The lessons learned about extremism after 9/11 are still being taught in schools 20 years on, the head of an academy chain has said.

Sir Steve Lancashire, chief executive of Reach2, the largest primary academy chain in England, said the events of September 11 2001 were a “world changer” in shaping views on extremism.

He is also a trustee of UK charity Since 9/11, which uses education to promote tolerance and combat extreme views.

Sir Steve told the PA news agency: “I think there are lots of ways in which the lessons learned from 9/11 are being taught in schools, we do have a legal duty of Prevent in schools, which is around ensuring that we fulfil our responsibilities to stop extremism and challenge extremism when we see it in schools.

“And there’s also the fundamental British values that we are teaching in the curriculum within our schools.

“But I think there’s also something, which in some respects is more important, and that is around the ethos and the culture of the schools.

“We are developing the values of tolerance, of respect, of kindness and it’s going through that more hidden curriculum in our schools that I think we’ll have most success around challenging extremism, particularly violent extremism.”

Sir Steve said research found a “prevalence” of “hateful extremism” used in classrooms by children, which includes racism, Islamophobia, homophobia or misogynistic views.

He spoke of how difficult it is for teachers to challenge these extremist viewpoints in an “appropriate way”.

Sir Steve said: “One of the things that we found during the research project is that we need to help teachers more to tackle difficult conversations when extremist viewpoints are expressed.

“Sometimes teachers are worried about saying the wrong thing, they’re worried about expressing some of their own views perhaps too strongly.

“And we found a real need for us to give professional development training to teachers, so they can successfully have conversations around extremist viewpoints and manage it in a sophisticated and sensitive way.

“So I definitely think that there are some really good examples of where our resources on 9/11 are used to teach the facts around extremism.

“But also there’s a need for us to get it higher on the agenda in our schools, because the curriculum in our schools is already pretty full, but we think this is really important and should have a higher profile in the school curriculum, so we’ll certainly be lobbying for that.”

Sir Steve went on to say that schools should teach pupils to think critically about what they have read online or on social media as the “best defence” against extremism.

He added: “Even though in all schools in England at the moment, nobody was alive when 9/11 happened, we can use the lessons learned from that.

“We can use the historical significance of that event combined with subsequent events that have happened and some of the issues that we see really relevant in the news right now around hateful extremism.”