Most teachers remember the time they took a deep breath, suppressed their nerves and took their first lesson. Most also remember the first time the words they intended to say did not come out as planned and were seized upon by a few mischievous students. And maybe the time they were put on the spot and asked their opinion on a contentious subject.

“Miss, do you have a boyfriend?” can seem tame next to some of the thorny topics which older pupils can put to their teachers. Certainly, many staff will feel uncomfortable answering their pupils’ searching questions. So, is honesty the best policy?

Southfields community college in Wandsworth, south-west London, is a mixed inner-city comprehensive in the lower reaches of the league tables and with a catchment area that includes some of the capital’s poorest areas. It hit the headlines earlier this year when Clare Short, the former international development minister, spent a week teaching there as part of the BBC series My Week in the Real World.

John Fullman is a teacher and training co-ordinator at the college, which has a number of graduate trainees. His advice is simple: be honest and open, but be careful. “You have to show the students that you are not lying to them,” he says. “They know if you are not telling the truth or clamming up because you are embarrassed.”

He says some students will wilfully misconstrue what a teacher says. He recalls having to tell a badly behaved Year 10 class that if they were his own children he would be sorely tempted to hit them. “One student then said to me, ‘Are you saying you’re going to hit us?’ so I had to repeat what I actually said.

“You have to be careful, but you should be able to argue better than the students. You have to be comfortable in the classroom, and your authority grows from that. The more confident you are, the better you can deal with touchy subjects.”

Jennifer Farrar, 28, has swapped a job in journalism for Southfields, where she is training to be a teacher. In eight months at the school she has never been told to “steer clear” of a topic and says she is comfortable with the idea of relating her own views and experiences - as long a they are relevant: “I find using your own opinions helps students to grasp some ideas, otherwise it can be too much like regurgitating a textbook.”

Teachers have a statutory obligation to be fair and balanced. The Education Act of 1996 states that children should not be presented with just one side of political or controversial issues, and teachers must ensure that pupils get a balance of opposing views. Guidance produced by the Qualifications and Curriculum Authority (QCA) states that teachers should try “not to reveal their preferences by facial expressions, gestures, tone of voice”.

Chris Keates, deputy general secretary of the NASUWT, the second biggest teaching union, says her organisation has handled cases in which students have taken exception to comments made by teachers. She says these often stem from parental complaints and are frequently made after an altercation between pupil and teacher. “It’s easy for a teacher to cause a problem without meaning to,” she says, “but most are aware of the need to speak appropriately in the classroom.”

Ms Keates believes that new teachers, particularly those who have not been trained in schools, are sometimes unaware of potential pitfalls in the classroom. The NASUWT runs induction courses for new members that cover “survival skills” such as behaviour management and equal opportunities issues which many students miss out on in their initial training.

David Perks is a long-serving teacher at Graveney secondary school in Tooting, south London. He believes that attempts to give a balanced picture to students are doomed to failure. He says students too often go away with the erroneous belief that they have both sides of the story. “It’s better to say to a class, especially sixth-formers, ‘This is my opinion but I want you to develop your own.’ That’s far more effective,” he says.

Some students will always disagree. “Showing that you accept that students’

views are as valid as yours allows you to raise controversial issues in lessons,” , he says. “By taking them seriously, by not being patronising and by encouraging them to argue an issue through, they engage with you on a deeper level.”

Of course, classroom debates are not just conducted between teacher and pupils. Often someone will pick up on a point made by a another pupil. As the QCAguidance points out, it is important that teachers clearly establish that it is not appropriate for students to disclose personal information or try to elicit it from the teacher.

And you should be prepared for all eventualities: “Children need to be clear about not putting pressure on one another to answer questions about their own experiences,”.the QCA says.