Annabel Graham's class at Hormead Church of England primary is in uproar.
Children are staggering out of the room with a table, others are stuffing old artwork into bin-bags while two boys crawl around the floor with a dustpan and brush.
"Isn't this fun?" yells Dawna Walter, host of BBC television's Life Laundry programme, above the chatter.
"Yes!" cheer the 24 seven to 11-year-olds at the rural Hertfordshire school.
Miss Graham won The TES Declutter Your Classroom competition with a heartfelt plea for help. Her frank confession that it was her own untidy nature that was behind a classroom stuffed full of junk prompted the no-nonsense Mrs Walter to help.
Breezing into the large classroom, with sloping ceiling and exposed beams, Mrs Walter was unfazed by the coats and bags on the floor, the sink full of unwashed paint-pots, aprons stuffed under the sink and Miss Graham's desk overflowing with paper and topped with an empty box.
"When I started here," said Miss Graham, "I was going to get rid of everything but I'm the kind of person who pulls everything out, shrieks, and then puts it back again."
Mrs Walter has been here before. "Do a small area," she advised. "And have fun, get motivated. Clutter causes confusion. Let go of old stuff and new things will arrive to inspire you."
She set the children to work hanging up their coats and bags neatly and within five minutes the entrance to the room was clear. The children were then asked to clear out their drawers and set loose to sort out the whole room.
Millie Taylor, seven, scrubs the sink and says: "After the sink, I'm going to clean the taps. It's fun."
Luke Pearce, eight, swept the floor. "I am tidy at home," he said. "But my brother, Jamie, comes into my room and messes it up - he's four. It can be frustrating, yes."
Eight-year-olds Georgia Maynard and Georgina Williams cleared old work from the shelves.
Tabitha Northover, 11, meanwhile, labelled an expanding file with days of the week for Miss Graham's literacy lesson plans. "I am enjoying it. The classroom has been a real mess," she said.
Just 30 minutes into the project and an old armchair and five bin-bags are piled in the playground and Miss Graham is directing the show. "No, don't throw away The Human Body. We're doing that next week," she tells one enthusiastic child.
"Miss Graham," asks one boy. "What are these pegs for?"
"I have no idea," she replies. "I've never even seen some of this stuff before."
An hour later, bin-bag number nine is hauled outside and the children gather round for a picture of their triumphant tidy-up.
Miss Graham said: "It is a distinct improvement. There is just a much better feeling when you come into the room."
Sophie Oliver, seven, agreed.
"It will make life easier. We've always felt squashed coming into the classroom," she said.
And what did the declutter queen think? "It was fantastic," said Mrs Walter. "The children were enthusiastic, they wanted to take pride in their classroom and really thought about it beforehand. I loved the fact that Annabel was focused and really wanted to change. It was a good example for the kids. Now I'd really like to spearhead a national Declutter Your Classroom day."
See more pictures of the clean-up at www.tes.co.ukdeclutter_your_classroom