried about strangers contacting them online.
"Compulsory SRE lessons for all children must be introduced as soon as possible – it will help prevent children being groomed and sexually exploited."
MP Maria Miller, chair of the Women and Equalities Committee, said it was striking that children were calling on the government to ensure that they receive sex and relationship education, and that the case for compulsory lessons had never been stronger.
Former Girls Aloud singer and Barnardo's ambassador Nicola Roberts said: "With sexting becoming such a huge problem, it's essential that children know how to protect themselves online.
"Children have told the government they want school lessons on sex and relationships to help keep them safe. Now it's down to the government to stop letting them fend for themselves online and protect children by providing compulsory sex and relationships education."
A Department for Education spokeswoman said: "High-quality education on sex and relationships is a vital part of preparing young people for success in adult life – helping them make informed choices, stay safe and learn to respect themselves and others.
"Education on sex and relationships is compulsory in all maintained secondary schools, and many academies and free schools teach it as part of the curriculum.
"We are actively considering what further steps we could take to improve the quality and availability of sex and relationships education."