Overstretched schools may be forced to send pupils home when non-contact time is introduced in Wales. Delegates at the annual conference of UCAC, the Welsh-speaking teachers' union, said this might be the only solution for hard-pressed schools that have to implement 10 per cent planning, preparation and assessment (PPA) time from September.
But the union threw out a proposal calling for non-contact time to be postponed until sufficient funding and staffing can be found to implement it properly.
Dilwyn Ellis Hughes of Ysgol Glan-y-Mor, in Gwynedd, said: "We should not be asking for it to be postponed, we should accept it and wrestle with it.
If it doesn't work and you have to send children home, then so be it."
Delegates at the Aberystwyth conference this week had previously heard Helen Arthur, a civil servant responsible for overseeing the implementation of the National Agreement, reject the idea of any delay.
Ms Arthur said: "PPA will happen on the existing timetable and I don't think there's any prospect of that being renegotiated."
After the meeting, Moelwen Gwyndaf, UCAC's general secretary, said the union supported the contract, but that there were concerns over implementation.
"Schools could find themselves sending pupils home, either through a lack of finance or because they can't find suitable staff," she said.
Schools, particularly in rural areas, are facing the prospect of lower incomes because of dwindling rolls, at a time when they are expected to recruit staff to cover PPA.
Addressing what outgoing president Huw Tudur described as a "disillusioned bunch", Ms Arthur discussed the role that support staff, particularly higher-level teaching assistants, will play in providing PPA.
But Robert Howells, head at Llanybydder primary, in Carmarthenshire, said that, with a recruitment budget of just pound;6,000 he was struggling to find a part-time teacher. "Higher-level teaching assistants just don't exist," he said. "The Government hasn't trained anybody. Even if they did exist, they wouldn't be much cheaper than a newly-qualified teacher."
The conference also passed a motion which called on the Assembly to provide more cash for workload reforms, so heads will not have to raid other parts of the school budget.
The two-day conference saw around 50 delegates carry a raft of other proposals. These included motions on Welsh as a second language, which the union plans to make one of its main campaigns over the coming year.
It will now push ACCAC, the Welsh qualifications, curriculum and assessment authority, to carry out a full review of Welsh-language teaching. The union believes that current courses put too much stress on teachers.
It will also demand a review of funding for peripatetic Welsh teachers.
UCAC members believe that variations in their conditions of employment leave these jobs, and the provision of Welsh-language teaching, in a fragile position. Concern was also expressed regarding the lack of job opportunities for NQTs.
There is a fear, principally expressed by members in the north Wales authority of Gwynedd, that teachers will leave Wales in search of work, leading to future shortages. UCAC wants to see the Scottish system adopted, with new teachers guaranteed a position for 12 months.
Deputy general secretary Gruff Hughes said: "If Scotland can afford it, then why the hell can't we?"