The government is being urged to create a "national plan for education" which includes the "requisitioning of local public spaces" to ease pressure on schools during the coronavirus crisis.
Buildings such as libraries and community centres should be made available for schools to use so more children are able to continue their education in "safe environments", according to the NEU teaching union.
Mary Bousted, joint general secretary of the NEU, said the national plan should "cover all scenarios", focusing on "blended learning" both in and out of school, more support for disadvantaged children, and the "requisitioning of local public spaces" to make more space for socially-distanced learning.
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"The consequences of Covid-19 are going to be felt in our education system for months to come," she said.
"What is needed, now, is a national plan for education, along the lines being developed by the Scottish government.
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"This should cover all possible scenarios and focus on blended learning, at home and at school; greatly increased support for disadvantaged children, including free internet access so that they can access online teaching and learning; and the requisitioning of local public spaces, such as community centres and libraries, so that pressure on school space is lessened and more children are able to return to school in safe environments."
Former education secretary Justine Greening has also said there are "plenty" of spaces that are not currently being used, which could be repurposed to help schools to accommodate more children.
Speaking to the BBC Radio 4's World at One programme on Monday, Ms Greening said: "I think there is plenty of office space and community space that is currently unused.
"I think there's no reason why we can't ask teachers who have left the profession to come back in – and, indeed, private tutors."
The use of retired teachers and community spaces to help schools to reopen has "not been ruled out", the prime minister's offical spokesperson said earlier today.