A girl enters the class to applause. She crosses the room. Her classmates applaud louder. She grins happily, somewhat surprised. She stops. So does the applause.
She looks a little mystified. So, she plays to her audience. She does a comic pirouette. Silence. She doesn't understand. Confusion is written on her face. She takes a few steps to her left. A burst of applause. Now she looks stupefied. She doesn't know "the rules".
Sometimes she is applauded but doesn't know why. At other times, her efforts are greeted by an almost cruel silence. Or by laughter. She likes the laughter. Her face is a wonder to behold. Her facial expressions say it all. Where am I? What am I supposed to be doing? What do you want me to do? "Look for our applause," says the teacher.
What she has to do (but doesn't know) is simply to go to the corner of the room, pick up a chair and bring it back to the middle to sit on. All her moves towards this action are applauded. Nothing else is. The girl only half gets it. She's no expert. In fact, this girl is a clown.
"Clowns exist in the mistakes. They're used to getting things wrong," says the teacher.
"But if they cause laughter, they're happy. They always hope that one day they'll get things right."
This is no ordinary classroom and no ordinary teacher. We are, in fact, in the middle of a clowning workshop at the National Theatre of Scotland's annual Youth Theatre Festival and the young people are exploring elements of European clowning led by actordirector Tim Licata.
"Clowns are not stupid," he says. "A clown is simply someone who doesn't know. He or she may be astonished or stupefied - but not stupid. It's about getting back to a state of not knowing."
The workshop is boisterous, noisy and exuberant. But there is always focus and concentration.
"You go through school in order to know what you're doing in life. In clowning, it's the opposite. It's about making mistakes and exploring them as creative opportunities," says Mr Licata.
What he is encouraging the students to do is the opposite of what most teachers do. He wants them to explore their "ridiculous side", to embrace their "personal stupidity".
Not that they need much encouragement after the first few exercises which are designed, quite literally, to have them falling about in laughter.
"Laughter destabilises. It subverts your skeleton. It makes you fall. It is the enemy of authority and the instigator of chaos. That's why all governments hate and fear being laughed at," says Mr Licata.
Over 100 young people will attend the clowning workshop along with workshops in music and movement, Samba drumming, physical theatre, aerial acrobatics, singing and comedy (among others). The week-long programme will also see each of the participating youth theatres produce a show of their own, with full professional back-up, at the Byre Theatre in St Andrews, where the summer festival is being held.
Seven youth theatres, with members aged 16 to 25, have come from across Scotland, from Dumfries to Inverness, as well as from Cork in Ireland, to take part in this fifth annual festival which first went international last year with youth groups from India and Belgium.
"These are young theatre makers who are being encouraged in their professionalism and art," says Simon Sharkey, associate director of the National Theatre of Scotland.
"The workshops are masterclasses designed to help them develop their ideas the best way they can and to give them as much professional experience as possible."
But the NTS summer event, held in early July, is not limited to those who wish to enter professional theatre.
"The NTS is a theatre without walls and we work with many youth theatres around the country. Not all members want to go on to work in theatre, but all can gain in confidence, in making decisions about planning, producing and creative matters," he says.
The NTS works with each of the seven participating youth theatres in advance to help prepare their shows, which are usually devised.
"They get exposure to each other's practice. They become part of a larger body informing and helping them here at St Andrews, and they gain work experience with professionals and learn to appraise each other's work," says Mr Sharkey.
"The international dimension adds to a rich experience. The fusion is fantastic and ultimately our aim is to get the young people to make theatre that can tour the world. But fundamentally it's about developing each individual."
Developing each individual is certainly central to Tim Licata's masterclass.
"Playing a clown is not playing a character. It's just you - a primal state, a first base for the actor. Allowing your silly side to come out is vulnerable. We can see your mistakes but we also have to see the realisation of those mistakes in the clown's eyes, in your eyes," he tells the students.
"Are there any rules in clowning?" asks one student.
"Yes," says Mr Licata.
"The first rule is - don't try to be funny. The second rule is - don't try to be funny. And that's also the third rule."
"Is that it?" asks the student.
"No," comes the answer.
"There's also a fourth rule which is - there are no rules."
And the end result of this two-and-a-half hour masterclass is not chaos or anarchy, but 20 superbly self-disciplined apprentice clowns, 20 young people who will never look upon themselves in quite the same way again.