As the petite, middle-aged teacher shouts desperately for the 20th time for the out-of-control class to be quiet, a faint, childish boy's voice can be heard, calling out above the deafening din: "Suck me off, miss".
The appalling scene of classroom disorder and disrespect is just one of many captured on film for a channel Five documentary, to be screened this week.

The documentary shows children aged from 12 to 15 completely ignoring her and other staff while they shout, scream, fight, swear and wander around the classroom at will.

In one scene a full-scale fight breaks out and a 6ft tall boy is seen wielding a rubber truncheon, as the terrified teacher calls for help. In another, pupils throw books, pens and balls of paper across the room for a full 15 minutes as the teacher protests, before they declare that they "don't give a poo". In yet more disturbing scenes, a boy in a computer class is filmed accessing hard-core porn sites and then protesting his innocence, saying "I just typed in '[filtered word]', miss".

Clearly shaken by her experiences, the teacher said she could not comprehend the behaviour she filmed, using a tiny camera hidden in a briefcase and a microphone disguised as a jacket button.

She is ignored or challenged constantly. In one maths class, a 12-year-old who was censured for saying, "poo, miss!" told her: "I've got just as much right as you to say what I want. I've got a right to speak up for myself."

"It was a constant battle," the teacher said. "Some pupils have got the idea that they can threaten the teacher with the police, with being summoned and sued. Teachers end up walking on eggshells, and when you do that, you can not discipline a child. The balance between the child and the teacher has swung too far in favour of the former - and they know it. The whole way they walk down the corridor says 'We are in control'."

Ruth Kelly, the Education Secretary said " they're just being naughty kids like we all were".

• Classroom Chaos, Five, Wednesday 8pm