Scotland's biggest teaching union has announced 16 new strike dates in a dispute over pay.
There will be strikes on 16 consecutive days in January and February, with teachers in two local authorities on strike on each of the 16 days, Andrea Bradley, general secretary of the Educational Institute of Scotland, said.
The action will start on 16 January and is due to last until 6 February.
On any one day, small parts of Scotland will be affected - but across the 16 days there will be an impact on much of the nation.
Scottish teachers are calling for a 10% pay rise - which the authorities say they cannot afford - and better working conditions.
Thousands of teachers walked out yesterday in the first national strike action for teachers in four decades, leading to the closure of every state school on the Scottish mainland.
National strike days will also take place on 10 January for teachers in primary and special schools, as well as early years, and on 11 January for those working in secondary schools and secondary special schools.
Announcing the latest action, Ms Bradley said: "We have been forced into the escalation of this action by the lack of willingness to negotiate properly and to pay teachers properly, by a government that says it wished to be judged on its record on education.
"The judgement of Scotland's teachers on the matter of pay is clear, with the first programme of national strike action that we have engaged in for four decades.
"It is now for the Scottish Government and Cosla to resolve this dispute, and prevent further strike action, by coming back to the negotiating table with a substantially improved pay offer for all of Scotland's teaching professionals."
Under new proposals teachers earning under £40,107 would receive an increase of £1,926 a year - 6.85% for those on the lower salaries - while those earning more would get 5%.
Shirley-Anne Somerville, the Scottish education secretary, called for the unions to return to the negotiating table yesterday.
"I appreciate the strength of feeling that's within the unions, that they want to see a 10% increase, but I would point out that since 2018, Scottish government has provided - including this year's proposal - a 21.8% cumulative increase in teacher salaries," she said on Bauer Radio.
Several industries are planning strikes across the UK this year, from transport to the NHS and education to delivery drivers.