Teachers have announced they will take further strike action next month and send a "united message" in a dispute over pay.
NASUWT members in primary schools will strike on January 10, while teachers working in secondary schools will walk out on January 11.
The strike will coincide with action by Educational Institute of Scotland (EIS) members, who will walk out on January 10 and 11, joined by Scottish Secondary Teachers' Association (SSTA) members on the second day.
The NASUWT is calling for a fully funded 12% pay award for 2022/23 and said the current pay offer tabled by ministers and Cosla amounts to a further real-terms pay cut.
Dr Patrick Roach, NASUWT general secretary, said: "We have been left with no choice but to call two further days of national strike action as a result of the failure of ministers and Cosla to offer an improved pay offer.
"At a time when teachers are facing the biggest squeeze on their finances in a generation, offering what amounts to a further real-terms pay cut is simply not good enough.
"Our members are not prepared to stand by while their pay dwindles and their living costs rise.
"The government and employers will need to bring forward a substantially improved pay offer if they want to see an end to this dispute."
Teachers have already rejected a deal which would see most staff in classrooms receive a 5% pay rise, although the lowest earning teachers would get a 6.85% increase.
Mike Corbett, NASUWT national official for Scotland, said: "Members are determined to continue with our campaign of industrial action and will stand together with teachers in other unions to send a united message to the Scottish Government and employers that they deserve a fair pay settlement.
"Teaching is a critical job and one that is uniquely and increasingly challenging.
"Teachers just want pay levels that reflect the years of training they have undertaken, the high level of workload involved and the skill involved in meeting the needs of all pupils.
"They want salaries that enable experienced teachers to remain in the profession long-term and which will incentivise new entrants to join teaching.
"They want pay levels that demonstrate they are respected and valued as the key workers they are."
The EIS strike action on January 10 will involve members in primary schools, special schools and early years sites.
The following day, EIS and SSTA members will stage another strike in secondary schools and secondary special schools.
Education Secretary Shirley-Anne Somerville said: "We remain committed to a fair, sustainable settlement for Scotland's teachers and will continue to engage with teaching unions and Cosla constructively.
"It is very disappointing that the teaching unions have rejected the latest offer – the fourth of which has been put to unions – which mirrors the deal accepted by other local government workers.
"The request for a 10% increase from the teacher unions collectively in Scotland is not affordable within the Scottish Government's fixed budget."
Katie Hagmann, Cosla's resources spokeswoman, added: "We are disappointed that strikes are going ahead.
"In an effort to prevent strikes happening, we as employers made a revised fourth offer to our trade union colleagues, that did include additional money.
"It was a fair and affordable offer which recognises the cost-of-living crisis as the priority by focusing on higher increases for staff on lower pay points.
"This means 6.85% for probationers, as well as between 5.71% and 5.1% for those on the lower to middle parts of the pay scale who will also receive their annual increment."
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