Teachers have gone on strike over concerns about violence and knife threats from pupils.
Some staff at Starbank Secondary School in Birmingham said they received little support from bosses in confronting badly-behaved pupils.
A teaching union says a “knife audit” needs to take place, along with extra training for teachers and a behaviour policy for pupils.
Birmingham City Council said it was in discussions with trade unions.
It added that “suitable provision has been made to ensure that lessons will continue” during the two-day strike.
Parents said they do not feel their children are safe at the school.
About 30 teachers took to the picket line at the school.
Paul Nesbitt, from the National Association of Schoolmasters and Union of Women Teachers (NASUWT), said there had been three incidents in the last three weeks, including one which saw a pupil bring in a 12-inch knife.
A teacher was also threatened with a knife, and the pupil was excluded for a number of days but later returned, he added.
Another teacher also suffered a “split lip” after being hit by a year seven pupil last year, the union said.
Staff have alerted union officials over “Fight Thursdays”, which they say take place on the school playing fields.
They also raised concerns over senior staff failing to respond to teachers who hit so-called “panic buttons”, which are installed on school computers as a means to raise the alarm over problems in the classroom.
“Even though the school was aware that they have students causing serious issues, there’s no risk assessment being carried out on these pupils” Mr Nesbitt said.
“Sufficient practical steps have not been taken to ensure poor behaviour is addressed and that teachers are supported in maintaining good order in the classroom.”
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Parent Emma Wall, who has a 13-year-old daughter with special needs who attends the school, said: “My daughter alone has been physically attacked. She has been verbally and mentally attacked.
“All they (the school) are offering is mediation, but that’s been going on since February.
“The school has not been safeguarding the children as they should be. I do not feel she is safe at school at all.”
Saima Begum, who also has a daughter with special needs who attends the school, said parents were “really shocked” to find out “how deep this issue is”.
“Some of these little kids in Birmingham are not afraid to use a knife, but to know that it’s happening in the school your child attends, that’s a shock to the system,” she added.
Another union, the National Education Union, said “the aggressive behaviour of some pupils towards staff” had resulted in members being assaulted but that it had called off its planned strike action because it had made “very significant progress” working with the school.
The school has been contacted for a comment.
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