Downing Street has warned that mass strike action in Britain on Wednesday will cause significant disruption.
Teachers, university staff, civil servants, train and bus drivers are all on walkout.
According to the Trades Union Congress (TUC), around 500,000 workers are set to take part in what will be the biggest strike in more than a decade.
Talks between teachers’ unions and the Department for Education (DfE) ended without progress on Monday.
Education Secretary Gillian Keegan has wasted an opportunity to avoid strike action on Wednesday, the National Education Union (NEU) said.
The first of seven walkouts planned by teaching staff across England and Wales is expected to affect 23,000 schools.
The DfE has offered most teachers a 5% pay rise for the current academic year, but the NEU wants a fully funded inflationary increase for teachers.
Some schools have announced closures. But others are still making decisions — meaning many parents are waiting to decide whether to make child care arrangements.
But Schools Minister Nick Gibb said the government expected the “vast majority” of schools in England to open some.