Apparently the old adage is true: everything you need to know in life you learned in kindergarten. Well, at least that's true if you had a good teacher. A new study by Harvard, Northwestern and Berkley economists looks at life outcomes, rather than test scores, of students who participated in Tennessee's Project STAR experiment (mostly designed to study class size).

The study finds that while high test scores in kindergarten don't translate into high test scores later in a student's education, they do translate into better life outcomes. Students who did well in kindergarten were more likely to go to college and more likely to earn more. By the time they were 27, students in the cohort made about $100 a year more for every percentile they moved on the test-score distribution over the course of their kindergarten year.

What factor mattered most? Class size in kindergarten did matter: Students in smaller classes (13 to 17 students) did better than those in larger classes (22 to 25 students). Peer effects and socioeconomics also mattered. But nothing mattered as much as the quality of teacher. The authors conclude that a standout kindergarten teacher is worth about $320,000 a year. That amounts to the additional money a class of students could expect to earn over their careers.