BOSTON: Hot weather is likely to lower children's academic grades, say Harvard scientists who have found that higher temperatures make it harder for students to study in lessons in school and concentrate on their homework.
The research found that every 0.55 degree increase above 21 degrees Celsius cost a child one per cent in their exam scores.
Researcher from Harvard University in the US analysed 10 million children's test scores taken across 13 years.
The study found that hotter weather made it harder to study in lessons in school and to concentrate on homework out of school.
It suggests air conditioning should be used to keep classrooms cool, the researchers said.
Colder days did not damage achievement, however the reduction in learning accelerated once temperatures rose above 32 degrees Celsius and even more so above 38 degrees Celsius.
The data showed that students were more likely to have lower scores in years with higher temperatures and better results in cooler years, 'The Telegraph' reported.
This applied across the many different types of climate, whether in cooler northern US states or in the southern states where temperatures are typically much higher.
The study is the first of its kind to provide clear evidence of performance going down as temperature goes up, researchers said.
Joshua Goodman, associate professor at the Harvard Kennedy School of Government said students were incrementally more likely to be "distracted, agitated and find it harder to focus".