The government has refused to reveal how many schools signed up to be early adopters of the controversial new baseline assessment for four- and five-year-olds.
The Reception baseline assessment (RBA) was due to become statutory this term, but was delayed for a year owing to the disruption caused by the Covid-19 pandemic.
Schools were instead given until 24 July to sign up for an optional "early adopter year", to "familiarise themselves with assessment materials" before the RBA becomes statutory, with assessments taking place in the second half of the autumn term.
Tes asked the Department for Education how many schools had signed up to be early adopters, but the department failed to provide a figure.
The DfE said it would reveal the information after the assessments had been completed.
Opposition to the Reception baseline assessment
The RBA, which evaluates children's skills in English and maths, is designed to provide a baseline for the DfE in measuring pupils' progress between their first weeks in school and their final Sats results in Year 6.
Last year, it emerged that 7,000 primary and infant schools in England had snubbed a chance to take part in a pilot study of the controversial assessment, carried out in the 2019 autumn term.
The government announced that 9,612 primary and infant schools had signed up for the optional pilot – just 57 per cent of those eligible.
And Tes later revealed that almost 200 schools dropped out of the pilot before it began.
Beatrice Merrick, chief executive of the Early Education charity, said the DfE's "reluctance" to reveal the number of early adopters was "surprising".
"It may mean that they are expecting a high drop-out rate between those who initially indicate an interest and who subsequently drop out when they see the materials, or are faced with the realities of trying to conduct these assessments while supporting children to settle in and start learning at a time of ongoing disruption during the pandemic," she said.
"We know that over 80 per cent of schools have turned down the option of being early adopters of the new EYFS [Early Years Foundation Stage] framework. Perhaps a similar majority of the sector has said no to baseline."
A spokesperson for campaign group More Than A Score added: "Heads and teachers have told the government over and over that RBA is a flawed and pointless assessment and, this year, that's more true than ever.
"This may be a message the government wishes to suppress, but it is in the public interest to know how schools are responding to these turbulent times. Are government tests useful to their work in settling Reception children?
"Knowing how many schools have signed up to the early adopter scheme would help to answer that question."
The DfE has been approached for comment.