An "educate against hate" website has been launched by England's Education Secretary Nicky Morgan, as part of a renewed drive against extremism.
The website holds information for schools and parents to tackle the "spell of twisted ideologies".
The government promises a "tougher approach" to preventing illegal, unregistered schools.
Mrs Morgan says the aim is to protect "impressionable minds from radical views".
The measures were announced at Bethnal Green Academy in east London, a school attended by three girls who ran away to Syria last February.
Mrs Morgan said this is "absolutely not about shutting down debate in schools" or "wrapping young people in cotton wool".
The education secretary called for a balance between preventing extremism and allowing an open debate with challenging ideas.
"That isn't easy, there's no hard and fast rule. Age appropriateness matters, as do the motivations of the speakers," Mrs Morgan said.
"It requires judgement - but just as we must be absolutely clear that we should never give those who peddle extremist ideologies' entry into our schools or colleges, so too we must guard against inadvertently hiding young people from views which we simply think are wrong and disagree with."
The anti-radicalisation website promises to provide "practical advice to protect children from the dangers of extremism", with information from the government and groups such as the National Society for the Prevention of Cruelty to Children.
It includes information on:
On BBC Radio 4's Today programme, Mrs Morgan said the website would advise on preventing all forms of extremism, including, for example, far-right views.
Parents and teachers should look out for changes in behaviour, including pupils adopting different beliefs and customs, she said.
Asked whether pupils should be able to wear face veils in school, the education secretary said "we're not going to tell people what they can and can't wear" but schools had the right to impose a uniform policy.
Mrs Morgan said such dress codes were "up to the school" but there were occasions when seeing someone's face would be necessary, for teachers as well as pupils.
NSPCC head Peter Wanless likened tackling the appeal of extremism to preventing grooming.
"We are contacted daily by worried parents and children themselves on all sorts of issues including radicalisation and dangers associated with extremism," said Mr Wanless.
"Spotting the signs of such abuse has never been more important if we are to help protect children from sexual exploitation, gang-related activity or other hate crimes."
Mr Wanless added he wanted parents to be aware of "tell-tale signs of exploitation".
Bethnal Green Academy principal Mark Keary said the website would be a "vital tool" and "educators have a crucial role to play in protecting children from the threat of radical views".
The Department for Education is also promising a "significant escalation" of investigations into schools operating without any formal registration or oversight.
In November, Ofsted said it had found 15 unregistered, illegal schools, including some in Birmingham and London.
A further three schools were discovered a month later, with calls from inspectors for more urgent action to close them.
There will also be a consultation on making sure information is shared to track pupils leaving a school to move to another part of the country.
Mrs Morgan said the website would give teachers and families "the expertise they need to challenge radical views and keep their children safe".
She said "improving intelligence" on where pupils went when they moved away from a school would cut the risk of "young, promising children falling under the spell of twisted ideologies".
"There will be no single knockout blow against those who seek to corrupt young people - but the action we are taking to protect children, inform parents and support teachers will put us firmly on the front foot."