Around 23,000 secondary school and higher education teachers are engaging in industrial action from today, in the latest move in a dispute over public sector pay
It means Teachers Union of Ireland members will no longer be responding to work calls and emails outside of their contracted hours.
Members working in secondary schools will also withdraw from Croke Park hours and refuse to supervise children or attend meetings outside of the normal school day.
They join members of the other main teaching unions, the INTO and the ASTI, who began industrial action last week.
All three unions will also join nationwide public sector strikes on Wednesday the 14th and 21st of October, forcing many schools and higher education institutes to close their doors.
Over 300 thousand public service workers are expected to join picket lines on these days, protesting what they believe is the "failure of Government to provide the basis for negotiations" on a new public service pay deal.
Ove 98% of TUI's members voted to take industrial action over the dispute.
"Every branch of the union we go to there is this anger about the cost-of-living and the fact that they feel that the Government is not taking it seriously," says TUI General Secretary Michael Gillespie
"The rent is going up everywhere in the country," he added, "If I've afforded to buy somewhere, now I'm driving a hundred kilometres a day, the cost of diesel, petrol has gone up."
