And similar proportions of boys and girls are calling for lessons in what to do when they see something upsetting online.
A survey of more than 1,000 pupils between the ages of 11 and 18 shows that 85 per cent of girls think that their school should teach them how to cope with sexist, racist or discriminatory behaviour online.
But it was not just girls who wanted lessons in online safety. Eighty-eight per cent of all pupils surveyed by the charity Plan International UK thought that their schools should teach them how to stay safe online.
And 80 per cent wanted lessons on what to do if they saw something upsetting online.
'What young people want'
In addition, a separate survey of 1,000 people aged between 14 and 21 revealed that more than a quarter of girls – 26 per cent – did not know what to do when their period started. And one in seven – 14 per cent – did not know what was happening to them when they began menstruating.
The government is currently carrying out a consultation on what to include in the new relationships and sex curriculum, which will be introduced in September 2019.
Plan International UK has said that it would like to see this curriculum include issues such as consent, how to navigate the digital world and how to manage periods safely.
Lucy Russell, the charity’s girls’ rights campaign manager, said: “We have to listen to what young people themselves want, because they are the experts in their own lives.
“Giving them the skills to cope with real-life issues is the best way to prepare them for adulthood. And what better place to do this than in schools, where they spend a large part of their day?”