At a recent respect-themed assembly, Geoff Hatch told a story about potty training his daughter. “When she did her business in the potty,” he told pupils, “my wife and I were on our hands and knees, praising this little poo that had come out and paying our respects to what she had done.”

This may be a little too much information for some, but for Mr Hatch, it provoked the desired response. “It got a good laugh,” he says.

By now, pupils are familiar with his life and family. Personal photographs line his office walls alongside pictures of fellow teachers on nights out. While he stops short of sharing his opinions, Mr Hatch believes in sharing his personal life with pupils.

Often the most memorable teachers, and those who really make a subject come alive, are the most unorthodox. Pupils easily become bored of predictable lessons and are more likely to learn when they are stimulated and engaged.

But the line between being a charismatic teacher who forms a personal connection with pupils, and one who goes too far, can be a fine one. And for teachers who overstep the boundary, the consequences can be disastrous for their reputation and career.

Rebekah Wright’s attempt to bond with her students paid dividends, but also ended in her losing her job and being hauled before the General Teaching Council for England (GTC).

Miss Wright, an RE teacher, had been appointed head of sixth form at Hardley School in Southampton with a brief of improving post-16 education. According to the GTC hearing, “Miss Wright was successful in achieving that objective, although her approach was, at times, unconventional”.

The hearing was told that Miss Wright had joked about applying bandages to a student’s pierced penis and had discussed students’ sex lives. She was sacked after the school’s headteacher investigated allegations that her relationship with students was inappropriate, although the GTC ruled earlier this year that her behaviour, although unwise, did not amount to unacceptable professional conduct.

But while Miss Wright’s behaviour amounted to “errors of judgment” that put her relationship with students “at risk”, according to the GTC, the line between unconventional and inappropriate is often blurred. While some teachers are reluctant to reveal anything about their private lives to pupils in case it could compromise their authority, others believe it is a way of connecting with young people.

Mr Hatch, a humanities teacher at the Joseph Rowntree School in York, believes that talking about his wife and daughter helps create a rapport with pupils. “I tell them stories about my wife and how we first met because I think it’s a romantic story,” he says. “If students can see teachers as real people, that can be a good thing.”

This approach has made him popular with his pupils, as well as winning him the title of secondary teacher of the year in the North of England at the 2008 Teaching Awards.

But a good relationship with pupils means different things for different teachers. Even the most well-intentioned behaviour is open to misinterpretation if it strays outside of convention.

At Banbury School in Oxfordshire, a parent made a complaint against a sixth-form tutor after he replied to an email from a pupil at 1am. This could be seen as diligent and showing genuine commitment to pupils, but the girl’s parents felt it was inappropriate.

“She had just sent him an email and he replied straight away as he happened to be online,” says Fiona Hammans, the headteacher. As a result, Dr Hammans changed the school policy, advising all teachers to maintain office hours, even while at home, and to communicate with pupils during this time.

Ian Jamison acknowledges the complications of trying to step outside of the teacher mould. “It is difficult, particularly when you’re a new teacher - sometimes you’re only five years older than the kids you’re teaching and it is hard to draw that line,” he says.

Now a teacher trainer at the Tony Blair Faith Foundation, he previously taught RE at Kingsbridge Community College in Devon, where he was renowned for his long ponytail, waistcoats and love of heavy metal music.

But his alternative way of doing things did not stop there. He made changes to the curriculum to allow for more hands-on learning, brought in representatives of minority faiths such as pagans, and took pupils on frequent trips out of school, including an expedition across the moors to teach about the concept of pilgrimage.

His approach did not endear him to everyone. At previous schools, he admits he had to battle with the senior management teams, but he was also popular, and he was named secondary teacher of the year at the 2007 Teaching Awards. However, he acknowledges that it is not an approach that will work for every teacher. “People’s lines are in different places, and that’s cool,” he says.

But he firmly believes there is a place for the maverick in the classroom. “The way human brains work, and particularly young people’s, they like novelty. They will tune you out - like fridge hum,” he says. “And if your teaching’s unthreatening and predictable then the kids’ brains will do the same to you. Teaching shouldn’t be predictable.”

Unconventional teaching does carry a risk, however. Fears of over-stepping the mark are perhaps stronger in some humanities subjects, where debate and argument can be a key teaching tool and perceptions of what is appropriate have changed.

Trevor Averre-Beeson, a former headteacher and now director of educational consultancy Lilac Sky Schools, knows only too well how a lesson can easily take a turn to the inappropriate.

