Teachers fear that the looming baseline assessment will be too rigid.
Early years specialists gave a cautious welcome to Government plans for the compulsory testing of five-year-olds this week.
The so-called baseline assessments will take place in the child's first half-term at school. There will be no test as such but teachers will observe children during normal classroom activities, and there are likely to be some standard tasks to assess the child's learning.
One in two education authorities already operate baseline assessments and they can continue to use their own schemes if they meet Government standards.
Education and Employment Secretary Gillian Shephard, launching the initiative, said: "We are on track to introduce nationwide baseline assessment for five-year-olds from September 1997 as part of the Government's continued drive to raise standards in education."
The scheme will be compulsory for all schools a year later. The launch coincided with the publication of the School Curriculum and Assessment Authority's draft proposals on baseline assessment.
The authority proposes three models for assessing five-year-olds which are being trialled in a random selection of schools this term. Consultation through questionnaires, a survey, conferences, and meetings will end on November 8.
The assessments will give teachers information for monitoring a child's work. Early years specialists recognise the need for assessment when children start school but warn against categorising very young children with dramatically different backgrounds in inflexible schemes.
One feared that some schools would be tempted to deliberately under-estimate children's skills so the value added by teachers would look more impressive in the national league tables.
Another, Margaret Morgan, chair of the National Association of Head Teachers' early years committee, was sceptical about using baseline assessment for valued-added league tables.
She said: "Life down at the sharp end with three, four and five-year-olds cannot be divided in the same way as the rest of primary education because we are talking about very young minds in children who have had a range of experience, however limited which has only lasted for a matter of months. "
Two early years specialists, Susan Hay and Wendy Scott, already unhappy that the Government's targets for nursery children are narrow and simplistic, fear baseline assessment might turn into another strait-jacket, especially in the hands of the 75 per cent of reception class teachers untrained to work with young children.
Susan Hay, chairman of the Childcare and Education Association for private providers, said: "Children are being made to fit the system rather than the system emcompassing the child."
And Wendy Scott, chair of the British Association for Early Childhood Education, feared that some parents might try and train their children for the tasks. There was the danger that checklists became meaningless when they were used out of context, she said.