How cold does your classroom have to get before board pens, computers and students stop working?

In the first Seeber’s Science column, Emily Seeber explains what happens when the school boiler stops working and the classroom temperature plummets...

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It’s January. The heating’s been off for a couple of weeks over Christmas and it hasn’t really started working again properly. The classroom temperature is plummeting as winter kicks in and you have quietly let the students keep their coats on. 

But what happens if it gets any colder?

At about 10°C, students start to struggle with their handwriting as their fingers become too numb to hold their pens properly. This is because the hypothalamus draws blood away from the extremities to keep core temperature up and protect vital organs. You’ll also struggle to write on the board. Time for a discussion task. 

As the temperature drops to about 5°C, everyone’s noses will start to run. Not good with a classroom full of virus and bacteria-ridden students. Keep your distance. The class have all lost interest in the lesson as well, no matter how well planned it was. Probably best not to worry too much about that. 

Below 0°C, signs of hypothermia become apparent. You might turn pale, lose coordination and feel weak and sleepy. Your pulse slows down. 

Then it gets much worse. 

Where can I find a spacesuit?

Scientists think that paradoxical undressing happens when your hypothalamus gives up drawing blood to the core and releases it back to the extremities, which gives you such an extreme hot flush that you start taking your clothes off. It has been observed in about 25 per cent of extreme hypothermia cases. So that’s roughly six kids. Or five kids and you. 

Luckily, you are always well prepared. So, once it became apparent that the room was not getting any warmer – and before the hypothermia set in – you started handing out space suits. It took about 45 minutes for the students to put them on, but they probably learned something during the process.

Once suited and booted, the lesson can proceed. 

Ink and board pens will stop working between 0°C and -20°C depending on the solvent, so hand out the pencils and revert to chalk. You realise how hard it is to hold anything while wearing a space suit. Time for that trusty discussion activity – space suits have microphones and earpieces. Or even a debate to "warm" things up a bit. 

You can keep using the computer. It actually gets more efficient. But the smart board will stop working below about -40°C.

When the air melts...

Once it gets really cold, more strangeness can be observed from inside the suits. 

At -183°C, the oxygen in the air starts to condense to form a pale blue liquid. Nitrogen goes a few degrees later. The moisture in the air makes the classroom look like a rainforest. 

Once it all condenses – which will be at a significantly lower temperature, because of the decrease in pressure – it’ll be about five millimetres deep on the floor. 

These kinds of temperatures are testing the limits of modern space suits.

If your classroom gets this cold, you will have witnessed something truly special – but, eventually, the students and you will experience hypothermia and die. Minus the paradoxical undressing. Those suits aren’t easy to get out of, which is probably worth the £45 million you dropped on them. 

Emily Seeber is head of science at Bedales School in Hampshire and tweets @emily_seeberHer Seeber’s Science column runs fortnightly. If you would like her to explain the science behind anything education related, email

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