The examples are contained in new guidance for schools on how they can help prevent violent extremism.

The guidance says schools should identify pupils at risk of being drawn into extremism and encourages teachers to allow classes to discuss controversial issues such as terrorism and racism.

Schools should also have a named teacher to whom pupils can report any concerns of grooming by extremist groups.

It was launched by Schools Secretary Ed Balls, who said it was a direct response to calls from schools for more support, and follows consultation with young people, teachers and local communities.

Mr Balls announced £4.68 million in funding for the initiative and said schools will be given a toolkit giving teachers practical advice about challenging extremism and building respect between pupils.

The initiative comes amid fears that disaffected young people could be targeted by extremist groups.

The announcement comes just weeks after Britain's youngest terrorist, 18-year-old Hammaad Munshi was locked up for two years after plans to cause death and destruction were found hidden in his bedroom. He was just 15 when he was recruited into a worldwide plot to wipe out non-Muslims.

In a visit to Hatch End High School in north-west London Mr Balls said the new guidance was not about asking teachers "to be monitors and to be doing surveillance".

But he added: "But if something concerns them, we want them to know who to turn to for help."