20,000 teachers in Northern Ireland go on strike today in an escalating dispute over pay.
The four main unions will stage a half-day stoppage, ending at noon.
They're due to step up the action with another four full strike days in the spring.
Those dates have yet to be announced.
Union representatives said teachers had been taking industrial action short of strike for more than a year.
In that time they said there'd seen no sign either Stormont's Education Department or Northern Secretary Chris Heaton Harris was in any rush to settle the dispute.
Education got a significantly reduced budget for 2023/4 with the overall spending envelope set by Mr Heaton Harris is the absence of the collapsed assembly.
It has been estimated that the department is £300m (€346m) short on what it needs to run an effective service.
Senior officials say that's the reason they can't fund a pay increase for teachers - in line with public pay policy.
But teaching unions say the pay gap with colleagues in Britain has been growing and that since the last pay increase in 2020/21 they've endured soaring prices.
Unions say they're now paid significantly less than colleagues in England, Scotland, Wales and the Republic of Ireland.
SDLP Education Spokesperson Daniel McCrossan said that pay gap was forcing teachers "out of the profession and out of the north".
"It's hardly surprising that many teachers in the North are now considering moving to the South, Britain or further afield to obtain fair pay for the job they do."
Sinn Fein MP for South Down Chris Hazzard is to accompany teachers to Westminster to hand in a letter of protest at Downing Street.
