Takaharu Tezuka on Tokyo's Open-Air Kindergarten

"When you put many children in a quiet box, some of them get really nervous," says Japanese architect Takaharu Tezuka, founder of Tezuka Architects. "In this kindergarten, there is no reason for them to get nervous. There is no boundary." Speaking at TEDxKyoto on his design for an open-air kindergarten in Tokyo, Tezuka discusses his playful and unorthodox approach to the creation of the eccentric building. The unconventional space blurs interior with exterior while accommodating a varied program of athletic, educational and relaxed space. According to Tezuka, the concept was based on a progressive philosophy employed by the school administration: "The principal says: if the boy doesn't want to stay in the room, let him go. He will come back eventually." On children, Tezuka's own philosophy is one of empowerment: "Don't control them. Don't protect them too much. They need to tumble sometimes. They need to get injured. That makes them learn how live in this world."

The client’s brief for this kindergarten was a simple one-liner: to provide a roof house for 500 children. Having visited Tezuka Architects’ Roof House in Hadano (AR October 2001) and having discussed the balance of practicality and delight with its owners, the kindergarten directors wanted their own inhabited roof deck.

While the original provided a shared space for family life - a simple surface for dining and reclining, with ladder access for each family member - this preschool in Tachikawa, 40km west of central Tokyo, provides a magical and stimulating environment for children between the ages of four and six years old.





Using its gently sloping roof to provide extensive external space, the building allows over 500 children to sit together in a circle, legs dangling over the edge, in a unique congregation as a young community. As Takaharu Tezuka is proud to point out, this is the largest kindergarten in Japan.

In accordance with priorities of the Montessori education method, while its simple form can be seen as a novel eye-catching landmark to fun, it also provides a flexible, robust and secure framework within which to encourage key notions of independence and freedom.

The Montessori methodology states that satisfaction, contentment and joy are encouraged when children are able fully to participate in daily activities, individually and collectively, in a place where they can understand, engage with and control their own environment.

As a hands-on approach to learning, which dismisses traditional tests and measurements of achievement, it encourages children to develop skills by doing activities that use the five senses and that promote movement.




In response, this building provides an ideal context for such activities, achieving continuity, containment and interaction in a single move.

With a looping plan that focuses on a central activity space, a continuous ring of interiors that shelter beneath a generous low-lying soffit, and a racetrack-like roof deck, this simple structure creates a wide variety of stimulating environments, without dead ends or unmanageable hidden places.

On the roof it is not uncommon to see children literally running circles around the staff. With some doing as many as 30 laps a day (5km), this is an entertaining and rewarding sight that speaks volumes about the accuracy and pertinence of the architect’s initial concept.




Recalling how his own children instinctively make circles in the ground, running (usually) in a counter-clockwise direction to mark out their territory, while usefully burning energy, the eccentric plan form emerged quickly as Takaharu Tezuka’s first response to site.

With no complicated algorithms or formulae used in the creation of its form, this was very much an intuitive reaction, expressed as a gesture on paper, which was then traced and scaled from the architect’s sketch and marked out on site by contractors.

Incorporating three semi-mature trees, it broadens where it can to maximise space, which also serves to accentuate the structure’s informality, with no obvious hierarchy or order.

Composed entirely of sliding timber screens suspended beneath a flush level soffit, both the internal and external perimeter- walls can be fully retracted for eight months of the year.

In accordance with Montessori’s principle that encourages children to interact with the natural world, such permeability provides seamless continuity between inside and out, unifying the central activity space with smaller pockets of residual space at the perimeter; places that provide more intimate spaces for animal shelters and small gardens where children can plant vegetables or flowers.

Remarkably, despite the relatively large scale of the building and the overwhelming number of children (some of whom travel for up to two hours to benefit from the above average standard of education and environment), the kindergarten only has five rooms.

With the loop broken down into four segments, each enclosure relies on low-level screens for subdivision, with the only full -height wall giving necessary isolation for the staffroom that sits adjacent to the main entrance.

Throughout the building, therefore, sounds (and smells) are free to flow from space to space, to create a sensorially stimulating atmosphere (and environment), which while being theoretically impractical, works well to create an ordered state of chaos that is believed to train each child’s focus and strengthen their ability to concentrate.

Internally, the spaces maintain the Montessori principle that classrooms should be child centric. With child-sized furniture, and no traditional teacher’s desk set in an intimidating position, the need to subdivide spaces was seen as an opportunity to engage and stimulate children.

Using Paulownia (an Asian hardwood that is almost as light as balsa wood), hundreds of feather-light timber boxes were made in four modular sizes that can be re-arranged by the children when directed to do so.

Ideal for storage, screening, sitting on and climbing, these boxes are just about robust enough, without creating opportunities for injury, being soft to the head and with edges softened by 5mm radii.

Within these fully flexible spaces the only anchors that exist are the tree courtyards, that bring light, air and life to the centre of the plans, the open plan lavatories situated at the ends of two segments, and the single sink units that sit in the space like individual village wells, attracting up to eight children at a time who gather round in so-called well conferences.

Other playful touches include the outdoor taps that allow children to clean up and wash down, set on free-draining timber logs; glazed rooflights, that give peep-hole views between roof and classroom; scramble nests around tree trunks; and a slide that provides the most direct route down from the roof.

Clearly the children were the principal client for this project. However, saving something for the teachers, Tezuka has maintained his promise to provide them with their own roof house, with a single stepladder in the staffroom that gives the adults their own direct access and escape route.