Families of pupils sitting GCSE and A-level exams next week have been advised to make alternative arrangements for getting to school during the rail strikes.
The RMT has announced industrial action on June 21, 23 and 25.
On June 21, pupils sitting GCSE history or dance with exam board AQA may be impacted by the strikes, while on Thursday those sitting GCSE physics papers could be affected.
A-level pupils studying German, religious studies or maths with this board could be impacted by strike action on Tuesday 21, while pupils sitting papers in A-level chemistry could experience disruptions to their journey to school on Thursday June 23.
In total, 17 GCSE and 22 A-level papers could be impacted by the strike action.
Headteachers have said families should look into alternative arrangements for getting their children to school to sit papers on time.
Julie McCulloch, policy director at the Association of School and College Leaders, said: “We are concerned about the potential impact on exam students of the industrial action affecting train services planned in June.
“The majority of students live local to schools and colleges and tend to take buses rather than trains so we are hopeful that the impact will be minimal,” she added.
“However, it is important that families are conscious of the industrial action and make alternative arrangements where students are reliant on train services.
“We would urge anybody who is concerned about their ability to attend an exam to talk to their school or college at the earliest opportunity to discuss the options that are available.”
Heads have been told to relocate A-level and GCSE papers if they cannot go ahead in the exam hall and that exams may begin up to half an hour later than scheduled to mitigate disruption.
The Joint Council for Qualifications said: “You should make sure that any exam or timetabled assessment takes place if it is possible to hold it”, adding: “This may mean relocating to alternative premises.”