Design and build studio Localworks has created the Mustardseed Junior School in Uganda with organically shaped classrooms built from natural and locally sourced materials.

The 1,146-square-metre building, located in the town of Sentema, is used as both a kindergarten and primary school for local children.

According to Kampala-based Localworks, all materials used to construct it came from local resources, including the walls that are built from earthbags filled with soil from the site.

No two rooms at Mustardseed Junior School are the same, which means students have a changing learning environment as they progress and move from classroom to classroom.

The use of earthbags – bags filled with earth and used to create walls – gives rise to curved walls that also help to create interesting learning environments.

"The choice of earthbags for the wall led us to curves, in order to avoid buttresses in a playful manner," Localworks told Dezeen.

The external walls stop short of the roof, leaving an opening that lets in natural light and fresh air to ventilate the interior spaces.

They are finished with an unpainted lime-earth render, chosen by Localworks from a number of samples that it developed to ensure the tone blends in with the surrounding environment.

"We used earth-pigmented lime plaster for which we did several samples to get to the colour we wanted – something warm blending in with the context, using earth from the site," Localworks explained.

Locally sourced sandstone slates cover the lower sections of the exterior walls to protect them from water damage.

"Rainstorms are quite impressive in Uganda and the backsplash of the water onto the lower part of the walls can damage them," said Localworks.

"Unstabilised earth walls are also very sensitive to water. The stone cladding at the lower level was a must to solve all these issues."

The roof's structure is made from eucalyptus trees that were cut down from the site to make way for the school's construction.

Supported by V-shaped columns and partition walls, this roof structure comprises scissor trusses of three different lengths to create variations in the overhangs that shelter the outdoor learning spaces.

Narrow openings in the roof structure filter natural light into the classrooms, while its underside is finished with woven mats made by local craftspeople.

Localworks designed Mustardseed Junior School as a "large home" with the intention of making students comfortable in their learning environment.

Warm tones and natural materials were used throughout the project, punctuated with pops of bright colours on window shutters and furniture.

"The architectural ambition is not programmatically prescriptive, but rather to inspire teachers and students alike to inhabit spaces in multiple and creative ways, to literally think outside the box and to treat the entire school, not just the classroom, as a greater learning environment," said Localworks.

Each classroom has a designated outdoor learning space and access to winding paths in the landscape that echo the organic shapes of the interior classrooms.

Localworks' landscape design also focuses on conservation agriculture and soil regeneration with the aim of enriching the natural environment and helping to boost biodiversity.

Instead of concrete, the school's foundations are built from packed sandstone blocks sourced from a quarry less than two kilometres from the site.

The structural slab was ground down to expose the natural stone aggregate and left as the final floor finish.

Bespoke furniture has been integrated into Mustardseed Junior School, including built-in benches and shelves, blackboards, and lightweight tables and chairs.

"Each classroom is given a set of sub-spaces to offer multiple activities, like a timber platform that can be used as a small library, a self-learning corner or even small theatre presentations," said Localworks.

"Since the school is being used, teachers have been very creative, mostly using the ceiling volume to hang art pieces from the kids, and the outdoor spaces also have been decorated with lessons written directly on the walls using chalk," the studio continued.

Mustardseed Junior School has been shortlisted in the sustainable building category of Dezeen Awards 2022, alongside a community centre in Rwanda made from local materials and an off-grid office building that floats on a harbour in Rotterdam.

The photography is by Will Boase Photography.