Strike action will close schools in four council areas on Wednesday as staff walk out in a dispute over pay.
The one-day strike by some council workers in Glasgow, Renfrewshire, East Renfrewshire and Inverclyde follows a three-day strike in September.
Council body Cosla has argued that a bigger pay rise is unaffordable.
Non-teaching staff involved in the dispute include catering, cleaning, pupil support, administration and janitorial workers.
As a general rule, primary schools in the four areas will be closed but some secondary schools will be open to S4, S5 and S6 students. Full details are on council websites.
For a number of pupils, this could be the 12th day they have lost to strike action within a year.
Some lost as many as eight days in school because of the teachers' strike between November and March, before they then lost a further three days when Unison staged a three-day strike across most of Scotland in September.
There will also be disruption to council-run nurseries.
More action is planned for four other council areas next week - South Lanarkshire, Dumfries and Galloway, Edinburgh and Fife.
The pay offer from Cosla would see the lowest-paid workers get a rise of about £2,000 a year while other staff would get rises worth at least 5.5%.
Members of the two other main council unions - Unite and the GMB - voted to accept this offer but Unison have argued that a better deal is possible.
Earlier this month, Unison Scotland's head of local government Johanna Baxter said: "The strength of feeling amongst Unison's 91,000 local government members, who voted overwhelmingly to reject Cosla's latest pay offer, is clear. They are determined to continue to fight to get an improved pay offer."
Cosla previously stated that the proposal was "as far as local government can go".
Council leaders from across Scotland are due to decide on Friday whether to implement this offer despite Unison's opposition.
One argument in favour of doing this is that staff will receive their pay rise - including money backdated to April - in time for Christmas.
But it also risks escalating the dispute with Unison which is expected to announce more strikes within the next few days.
Unison is also warning that it could ballot other council workers - such as refuse collectors - to see if they would also be prepared to go on strike.