“Turns out one of the most effective ingredients for these early child care programs is interacting with the child. What I mean by interacting is a give-and-take. The term that’s used by the child development specialist is scaffolding, like building a sculpture — in this case of a human being. Staying with the child, taking the child to the next step, challenging the child. In that sense it’s very personalized education.

“It’s very time-intensive education, but it’s education that stays with the child. It also has another effect, which is that it engages, through the enhanced stimulation of the child, the parent. Parents themselves visit the center, so that there is also stimulation of the parent-child relationship that lasts long after the program itself is formally ended at age 5.”

James Heckman, Professor of Economics at the University of Chicago, “How Investing in Preschool Beats the Stock Market, Hands Down,” NPR, December 12, 2016