Teachers are preparing 11-year-olds for tests in English by getting them to learn passages of text and stock phrases to be regurgitated later, word for word.
England's test regulator has warned schools against "unacceptable" over-preparation for key stage 2 assessments.
Cases where answers from one class are suspiciously similar will be investigated for malpractice, the Qualifications and Curriculum Authority has said.
The QCA's latest test guidance says: "In the past, some pupils have learnt or practised pieces of writing ... to reproduce in the English writing test. This is not acceptable. If pupils' responses do not relate to the writing prompt given in the test, they will not gain any marks for composition and effect.
"If several pupils in a class write using similar or identical words or phrases or form, their work may be reviewed for malpractice."
Sue Palmer, a TES columnist and literacy consultant, said she had received similar reports from teachers and test markers.
"I have heard of schools where pupils practise writing a story and report writing for the whole of Year 6. The kids are bored out of their heads but the school feels it has to do it because of the pressure to improve results," she said.
Dr Bethan Marshall, of King's college, London, said: "Sometimes pupils are encouraged to use rhetorical triplets, such as 'I would like to persuade, urge and plead with you' to do something. It's redundant - it doesn't teach you to write better, just to follow rules."
This summer, the QCA admitted that Year 6 pupils were spending two hours a week practising English test papers, and further time on maths and science papers, at the expense of other subjects.
John Gawthorpe, head of Mayhill primary, Odiham, Hampshire, said: "This is what happens when politicians do not trust teachers to make sound professional judgements."
A QCA spokesman said that changes to the tests, introduced last year, made it more difficult for pupils to write according to pre-prepared suggestions.
Evidence that some secondary teachers do little to stop students flouting coursework rules has emerged in reports on this year's A-level and vocational exams.
For media studies, some teachers were passing off candidates' work as authentic even where coursework was nearly identical.
This was also identified as a problem by Edexcel in its popular GNVQ in information and communications technology. The board has warned schools about textbooks or online courses which give guidance to pupils on what to write for coursework. Candidates could not expect to get higher grades if they took this approach.
* The Welsh National Assembly this week approved the removal of statutory tests for 11-year-olds.