The third teacher: the pedagogy behind every design choice at HEI Schools
At HEI Schools Saigon Central, the physical environment is treated as a child's "third teacher". The spaces are designed around five evidence-informed principles: biophilic design, sensory and acoustic regulation, child-shaped environments, visual safeguarding and spatial psychology. A University of Salford study of 3,766 primary pupils found that the physical features of classrooms explained 16% of the variation in their learning progress over a year.
The question asked before every wall
Handed the keys to an empty building, most people ask: "How do we make this beautiful?"
Over the years, the team at HEI Schools Saigon Central learnt to ask a different question: "What will this space teach the children?" It sounds abstract, yet it leads to very concrete decisions: the height of a shelf, the position of a toilet, the colour temperature of a light bulb, the fabric of a curtain. Added up over eight to ten hours a day, and hundreds of days in a child's early years, those decisions make a real difference. This post shares the pedagogy behind every centimetre of the school.
What does "the third teacher" mean?
The idea comes from Reggio Emilia, the approach to early childhood education that grew up in the town of Reggio Emilia, northern Italy, after the Second World War. Its founder, Loris Malaguzzi, is often quoted as saying that children have three teachers: the adults, the other children, and the physical environment.
This is more than a metaphor. Every wall, every patch of light and every shelf height sends a message to a child, without anyone saying a word. A shelf that is too high says: "You need a grown-up to help." A shelf at the right height says: "You can do this yourself."
HEI Schools, the Finnish early childhood education model developed with the University of Helsinki, shares this foundation and adds a Nordic perspective: learning happens everywhere and all the time, and children are active participants rather than passive recipients.
So what does the research say?
How does classroom design affect learning?
For a long time, this question was answered by instinct. Then the HEAD (Holistic Evidence and Design) project, led by Professor Peter Barrett at the University of Salford and funded by the UK's Engineering and Physical Sciences Research Council, put numbers on it. The team followed 3,766 pupils in 153 classrooms across 27 primary schools in England, measuring their progress in reading, writing and maths over one school year. Differences in the classrooms' physical characteristics explained 16% of the variation in that progress.
Put another way, moving an average child from the least effective classroom to the most effective one was linked to around 1.3 extra "sub-levels" of progress in England's national curriculum, at a time when the expected progress for a whole year was 2 sub-levels.
Barrett grouped the most influential factors into three clusters, known as the SIN model:
Naturalness: light, temperature and air quality. This cluster had the strongest effect.
Individualisation: children's ownership of the space, and how flexible it is.
Stimulation: colour and visual complexity, at a moderate level. More is not better.
That last point deserves attention. Walls covered in bright pictures do not help children learn more. In a small Carnegie Mellon study, kindergarten children taught in a heavily decorated room spent more time off task (38.6% against 28.4%) and learnt less (42% against 55% correct) than in a sparse room (Fisher, Godwin & Seltman, 2014). The authors caution that it was a small laboratory study, but the message is clear enough: visual overload competes for young children's attention.
Another widely cited study, by the Heschong Mahone Group (1999), drew on more than 21,000 student records in California, Washington and Colorado. Pupils in classrooms with the most daylight progressed about 20% faster in maths and 26% faster in reading than those with the least. In the spirit of honesty, it is worth adding what happened next. When the same group studied a different school district in 2003, the amount of daylight was not linked to performance. What mattered was the view: pupils did better in classrooms with a better, larger view of the outdoors.
Five design principles at HEI Schools Saigon Central
1. Biophilic design: light and natural materials
The biophilia hypothesis, proposed by the biologist Edward O. Wilson, suggests that humans have an innate need to connect with nature. Recent meta-analyses have linked time in natural environments with lower salivary cortisol (a physiological marker of stress), lower blood pressure and better recovery. The certainty of this evidence varies, and results differ considerably from study to study.
At the school, this becomes:
Lighting in neutral (3500K–4500K) and white (5000K–6500K) colour temperatures, with lumen, lux and colour rendering (CRI) levels planned for each area according to what happens there.
Natural wood surfaces and cork flooring, which give children real feedback about weight, temperature and texture, something plastic cannot do.
A soft, muted palette rather than highly saturated colours, so that visual stimulation stays at a moderate level.
2. Sensory regulation and acoustics
This is the element almost no one sees, yet children's ears live with it every day.
