NASUWT Scotland has called on members to continue their "work-to- contract", started six months ago in protest at changes to teachers' pay and conditions and pensions.
Outgoing Scottish president Zaf Hussain, his successor Mike Corbett, and national president Paula Roe urged delegates at the union's Scottish conference in Edinburgh last week to stick to their guns, although some might find it difficult if there were only a few NASUWT members in some schools.
Mr Corbett said staff morale had been eroded by Curriculum for Excellence, continuing concerns about the new National qualifications, and worries about changes to pay and conditions. Members had also reported being affected by cuts to supply teachers' pay and the number of support assistants in class, he said.
The incoming Scottish president also bemoaned the government's failure to carry out a valuation of the Scottish teachers' pension scheme.
"How on earth can the Westminster government demand increased contributions when they don't yet know if they are needed?" he asked.
Last year's attacks on teachers' terms and conditions had targeted "the weakest and the most vulnerable" groups of teachers - probationary teachers, supply teachers and those on maternity leave. The only way to "deal with a bully" was to stand up to him, said Mr Corbett.
"We have done that, colleagues, since 30 November last year and we need to continue to do that or the powers-that-be will come back for more.
"We need to continue to be strong in our action and identify ways in which we can intensify it to get our message across," he added.
"It occurred to me that perhaps Professor McCormac can help us here: if he doesn't want us to leave the premises during the school day, maybe we should spend our full 35-hour week in school and not take a single jotter, textbook or Powerpoint slide anywhere near our family home."
UK president Paula Roe told delegates they had to ensure all members were prepared for continued protests.
"We are professionals and it is never easy to take action. It is a last resort. But this action is asking you to work to your contract. Three members in a school can have a tremendously powerful effect."
The measures taken by NASUWT members were "action that has been and will continue to be pupil-friendly and parent-friendly", she said.
Working to contract, as opposed to striking, allowed the NASUWT to react in a flexible way to all the issues facing the teaching profession, not just those relating to pensions, she added.
Low morale over cfE and pensions
A survey of NASUWT members showed 40 per cent were unhappier in their jobs this year, compared with last year.
A third of them said the main reason for the deterioration in their morale was related to Curriculum for Excellence, while one in five cited changes to the pension scheme, and 14 per cent said their morale had been affected by changes to supply teacher conditions and the pay freeze.
"Morale is the lowest I have experienced in all my years of teaching," a primary teacher from Highland told the survey. "CfE was supposed to help ease the strain and allow teachers to teach. Now it's a tick box."
A secondary teacher from Dumfries and Galloway added: "Most teachers feel we are being asked to do much more work for less pay and not many benefits, and our careers are drastically changing to something completely different to what we signed up for."
Five per cent of teachers blamed changes to the chartered teacher scheme for their low morale.
"The CT pull-out hit me hard and still makes me feel betrayed and disillusioned," one secondary teacher from Edinburgh said.
The statistics also revealed that 54 per cent of the schools in which NASUWT members were teaching had fewer classroom assistants this year compared with last, while 59 per cent of staff had less access to classroom assistants this year compared with two years ago.