The SNP Government's cherished aim of limiting class sizes to 18 for P1-3 could be officially declared dead if ministers adopt the policy recommended by their own review group.
The group, established last November by former education secretary Fiona Hyslop, is understood to have come out against setting prescriptive limits on class sizes. While it will acknowledge that the number of pupils in a class has an impact on children's learning, it also draws attention to other key ingredients such as better pupil-teacher ratios, improved staff training and enhanced support for teachers.
A significant factor in the deliberations of the group, which was chaired by David Cameron, former president of the Association of Directors of Education in Scotland, is that its findings were unanimous.
This means the unions have agreed with the local authorities and the Government, which were all represented, that flexibility in fixing class numbers is the way forward.
The TESS understands that the formula arrived at to secure the consensus is that an upper limit for class sizes, for secondary as well as primary pupils, should be enshrined in legislation. This would be backed up by an agreement on pupil-teacher ratios, setting out what a minimum level for school staffing ought to be.
The group emphasises the importance of determining limits nationally in order to provide consistency throughout the country. But it also underlines the importance of autonomy so that, if some schools wanted to reduce numbers in the earlier years or in classes where pupils needed extra support, they would have to run larger classes elsewhere.
The unions' reservations are also likely to have been tempered by an acknowledgement that, whatever limits were eventually decided, they should be lower than those in the current teachers' contract (33 in primary and S1-2 and 30 from S3-6). The review group accepts the possibility of further reductions agreed nationally through the Scottish Negotiating Committee for Teachers.
But its report is also expected to point out that a fixation with class size is becoming increasingly outdated, as the nature of learning changes. The role of a "class" as the only vehicle for learning is giving way to individualised learning and to teaching in different groupings.
The findings of the review will be a mixed blessing for ministers. While it has accepted that there is a place for reducing class sizes, it has also concluded that the policy cannot be endorsed on the basis of research, teacher workload or parental demand.
The Government will point out that the group was set up by Ms Hyslop to examine the best mechanism for setting limits, rather than what those limits should be. At the time, she accepted that this could mean decisions might be taken nationally, locally or on a school-by-school basis.
The review was established because of the "hotchpotch" of class-size arrangements, which have been arrived at in a variety of ways through legislation, circulars and teachers' conditions of service.
The previous administration's policy of limiting S1-2 English and maths classes to 20 had been done by circular, the original maxima of 33 in primary schools and 20 in practical classes had been negotiated with the unions and remains part of the teachers' contract, while the ceiling of 30 in P1-3 is set out in statute.
The Government has been steadily moving away from its commitment to limiting P1-3 classes to 18 pupils since the arrival of Michael Russell as Education Secretary last December. He announced a new policy of "realism" in the face of unrelenting council criticism that the class-size pledge was both unaffordable and undesirable.
Mr Russell agreed a deal with the local authorities which allowed them more flexibility over free meals and nursery hours in return for a commitment that 20 per cent of P1-3 classes would have no more than 18 pupils by the start of this session.
The Government has also departed from its original policy by legislating for no more than 25 pupils in P1, after a series of legal challenges by parents made it clear the legal maximum was still 33.
However, the principle of placing requests would still allow the 25-pupil limit to be exceeded if parents won an appeal to get their child into the school of their choice. Mr Cameron's group is keen to have this loophole of the "excepted pupil" closed.
Neil Munro email@example.com.