Almost a third of teachers (31 per cent) have been abused online in the past year, a survey has suggested.
The poll, by NASUWT, showed that of those, 60 per cent had been abused by pupils and 50 per cent by parents.
The survey, which 1,507 teachers completed, showed that even when such abuse was reported, no follow-up action was taken in 45 per cent of cases, and 38 per cent of teachers felt it was necessary to stop using personal social media accounts because of concerns over privacy and abuse.
It also raised concerns about pupils accessing online sexual content, with 62 per cent of teachers reporting pupils viewing or sharing such material, with 16 per cent of these being children of primary school age.
Union general secretary Chris Keates said: “The findings of this survey paint a shocking picture of what is happening in our schools, where on a day-to-day basis teachers are getting no support despite being subjected to appalling levels of online abuse, while pupils’ ability to view and share inappropriate online content seems to continue virtually unabated.”
In total, 35 per cent of teachers said that students have cited clearly fake news or false information from the internet as fact in their work or classroom discussions.
Ms Keates said the finding was "worrying" and shows the power that internet firms have in shaping public opinion, especially among young people.
In one case, a union member said that "some students did not attend school and hysteria ensued because they thought there were killer clowns roaming the streets with weapons".
Another said that pupils "often mistake spoof news sites for real news".
"It is worrying that over a third of teachers had experienced pupils citing fake news or inaccurate information they had found online as fact in their work or during classroom discussions," Ms Keates said.
"This demonstrates the great power that companies such as Facebook and Google now have in shaping public opinion, particularly among young people who have never known a world without internet and who are less equipped to analyse the information they see presented to them online and assess its plausibility.
"It is important for children and young people to be made aware that not everything they see and read online is real."
She said that teachers were trying to help educate pupils when they cite false information, but added that as with other forms of technology misuse, it was important for online providers to "take responsibility for the material hosted on their platforms and to take steps to tackle those who seek to misuse these sites".
Last month, Andreas Schleicher, the Organisation for Economic Co-operation and Development's (OECD) director of education and skills, said that in the modern digital age, schools should teach pupils how to think critically and analyse what they read on social media and news sites.