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What a year we are having! Our classrooms, which were once a place of safety and stability, have changed, in ways we could never have imagined. They have been deep cleaned, rearranged, closed, re-opened and in many cases, moved online and many now only exist virtually. For those teaching pupils in classrooms, the view looks very different. Some children may be absent, classes may be smaller, faces may be masked, screens may have been put up and there may be tape on the floor over which the teacher is not able to step. Collaborative hubs and table clusters may have been swapped for rows facing the front, mixing is no longer allowed and seating plans are fixed for weeks at a time.

For those teaching younger pupils who cannot be expected to socially distance, classrooms may feel more normal but resources that cannot easily be cleaned and sanitised may have been removed. We work knowing that at any moment we could receive news of a positive test result, and either close contacts, a full class or an entire year group bubble sent home to isolate and teaching immediately moved online. The global coronavirus pandemic has had a massive impact on our classrooms, it is arguable that it is the biggest disruptor of education many teachers have ever experienced.  

With increasing amounts of evidence that the virus is airborne, now, more than ever, the classroom environment is being scrutinised. We need to find a balance between effective ventilation and ensuring the classroom environment remains conducive to learning. One of the most common recommendations to reduce the risk of viral transmission in classrooms is to ensure good ventilation and maximise airflow by opening windows and doors. In addition, we are being asked to turn off recirculating air conditioning systems and use only fresh air intake systems. Problems may arise when the temperature outside makes for an uncomfortable learning environment.

But just how does the classroom environment impact on pupil’s health, wellbeing and ability to learn? What can we do to monitor and control that environment? Are there other opportunities to support children’s learning beyond the heavily constrained classroom environment?

The impact of the classroom environment

Ground-breaking research by Professor Stephen Heppell and his team at the University of Bristol in the UK is shining a light on the impact of classroom environmental factors on student performance. These factors are often overlooked when attempts are being made to improve outcomes for students. Getting to grips with them has never been more important. Professor Heppell’s research focuses on the seven key factors that influence learning. By understanding and monitoring these key factors, we can identify simple remedies for classrooms that can be implemented immediately (Table 1).

This research is particularly important in light of the COVID-19 pandemic, where factors such as airflow, temperature and humidity all play a role in disease transmission, and more generally, under every school’s responsibility to provide a safe and effective learning environment.

You’ll be happy to hear that if you can monitor these factors and optimise the classroom environment for learning, you will also reduce the risk of COVID-19 transmission.

Seven key factors

What are the seven key factors and why are they important?

Carbon dioxide – Carbon dioxide levels above 1,000 ppm increase sleepiness, hamper the ability to concentrate, increase heart rate and feelings of nausea. The severity of symptoms increases as levels increase and varies from person to person.

Pollution – Exposure to Volatile Organic Compounds (VOCs) can cause headaches, dizziness, tiredness, nasal congestion, coughing, wheezing and sore throat. It can also trigger allergies, asthma, skin irritation and eczema. Long-term exposure makes it more difficult to concentrate, learn new things and remember.

Fine dust (PM2.5) – Micro-particulates can travel into children’s lungs and exacerbate asthma, impact levels of attendance and have been associated with cognitive impairment.

Light – Children don’t learn as well when light levels are low, and behaviour suffers too. If light levels are uneven across a classroom there are equity issues too. High levels of natural light are ideal, and any electrical lighting should have suitable Kelvin values.

Temperature – Temperature levels are proven to influence the performance of children in the classroom. There is an optimal temperature range for learning, outside that range performance suffers immediately.

Humidity – Humidity has an effect that is closely linked to temperature, and raises similar concerns, it also contributes to other health risks such as the growth of toxic mould spores. Dehydration reduces cognitive performance.

Noise – Noisy rooms obstruct children’s ability to concentrate and perform, wherever they are. The type of sound matters too, and if background music is present, then it should be below 80 beats per minute.

Taken individually, optimising each of these factors will only have a small impact on learning. But when addressed collectively, we see an aggregation of marginal gains, a measurable impact on learning and improvement in student outcomes.

Table 1. shows the guideline levels for each factor based on Professor Heppell’s research and suggests simple remedies to optimise levels in classrooms.

Case studies

Worldwide, there are 100 case study schools and universities involved in Professor Heppell’s research. Some of the biggest impacts have been seen when the children become actively involved. They monitor and record their own classroom conditions and experiment with ways to influence their environment to make the conditions more favourable. It is a live science investigation taking place in their own classroom, the children are highly engaged and come up with innovative solutions. Several classrooms have installed plant walls, with each plant owned by an individual pupil, to improve the environment and increase classroom oxygen levels.

Table 1. The seven key factors that influence learning, guideline levels and simple remedies.

