But there are common threads, ideas and solutions. In the Friday forum we're asking you to share your experiences. This week, sixth-formers who stumble under the demands of AS and A-levels; their confidence unravels and, with it, their attitude to school and staff. What to do? Caroline Drennan, head of sixth form at a London independent girls' school, starts by focusing on what the pupil can do, rather than what she can't. Primary head Mike Kent, LEA adviser Liz Henning, sixth-former Meg Shakesheff and psychiatrist Raj Persaud also comment. You can contribute by going to the behaviour chatroom at www.tes.co.ukbehaviour
Pupils under pressure can turn truculent. The relentless expectations on those regarded as high achievers these days means that, even as late as sixth form, behaviour can deteriorate.
The exigencies of the A-level system, with the extra demands of AS, mean students need to hit the ground sprinting, and if they set off on the wrong foot they can be in trouble before they know it. If they've ridden high through GCSE, they're sometimes ill-equipped to deal with any sense of failing, particularly if they feel school, parents and peers are banking on their continuing success. Once these pupils start to falter, their confidence begins to unravel and, with it, their attitudes towards school and staff.
Caroline Drennan, head of sixth form at the Godolphin and Latymer school, a girls' independent day school in west London (pictured), has become familiar with the pattern, which she believes is exacerbated by the AS system. There's no time for finding your feet any more, she says. If pupils want to achieve top grades they have to start on a high note. If they don't manage it, some can't cope with the difficulties. "By their first Christmas in sixth form they're essentially halfway through their AS course, and if they've been struggling they begin to feel they're never going to make up the ground. That's when things start to fall apart for some."
Deteriorating behaviour due to crumbling self-esteem can be one of the hardest things "to get to the bottom of", she says.
"These girls come into sixth form having distinguished themselves at GCSE.
They might have chalked up a string of As, perhaps a few Bs; they've done pretty well, but perhaps not as well as some of the real high-fliers. But it's quite a leap to A-level: the work is much harder, and with AS they've got to make the leap quickly. They become disorganised, forget their homework, forget to bring books to class. They become slightly disruptive, a bit chatty, not paying attention, a bit jokey, turning up to lessons late, taking days off, courting confrontation with the teacher."
Ms Drennan says teachers come to her exasperated that particular pupils seem to have turned against them; that students have insulted them in front of other pupils, trying to humiliate them; that they've stormed out of lessons. "What's happening is that the girl's self-esteem is taking a nose-dive and she is trying to remove the pressure point from work to confrontation. If you tackle a girl head-on when she's in that kind of state, that's when you get the explosions.
"The trick is to recognise what's happening as soon as possible. We talk a lot as a staff to support each other and I will always try to show teachers that in these cases the problem probably won't just be with them but with other subject teachers as well."
The Godolphin and Latymer, highly selective and oversubscribed, is a former girls' grammar that became independent in the 1970s. It draws from the professional middle classes of west London, and has at least four applicants for every place. Parents generally expect their daughters will do well. The school's results justify their hopes: more than 88 per cent of pupils achieve A*s or As at GCSE and 89 per cent achieve As and Bs at A-level. About 15 per cent of pupils go on to Oxford or Cambridge.
For girls, that expectation can become a real burden. "Quite often you get the feeling you are fighting the aspirations of parents," says Ms Drennan.
"In my initial discussions with girls who are going off track they will sometimes plead with me not to contact their parents, and, although I always do involve them, I think carefully about when I make the contact.
Sometimes their reaction can be draconian, so I will negotiate with the student. I agree to back off on contacting parents if they agree to turn up to lessons on time, moderate the way they talk to teachers, and get down to the work."
Although the school has an academic focus, a great deal of staff time and effort is devoted to a rich extracurricular programme and to supporting students. "There is a lively, creative atmosphere here, and my head (Margaret Rudland) is committed to the girls' individual welfare. We go to great lengths to explain that we are there to support them, no matter what their difficulties."
She believes girls often become disruptive in the sixth form because confrontation is easier than discussing the problem. "They would rather you shouted, because if they have to talk it through they have to face up to the difficulty and they feel guilty. They find it easier to say it's their sister's illness or their parents' divorce which is causing them to go off the rails rather than their finding the work too difficult.
"If they do tell their parents about their problems it usually comes out in the form of complaints about teachers."
For that reason, whenever Ms Drennan holds meetings with parents and the student in such cases, she also invites the teacher in question to attend.
"I always listen to what the parents have to say, but I will also ask the girl about her lessons and try to get her to face up to the fact that her behaviour has been provocative; so that it's coming from her, not me. That also opens the door for reconciliation between her and the teacher."
Her own style, she says, is to avoid confrontation, to raise her voice as sparingly as possible, to treat her students as fellow adults. "I always try to follow things up once the heat has gone. In cases where girls are losing confidence, I start from the premise that they can get back on track, that all of them can do well, and I will talk this through with them regularly, going to see them in the common room, helping them to take a step back."
Ms Drennan believes girls, in particular, get bogged down and dispirited if they cannot get on top of their work. Boys tend to take more risks at A-level and are more cavalier in their approach to difficulties, whereas girls "just see this mountain of work they can't do".
She says: "I start by focusing on the things they can do. If they're struggling in one thing, there's usually something else they are doing well. We had one girl who was in real trouble, she was falling out with all her teachers, but she was amazing at dance and was managing younger girls in one of our dance extravaganzas, so that's what I focused on. We worked on her problems step by step from there.
"There is usually a way through, though you have to accept there is a limit to what you can do. It doesn't always work. You don't always win. If you accept that, you are more effective in the long run."
Many girls at Godolphin and Latymer aim for careers in medicine, but A-level sciences are a challenge and students can struggle if they've been over-ambitious - or others have been over-ambitious for them. In such cases Ms Drennan will steer parents and pupils towards options that are achievable, and any behaviour problems will fade away. "Sixth-formers rarely start misbehaving without a reason."
Sometimes she finds peers will help. "Often when I'm on the lookout for a student, friends will come up to me and say, 'Are you looking for so-and-so? We're helping her to get organised'. That can be positive, but I always check with the student concerned that she is happy with that."
Sometimes, she says, difficulties can be resolved simply by helping students organise and divide up their workload into manageable chunks. The key, above all, is to make them realise that talking about problems is the way forward, no matter how painful. "We have to get them to see that having work difficulties is not a weakness and that by talking things through these difficulties can be resolved."
Friday magazine is offering every reader a free copy of Elaine Williams's TES survival guide, Managing Behaviour (worth pound;2.99). Simply collect eight of the 10 tokens that will be printed in Friday throughout our series. Details of how to obtain your copy will appear in a few weeks'
time. You can find token five on page 3