"Is that your little husband?" asks Jane Southwell. She is holding up a photograph of a teenage girl for her reception class to comment on.
"Dylan thinks it might be my husband," she says. "Anyone else?" Isaac raises his hand. "I'm going on holiday, and it's a scary holiday. It's got skeletons and bats," he says.
Mrs Southwell explains quietly that what she is actually looking for are comments on the picture.
"I think it's a boy," volunteers Ella. "Because it's got black skin."
At this, Isaac perks up. "I think," he says, "maybe he changes into a bat."
This is the reception class philosophy lesson at Moorlands infants, in Bath. The lesson, in which pupils are invited to discuss ideas on a topic, forms part of a documentary to be shown on Channel 4 next week.
Secret World of the Classroom follows the children during their first term as they take part in lessons, make friends and take their first steps towards independence. Fran Landsman, producer and director, wants viewers to enter the pupils' world.
"For the first time, the children are on their own, making their own friends," she said. "Little things can seem quite big. If nobody's playing with you that day, it's huge. I wanted to show what it is to be four years old."
Cameramen, crawling on hands and knees, followed the pupils as they learnt how to get on with one another. Isaac, for example, struggled to understand that it was not acceptable to bite or push his classmates.
By contrast, shy Grace just wanted to make friends. Succumbing to peer pressure, she coveted everything the other girls had, including painted nails, earrings and headlice.
The camera follows Mrs Southwell as she helps Grace to find other girls to play with. "She needs to learn to make friends," she says. "If you learn now, you can save a lot of pain later on."
Ms Landsman said: "A lot of these troubles go on to adulthood. You'll see people in cliques at a party and not know how to join them. But at that age you can say, 'Can I play with you?'"
Four-year-old Dylan, meanwhile, has mastered the rules of social interaction. Addressing recalcitrant friends, he says: "If you don't let me play rough games, then I'll never, ever invite you to my party again."
They find it a difficult argument to resist. But pupils' conversation also ventures into territory which many adults would find uncomfortable.
"I want to have sex with you," Joshua tells Molly as they stand in the playground. Molly promptly bursts into tears.
Ms Landsman said: "You forget how much young children pick up. But the teacher didn't make them feel they were bad people for saying this. She really seemed to love them all."
Under Mrs Southwell's guidance, pupils develop as the term progresses.
Isaac learns to dress himself, Dylan to manage his boisterous behaviour, and Grace to make friends.
"When they're older, they're not going to remember me," she tells the camera. "That's as it should be. But I hope they'll take with them some of the social and emotional lessons they've learnt. And I hope these will help them as they move on with their lives."
Secret World of the Classroom will be shown on Channel 4 on August 22 at 9pm