From Harvard Magazine:
Attending a quality kindergarten that provides experienced teachers and small classes yields measurable benefits, such as higher salaries in adulthood. That finding, in a study led by professor of economics Raj Chetty, has caused a stir by demonstrating that even the earliest school experiences can affect students’ subsequent quality of life, exerting more influence than researchers previously thought. Chetty and his colleagues, including Harvard Kennedy School associate professor of public policy John Friedman, examined data from Project STAR, a study of nearly 12,000 Tennessee kindergartners conducted in the mid 1980s. The children were randomly assigned to their teachers and to classes that were small (about 15 students) or large (around 24 students) and subsequently tracked (see “The Case for Smaller Classes,” May-June 1999, page 34).
Previous analyses of Project STAR showed that children in small classes, and those with the best teachers, scored higher on standardized tests in the primary grades. But by the time those students reached junior high, the advantage vanished, a phenomenon known as “fade out.” “By the time they’re in seventh or eighth grade, the kids in a better kindergarten class are not doing any better on tests than the kids in not-so-good classes,” Chetty says. Conventional wisdom held that the boost from a good kindergarten ebbed with time. “What’s really surprising about our study,” Chetty says, “is that [the advantage] comes back in adulthood.” When he and his colleagues looked at what the students—now in their early thirties—recently earned, they found that those who had the best kindergarten teachers make more money.
More here.