Staff from 50 schools were warned about the rise of so-called 'sexting' among pupils at a conference in Lincolnshire.
Experts explained how the number of children exchanging explicit messages was on the increase.
On Wednesday, staff were told they need to be educating Lincolnshire teenagers about the dangers of such practices.
The conference took place at William Farr school in Welton. It included a talk by Professor Andy Phippen who said some youngsters did not see any problem with exchanging explicit messages.
Event organiser lan McKenzie said: "Sexting is a relatively new phenomenon because of the development of technology. Many young people find this normal behaviour and part of the flirting process and don't realise it is actually illegal.
"Teenagers are saying 'why don't we get spoken to about this so we understand?'"
The charity Beatbullying claims one-in-four 11 to 18-year-olds have received a 'sext' by phone or e-mail.
Detective Chief Superintendent Keith Owen, Head of Crime, Lincolnshire Police, said: "It is illegal to take, hold or share indecent photos of anyone under 18 in the UK. Sexting by young people may involve "taking an indecent photograph of a child" which is a serious criminal offence.
"Inevitably sexting involves forwarding images. Although receiving the images is not an offence, keeping them counts as 'possessing an indecent image'. Anyone who then forwards the message with an image of a child is likely to be committing a further offence of distributing indecent images of children.
"We want young people to be aware of the legal implications of sexting."