There is a "real danger" schools could be shut until summer, a leading education figure has warned - because of a "lack of planning".
Children's Commissioner Anne Longfield said a "clear roadmap" for reopening is "lacking" and has called on MPs to "think creatively".
The blow to parents comes hours after reports emerged that information about a return to classrooms could be released within days.
Ms Longfield set out her stall on getting kids back in lessons in a report titled 'Roadmap to reopening schools', which was published online on Tuesday.
She said: "Unfortunately it is a lot easier to close schools than to reopen them.
"Everyone recognises the necessity of reopening schools as soon as possible, but hope alone will not make it happen.
"What is lacking is a clear roadmap towards this.
"There is a real danger that schools will remain closed until Easter at the earliest, or even into the summer - not because the virus makes this inevitable, but because of a lack of planning.
"The exam question that needs to be asked at the top of government is: how many children of what age could return when and where , under what level of community transmission; and what should we do now to facilitate that?
"This should be the subject of daily briefings and meetings as part of the No. 10 and Cabinet Office Covid response.
"SAGE can provide modelling of different options – and at the end of this note we suggest what evidence would be helpful - but ultimately it is for government to think creatively about what those different options might be, explore all possibilities, come up with a plan, and ultimately make something happen."
Ms Longfield then set out a number of options for the gradual reopening of schools, which included some year groups returning before others and children getting back in on a rota basis.
The commissioner also stated that "effective testing" should be rolled out in schools and teachers and other staff should be prioritised for vaccines to support the reopenings.
And she added that a "turbo-charged catch up plan" would be needed once kids were back in the classroom to bridge the knowledge gap left by the pandemic.
The focus on the effects of lockdown and the pandemic on schooling has increased in recent days, with fears a 'lost generation' is being created.
Prime Minister Boris Johnson said yesterday that there was a possibility restrictions could be relaxed in three weeks, although Downing Street swiftly clarified and said February 15 was the date when lockdown will be reviewed.
School bosses have said they believe classes will stay shut to most kids until after the Easter holidays, which are at the beginning of April.