From Popsci.com 22/01/14:
When a storm is brewing and the streets are soon to be rendered useless by mounds of snow, there's really only one thing running through every student's mind: please let tomorrow be a snow day. Now there's science to back up canceling [sic] school due to nasty weather. According to a study by Harvard Kennedy School assistant professor Joshua Goodman, keeping the school doors open can actually hurt learning more than a snow day closure.
The explanation for this, according to the article, is as follows. When a school remains open during a period of heavy snow, a lot of parents keep their children at home, whereas others might make it in to class. That throws the pupils’ progress out of sync, often resulting in the children who didn’t attend school during the snowy period missing out relative to their peers. However, where schools take the decision to close because of snow, substitute days are often added to the school calendar to make up for the missed time. (Well – they do in the US apparently.) That keeps classes in sync and ensures the world is a happy, shiny place.
More pragmatically, there are a lot of other reasons why it might be better for schools to admit defeat during inclement weather and close for the day rather than trying to soldier on with skeleton classes. In most areas of the UK where snow is a rarity rather than a predictable yearly battle, pupils won’t be concentrating on schoolwork when there’s tobogganing to be done or snowmen to build outside. I remember from my school days that the onset of snow during a maths lesson turned into a free-for-all at the windows. Somehow algebra can’t compete with the prospect of playing in the snow.
What’s more, taking the decision to close a school when the weather dictates it really isn’t safe to open avoids all of those other problems, too. You know, like children slipping and injuring themselves in playgrounds resembling ice rinks. Then there’s the dangerous chaos that ensues from mums and dads doing the school run in a hurry in deep snow. Cars, small children and ice are a dangerous combination.
And head teachers have got their blood pressure to think about, after all.