The Core Knowledge Blog

An intriguing new study suggests that while the effects of a high quality preschool program seem to fade out after a few years, they may re-emerge spectacularly later in life.  The study by Harvard economist Raj Chetty and several colleagues is written up in the New York Times under the attention-grabbing headline “The Case for $320,000 Kindergarten Teachers.”  The large-scale study looked at the life outcomes of 12,000 children who had been part of an education experiment in Tennessee in the 1980s.

“Just as in other studies, the Tennessee experiment found that some teachers were able to help students learn vastly more than other teachers. And just as in other studies, the effect largely disappeared by junior high, based on test scores. Yet when Mr. Chetty and his colleagues took another look at the students in adulthood, they discovered that the legacy of kindergarten had re-emerged. Students who had learned much more in kindergarten were more likely to go to college than students with otherwise similar backgrounds. Students who learned more were also less likely to become single parents. As adults, they were more likely to be saving for retirement. Perhaps most striking, they were earning more.”

The economists don’t pretend to know the exact causes. “But it’s not hard to come up with plausible guesses,” Leonhardt notes.  ”Good early education can impart skills that last a lifetime — patience, discipline, manners, perseverance. The tests that 5-year-olds take may pick up these skills, even if later multiple-choice tests do not.”

It’s a fascinating study and thesis, but consider this is not a case of something new under the sun.  The well-known Perry Preschool study showed similar effects albeit with a much smaller sample size.   The lives of 128 African-Americans were studied beginning with their preschool years in Michigan in the mid-1960s.  By the time they reached middle age, those who attended a high-quality preschool program earned more, were more likely to be employed, had fewer arrests, and were more likely to have graduated high school than those who did not.

The new Tennessee study shows similar effects, including higher earnings.  “All else equal,” writes the Times’ David Leonhardt, they were making about an extra $100 a year at age 27 for every percentile they had moved up the test-score distribution over the course of kindergarten.”

It’s the all else equal part that always undoes me.  All else is seldom equal given the limitless differences in inputs, interests and experience among even those with superficially similar lives.  Indeed, it strains the imagination to think that even the best kindergarten teacher can implant the traits of patience, discipline, manners, and perseverance so firmly into a five-year-old  that they persist for life.  It seems much more likely that children with those characteristics are more likely to thrive in an environment that recognizes and nourishes them.  Drop a seed into fertile ground and it will sprout.  Drop the same seed into dry sand and nothing will happen.  Coaxing that seed to sprout is clearly the first step, not the only one. This doesn’t diminish one’s appreciation for the skills of a great teacher–creating a positive, nurturing classroom environment is clearly a prerequisite for all other accomplishments.  But trying to point to a teacher as the prime mover shows a dogged and even simplistic determination to find the One True Factor upon which all others pivot.  It is entirely likely that noncognitive traits are more malleable than general intelligence, and more responsive to early intervention.  But common sense would suggest those traits still need to be reinforced and nurtured throughout childhood, by the majority of adults with whom a child comes in contact. 

One other question the study raises:  if perseverance, self-control and curiosity are the keys to life success, then why does improving those traits not lead to a measurable improvement in standardized test scores  at every step of a child’s academic career? 

The study has yet to be peer reviewed, and will no doubt be closely examined. Meanwhile, the idea of paying even the best early childhood educators north of a quarter of a million dollars a year is clearly fanciful.  Even if the study is unimpeachable, it’s impossible to know who these life-changing educators will be.  We can only identify them in retrospect, if at all.