By Gary Eason
Education editor, BBC News website
Can staff make the journey to school safely?
The government has said some schools which shut due to bad weather could - with hindsight - have stayed open.
England's schools secretary Ed Balls said decisions had been taken responsibly based on the forecast conditions.
He denied that head teachers had acted out of fear of health and safety legislation.
Many parents - faced with having to take time off work to care for their children - are puzzled and angry.
In some cases the decision to shut on Tuesday was taken on Monday - and not rescinded when it apparently might have been.
Mr Balls said on BBC Radio Four's The World at One: "Today in London it's quite sunny. And you look out and think 'why is the school closed?'
"But last night, when the weather forecasts were for very heavy snow, in order to give parents certainty, decisions were made by many local authorities and schools to say, 'We'll have to keep the school closed for a second day'.
"There's always a balance to be struck. In retrospect maybe the schools could have opened.
"But I think many parents, wanting to plan their arrangements for today, would have been pleased to have certainty yesterday about what was going to happen today."
He dismissed the idea that unnecessary regulations were tying head teachers' hands, but added: "It's important that our kids are safe in schools."
The government takes the view that this is an issue for local decision making.
Head teacher's call
The decision is taken usually by the head teacher, perhaps in consultation with other members of the school's senior management team and the chair of governors.
The key issue is the safety of the pupils, which can be affected by different factors:
1. Can they get to school? In the case of secondary schools in particular, children may have to travel many miles. If transport is impossible, they cannot get there.
2. Can they get home? It might be fine in the morning, but if severe weather is expected to prevent a return journey, the school may decide to close.
3. Is the site safe? Adjacent schools may take different views on the slippery conditions if, say, one has a very sloping site.
4. Can the staff get there? Lent Rise Combined School in Buckinghamshire gave as its reason for closing: "Over two thirds of our staff come from quite some distance and we cannot compromise their safety or the safety of the children due to inadequate cover/supervision being available."
Whether or not staffing levels are adequate is also a matter for local discretion - other than for very young children, for whom there are legal requirements.
But this general principle of local autonomy seems to be contradicted by the decision of Birmingham City Council, for example, to close all its maintained schools and colleges.
The blanket closure was ordered on Monday evening.
School may be out, but there's fun to be had
The strategic director of Birmingham's children, young people and families department, Tony Howell, said: "Conditions are expected to be extremely cold and icy and more dangerous than yesterday.
"Our highways department is expecting very difficult conditions on the roads and is advising the public not to travel unless essential."
A very different view was taken in Shropshire County Council, whose John Baxter said: "We didn't want a situation like the Birminghams and Solihulls where we just did a blanket closure because if schools can open then it's better for the children - because in many instances their parents are working and they have to make all sorts of arrangements."
There is anger and precious little sympathy among some parents contacting the BBC, however.
Scott Sutherland, from Aberdeen, said: "Closing schools pre-emptively based on the forecast is ridiculous."
Lynn Purser, of Harrogate, wondered why it was necessary for everyone to live so far away from work and school.
"All our local schools have children brought in by bus from miles around, even from places which have their own schools. Little wonder that we have closures, often because the teachers live so far away too.
"Hate to harp back on the old days, but I started school in the winter of 1962/3, and walked, following the snowplough."
One mother - obliged to stay at home - suggested local authorities should see teachers as essential and follow the example of many businesses which put staff in hotels overnight - as one teacher being off prevents potentially 30 parents from going to work.
In Kent, which bore the brunt of the bad weather at the start of the week, the council's guidance to schools is that it is important that their decision to close should be supported by local authority (LA) managers.
"Failure to get LA support for closure could result in the LA being unable to defend any legal action brought by parents against the school failing to discharge its legal responsibilities," it says.
The guidance also says: "If staff cannot attend their usual place of work they should contact their local school to see whether they can assist staff there."
It is not clear how many school staff have done that this week.