Two thirds of primary teachers believe sex education should be compulsory for pupils in their schools, and many of those recommend it for children at seven.
A TES survey of almost 2,000 teachers showed three-quarters of them want compulsory sex and relationships lessons. More than 60 per cent in primaries, but only 35 per cent in secondaries, felt it should start in Year 5 or 6. A quarter of primary staff would like lessons to begin in Year 3.
The survey results come as the Government this week launched a review group to investigate sex education, a vital part of its drive to make pupils lead healthier lives. At present, sex education is only statutory as part of the science curriculum for 11- to 14-year-olds.
Our survey was carried out to launch a TES series, called The Big Five, examining the ambitious outcomes for children that schools are expected to meet: these are for young people to be healthy, stay safe, enjoy and achieve, make a positive contribution in life and reach economic wellbeing. These aims were first introduced five years ago as part of the Government's Every Child Matters policy, and form the basis of its Children's Plan for the next decade.
Yet more than two-thirds of the teachers surveyed said that the five outcomes had made little or no difference to their teaching.
The first report in The Big Five series also reveals that government statistics showing a national obesity epidemic among children are based on body-mass index, a measurement that nutrition experts, including the Department of Health, acknowledge is inadequate. In fact, nutritionists argue that fat is a necessary part of children's diets.
In many schools, the focus in sex education is on biological functions, rather than relationships, contraception and sexually transmitted diseases. Some do offer more detailed information, as part of the personal, social and health education curriculum. But parents have the right to withdraw their children from these classes.
Our survey found that almost half of the teachers had been asked to teach sex education on occasion - but three-quarters of those had been given no training.
Rebecca Findlay, from the Family Planning Association, said: "Teachers suddenly feel themselves thrown head first into a subject they nothing about teaching."
Only one in 10 felt parents might object if the subject were to become compulsory. But Beverley Hughes, the children's minister, told The TES that parents and faith schools would be reluctant to accept it as statutory. "We're aware that young people say the quality of sex education is very patchy and poor in places. We do want that to improve. But it is a very difficult issue. We have to take people with us."
Ralph Jaggar, head of Ackton Pastures Primary School in Wakefield, West Yorkshire, recently introduced such classes for Year 3 pupils. As well as learning about emotions and relationships, children are taught about puberty and the physical differences between men and women.
"Year 3 is the optimum time to teach about puberty," he said.
Sex in its true colours, page 31
Lessons in bonding, page 25.