My co-teacher is stirring sugar into a pitcher of hot water. Our students, ages 4 and 5, stand around the table, watching the sugar intently. “It’s dissolving!” one student cries out. “What does that mean—dissolving?” my co-teacher probes. Another child raises his hand. “It means, like, disappearing, or disintegrating.”

My students are the children of doctors, lawyers, teachers, and other professionals, and have been hearing words like “dissolve” and “disintegrate” since they were babies. The extensive vocabularies of children like them have been causing quite a stir among researchers and policymakers for two decades now, since the publication of astudy finding that children of professionals might hear 45 million words uttered before the age of 4, and that children on welfare might hear just 13 million. This early difference in exposure to vocabulary, the study claims, can shape how well kids do in school later on.

Betty Hart and Todd Risley, then child psychologists at the University of Kansas, published those findings in 1995. They later called this disparity the “word gap,” and their work on it has been cited in more than 5,000 academic publications, inspired dozens of news articles, and garnered eager, vocal advocates, chief among them Hillary Clinton. These advocates see campaigns to encourage parents to talk more with their young children as a first step toward closing the achievement gap. But some experts are pushing back, saying that efforts to close the word gap, while well-intentioned, might represent just another attempt at a quick fix to solve complex social and economic problems.

[For more of this story, written by Amy Rothschild, go to http://www.theatlantic.com/edu...the-word-gap/479448/]