An air raid siren sounds and the children in the school hall dive under the desks. After the "all clear" sounds, the voice of forces' sweetheart Vera Lynn resumes singing and the pupils return to selling cups of tea and ration cakes to parents.
Diminutive wardens check identity cards and issue ration books. Guides offer tours of everything from a 1940's shop, to a museum of wartime artefacts, French and English farmers' markets and Betty, a Second World War bomber made of cardboard boxes complete with radio and headphones.
It's key stage 2 curriculum day at All Faith's Community primary in Strood, Kent. The theme is the Second World War with a French twist and pupils are sharing what they have learned during the past term with their parents and visitors.
The day starts with singing wartime favourites such as Kiss Me Goodnight Sergeant Major along with a play about youngsters evacuated during the war, which was written and performed by the pupils after six weeks of drama and literacy sessions, including looking at play scripts and empathetic writing.
It is the culmination of weeks of imaginative teaching across the entire curriculum, which encouraged children to do their own research and even included a day trip to France.
"For many children, the trip was a first and very exciting," says Heidi Taylor, the head, who is dressed in period costume, complete with rollers and a headscarf worthy of Coronation Street's Hilda Ogden. "During the ferry trip, they thought about how the soldiers must have felt to be leaving their families and going into the unknown. In Calais, they visited the war museum and found out about munitions and the number of deaths and casualties. And then there was a visit to a hypermarket."
Every opportunity is taken to make learning practical and meaningful for the children - from calculating the exchange rate of sterling into euros, to weighing out rations of sugar, meat and cooking fat.
"That's not much food for a week, is it?" says Shannon, eight, who's serving customers at the 1940's shop. "But they had vegetables, too, which they grew in their gardens," she explains to a parent. "Do you need anything else? You can have one fresh egg, or this packet of dried eggs, which gives you 10 eggs. Let me stamp your ration book."
Across the room, Claude, the 10-year-old museum curator, proudly tells a parent how gas masks protect the lungs, the necessity for a chamber pot under the bed during the night and how to wash a T-shirt using a washboard and carbolic soap. In other parts of the school, children are making egg-free ration cakes and apple desserts with condensed milk from original recipes.
Tolga, 10, is explaining the D-Day landings: "Germany wanted to invade France but couldn't because the English got there first and helped the French to defeat the Germans," he says. Jack, seven, has helped make a map of where people were evacuated in the UK, which is surrounded by photographs of forlorn children. "We found the pictures on the internet,"
he says. "We went on Google and put in Battle of Britain and printed off the ones we liked."
Byron, eight, has taken on the role of a wandering storyteller. He is reading an interesting tale he has written about being evacuated to stay with a stranger in the country. Luckily, he liked Mrs Smith and had lots of adventures with her. "That's great, mate," says one appreciative parent.
"They've all done really well," says another. "You have to be confident about what you've learned to be telling the parents about it like this."
Marion Browning, deputy head, agrees: "Curriculum days give the children an experience they do not usually get - the chance to explain to adults what they have learned. And the parents and children always enjoy them."
Recent events have included an Africa day, Tudor day and Egyptian day.
The pupils are given scope to develop the projects themselves and to explore their own interests and ideas. "I give them the kernel of an idea and they build it up," says Marion.
"They make all the decisions about how to explore the topic. And when they don't have the skills they need, they come to us and say, 'We need to know how to do this'.
"It's good for the children. This way they do a lot of learning, the subjects taught are meaningful and link together and they have a lot of fun."