At issue is how to bridge the infamous "word gap," the fact that affluent children hear far more words before they start school than low-income kids. "Yes, you can talk more, but what is the quality of your language?" said Caitlin Molina, executive director of the Providence Talks program. [...] coaches provide strategies. Brown University has begun an independent study to track whether the improvement was enough to make a difference once those children begin kindergarten. In New York, Mendelsohn is studying a program that coaches parents at the pediatrician's office, while they're waiting for routine well-baby visits. The coaches use a prop — a free book or toy — to explain strategies for conversation and engagement, and record the parent trying.