He recalls that when fears over the spread of Aids emerged in the 1980s, a Department of Education and Science diktat told teachers they had to tell children about it. When colleagues were reluctant, as head of year Mr Averre-Beeson shouldered the burden of telling a room full of different age groups. He had just started speaking when he was asked: “Sir, can you get Aids through oral sex?”

“It was quite an embarrassing question to be asked in front of so many people,” he says. “I could see an immature group of Year 9 boys at the front were quite puzzled as to what it was, and realised I would have to explain. As soon as I did, I realised what dodgy territory I was in.” At a parents’ evening a few weeks later the lesson came back to haunt him. “One of the parents asked why I was holding assemblies telling children how to have oral sex.”

But while that was an uncomfortable episode, teachers now operate in an atmosphere of greater suspicion, which can lead to a more risk-averse approach.

A few weeks ago, a teacher came to Dr Hammans’ office at Banbury School in a blind panic. His pupils had filmed some videos during class, which he had taken home to edit. It was only then he realised how it could potentially be perceived.

“There is a ridiculous sensitivity among young professionals,” says Dr Hammans. “Ten years ago, it would never have occurred to any teacher, but as a society, we are much more cautious than we were.”

To some extent this caution is understandable. Without it, teachers could find themselves in a compromising and potentially career-threatening situation. Hannah McIntyre, a classics teacher, learnt the dangers of getting too close to her pupils the hard way.

As a 24-year-old student teacher, she was keen to develop a friendly relationship with her pupils at Merchant Taylors’ Boys’ School in Crosby, Merseyside. As a result, they knew her boyfriend’s name, Richard, and the banter between teacher and pupils included innuendos about her “Dick”. Unfortunately, it went too far and she realised she was unable to control it.

“I had wanted to be a decent teacher who wasn’t heavy handed, but I think to them I became a joke teacher,” she says.

When three pupils knocked at her door one evening, she let them in and bought them cider to try to get rid of them. They ended up staying over and one of the 16-year-old boys later told his mother he had sex with the teacher. Although she was cleared by a court, the ordeal left her teaching career in tatters.

Miss McIntyre’s approach may not have won universal approval from colleagues, but she believed she was creating a light-hearted and effective teaching environment. For a professional who brings their heart and soul to their work and cares passionately about the well-being of their pupils, developing a close relationship with pupils risks crossing the line.

It may be an unfortunate sign of the times, but Dr Hammans recommends that teachers who are embarking on an unorthodox approach protect themselves by checking with senior management first. It may run counter to the whole idea of the free spirit of education, but it may be the best way of making sure you are not heading for a fall.

“If you were going to be unconventional, you would have to talk it through with your head of department first,” she says. “It is a real shame, but we are in a position where it is just too risky.”

Discipline can be another potentially dangerous area. This aspect of teaching is the most stressful for many teachers and effective discipline often takes years to get right. In certain scenarios, some teachers feel that swearing might give them authority - or kudos - in front of some groups of pupils, although others believe it is never acceptable.

While working as a head of department in the 1990s, Mr Averre-Beeson received a complaint from a parent about the way her son had been punished in class. “When boys broke wind or burped, this teacher made them sit on the corner of the window with the offending part of their body hanging out of the window,” Mr Averre-Beeson recalls.

This teacher was popular among the pupils and the punishment was done in good humour. Yet when parents heard about what was going on, they raised objections. “It runs the risk of being misunderstood and of being a poor model of behaviour for the children,” Mr Averre-Beeson says. The teacher was asked to find a different way of disciplining offending pupils.

But while this mode of punishment took a while to reach the ears of parents, teachers’ classrooms are no longer such private spaces. The frequency of lesson observations and the need to tick boxes, plus the move to encourage pupils to express their own opinions, means many teachers feel there is no longer the opportunity to try something a bit different. On top of this is the profusion of opportunities for pupils to tell the world about what is going on, through Facebook, YouTube or www.ratemyteacher.com, to name just a few.

“There has always been a risk, but in an electronic age, there is much more opportunity for casual communication,” says Malcolm Trobe, policy director at the Association of School and College Leaders (ASCL). “Good banter between pupils and teachers is always very important, but it has to be at a professional level. You are seeing less of the Dead Poets Society kind of teaching, as it’s deemed too high risk.”

Teacher training reflects this change in culture and new teachers are expected to be guarded and stick to the rules. At Banbury School, the teacher who emailed a pupil in the early hours of the morning was an experienced, older teacher and Dr Hammans believes a younger member of staff would have been more wary of taking a risk. Because of increased assessment and accountability, new teachers have much less room for experimentation than previous generations.

