Eleven-year-olds in more than half of Wales's primary and junior schools will sit national tests this summer, even though Sats are no longer compulsory.
A TES Cymru poll published last week showed teachers were overwhelmingly in favour of getting rid of the testing regime for 11 and 14-year-olds.
But Year 6 pupils in 795 schools across Wales will sit tests in the core subjects of English or Welsh, maths and science later this year, according to figures released by ACCAC, the Welsh qualifications and assessment authority.
These schools, nearly 54 per cent of the total, have requested external marking of this summer's voluntary Sats papers. Around 681 schools (46 per cent) declined the offer, although some may use the papers in class.
John Valentine Williams, ACCAC's chief executive, said there was no clear pattern to the requests for external marking. He suspects clusters of primary schools have come to agreements with neighbours, in what will be an interim year for assessment.
Key stage 2 papers will be available next summer but without external marking, as the system moves towards placing a greater reliance on moderated-teacher assessment and developing new skills tests for 10-year-olds, as per the recommendations of last year's Daugherty review.
Primaries in Monmouth have collectively agreed not to take the Sats, and are instead using standardised tests from the National Foundation for Educational Research (NFER). Jon Murphy, head of 302-pupil Usk Church in Wales primary, believes Sats led some schools to concentrate too heavily on English, maths and science, which meant Y6 pupils missed out on creativity and fun.
He said: "Standardised tests don't have the pressure, and will be more productive and useful."
Kate Evan-Hughes, head of 125-pupil Llandogo primary, Monmouth, said:
"Assessments need a diagnostic element, and there wasn't a thorough diagnostic element to the Sats. The NFER tests will give secondary schools more useful information about pupils."
However, in Abergavenny and Newport, in Gwent, many pupils will find themselves sitting Sats this summer.
Tricia Brown, Y6 teacher at Our Lady and St Michael's Catholic primary, Abergavenny, believes teacher assessments more accurately reflect children's abilities.
But she said: "We thought we would do the tests as an assessment, so children and parents know where they are. Having them externally marked gives us an objective view.
"We have always done Sats as part of a balanced and varied curriculum. We have never taught differently because of it, and we don't feel it puts pressure on the children."
Anna Brychan, director of the National Association of Head Teachers Cymru, said: "Although we recognise the tests are deeply flawed, many schools were using them in the context of raising standards and benchmarking their performance against others. Schools are perhaps reluctant to let go of them because they are currently the only benchmarking mechanism they have."
Heledd Hayes, the National Union of Teachers Cymru's education officer, said: "Schools are not doing Sats because they like them, but they will use the information sensibly. Everyone knows the tests are going."