Teachers are to stay home from 1 to 4 October, which is Monday to Thursday, which will be followed by a national bank holiday on Friday 5 October.
The action will be phased, taking place in specific parts of the country on each different day.
First up, on Monday will be Lisbon, Setúbal and Santarém, followed by the Alentejo and the Algarve on Tuesday, then central Portugal on Wednesday, and lastly the north and the Azores, on Thursday.