Parents are being told to prepare for last-minute school closures next week, as thousands of teachers go on strike.
Next Wednesday is the first of four days of planned industrial action from the 6,500 local members of the National Education Union in a dispute over pay.
School leaders say there is widespread uncertainty over the impact of the action, as staff do not have to inform their employer whether they will be taking part in the walkout until the day of the action itself.
However, some schools have already said they will close, while others have warned that they may have to merge classes, introduce remote learning or hold 'activity days', rather than curriculum-focused teaching.
Some are considering restricting attendance to vulnerable children or those of key workers.
The situation has left parents in limbo, wondering whether they will need to make last-minute childcare arrangements or take time off work.
Katrin Oldridge, who runs parenting advice website Norwich Mumbler, said: "I fully support teachers' right to strike.
"However, I do also understand some parents' point of view as it can be disconcerting to have to make childcare arrangements at short notice.
"It can be stressful and worrying not knowing for sure."
Among those to confirm they will close are Cawston Primary, near Alysham, and Lionwood Junior and Infant School, in Thorpe Hamlet.
Daniel Thrower, chief executive of the Wensum Trust, which runs several schools in Norfolk, said: "Schools may not be able to deliver normal provision and some of the options we are considering are merging classes, having activity-based days, utilising staff from other schools where feasible, restricting attendance to vulnerable children and those of critical workers, or closing schools.
"I want to reassure parents and carers that our headteachers will only consider restricting attendance or closures if they are unable to provide safe staffing levels."
The NEU is legally obliged to inform schools of its member numbers two weeks before the day of an industrial action.
However, the members themselves are not required to notify the school until the day itself whether they will be joining in.
Jonathan Rice, executive headteacher at Caister Primary Federation, said: "These are incredibly difficult decisions. While we are able to ask NEU members whether they will be striking, they are under no obligation to tell us, so there is a lack of certainty about how many teachers will be in school on the day.
"Then there is the issue of cover. Colleagues who are members of other unions cannot strike, but may have voted for strike action in their own ballots and will want to be supportive.
"The potential for picket lines is an added factor - some colleagues will not want to cross them.
"Utmost in all headteachers' minds will be the parents of the children in their schools. They need to know as soon as possible.
"Communication is vital and this may force headteachers to make an early decision, even if that is based on limited information."
The union is calling for fully-funded, inflation-busting pay rises for teachers and for improved education funding and working conditions.
The government has offered a 5pc increase for teachers.
By the end of this year, the starting salary for teachers is due to rise to £30,000 - but union bosses argue the increase is well behind the rate of inflation.
Scott Lyons, district secretary of the NEU in Norfolk, said: "All schools have been told of the number of members they have so we are doing our bit to keep them informed.
"We are now asking schools to inform parents of what they are doing and headteachers desperately need to make decisions about what they are doing as soon as possible.
"I have already heard of some making decisions to close and others looking at remote learning opportunities - but parents have to be kept in the loop.
"Ultimately we do not want to be striking, but we need to government to take the discussions far more seriously than they have been."
Industrial action is planned on the following dates in Norfolk and Waveney:
Wednesday, February 1
Wednesday, March 1
Wednesday, March 15
Thursday, March 16
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