GCSE exams happen in May and early June and often overlap with the World Cup or European Championships.
A study of 3.5m GCSE students’ results between 2002 and 2008 suggests they dropped, on average, a quarter of a grade in each exam during such events.
Both boys and girls were affected, with poor boys hit the hardest.
The researchers, led by Robert Metcalfe at Oxford University, suggested that in even years, when tournaments are held, there are “increased inequalities”.
Dr Metcalfe said: “For the most affected, which are disadvantaged boys, they have a much larger drop, the effect is doubled.”
It means this group can drop about half a grade in each exam taken during a big football competition.
Source: BBC News