No one said it was going to be easy but teachers, just 24 hours into their campaign of industrial action, are already on the defensive. The ASTI has sought to set the agenda for its strike action by spending about £200,000 on an expensive TV and newspaper advertising campaign.

The debate was supposed to be the contribution teachers have made to the education system and how this society values its teaching profession. Instead, as anyone who listened to Liveline or The Marion Finucane Show in recent days will know, it is about more awkward issues - specifically, what teachers are prepared to give in return for their 30 per cent pay claim.

The answer, for now at least, is nothing - despite the very short working year, the long holidays, and the lack of accountability in the second-level system.

The public is also beginning to focus more clearly on one other salient aspect of this strike, the fact that the ASTI is on a solo run. The other two teaching unions - the Irish National Teachers' Organisation (INTO) and the Teachers' Union of Ireland (TUI) have so far progressed their claims through the Programme for Prosperity and Fairness. But the ASTI has stepped outside the partnership fold.

When the ASTI's 30 per cent claim went to arbitration it was completely rejected. The Public Service Arbitration Board told the ASTI, in unambiguous terms, to pursue its demands through the PPF - like the other teaching unions.

The ASTI now finds itself in a difficult situation. It says it wants to enter "meaningful negotiations" with the Government. But it must know that the PPF is the only game in town. Is it realistic to expect the Government to reward the ASTI for stepping outside the PPF - when the other teaching unions are within it?

The ASTI has another difficulty. It rightly claims some measure of credit for creating a boom economy but, as the Government has warned, its actions could help to destroy the partnership model, which has also been at the heart of the State's economic success.

The Minister for Education, Dr Woods, has created further tactical difficulties for the ASTI by inviting it to attend the first meeting between the new benchmarking body and the public service unions next Monday. The benchmarking body was set up under the PPF and links public to private sector pay. It could deliver significant pay increases for teachers.

If the ASTI refuses to attend this meeting, it will look as though the union has squandered an opportunity to settle the dispute - and to win concessions for its members. It also gives the ASTI an opportunity to catch up with other graduate professions.

But if it does attend, the ASTI will make an important concession; it will be working its claim through the PPF framework.

It is already clear that benchmarking could hold the key to the teachers' dispute. The ASTI has always opposed the concept of benchmarking because of fears that it could lead to some kind of performance-related pay. But now it may have no choice but to co-operate with the body.

Chaired by Mr Justice Quirke, the benchmarking review body will ask the teaching unions to make their case for more money. This will put the onus on the ASTI to justify pay increases for greater productivity and a willingness to adopt the kind of disciplines evident in the private sector.

This could present difficulties for the ASTI. Irish secondary teachers work for 167 days a year while their counterparts in Northern Ireland work a full 195 days a year. Their pay has fallen behind other graduates but they remain among the best paid in the OECD. They are working in a system where there is virtually no accountability to the Department of Education - and where their promotion for most jobs is still based on seniority.

It is also a system which in pay terms does not differentiate between the vast majority of dedicated, hard-working teachers and those who have long ago lost interest in the job.

All this may have to change if the ASTI is to benefit fully from the benchmarking body - but it may have backed itself into a corner.