Fed-up teachers in England and Wales will stage a series of walkouts over pay in February and March.
The National Education Union announced national strikes on February 1 and March 15 and 16, as well as regional action on four other days.
More than 23,000 schools in England and Wales are expected to be hit by the first walkout, with heads given guidance on switching to online lessons if they haven't got enough staff to keep schools open.