It was meant to provide a "snapshot" of young children's abilities as they start their education and to help teachers plan their development. Instead, the so-called child development assessment profile (CDAP), launched last September, has created a series of problems for the Welsh government that show no sign of abating.
The controversial policy requires early years teachers to monitor up to 114 types of behaviour displayed by children aged 3-5 in the six weeks after they start foundation classes.
Teachers warned when it was announced that the policy would be too complicated and unwieldy and have ridiculed several of the categories to be monitored, such as whether a child can stand on one leg for two seconds.
After months of overwhelmingly negative feedback, the government was forced into an embarrassing climbdown last month, announcing a full review and relaxing the reporting requirement to parents. But, despite this, it seems the policy may still spark classroom clashes.
Last week, teaching union the NASUWT told its members in Wales to stop using the assessment profile, putting itself in conflict with ministers and creating potential problems between its members and their employers.
The government has issued a stern warning. A spokesman said that the statutory duty to use the CDAP to assess children when they enter the foundation phase remains in force. "We would hope that the NASUWT is not advising its members to break the law. Should teachers choose not to administer the CDAP, then Welsh ministers will consider what, if any, steps are needed to ensure compliance."
Although headteachers are no fans of the policy either, the NASUWT has advised its members to contact the union immediately if they are told to continue using the CDAP by their schools.
Rex Phillips, the NASUWT's Wales organiser, said that he did not expect heads to place any pressure on its members to use the assessment profile, and he urged them to respect the union's position. "There's no point in schools continuing to use it," he said. "It is fundamentally flawed and workload-intensive."
Heads' union NAHT Cymru is exasperated. After its joy at winning the battle for a review, it now faces the possibility of several months of damaging clashes between its members and their staff.
Anna Brychan, director of NAHT Cymru, said that this period would be better spent discussing what a new model may look like instead of arguing about the "discredited" system.
"Obviously, our members have no choice but to comply with statutory requirements, but it is time for this debate to move on to the next phase," she said. "Entering into disputes at this stage feels a bit like snatching defeat from the jaws of victory."
Other classroom unions are waiting for the results of the review, which will be launched in March.
Teaching union the NUT said that it is seeking improvements to the system or, ideally, for it to be scrapped completely. But during the review period its members will work as normal and follow the process while monitoring its failures.
TOO MANY TESTS
Like many early years teachers, Judith Michael, a nursery teacher at Alltwen Primary in Neath, found the CDAP overwhelming.
"I had 29 children to assess in six weeks," she said. "I spent all of my time looking at what they were doing and trying to tick boxes. I didn't feel I was giving them the experience I would have liked them to have when coming into the nursery."
Ms Michael, who has been a teacher for nine years, said the tests were flawed in a number of areas. "It doesn't give you a complete picture of the child's abilities. I appreciate you have to have some sort of on-entry assessment for children. But the emphasis should be on nurturing them in the first few weeks, not testing them on what they can and can't do."