“The initial teacher training is marked on competencies that you have to show. If you have any eccentricities, it is best not to show them while you are in training,” says Dr Hammans. “I suppose our most quirky teachers are more experienced. They know where the risks might be perceived. When you’ve been teaching a while, you can judge what’s appropriate.”

Kevin Harcombe, headteacher of Redlands Primary School in Fareham, Hampshire, agrees: “I find there are some really great teachers coming out of colleges now, better than ever, but it is very structured and incremental.

“I’m not terribly critical (of the current teacher training system) - a lot of them come in and hit the ground running. But we almost have to give them permission to inject their personality into their teaching.”

Perhaps caution about unconventional teaching is the price we have to pay for a more rigorous and consistent education system. If previous generations of teachers were open about their quirks and could be more spontaneous, the downside was that the quality of teaching and learning was more open to chance. As pedagogy has been standardised in almost every aspect to meet raised expectations, the attempt is to make good practice widespread, and not just for the few designated oddballs.

”`Unconventional’ makes people think of charismatic, Mr Chips type figures, and while that’s great, and it is great if you are one, that is not what a lot of people are like,” says Mr Jamison. It is also more difficult to reproduce, he adds. “You can’t teach someone how to be charismatic, but you can teach someone to use good practice to engage children.”

Some teachers will mourn the loss of the unconventional approach. There is no problem with teaching by the book if it achieves the objective and helps children to learn. But this is not always enough to keep children engaged, particularly in schools where the odds are stacked against pupils’ achievement.

Mr Harcombe does not think that predictable teachers would survive in tough schools. “I have been into some schools that are officially outstanding, and they seem a little bit dull and worthy,” he says. “They tend to be schools that have a more middle-class intake, but if you are in schools that have more mixed backgrounds you would never get away with being boring.”

At Netherhall Learning Campus in Huddersfield, Jonny Heeley credits rapping and unusual lessons with turning the maths department around. When he joined the school eight years ago, 12 per cent of pupils got A* to C grades at GCSE maths; last year it was 56 per cent.

At first there was a very poor attitude to learning, following a high turnover of staff and a stream of supply teachers.

“As soon as I started to teach them something, they were throwing their books around the room,” says Mr Heeley, who was named secondary teacher of the year in the 2007 Teaching Awards.

It was when he realised the depth of their passion for rap music that he began to really connect with his pupils, and decided to rap his maths lessons. It was a risk, but it paid off. “It could have gone either way,” says Mr Heeley. “I was worried they might just think I was taking the mick. But they thought it was hilarious. I think they thought, `Good for you’.”

Now dubbed MC Protractor by pupils, Mr Heeley takes children around the school during his lessons, relating shapes in the playground or football scores to maths. A self-confessed showman, MC Protractor realises that not every teacher would be comfortable rapping, but believes teaching outside the box with confidence is key to getting difficult pupils engaged. “Kids have got to feel safe and they need a routine, but at the same time, they also need excitement and motivation,” he says.

Far from seeing unconventional teachers as a risk, when he is recruiting Mr Harcombe actively seeks out teachers who stand out from the crowd. “What I’m looking for is someone with a personality and a bit of presence. It is also the `GSOH’ that you see in dating websites - good sense of humour,” he says.

“The really high-achieving teachers can work out of the box as well. That’s why we have people and not computer programs coming into schools.”

It may have been easier to be unconventional in the pre-Ofsted era, which was perhaps also a time when pupils did not make allegations against their teachers so frequently, but MC Protractor and colleagues are proof that it can be done.

But while an unconventional approach to teaching may have greater potential for success, there is also a greater element of risk. The secret to becoming one of those teachers who can inspire and change lives may lie in staying just the right side of the line.

THOSE WHO CROSSED THE LINE

- Sean Riordan was suspended from teaching for 20 months in April after he was found guilty of unacceptable conduct by the GTC. Mr Riordan, who taught maths at Chamberlayne College for the Arts in Southampton, discussed prostitution, dog porn and “morning glory” with his pupils, the GTC was told.

- Rebekah Wright, head of sixth form at Hardley School near Southampton, was fired in November 2006 for discussing pupils’ sex lives and admitting to seeing a pupil’s pierced penis, although she was cleared by the GTC in April this year of unacceptable professional conduct.

- Ian Bangay was allowed to return to the classroom, although a GTC hearing found he had abused his position of trust in sending personal letters to an 11-year-old pupil at Coppice Valley Primary in Harrogate, North Yorkshire. Mr Bangay admitted it had been wrong to enter into “lengthy and personal correspondence” with the girl.