Summer heat and student learning

Many of us would appreciate the idea that it is difficult to concentrate on hot days, even without the distraction that we could be hanging out at the beach. So, that raises legitimate questions. Does students' learning suffer when it is hotter? Should students avoid summer school, if they are trying to maximise their grades? These questions aren't of purely academic interest. Climate change means that we will likely have increasingly hotter summers over time, which makes these questions increasingly relevant for the future.

A 2017 article by Hyunkuk Cho (Yeungnam University School of Economics and Finance in South Korea), published in the Journal of Environmental Economics and Management (sorry I don't see an ungated version), provides some indication. Cho used data from 1.3 million Korean students, from 1729 high schools in 164 cities, and looked at the relationship between the number of hot summer days and the students' scores in the Korean college entrance exam, which is held in November (at the end of the northern autumn). They found that:

...an additional day with a maximum daily temperature equal to or greater than 34°C during the summer, relative to a day with a maximum daily temperature in the 28–30°C range, reduced the math and English test scores by 0.0042 and 0.0064 standard deviations. No significant effects were found on the reading test scores. When an additional day with a maximum daily temperature equal to or greater than 34°C reduces the math and English test scores by 0.0042 and 0.0064 standard deviations, ten such days reduce the test scores by 0.042 and 0.064 standard deviations, respectively. The effect size is equivalent to increasing class size by 2–3 students during grades 4–6...

If you're in a temperate climate like New Zealand, you might read that and think, 'we don't have that many days greater than 34°C, so probably there is no effect here'. But, Cho also found that:

...hot summers had greater effects on the test scores of students who lived in relatively cool cities. If cities with an average maximum daily temperature below 28.5°C have one more day with a maximum daily temperature equal to or greater than 34°C, relative to a day with a maximum daily temperature in the 28–30°C range, the reading, math, and English test scores decreased by 0.0073, 0.0124, and 0.0105 standard deviations, respectively...

Interestingly, the analysis was based on the summer temperatures, while the test was taken in the autumn. Cho found no effect of the temperature on the day of the test itself. The results aren't causal, so some more confirmatory work is still needed.

However, if we were to extrapolate from the main results a little, students exposed to temperatures higher than the norm for a particular area may well be made worse off in terms of their learning. If you're wanting to maximise your grades, the beach should be looking like an even more attractive option now.