High ceilings, hard tiled floors and flat walls create echo. A noisy, reverberant preschool room stresses children and forces teachers to raise their voices all day, a loop that wears everyone out. Young children are still developing the ability to pick out speech from background noise, so a noisy room directly affects how they take in language.
The school's answer: sound-absorbing ceilings and walls, cork and wooden floors, textured curtains, woven rugs and plants, all of which soak up sound.
3. Child-shaped environments
The HEI Way value of Active Participation comes to life through one simple decision: children are allowed to move the furniture.
Cushions, rugs and learning materials are not fixed in place. Children pull, arrange and build their own play corners. It sounds small, but it teaches them that the space belongs to them, and that they can shape the world around them. This is exactly the "individualisation" in Barrett's SIN model.
4. Visual safeguarding
In early childhood, safety is absolute and non-negotiable. One wall in the wrong place, or one tall shelf blocking a teacher's line of sight, creates a blind spot where a child cannot be seen. The design rule is simple: stand where the teacher stands and ask, "Can I see every child from here?"
Low shelves, glass partitions and open layouts serve both the Reggio spirit of transparency and connection, and the first layer of child protection. The leadership team and teachers can keep watch across areas without interrupting children's play.
One operational detail few people notice: toilets must be close to classrooms. A distant toilet forces a teacher to leave the room and opens a gap in supervision, a safety risk hidden behind a "tidier floor plan".
5. Spatial psychology
The final principle shifts design thinking from decoration to psychological guidance.
Every space is designed to manage cognitive load, guide behaviour, encourage calm and give structure to how people move. A wide corridor in the right place reduces pushing. A low, sheltered nook gives a child somewhere to retreat when their senses are overloaded. Some space is deliberately left empty, because empty space is part of the design too.
Materials and air: the invisible side of health
Children spend eight to ten hours a day at school, breathing the air inside it. The school prioritises low-VOC (volatile organic compound) materials, paints and adhesives, gives the building time to air out before children arrive, and plans for air circulation from the floor-plan stage. Air quality, together with light and temperature, belongs to the Naturalness cluster, the group with the strongest effect on learning progress in the HEAD study.
From space to each child's journey
A good environment is necessary, but it is not enough on its own. At HEI Schools Saigon Central, the space works hand in hand with each child's Individual Development Plan, which has four touchpoints across the school year:
Stage | What happens | When |
First parent meeting | Listening to the family about the child's eating and sleeping habits, allergies and family culture | Before the child starts |
Smooth Start week | Helping the child move gently from home to school | The child's first week |
Second parent meeting | Sharing a personalised plan based on observation, and agreeing goals together | After the child's first two months at school |
Third parent meeting | Looking back on the child's growth through their learning portfolio | End of the school year |
What parents can take away
Beauty is visible at once. But it is the invisible things (clear sightlines, the quality of light, how sound carries, how fresh the air is, furniture at a child's height) that nurture children every day. The aim was never simply to build a room. It was to build a third teacher, one that works quietly, every hour of every day, even when no one is noticing.
If you would like to see the third teacher at work, you are warmly welcome to book a school tour.
References
Barrett, P., Davies, F., Zhang, Y., & Barrett, L. (2015). Clever classrooms: Summary report of the HEAD Project. University of Salford.
Barrett, P., Davies, F., Zhang, Y., & Barrett, L. (2015). The impact of classroom design on pupils' learning: Final results of a holistic, multi-level analysis. Building and Environment, 89, 118–133.
Fisher, A. V., Godwin, K. E., & Seltman, H. (2014). Visual environment, attention allocation, and learning in young children: When too much of a good thing may be bad. Psychological Science, 25(7), 1362–1370.
Heschong Mahone Group. (1999). Daylighting in schools: An investigation into the relationship between daylighting and human performance. Pacific Gas and Electric Company.
Heschong Mahone Group. (2003). Windows and classrooms: A study of student performance and the indoor environment. California Energy Commission.
Twohig-Bennett, C., & Jones, A. (2018). The health benefits of the great outdoors: A systematic review and meta-analysis of greenspace exposure and health outcomes. Environmental Research, 166, 628–637.
Yao, W., Zhang, X., & Gong, Q. (2021). The effect of exposure to the natural environment on stress reduction: A meta-analysis. Urban Forestry & Urban Greening, 57, 126932.
Wilson, E. O. (1984). Biophilia. Harvard University Press.
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