Children attending new "free schools" could be taught in pubs, undertakers, pet shops and hairdressing salons under proposals published by the Government.
Education planning laws will be relaxed to boost Education Secretary Michael Gove's flagship policy under the terms of a consultation launched this week.
Other buildings that could be converted into schools include takeaways, betting offices, ice rinks and banks.
Until now, anybody wanting to set up new schools in existing buildings had to have planning permission, but the coalition wants to change the law so this is no longer necessary.
Ministers are also looking into how schools can "co-exist" with other businesses in one building.
But unions have warned that the changes could leave children and teachers working in unsuitable and unsafe locations, and claim that "shoehorning" schools into "any old building" is wrong.
A number of buildings, including clinics, creches, law courts and museums can already be used for educational purposes.
"The Government. wishes to create the freedom for innovative and creative schools development and to that end is seeking to broaden the potential stock of available accommodation for schools as far as possible," the consultation says. "Clearly, there will always be some properties which, for different reasons, may be unsuitable for use as schools and we would expect school promoters to eliminate them from their consideration."
Changing the law would save new school providers up to pound;12,000 because they will not need planning permission.
Christine Blower, general secretary of the NUT, said "It shows a complete lack of understanding about schools as learning environments to think they can be shoehorned into any old disused building.
"It also shows a lack of respect for pupils and teachers to make them manage without the specialist facilities that every school deserves."
Chris Keates, general secretary of the NASUWT, said: "In the 21st century, the ambition for our children and young people should be state-of-the-art facilities, not a rundown flat over the local off-licence."
Kevin Dodd hopes to open a free school on a disused steel works in Consett, County Durham, which closed more than 20 years ago.
He said: "It's useful that these planning laws give the possibility of using a range of buildings, but as a headteacher I want to ensure health and safety is paramount, despite what the Government say we are legally able to do."
Officials admit there could be an impact on the neighbours of new free schools "in terms of noise, parking and litter problems".
But the consultation, which closes on December 10, also says staggered opening times and the fact that the schools will be more "local" - with children travelling smaller distances - will make them less disruptive to a local area.
- Original headline: PE in the morgue and Eng lit under the drier