Hundreds of thousands of teachers and heads will be balloted for strike action in the autumn from today.
The National Education Union (NEU) and the National Association of Head Teachers (NAHT) will ask members in England to vote over fresh industrial action after branding the Government pay offer an "insult".
All the major education unions are threatening to coordinate their walkouts in the autumn term if school staff back strike action, in a major escalation of the fractious dispute over pay.