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 report warned that some pupils, including those in primary school, were being exposed to hardcore pornography, and that the images they saw were affecting their views of sex and relationships.
MPs pointed to research that found that nearly a third of 16-to-18-year-old girls had experienced unwanted sexual touching at school. The research also found that most girls and young women had faced some form of sexual harassment at school or college.
Pupils reported hearing girls being called “slut” or “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. One teacher spoke of "many young girls, sobbing and humiliated in my office, because partially naked images have gone viral".
No coherent plan
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: "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.
"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."
Meanwhile, members of Girlguiding UK have launched a petition calling on education ministers in England, Scotland and Wales to end sexual harassment in schools. The petition calls for schools to take a zero-tolerance approach to the problem.
It also highlights the role played by compulsory sex and education lessons in preventing sexual harassment in schools.
'From groping to cat-calling'
Girlguiding's advocate panel, a group of 14- to 25-year-olds who represent the movement's 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 oversensitive.
"It needs to stop. Schools should be safe and empowering places and we should feel able to learn without fear."
MPs called for all schools to collect data on reports of sexual harassment and for police to keep specific records of incidents.
Kevin Courtney, general secretary of the NUT teachers’ union, 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 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."