Students who learn in hotter classrooms perform worse on college-admissions tests, according to a new study from the National Bureau of Economic Research.
Researchers tracked 10 million high school students who took the PSAT multiple years between 2001 and 2014. On average, students improved their score by a third of a standard deviation by retaking the test. But a student’s performance dropped by nearly 1 percent of a year’s worth of learning for every degree Fahrenheit hotter the outside temperature was during the school year before a student took the test. The effect was three times as strong for low-income, black, and Hispanic students. In schools with air conditioning, 75 percent of the declines associated with hot days disappeared.