Teachers have gone on strike protesting over violence, threats and "poor management" at a Lancashire school.
Staff at Darwen Vale High School in Darwen said they had a lack of backing from management when they confronted pupils over bad behaviour.
About 70 teachers formed a picket line outside the 1,100-pupil school during the one-day walkout on Thursday.
Head teacher Hilary Torpey said management was in talks with the unions over how to improve staff support.
The unions say pupils' behaviour includes challenging teachers to fights, pushing and shoving staff, pupils making malicious allegations, constant swearing, and filming lessons on mobiles and threatening to post them online.
'Sad but necessary'
There have also been problems with cyber bullying and pornography, it is claimed.
It is alleged that when teachers confiscated pupils' phones they have then been returned by management, leaving staff "totally undermined".
Members of the National Association of Schoolteachers/Union of Women Teachers (NASUWT) and the National Union of Teachers (NUT) were all on strike.
The dispute was also supported by members of the Association of Teachers and Lecturers (ATL) and the support staff union, Unison.
Parents of children at the school were told no classes would be held during the walkout.
Avis Gilmore, secretary of Lancashire NUT, said: "Our members have felt it very sad and very necessary to take this strike action because of the failure of management to really listen to them and to support them in dealing with pupil behaviour."
Simon Jones, a local National Union of Teachers (NUT) official manning the picket line, said he was delighted with the turnout and support they received.
"This is not a strike against pupils. It is about management, and management failure to support staff in dealing with challenging behaviour," he added.
"No-one wants to demonise the children here, they are no better or no worse than any other.
"The biggest difference between this school and other schools is the management failure to support staff."
Head teacher Ms Torpey, who began her first full academic year at the school in September, said she was disappointed with the strike.
"My main priority is around the wellbeing and education of our pupils and the best interests of the school. I want to ensure disruption is kept to a minimum," she said.
"I am disappointed that the trade unions have chosen to take this action. The vast majority of pupils at Darwen Vale behave well and take their education seriously.
"We are in discussions with the unions and with the staff around how we can best resolve this situation so that staff feel well supported when they do need to deal with behaviour issues."
Harry Devonport, director of education for Blackburn with Darwen Council, said he was keen for the situation to be resolved.
"I think it's very sad that we have got to the position where teachers feel it's necessary to strike," he said.
"Our main concern has to be the wellbeing and education of the pupils, and the best interests of the school, including the staff, so I really want to work with everybody to ensure a swift resolution with these issues."
The unions said they could not rule out further strike action.
In its latest Ofsted inspection in June 2010, Darwen Vale was rated as a good school where pupils' behaviour was also given a good rating.
Pupils are being taught temporarily at former Holden Fold school buildings, which have a capacity of only 800.
The original Darwen Vale High School is being rebuilt under the Building Schools for the Future programme.
The new £18m school is scheduled to open in September 2012.