A teacher in Britain helped her students cheat but got the answers wrong, reveals a probe initiated after 18 out of 19 pupils gave the same incorrect answer in the exam.
Investigators found that students had been illegally helped by the teacher during the exam, Standard Assessment Tasks (SATs).
In another school, its head changed papers - only to turn a right answer into a wrong one, The Sun reported on Monday.
The cheating was detected when authorities spotted answers had been altered using a different pencil.
In a third school, the analysis of papers found evidence of 93 changes by teachers.
After a probe was announced, the head went on sick leave and then quit.
The media report said that all three cases led to "maladministration" findings and many students had their maths, English and science test results scrapped.
The probe was carried out by the Qualifications and Curriculum Authority.