FactorGuideline levelsRemedies
Carbon Dioxide (CO2)Optimal below 1000ppm and should be no higher than 2,200ppmOpen doors. Open windows to promote air circulation. Add plants or a living green wall to every classroom. Introduce a bring your own plant scheme.
Pollution (VOCs)As low as possibleAir filtration equipment could help. Plan routes to and from schools avoiding most polluted routes. Use lower VOC paints, varnishes, personal hygiene, cleaning and craft products.
Fine dust (PM2.5)As low as possibleAir filtration equipment could help. Move car drop off and pick-up bays away from buildings. Increase fresh air circulation if outdoor PM2.5 levels are lower.
Light (Lux)Above 500 lux. Target of  +750 luxRemove paper and all obstructions from window and door glass. Paint walls with high refraction index paint. Use bright white LED bulbs.
Temperature (oC/oF)Optimal between 18-21oC or 64-70oFCut the heating. Open the windows. Promote fresh air circulation. Generally, too hot is more detrimental to learning than too cold.
Humidity (%)Tracks with temperatureNo rugs – they store damp. No outdoor shoes – they track damp in. A tray of charcoal briquettes or silica-based cat litter will reduce humidity.
Noise (Decibels)Optimal under 70dBA. Above 72dBA starts to be distractingInstall sound absorbing panels. Hang rockwool-filled, white umbrellas from the ceiling. Give students the ability to monitor and own the problem. Add soft pads to table and chair legs.

Virtual classrooms

Beyond what can be achieved in our own classrooms, the pandemic is forcing us to adopt technologies not previously used to their full potential. Blended learning between the physical and virtual classroom has become common place in many schools. However, this comes with its own challenges and the digital divide is becoming much more apparent. Those who have sufficient access to devices, strong internet connectivity and appropriate parental support at home can transition to the virtual learning environment with greater ease than those without these privileges. The move to learning from home also raises another question-How can we use our knowledge of optimising classroom environments when our students are at home? As teachers, we can do little to directly influence or optimise the home learning environment, but by increasing children’s knowledge and awareness of the factors influencing their learning in the classroom, they are better placed to take ownership of their home learning environment. They may be more likely to find a quiet and well-lit place to work and understand the importance of opening a window and good air circulation.

There is another way

Often overlooked, greater use of the outdoor school environment is an ideal solution to many of the challenges I have highlighted. The risk of viral transmission is lower outdoors and many of the key factors that influence learning are improved outdoors. After carrying out their COVID risk assessments, many schools have increased use of their outdoor spaces for learning, to help reduce the risks faced by pupils and teachers. As an outdoor learning specialist, I’ve worked with school groups for the last 13 years and witnessed first-hand the wide-ranging benefits of teaching and learning outdoors. Outside, children have more space, they can move around while maintaining greater distances, as opposed to being stuck at an allocated desk in the classroom. Evidence shows that children learn better outdoors, it improves wellbeing and behaviour, and teaching outdoors has a positive impact on teachers too (1). We all need benefits like this, now more than ever.

In my experience, almost the entire 4-11 curriculum can be taught outdoors and many 11-18 subject areas too. The outdoors provides greater context, resonance and meaning for learners at all stages, not just the early years, it is a fantastic free resource that should be placed at the heart of our planning. Access to this valuable resource is free, unlike the technology required to move to learn online, and it is accessible to all pupils. Looking again at the seven key factors that influence learning, depending on the location of your school, all are improved simply by moving to teach outdoors. CO2, VOCs and PM2.5 are reduced, it is quieter and there is abundant natural light. Thinking back to the aggregation of marginal gains, combining all these things together creates a much more effective learning environment and will have an even greater impact on pupils. Add in the reduced risk of coronavirus transmission, and the question becomes, why are we learning indoors?  

Where do we go from here?

Coronavirus will be with us for some time, and just like it has driven us to use online platforms and distance learning much more widely, we could seize this opportunity to develop and grow our curriculum-based outdoor education provision. If you’re new to learning outdoors, start with just one hour a day straight after a break time, so your students are already in their outdoor clothing, and build up from there. Look through your curriculum and short, medium and long-term planning to identify opportunities to take learning outdoors. I’ve provided a link to some free resources and lesson plans that will help you take your first steps or expand your current provision.

When learning indoors, take control of your classroom environment, monitor the key factors that impact learning and take simple steps to improve the environment for your students. Encourage pupils to understand these factors and empower them to take control of their own learning environments, it will improve their metacognition and understanding of how and where they learn best.

Taking these steps will help you find positives in this most challenging of times and the benefits will be felt by you and your pupils long after the pandemic is over.

Resources and classroom monitoring equipment

For a free collection of curriculum-based outdoor learning activities see

To find out how to monitor your classroom environment and learn more about the seven key factors see

Dr Katherine Forsey is the Learning Rooms and STEM Consultant for Gratnells. Katherine works with schools, teachers and technicians providing training and leadership in practical science, STEM and outdoor learning. Katherine is a Chartered Science Teacher and Outdoor Learning Specialist. Tweet @DrBiol. Website: