BTW, I highly recommend Tyler’s book—it’s full of fascinating insights. He finally explained to me why I was so bored in school, despite my love of learning. All I recall from school is staring at the clock waiting for it to hit 3:20, and waiting for summer vacation. When I read proposals for a 12-month school year all I can think of is the book 1984. And I am an educator.
What's the possible justification for these proposals? There are studies suggesting that summer vacation is a primary source of the learning gap between students with low and high socioeconomic status. As measured by test scores, poorer students often improve as much or more than affluent students during the school year, only to fall behind massively during the summer. This raises the possibility that we could slash the achievement gap simply by extending the school year.
Yet I'm not sure that the logic underlying such conclusions is sound. As a useful analogy, imagine two countries: Niceland and Struggalia. Over the past 20 years, Niceland has experienced an extremely consistent rate of economic growth, with a 3% increase in GDP every year. Struggalia, on the other hand, alternates between contractions and recoveries, and its average annual growth rate in the last two decades has been only 1%.
Economists parachute into Struggalia and discover an interesting empirical fact. During times of recovery, Struggalia grows at an average rate of 3%—just as much as Niceland! The cause of Struggalia's long-term growth problems, the economists conclude, is straightforward. If only Struggalia didn't suffer from intermittent recessions, it would experience the same long-term growth as Niceland.
Another economist, however, begs to differ. She notes that Struggalia's rapid growth during periods of recovery comes primarily from increased use of capacity that already existed: workers and factories that idle during the recession return to productive use. If Struggalia didn't have such deep recessions, she declares, GDP wouldn't grow at the same speed during good times, because it would no longer be bouncing back from a period of idle capacity. The boom/bust cycle might be bad in its own right, and it might have more complicated effects on long-term growth, but eliminating it certainly wouldn't make Struggalia as prosperous as Niceland. In fact, the maverick economist claims, it's not clear that Struggalia could grow much faster than 1% at all, even if it smoothed the business cycle completely.
Does this sound plausible to you? It does to me—the latter economist is arguing that Struggalia's economy is mostly trend stationary rather than difference stationary. Is student learning mostly trend stationary as well? I don't know, but it certainly isn't difference stationary, and naive extrapolations of the rates of improvement we see during the school year are unlikely to hold if summer vacation is slashed. In fact, if students are anything like Struggalia, we might not see very much improvement at all...