The BBC has uncovered evidence of organised cheating at primary schools run by the Silver Birch Academy Trust.
A former head says pupils at one school were given answers in Sats exams, taken by 11-year-olds in England.
Suzanne Barham has told BBC Panorama she was also ordered to change other test scores at three schools in 2017.
Mrs Barham, the then head teacher at Longshaw Primary School in north-east London, which was part of Silver Birch, told Panorama: “We were told to go and work with specific children and to give them a little help.
“That’s what happened, those children were given answers.
Mrs Barham says she was ordered to cheat by the trust’s chief executive, Patricia Davies, and agreed to do it because she was afraid of losing her job.
She says she was also ordered to cheat on a Sats reading exam.
“Mrs Davies called me into her office, and it’s a reading paper, so you can’t read it to them, and she said, ‘I want you to read it for them’.
The Standards and Testing Agency investigated the cheating claims after parents complained and the results were allowed to stand.
But they did not talk to the parents or pupils like Kelly’s daughter Sophie. She has told Panorama that a teacher walked around in the exam giving out answers in her maths Sats exam.
“She sort of walked past, looked at my test and she stopped and she just pointed at it and went, ‘that’s the answer’ and told me the answer. I was so annoyed. I just looked at her like, ‘what are you doing, this is a test’.”
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