"Stand up and take a partner. Now face your partner and look them up and down, as if you'd never seen them before."
The group stand back-to-back and are asked to slightly change their appearance. Watches come off, ties are loosened, hair is brushed in a different style. One member threatens to take off his trousers. Then they turn and identify the changes in their partners.
"A lot of your role this year is about handling change," says tutor Roger Opie. "A lot of leadership is about how to handle change."
This leadership programme run by the Industrial Society was designed for the heads of bluechip companies. But those taking it are not captains of industry - not yet anyway. They're senior prefects at Millfield School in Somerset.
Co-educational Millfield, whose fees of nearly pound;18,000 a year make it one of Britain's most expensive private schools, runs the day-long programme to give new prefects a crash course in managing people.
The school adopted the course after heads of department took a similar programme. It was an attempt to update the prefects' role, said deputy head Rob Decamp. "The idea that the biggest rugby player would make the best head of school because they can bully has long since passed.
"It's about how they treat their peers. It's something that at the age of 17 they have never had to think about - how do you ask someone your own age to do something?" The programme includes a range of tasks designed to encourage teamwork. They learn how to listen to fellow pupils, the importance of communication, how to motivate people, and how to recognise and deal with different personalities.
A growing number of schools - both independent and state - are using the programme, said Mr Opie, who as well as being the course tutor is also director of education at the Industrial Society.
"It's not so much what do you do if you catch your best friend smoking behind the bike sheds," he says. "It's about attitude - how to get the best out of people."
Esther Harazi, 18, did the leadership programme last year. She said: "It's hard to tell someone the same age 'well done - you did really well there'. But this (the course) makes you think. It helps you to tell someone they did or didn't do a good job."
James Lansdell, 17, said: "As a head of house, I'm constantly having to keep people enthusiastic and get people doing things. The course is going to be useful for that."