Students who learn more in kindergarten earn more as adults and are more successful overall, according to a new study.

Kids who progressed during their kindergarten year from earning an average score on a particular standardized test to scoring in the 60th percentile can expect to make about $1,000 more a year at age 27 than students whose scores stay average.

Add in other advantages, like smaller kindergarten class size, and the earnings boost goes up to $2,000 a year.

"Kindergarten interventions matter a great deal for long-term outcomes," said study researcher John Friedman, a Harvard University economist. "For instance, being in a smaller class for two years increases the probability of attending college by 2 percent."

The researchers looked at 12,000 children in about 80 schools across Tennessee who were randomly placed in classrooms of different sizes. When the cohort of students hit age 30, the researchers followed up to determine how successful the individuals have been.

The findings revealed that kindergarten matters ⎯ a lot. Students of kindergarten teachers with above-average experience earn $900 more in annual wages than students of teachers with less experience than average. Being in a class of 15 students instead of a class of 22 increased students' chances of attending college, especially for children who were disadvantaged, Friedman said.

Children whose test scores improved to the 60th percentile were also less likely to become single parents, more likely to own a home by age 28, and more likely to save for retirement earlier in their work lives.

"A study like this highlights how important kindergarten and other early education is for students, and for their later-life outcomes, not just in thinking about a single student, but also in thinking about inequality across students," Friedman said in a video put out by the National Science Foundation, which funded the study. "I think our study will make policymakers focus on how the decisions that they make impact not just schools today but also the long-run futures of our children."

The researchers presented the study at an academic conference in Cambridge, Mass.