Urgent action must be taken to end the "widespread" sexual harassment of girls, MPs have demanded after a shocking picture of the scale of abuse in schools was laid bare.
Groping, name calling and bullying is part of "everyday life" for schoolgirls but is dismissed by teachers as "just banter", a Commons committee found.
Its disturbing report warned that some pupils, including those in primary school, were being exposed to hard-core pornography and the images they saw were twisting their views on sex and relationships.
MPs pointed to research that found nearly a third of 16- to 18-year-old girls said they had experienced unwanted sexual touching at school and most girls and young women had faced some form of sexual harassment at school or college.
Pupils also reported hearing girls being called a slut or a slag on a regular basis, according to research highlighted by the Women and Equalities Committee.
It heard the "slapping of bums and flicking [lifting up] of skirts" was common while one teacher told how they had had "many young girls sobbing and humiliated in my office because partially naked images have gone viral".
Too many schools were failing to deal with the problem while the government and watchdog Ofsted had no coherent plan for how the causes and consequences should be tackled, it found.
Conservative MP Maria Miller, who chairs the committee, said: "Our inquiry has revealed a concerning picture. We have heard girls talk about sexual bullying and abuse as an expected part of their everyday life; with teachers accepting sexual harassment as 'just banter'; and parents struggling to know how they can best support their children.
"It is difficult to explain why any school would allow girls to be subjected to sexual harassment and violent behaviour that has been outlawed in the adult workplace. The evidence shows it is undermining the confidence of young women. Failing to reinforce what is acceptable behaviour could well be fuelling the 'lad culture' that the Government has already identified as a problem in colleges and universities.
"Despite this, the Department for Education and Ofsted have no coherent plan to ensure schools tackle the causes and consequences of sexual harassment and sexual violence.
"There are some examples of excellent work being done by schools and third sector organisations to prevent sexual harassment and sexual violence. But too many schools are failing to recognise this as a problem and therefore failing to act.
"The Government must take a lead and make it clear that sexual harassment in schools is completely unacceptable and support schools, teachers, parents and young people to tackle this widespread problem."
It looked at recent Girlguiding's Girls' Attitudes surveys, which found in 2014 that 59% of girls and young women aged 13 to 21 said they had faced some form of sexual harassment at school or college in the past year.
MPs also highlighted polling by campaign group End Violence Against Women in 2010 that reported 71% of all 16- to 18-year-olds pupils had heard sexual name-calling, such as "slut" or "slag" used towards girls at schools regularly while 29% of girls in the age group told of being groped.
The report said there was not enough information to show sexual harassment and violence was a growing problem in schools but there was "significant" evidence to suggest that easier access to pornography was exacerbating the problem.
It warned that the type of pornography many children were exposed to was often "more extreme" than adults realised and it was having a "negative impact" on youngsters.
Girlguiding's advocate panel, a group of 14- to 25-year-olds who represent the movement's young members, said: "As young women, many of us are still in school and experience or witness sexual harassment from groping to cat calling on a daily basis.
"It's humiliating and frightening and affects what we wear, where we go, our body image and our confidence to speak out in class. Yet, it's often dismissed as banter or a compliment and we are told we are overreacting or being over sensitive.
"It needs to stop. Schools should be safe and empowering places and we should feel able to learn without fear. That's why we need a zero tolerance approach to sexual harassment where schools take the issue seriously, sex and relationship education is compulsory, and schools are held accountable for preventing and tackling sexual harassment."
MPs called for all schools to collect data on reports of sexual harassment and police should keep specific records of incidents.
Kevin Courtney, National Union of Teachers general secretary, said: "Government education policies hinder schools' ability to tackle sexual harassment and sexual bullying effectively by leaving no time for pastoral care or personal, social, health and economic education (PSHE) within the curriculum or school day.
"Support and guidance from the Department for Education about how to best mitigate the effects of sexual harassment and sexual violence is urgently required."
The NSPCC spokesman said the problem had been "swept under the carpet" for years.
A spokesman said: "Sadly, these findings are not new.
"We know through calls to Childline that sexual harassment, and even abuse, in schools is something that many pupils up and down the country suffer on a daily basis but for years it's been swept under the carpet.
"We welcome the inquiry and its recommendations but now want to see action taken and robust measures put in place.
"We hope the Government will focus on measures that prevent abuse as well as prioritising the reporting of it - otherwise it becomes a case of trying to close the stable door once the horse has bolted."
Shadow women and equalities minister Angela Rayner said: "The Tories are failing to deliver a safe environment for our children to learn and thrive in. It is vital that teachers and staff receive greater support and guidance to tackle the shocking levels of sexual harassment and violence experienced by children in our schools.
"But under this Tory Government, schools are at breaking point. They are facing the first real terms cut in funding for nearly two decades which will inevitably make it more difficult to tackle the harmful attitudes that lead to sexual harassment and violence."