Tens of thousands of teachers are taking part in the one-day walkout, according to union leaders, in the latest stage of industrial action over pay, pensions and conditions.
Members of the NASUWT, along with the National Union of Teachers (NUT), are staging walkouts in the North East and Cumbria, the South West, South East and London.
The Government said that just over a quarter of schools in the four English regions hit by the strike had been forced to shut their doors, as it condemned the action.
More top news
Sleet and snow for some parts of Scotland. Elsewhere in the UK will be cold, cloudy and with some showers.
At least 52 people have been killed after a fight broke out between two rival drugs gangs in a Mexico prison.
Lord Coe has accused Nestle of hypocrisy following its decision to withdraw sponsorship from the IAAF Kids' Athletics Programme.