Researchers at Harvard, the University of California Los Angeles (UCLA) and Georgia State University analysed results of more than 10-million U.S. secondary school students over a 13-year period and found that in years when there was hot weather during exams, the results were lower — and there were better results in cooler years.
The researchers suggested the hot weather made it harder for kids to concentrate on studying in lessons and out of school.
Nick Brook, deputy general secretary of British school leaders' union NAHT, tells HuffPost the research goes to show how many different factors there are that can affect an individual pupil's exam performance on the day.
"From hot weather, to feeling ill, to problems at home, to simply not having slept — children aren't always able to show their full abilities in one high-pressure end-of-year exam," he says. "Test data can therefore only ever be part of the picture when judging a pupil's success or a school's effectiveness."
Mark Smith, assistant principal director of sixth form [Grade12] at Beal High School in London, added: "All of us, even when we're having to work, find it harder when it's really hot."
Smith says the conditions in which students write their exams could be changed to ensure they are cooler: "Most schools do exams in sports halls, which aren't airy spaces, and you can't have the doors open easily to let air through because of noise from the rest of school — so they're not the nicest places to be taking exams," he said.
He also says some schools are strict about every student is wearing the correct uniform, including blazers and ties, so they're not wearing comfortable clothing — but in hot weather his school allows children to remove blazers and ties.
Smith says if a heatwave were to happen during the exam period, it may be worth parents or the school discussing "special considerations" for students, as this is usually applied when there are circumstances that negatively impact exam performance.
The study concluded that a "simpler resolution" could be access to air conditioning in schools.