There were eight reports of rape at Hertfordshire schools – including one of a boy aged under 13 – in just four years between 2011 and 2015.
Figures provided by Herts Police show there was a total of 68 alleged sex offences reported in the period, which also included allegations of sexual assaults, grooming and exposure.
And of the reported rapes, three girl victims were aged under 13. On one particular day, there were four separate reports that boys under the age of 13 were sexually assaulted.
Children’s charity Plan International UK said students are being let down by the government because sex education is not mandatory in schools.
Kerry Smith, the charity’s head of girls’ rights, said: “We’re failing young people when it comes to learning about healthy relationships and consent.
“Quality sex and relationships education helps young people to develop healthy attitudes towards sex and relationships while helping to tackle inappropriate and aggressive sexual behaviour.
“While any cases of suspected sex offences in schools is troubling, the rise in cases may be attributable to children being made more aware of what constitutes normal relationships.”
She added: “It is worth recognising the work that has been done by police, schools and other authorities to encourage children to report such allegations so they can be investigating thoroughly. Only by doing so will we create the safe and secure learning environments our children deserve.”
Although Plan International UK obtained figures from police forces across the UK, the charity said figures are not comparable as the systems used for recording and capturing figures are not generic.
Nationally, the number of sexual offences reported in schools each year more than doubled between 2011 and 2015.
Other national findings include 66 per cent of alleged victims are female, 94 per cent of alleged offences are committed by males, and 15 per cent of alleged offences are thought to be committed by school staff, including teachers.
A spokesman for Herts County Council said: “All Hertfordshire schools work closely with the police and the Hertfordshire Safeguarding Children Board to ensure that the safeguarding of children and young people is their highest priority.
“Schools have regular training on safeguarding and we provide help to deliver a quality PSHE curriculum which includes education on safe sex and healthy relationships.
“We have also developed, in partnership with school nursing, a toolkit for school staff to increase their confidence in talking to young people about sex and relationships and to provide support to young people who need it.”
The council spokesman added that Youth Connexions provides workshops in schools to help prevent child sexual exploitation and the Unplugged programme, which ‘develops resilience in young people’ is currently being piloted.