Significant” changes to grade boundaries have been blamed for a 7.5 per cent drop in Monmouthshire pupils passing English language exams.
Raising the number of marks needed to pass last year’s GCSE English Language exam has had a knock-on effect on wider performance levels, a senior council officer has said.
All four secondary schools missed Welsh Government targets for the number of pupils achieving A*-C grades in at least five GCSEs last year.
Caldicot School was expected to get more than two-thirds of its pupils to reach the threshold but less than half made the mark.
Pupils sitting the GCSE English Language paper set by the Welsh Joint Education Committee (WJEC) in June needed 220 marks to achieve a C grade.
But pupils taking exams in June and November 2017 needed 200 and 204 marks respectively to achieve the same grade.
Will McLean, chief officer for children and young people at Monmouthshire County Council, said: “The magnitude of the jump from 204 to 220 was more significant than anybody had expected.
“When schools received their results, I had every single head teacher ringing me to talk about English Language.
“If there’s a significant impact on English, it impacts on all other threshold measures.”
Measures used by schools to assess performance include the Level 2 inclusive threshold, where students achieve five A*-C grades in English or Welsh first language and Mathematics.
In 2018, 59.5 per cent of Monmouthshire pupils met this threshold – down from 67 per cent in the previous year.
A report says 67.2 per cent of Caldicot School pupils were expected to reach this threshold but only 47.7 per cent did.
“Caldicot had a very challenging summer last year,” said Mr McLean.
“We’ve only got four schools and if a school has a fall of around 18 per cent, that has a significant effect on the number we achieve collectively.”
At Chepstow School, 66.4 per cent achieved the threshold compared to a 73.4 per cent target, while 69.4 per cent hit the target in Monmouth Comprehensive – compared to a target of 71.5 per cent.
A target of 69.5 per cent was set for King Henry VIII School but this was not hit, with 63.7 per cent of pupils reaching the expected levels.
Despite the decline Monmouthshire ranks in the top five authorities in Wales for pupils attaining the Level 2 threshold.
GwE, the education consortium for north Wales authorities, had lodged a formal complaint against the grade boundary changes,
But following an investigation, Qualifications Wales found no evidence that pupils sitting the GCSE English exam last June were “unfairly disadvantaged”.