Agigantic green ball is on the loose, being herded around by a gang of schoolchildren, who gleefully speed it towards a circle of squishy foam animals, crashing into a projector hanging from the ceiling along the way. Other kids leap between the vinyl-covered creatures, hopping from turtle to tiger, while one boy begins rodeo-riding a seal. In the room next door, another class hurtles themselves down a series of glossy red slides that radiate from a stepped podium, while others are busy with scraps of gold leaf, taking turns to jump up and stick their sparkling fingerprints on the walls of the Nottingham Contemporary. This is exactly the kind of merry mayhem that the modernist architect Lina Bo Bardi imagined when she drew an illustration of the public piazza of her Museum of Art in São Paulo (Masp) in 1968. At the height of Brazil’s repressive military dictatorship, she pictured a world of innocent play, where children clambered over rainbow carousels, crawled through tubes and slid down the red ribbon-like slides of her “practicable sculptures” – which never saw the light of day. “She depicted an impossible reality,” says Jane Hall, a member of the Turner prize-winning architecture collective Assemble, who have been commissioned by the Nottingham gallery to bring some of Bo Bardi’s playful schemes to life more than half a century after she drew them. “You could never have had children occupying public space in this way under the dictatorship, but she wanted them to be the lifeblood of the institution.” As Bo Bardi implored: “The young will be the protagonists in the life of the museum through design, music and theatre.” The Nottingham show takes her evocative drawing as the starting point for the installations, which see two of her playful sculptures created for the first time, along with a third that was developed in collaboration with local schoolchildren. A vitrine at the entrance to the gallery presents a gloopy clay tableau of amorphous bits and bobs produced with the schoolkids, which was then “interpreted” by Assemble (with a good deal of artistic licence) into the play structure. The result is an enigmatic thing, a green wooden latticework cocoon upholstered with squidgy blue cushions, which emit recordings of playground noises when you press them, all surmounted by the momentous inflatable green ball, crowning the structure like a big shiny pea. “We never imagined they would climb up it,” says one invigilator, looking on slightly aghast as a group of children scale the wooden structure and take turns to launch themselves on top of the inflatable ball, trying as hard as they can to pop it. “We hadn’t predicted that they would use the animals as trampolines either.” Adults can never predict what children will do, which is what makes this show a surreal delight (and a possible headache for those running the space). Unlike the usual prescriptive playground equipment designed by grownups, the things in these galleries are intended to be triggers for an unforeseen universe of imaginative play, directed by the children themselves with anarchic joy. It might not be as elaborately equipped as the soft play centre up the road, but it’s free – and it comes with the added frisson of being allowed to charge around like this in the hallowed surrounds of a contemporary art gallery. The process has been a boon for the local schools, too, injecting some freeform mischief into the curriculum. “Schools can sometimes build a system that saps the imagination out of children,” says Ross Brooks, interim headteacher at the Jubilee Academy in Bilbrough, one of the schools involved. “The art curriculum can often be quite standardised, but this project has really opened our pupils’ eyes to a different world. I’ve noticed them mixing with others who they might not normally play with in the playground, and really working cooperatively together.” As part of Nottingham Contemporary’s Schools of Tomorrow programme, artists have been resident in seven primary schools and one nursery for the last three years, conducting activities that also feature in the exhibition. The precarious projector shows footage from a GoPro camera that was strapped to toddlers’ heads – play through the eyes of the children. Another wall spells out a series of rules for play, intended to be edited and added to with sticky notes by visitors during the length of the exhibition. Another shows a typeface developed by pupils, which has been used to scrawl further prompts for play on the walls around the gallery. “Just stop then start,” says one slogan. “Forget time,” says another. The children evidently had a great time in these workshops and, from the schools’ perspective, the impact is clear. “It might be quite common to be the first generation of the family to go to university,” one teacher tells me. “But for some of our kids they’re the first member of their family to ever go to a gallery. This exhibition is literally opening doors.” As social outreach, the programme has brought benefits, but the workshops don’t particularly translate into much that is meaningful on the gallery walls. Instead the work feels a bit like vignettes from the institution’s annual report, dutifully recording the outputs of the learning team. The use of Lina Bo Bardi also feels a bit thin. In recent years, she has become a fashionable figure to be cited by socially minded artists and architects alike, keen to align their work with her inclusive, user-driven approach to the design of buildings and public spaces. Having been less celebrated than her male counterparts for much of the 20th century, she has posthumously enjoyed a spate of exhibitions over the past decade, one of which Assemble also designed. Perhaps because of this, the Nottingham show seems to assume its visitors will be familiar with her work, and limits her presence to a single screen showing a few images and quotes. Why her, visitors might wonder. Why this particular drawing? Why now? Still, such questions seem to bother the kids little as they hurtle around the rooms, bouncing between the play structures in euphoric disbelief that an art gallery could ever be so much fun. You can almost hear the ghost of Bo Bardi chortling as the whoops of delight echo through the building. Assemble + Schools of Tomorrow: The Place We Imagine is at Nottingham Contemporary until 4 September 2022.