Christine Blower of the NUT said: "We really feel that not having made any inroads by other means, [that reluctant] strike action is what we have to do now."
 
The strike is expected to cost companies up to $135m in lost working hours for parents who have to take time off or pay for childcare.
 
Rising costs 
 
Jessica Garner, a newly qualified teacher, said: "The way that I am having to live at the moment on my salary knowing its not going to be reflecting the cost of living, is going to lead to me having to leave the profession."
 
But John Ransford, a government associate, maintains that teachers are well-paid.
 
He said: "Teachers have not had brilliant settlements but in terms of the average, they are above average. Teaching is now a well-paid, well-resourced profession."
 
Hundreds of coastguards went on strike on Wednesday night, signalling the start of a series of walkouts by 100,000 civil servants across the UK.
 
Civil servants from 10 government departments and agencies will also strike.