A number of schools are closing next week and others are ditching uniforms, as temperatures in parts of the UK are predicted to hit 40C (104F).
A national emergency has been declared after a red extreme heat warning was issued for Monday and Tuesday.
Schools are not being ordered to shut, but are being encouraged to take steps to ensure pupils are safe.
Teachers say schools will need to judge whether or not to fully or partially close in some instances.
But one teaching union said widespread closures were "unlikely at this stage".
