This is an increasingly common feature of appointments procedures and is not a bad idea, provided it is handled properly. The biggest dilemma is for teachers who are not natural performers, as they often worry about trying to be more extrovert than usual.
The best advice I can give is to try to be your natural self, even if your natural self is so puny that it would seem better to be someone else. Many, though not all, of those who try to put on an act come to grief, as they simply feel uncomfortable pretending to be something they are not, and the falseness shows.
In fairness, the school ought to let you know what kind of class you are teaching, though I heard of one applicant who was sent a text message the night before with no information other than an instruction to come and teach a class. They may even give you the topic to be covered. If they don't, it would be worth phoning and asking if your proposed subject has been covered recently.
There is no reason why you should not wheel out one of your favourite lessons, without being showy. Even if you sense that your style of teaching is not common in the school, teach the way you feel comfortable. That way the school knows what it is getting.
Don't look pole-axed if someone asks questions in the interview about your demo lesson, and don't be surprised if no one mentions it. The one certainty about interviews is that they can be just as varied, and sometimes just as weird, as the people who conduct them.
Get to know the class
Remember you are not going to teach a lesson - you are going to teach children. Introduce yourself, tell them something about yourself, ask their names, engage them. Give them name stickers and use their names, look at them when you are talking to them and listen and respond to their answers.
Teach something you feel comfortable with, that is appropriate to their age and ability range and that (with luck) will be a successful lesson. The lessons I have observed that made my heart skip are those where the teacher cares about the young people and helps them all have a good time and feel good about themselves while learning.
Liz Wilson-Chalon, Somerset
Take a few risks
Your lesson needs to stand out, so don't go for the safe option. Think of some exciting science experiment, an art activity that will have the class buzzing, or poetry work that will make them laugh. Acknowledge on your lesson plan that it could get noisy, but that you want the children to be enthused and to discuss the activity in animated terms.
Don't go for a lesson that involves handing out endless bits of paper; the children can become restless. Plan an activity that does not need a lot of setting up. Try to bring all that you need to the school yourself - apart from paper and pens - and don't give them a long list of requests. Think carefully about timing; make sure your lesson has a clear end to it and that you do not run out of time.
Finally, don't just choose a core subject for the sake of it; choose something you are enthusiastic about. When you talk, show that you are excited and interested. Children respond to this. You might also enjoy the experience more yourself.
Fiona McDonnell, Cambridge
Keep it simple
Connecting positively with the class is important. When I was interviewed for my first job, the head was impressed that I asked the students to say their names as they volunteered answers to questions. Keep your lesson objectives simple and don't plan too much. The observers want to see that you can introduce a topic or skill, teach about it and assess if the class has understood. Always have an extra extension task up your sleeve in case the students race through your lesson, having covered the material a few weeks earlier.
Laura Seabright, Lewisham