National Education Union members have voted in favour of a fresh ballot for strike action, which would give it a mandate for action up until Christmas.
A successful motion at the union’s annual conference in Harrogate also calls for three further days of strike action in late June to early July.
The NEU’s previous ballot, which closed in January, is valid until July this year.
Teacher members of the union have already taken six days of action, and are due to walk out again on April 27 and May 2.
