A naked man lies above a naked woman. His hand is on her shin; hers is on his chest. Both are smiling. This is an ivory sex aid from 19th-century China, but it is also part of a new way to teach 21st-century sex education.
Academics from the University of Exeter found the carving among a forgotten collection of 1,000 sex objects from around the world, amassed by the pharmaceutical entrepreneur Henry Wellcome. Items include phallic amulets and Peruvian pots decorated with images of fellatio and anal sex. There is also a pin from Borneo, which was inserted horizontally through the penis as a form of birth control.
Rebecca Langlands, a classicist, and Kate Fisher, a historian, began inviting school parties to come and visit the collection. "It got them talking," Dr Langlands said. "The kids were talking about stuff they'd never normally talk about. A lot of them came in saying, `I know it all already', but it wasn't what they were expecting."
She and Professor Fisher worked with sex education specialist the RSE Hub to develop lessons that focus primarily on two of the objects: a metal chastity belt and the 19th-century Chinese carving. Although ancient, the items can help to generate discussions about modern pornography, gender politics and body image. Teachers show students pictures of the objects and ask what they think they might be used for.
"Is a chastity belt something that seems bizarre to us, or can we see similar things in our own culture?" Dr Langlands said. "Depending how confident the teacher is, you could very nicely segue into a conversation about female genital mutilation, and about control of female sexuality."
The ivory carving, meanwhile, may have been used by Chinese doctors to teach their patients how to have a good sex life. This was believed to contribute to better overall health. "Classes can talk about sex education - should having a good sex life be a part of sex education?" Dr Langlands said.
The ivory woman also has very obviously bound feet. "That opens up discussion about body image, body modification and the norms around that," she added. "It's a horrendous thing. But then you think, what about high heels? Those can be incredibly painful."
"For me, the crucial thing is the distancing aspect," said Alice Hoyle, coordinator of the RSE Hub. "We're looking at quite difficult issues: gender relations and power and porn. But to go straight in with a conversation about modern-day porn can be much too sensitive for students.
"This allows a safer conversation, because you're talking about the past. You're not talking about anything going on for anyone in the present. Yes, you might end up talking about those issues, but in the context of the past."
Laura Kerslake, who teaches ethics at Exeter College in the south-west of England, agrees. She showed her students a range of objects, including a Japanese carved shell that opens to reveal a naked woman, her legs spread.
"I wondered if there was going to be lots of silliness, giggling," Ms Kerslake said. "But they were very mature about it. Traditional sex education is all about quite graphic images of bodily parts, but this wasn't about that at all."
Her students also looked at a stone carving of an erect penis, which would have hung above shopfronts in ancient Rome to indicate prosperity. "I was thinking, what if that had been a modern image?" Ms Kerslake said. "They'd have curled up in embarrassment.
"But this takes the focus off [the students]. These objects allow them to look at the world outside themselves. The most important thing is that they come from another culture. It's not about the fact that it's a penis or a vagina, but about what it says about another culture, and about that culture's attitude to sex.
"We think we're so liberal nowadays, that our culture invented sex. But, actually, compared with a culture that was prepared to put a stone penis above a shop, we're not."