An investigation has found tens of thousands of Britain's schoolchildren have been caught sharing sexual imagery online, leading to further calls for the government to introduce compulsory sex education in schools.
Figures obtained by the Times newspaper showed more than a third of all 'sexting' cases involved children aged 12 and 13.
More than one in ten cases involved a “non-school adult”.
50 of Britain's biggest secondary schools were asked for details of sexting cases since 2012.
Sexting in schools in numbers
The Times reports that the true figures are likely to be much higher as many cases would never be discovered by the school.
Sexting is defined as sexual or indecent imagery of minors shared via a mobile phone, webcam, digital camera or website.
Calls for compulsory sex education
Former Conservative culture secretary Maria Miller has called for the government to require compulsory sex education lessons in schools - something she said she had changed her position on due to the "appalling" effect sexting has on youngsters.
She also urged education secretary Nicky Morgan to make it compulsory for schools to report to the police any sexting by or to children.
The highest number of sexting cases was recorded by Hinchingbrooke school, Huntingdon, Cambridgeshire, which identified 116 cases involving inappropriate online behaviour since 2012.
An NSPCC spokesman called the figures "extremely worrying" and said sexting can make youngsters targets for sex offenders.
“Personal, social, health and economic education should be on every curriculum as it is at the front line of child protection,” the NSPCC spokesman said. “Sexting needs to be covered so that young people feel more able to approach trusted adults and get the support that they need.”