Removal of asbestos in old buildings and the effects on academic performance while schools are turned into building sites are two concerns of teachers and parents, the Educational Institute of Scotland says.
Major work has begun on seven sites as part of the initial pound;220 million plan to renovate all 29 secondaries and one primarynursery.
Charlie Gordon, council leader, said at the scheme's launch at Cleveden Secondary: "This programme will take three years as against 20 years if we had done it in the traditional way."
Over the period, the total cost will rise to pound;1.2 billion, a third of which will come from the Scottish Executive at around pound;14 million a year. Conventional funding would only have allowed about three new schools in contrast to the 12 under PPP funding, Mr Gordon said.
The city council stresses that an independent survey has shown a potential saving of pound;36 million over the 30-year contract, mostly on repairs, maintenance and back-up services.
Glasgow also has invested some pound;8 million over the summer in new technology in all secondaries, half of their projected ICT spend. More than 3,000 new computers, linked to a central server for learning programmes, are already in place.
Ian Valentine, Cleveden's headteacher, said: "In a year's time,
all our pupils will come together in a single building with accommodation, equipment and CT of a quality far better than anything I have experienced in over 30 years of teaching."
But Willie Hart, EIS local secretary, said teachers remained cautious. "I know we will be seen as the spectre at the feast but Glasgow is appalling at providing information to staff about what's going on," Mr Hart said.
He remains "highly sceptical" about PPP funding and the "excessive trust" in it, although he recognises that there were few alternatives for the city. "We certainly hope Glasgow does not become a guinea pig or an educational Skye Bridge," he ventured.
Every secondary, Mr Hart points out, will end up with less space, with practical difficulties for teachers who have to move between classes. "It's dishonest to pretend difficulties are not there, although teachers will do everything to minimise them. We are still apprehensive about the impact of building work and the disruption that will cause."
He hoped that levels of disruption would be considered when pupils sat their final exams.
The union is still concerned about the removal of asbestos in every school. The city council had been served with an improvement notice but health and safety inspectors said they were reasonably satisfied with progress, Mr Hart said. Full details about plans for handling any asbestos removal will emerge by the end of the month.
Mr Gordon promised that Glasgow's secondaries would be among the most modern in the world, equipped with state of the art technology. All classrooms will be networked with a minimum of two new-generation computers per classroom. Internet links for schools will be free. Gerry McCann