The strike was confirmed by the Educational Institute of Scotland (EIS), the Scottish Secondary Teachers' Association (SSTA) and the Teachers' Union NASUWT after last-ditch talks with the government failed on Monday.
"While it is now too late to halt this week's strike action in schools, we hope that fresh talks may take place later this week to advance discussions towards an improved offer," EIS head Andrea Bradley said.
Industrial action went ahead after the teachers unions rejected the offer of a 5% pay raise, including up to 6.85% increase for the lowest-paid staff, demanding a 10% hike that teachers expect to offset the surge in the cost of living.
A spokesman for First Minister Nicola Sturgeon told reporters last month that she understood the teachers' plight, but he argued that the Scottish government was operating within a tight budget which was already eaten up by rampant inflation.
In late November, 2022, almost all Scottish schools closed due to a strike by teachers demanding a 10% increase in wages. This was the first nationwide teachers' strike in Scotland since the 1980s.
The United Kingdom has been facing a wave of strikes in recent months. Railway and airport employees, lawyers, postmen and workers in other areas have been protesting against job cuts and low pay while also demanding the improvement of working conditions. The strikes are driven by record inflation in the country.