The hotter the sky, the lower the exam results?

A large study from researchers at Harvard University and other US universities said that in the hotter years, students were able to do worse exams.

Research conducted by experts at Harvard, University of California Los Angeles (UCLA) and Georgia State University said they have clear evidence that when temperatures rise, school performance is reduced.

The researchers analyzed test scores of 10 million American high school students in 13, from 2001 to 2014, through different climatic and weather conditions in the United States.

Students are more likely to have lower grades during the years with higher temperatures.

The results show that students are more likely to get lower grades in the years with higher temperatures and achieve better results in cooler years.

This is true in many different climates - whether in the northern US states are colder or in the southern states, where temperatures are often much higher.

The study, called "Heat and Learning", suggests that it is more difficult to get hot in school and focus on homework.

The researchers calculated that for every 0.55 ^° C increase in average temperature, learning outcomes were reduced by 1%.

Cold days do not seem to ruin academic achievement, but negative effects start to be measurable when the temperature rises above 21 ^° C.

Reducing learning results increases rapidly when the temperature rises above 32 ⁰ C and even more when the temperature is above 38 ⁰ C.

Joshua Goodman - a professor at the Harvard Kennedy School, says that the heat makes students more likely to be "distracted, agitated and find it harder to concentrate".

According to him, the finding also raises bigger questions about whether climate change and global warming affect school performance.