Violent outbursts by pupils are relatively rare. It is the low-level disruption which wears teachers down and is cited as the main reason for giving up by half of those who leave the profession early.
Tapping pens, popping gum, whistling, writing notes to each other, answering questions stupidly to provoke laughter, taking calls on their mobile phones or using them to take photographs, giving the wrong name to a teacher who doesn't know them, all wear teachers down.
Sometimes pupils outside the classroom will rattle the door or open it to call out or throw things. Teachers say their morale takes a battering when they constantly have to face classes where pupils get up from their chairs, shout across the room, decline to work or hand in homework. Significant numbers feel they spend most of their time supplying pencils, nagging or handing out punishment exercises.
Liz Henning, a behaviour and maths consultant and former head of maths in Rochdale, said: "I have seen teachers at the end of their tether because they are facing this kind of thing constantly. It affects their health and has implications for their family life."
Recent research shows there has been a significant increase in this type of disruption in the past 10 years. A lot of it, Ms Henning believes, is to do with task avoidance, rather than maliciousness, but is still hard to deal with.
Ruth Kelly, the Education Secretary, told new heads in Blackpool that the best schools had a clear behaviour policy, supported by the community and developed with parental and pupil involvement.
"The policy is consistently, fairly and rigorously applied. It is a zero-tolerance policy because any incident and any level of bad behaviour is dealt with promptly and appropriately.
"Parents and pupils appreciate that the word of the head is law - whether it is to ban mobile phones in class or on what the school uniform is.
"That encourages a culture where bad behaviour is unacceptable and good behaviour is rewarded."
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