A strike by pupil support assistants has resulted in Glasgow City Council closing 10 schools for children with extra learning needs and disabilities.
The 24-hour action is over a dispute about extra duties such as healthcare and the administration of medicine.
The union, Unison, said members had not been properly trained for these duties or offered the correct pay.
The council said it had offered to improve pay but the union had rejected its attempts to reach a compromise.
Glasgow City Council said seven schools for complex learning needs had closed: Broomlea School; Milton Secondary; Croftcroighn Primary; Newhills Secondary; Langlands Primary; Linburn Secondary and Hampden Primary.
Ashcraig Secondary, Kelbourne Park Primary and Hazelwood School - which educate children with physical, visual and hearing impairment - are also closed.
All mainstream schools are open but some children have had to stay home following a risk assessment by the headteacher.
The council said the only mainstream school affected by the action was Hyndland Primary which was closed to P1, P2 and P3 pupils.
Unison said the council expected pupil support assistants (PSAs) to take on "significant" extra duties which should be delivered by professional healthcare workers.
These include: blood glucose monitoring, injections, gastronomy tube/peg feeding, tracheostomy care including suction, catheterisation and catheter care.
The union said PSAs were currently paid an annual salary of £11,800 and it wanted the extra duties assigned to a higher grade post than that held currently held by PSAs.
It said there had been "no offer of increased pay for all PSAs, instructors or care staff for the administration of medicines".
Unison official, Carol Ball, said: "PSAs took their job to deliver education, not healthcare.
"Despite council claims PSAs are not receiving proper training to carry out what are medical procedures.
"And the council can't have it both ways. If PSAs have been trained and have the skills and responsibility of delivering these complex needs then the case for keeping them on the lowest level of pay collapses."
Councillor Stephen Curran, executive member for education and young people, said the union had rejected all attempts at reaching a deal.
"We are really disappointed and sorry that Unison has decided to go ahead with the industrial action which will stop our most vulnerable young people coming to school," he said.
"We had organised another meeting on Tuesday to discuss our latest compromise offer - this has again been rejected.
"Throughout this dispute we have listened to their concerns and have offered to improve the pay of support staff."
Mr Curran added: "It is clear that Unison is not prepared to agree a compromise which would be in the best interests of their members."