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".