As morning coffee-break ends and the in-service day sticky buns disappear, head Peter Reid announces to everyone in the dining hall: "I am now going to hand over Broxburn Academy to the senior pupil management team."
S6 pupil Laura Black steps up to applause. She is school captain and, for the next two hours, will be "headteacher".
"Thank you very much," she says. "Could you now, please, place your chairs back at the tables where they belong and make your way to your first classes? You're already late!"
The laughter ripples through the hall as the "pupils", ie, Broxburn staff, replace their chairs. They know the tables have now been well and truly turned.
For the next two hours, they will be attending classes outwith their own subject areas and will be taught by 40 volunteer S4 pupils who have given up their holiday to take part in this CPD experiment.
"The idea is to let pupils consolidate their learning through preparing and teaching a lesson in a subject of their own choosing and to let teachers see what other departments do," says Mr Reid.
"We developed the idea after a visit to Hawick High, where they undertook a similar venture using only the technical department. But we decided to go the whole hog and involve all departments," he explains. "It will benefit the pupils and increase subject understanding and how we teach," says PE teacher Stephen Daly, who has helped organise the morning "teach-in".
"It will also let the teachers see how the pupils perceive them as they will naturally model our style and approach."
Three members of the parent council have become "pupils". On the way to class, one is pulled up by "senior management" for carrying hot coffee in the corridor. She is reminded of health and safety and places the offending cup in a bin.
The "teachers" get off to a flying start. In drama, S4 "teachers" Rachel McIntyre and Rhianne Jervis are using tableaux, hot-seating and improvisation to inspire their "pupils" to develop characters from Little Red Riding Hood.
In English, pupil teachers use containers of "mystery smells" to stimulate images and ideas, and explain how personification, metaphor, simile and alliteration work to inspire poems from their students.
Key-fobs are being made in craft and design, two "pupils" creating the letters "M" and "P", one crafting a "diamond" and another, after some over-enthusiastic sawing, managing only "a shape" and admitting it to be "not quite Credit level".
Back in drama, the first lesson is drawing to a close and the "pupils" (including English, modern languages, PE and art teachers) self-evaluate: we improvised and learned the lines well; we made good use of movement and the hot-seating gave us a clearer idea of how characterisation works.
Professionally, they comment on how they could use these techniques: hot seating would fit with oral work and dialogue in modern languages; tableaux would be of use for life-drawing; tableaux and hot-seating for literary work on characterisation in English.
And what did the pupil teachers learn?
"I think we're able to appreciate more what the teachers go through every day. We were stressed but we enjoyed it and I think we'll be more confident and explain more in the second lesson," says Rachel McIntyre.
In the second (repeat) history class of the morning, the mature "pupils" have just finished bashing each other with plastic swords in a warm-up re-enactment of the Battle of Bannockburn and are now discussing and listing in order of importance the reasons for the Scots' unexpected victory.
S4 "teacher" Jenna McEwan explains: "I wanted to get them to do stuff at the start and to discuss, rather than just teach from a text-book. That's how I like to learn.
"The second lesson has gone better because of the practice and experience of the first one," she says.
And for the "pupils"?
"My perception of the Battle of Bannockburn has changed a good bit," says English teacher Barham Brummage.
"So, I definitely learned some history. I think the day overall has been a success and all the staff feel buoyed up by it. It's been a 'hands-on' experience and thought-provoking too," he says.
"I was really impressed by the way pupils used the smart board and got us to question and discuss things, and the benefits of that approach have been reinforced and will stay with me.
"I was a bit sceptical in advance," he admits, "but I'd say now that the pupil 'teach in' would be well worth repeating."
LAURA'S LESSONS AS HEAD FOR A DAY
Laura Black, school captain and 'headteacher'
"I must have visited some 15 classes and was surprised how much class interaction a headteacher can do. I've learned you have to think on the spot a lot as well as plan ahead.
"I've definitely learned teaching is harder than it looks and a lot of the S4s have said it'll change their attitudes and that they have real respect now for a teacher who can control, keep a class focused and keep the lesson interesting.
"We only had one behavioural problem - a maths teacher mucking about in a dance class. I just took her aside and had a quiet word. It was nothing serious."