They were joined by thousands more across government departments as civil servants too went on strike.
None of them wanted to be there, but felt the time had come to take a stand.
And they know worse could be coming when Secretary of State Chris Heaton-Harris announces his budget for Northern Ireland today, with further swingeing, devastating cuts expected.
Their resolve will be tested, but they are now dug in for the long haul.
So, there could well be more days like yesterday on the industrial dispute front.
Schools remained closed as a result of the walkout by teachers.
It will have been an inconvenience to parents.
Some will have lost pay they can ill afford to by having to take a day off work.
But teachers maintain there is little option other than protesting against the cuts and the squeeze on their salaries.
They have seen colleagues leave the profession for better paid jobs elsewhere, and young people choosing other careers rather than go into education.
They are worried that the waiting list for places in special education schools is growing by the month, increasing disparity and impacting the most vulnerable children in society.
There may be a religious divide in the education system, but there’s also an economic one.
With the ending of schemes like Holiday Hunger, the Extended Schools Programme and counselling services due to budget cuts, it is those pupils who need help the most who will suffer.
It may be 25 years since the signing of the Good Friday Agreement, and last week’s reflections on all the good that brought were a necessary reminder of how far we have come as a society.
But any society that has emerged from decades of conflict needs support to grow.
What support there was is now disappearing fast.
By the end of today, Stormont’s departments will know what extra challenges they face in meeting the needs of the community.
Why should people here have to settle for less when the prospects could be so good?
If those who hold the purse-strings in Westminster are serious about making this place work, then they should give the teachers, the civil servants and everyone else in the public sector the tools and recognition they need to do the job properly and to the best of their ability.