Teachers are going on strike today for the first time in 21 years.
The National Union of Teachers (NUT) is holding the one-day industrial action in protest against the three-year pay package agreed by the government in January this year.
Teachers will receive a 2.45 per cent pay rise from September 2008 followed by increases of 2.3 per cent in 2009 and 2010, as agreed by the School Teachers' Review Body.
As this is below the 4.1 per cent retail price index the NUT argues its members are receiving a real-term pay cut.
"Teachers do not take the decision to strike easily, or lightly, but teachers' patience has been stretched to the limit," NUT acting general secretary Christine Blower said.
Thousands of schools are expected to be affected as a result today, with the BBC predicting 7,800 schools in England and Wales will be forced to partially close or shut their gates completely.
The NUT argues its strike addresses a longer-term problem of the quality of teacher staffing, fearing that year-on-year pay "failing to keep pace with inflation" has a negative impact on the teaching pool.
"It saps morale and causes problems of recruitment, retention and teacher shortages, not to mention real financial difficulty for our members. It is time to call a halt," Ms Blowers added.
"You cannot run a world class education system if teaching doesn't attract enough graduates. it is time for the government to listen."
It is not clear whether the strike will affect a government-backed world record attempt for the world's biggest lesson, due to take place today.
International development secretary Douglas Alexander will attend the lesson as hundreds of schools around the UK aim to participate in the same "core lesson" being taught in 120 countries.
He may be required to lead the lesson himself if striking teachers abandon the classroom he finds himself in.