Hotter School Days, Less Learning Unless There's AC

Many previous studies have tried to assess the effects of

temperature on learning. Students in hotter countries tend to

score lower on comparable measures of academic achievement than

those in more temperate climates, but there are many differences

across countries, other than average temperature, that are

difficult to hold constant.

In this study, the researchers reviewed the PSAT test scores of

10 million U.S. students from the high school classes of 2001

through 2014, all of whom took the PSAT at least twice. They also

collected or generated data on daily temperatures near schools,

the penetration rate of air conditioning at schools, and many

other demographic, educational, and environmental factors.

Comparing a student's score on the test to the same student's

score one year later allowed them to isolate the impact of

experiencing a hot school year prior to the test.

The key finding is that higher temperatures over the course of a

school year reduce academic achievement. Each additional school

day with a temperature in the 90s, rather than the 60s, reduced

achievement by one-sixth of a percent of a typical year's gain.

If the temperature exceeded 100Γäë, the adverse effect was even

larger. Weekend and summer heat had little impact; the effects

were associated only with higher school-day temperatures. The

study controls for the correlation of heat, air pollution, and

other local economic shocks.

Without air conditioning, each 1Γäë increase in average school year

temperature is associated with a one percent decline in the

amount learned during the school year. For schools with air

conditioning, however, the negative effects virtually disappear.

The researchers note that lower-income and minority students are

more likely to attend schools that are not air conditioned. They

estimate that, for most regions of the United States, investing

in school air conditioning systems leads to sufficiently high

income gains for students in the long-term to out-weigh the costs

of that initial infrastructure investment.