NASUWT general secretary Chris Keates said the teaching profession is in "crisis" following "three years of attacks by the Coalition Government".
Teachers' unions have announced a rolling programme of regional strikes over the next few months, affecting schools across England and Wales.
It is thought the action could be followed by a national walkout in the autumn over a dispute on pay, pensions, working conditions and jobs.
Education Secretary Michael Gove said in a letter to both unions in March that he was wrote willing to meet them to discuss their dispute, but also insisting that the "direction of travel" on both of their key issues is "fixed".
From this autumn, teachers' pay will be linked to performance in the classroom, with schools setting salaries, rather than following a national framework.
More than 2,500 schools in the North West of England could be affected today as teachers stage a walkout over pay, pensions, working conditions and jobs.
Members of the National Union of Teachers (NUT) and NASUWT will take part in a strike, the first in a planned national rolling programme of strikes across England and Wales which will continue in the Autumn term.
Twenty two authorities, and a possible 2,765 schools, across the North West will be affected as joint rallies are held in Liverpool, Manchester, Chester and Preston.
Chris Keates, General Secretary of the NASUWT, will address the rally in Liverpool at midday.
A Department for Education spokeswoman has insisted that teaching is an attractive profession.
She said the coalition's reforms gave schools "more freedom" with an education system that matched "the world's best". She added:
These are surely ambitions the NUT and NASUWT should be supporting.
We are very disappointed that the NUT and NASUWT have decided to take strike action, which less than a quarter of teachers actually voted for.
Industrial action will disrupt pupils' education, hugely inconvenience parents and damage the profession's reputation in the eyes of the public at a time when our reforms are driving up standards across the country.
More than 50% of teachers are unhappy with their jobs and are considering leaving the profession, a new survey has found.
Government reforms to pay and pensions, heavy workloads and school inspections are to blame for dissatisfaction, the report said.
The poll comes the day before members of the NASUWT teaching union and the National Union of Teachers (NUT) working in the north west of England stage a one-day walkout, action which has been condemned by the Department for Education.
Teachers at the National Union of Teachers annual conference in Liverpool have called for a boycott of school inspections as they warned they had no confidence in Ofsted chief Sir Michael Wilshaw.
Liam Conway, an NUT member from central Nottinghamshire said:
Good teachers are literally dropping like flies because of Ofsted. We owe it to all of our teachers who are literally being torn to bits by Education Secretary Michael Gove and Sir Michael Wilshaw and their band of crocodiles and lions.
The union must do more to work out a way to boycott Ofsted. It is time to stop hiding behind legal impediments.