The Government's anti-radicalisation strategy has been rejected outright by the National Union of Teachers (NUT) over concerns it is silencing conversation in the classroom and damaging community cohesion.
The union called on the Government to withdraw the Prevent strategy regarding schools, which since summer 2015, has obliged teachers to refer to police pupils they suspect of engaging in some sort of terrorist activity or radical behaviour.
The duty has been largely considered a failure by teaching leaders partly due to the fact that around 90% of referrals end in no action being taken, with a catalogue of high-profile examples.
NUT executive member Alex Kenny, speaking at the union's annual conference in Brighton, said: "We want to keep children safe from those organisations who promote hatred and violence. But there are limits to what we can do, and Prevent is making that harder.
"Four thousand referrals in the last 18 months is not a sign that the strategy is working, it's a sign that the strategy is flawed."
In an appeal to Government, he said: "Listen to what we are saying, think about what we are saying, and stop what you are doing."
Members voted unanimously to ask the Government to develop an alternative strategy to safeguard children and identify risk, and develop resources for teachers discussing difficult or controversial subjects such as religion and terrorism.
They also called on the Government to conduct an urgent review of the Prevent strategy following an independent assessment from terrorism legislation expert David Anderson QC, who said the duty had become "a significant source of grievance among British Muslims, encouraging mistrust to spread and to fester".
Kevin Courtney, NUT deputy general secretary, said children who were discouraged or too frightened to speak publicly in the classroom were turning online where they were potentially at risk of being groomed.
He said: "The best contribution teachers can make is to encourage discussion in the classroom.
"But we worried that people are increasingly unwilling to talk about their view of the world - Muslim children in particular - because they are frightened or their parents are worried that their names will be put on some list."
Mr Courtney said concerns are so acute that a group of young Muslim girls at a state school in East London refused to discuss issues surrounding Charlie Hebdo in the fortnight after the Paris attacks over concerns their thoughts - none in support of the attacks, but possible opinions on the depiction of the Prophet Muhammad in cartoon form - would land them in trouble.
Other examples of young people erroneously referred to Prevent included:
:: A 17-year-old who had a Free Palestine leaflet in his possession
:: A four-year-old who misspelled "cucumber" as something resembling "cooker bomb".
:: A 10-year-old Muslim boy mistakenly wrote he lived in a "terrorist house" rather than a "terraced house"
:: A 15-year-old student who clicked on the Ukip website to research attitudes to immigration
And a citizenship teacher said his pupils were unable to research their politicians' voting record on foreign policy in Syria because the network which provides IT services to schools in London blocked any website mentioning IS - driving them to research the subject at home, alone.
Mr Courtney said: "That inhibition of debate, we think, is the biggest problem. That's why we want the Prevent strategy replaced with something, discussed with us, which puts teachers at the forefront of engaging children in those sorts of discussions and which uses safeguarding procedures."
Gary Kaye, a teacher from North Yorkshire, said the Prevent strategy created "suspicion in the classroom and confusion in the staffroom".
Latest figures show, on average, two teachers call the Government hotline every school day over concerns a pupil may be becoming radicalised.