Kathy Hirsh-Pasek, a professor of psychology at Temple University and an author of “Einstein Never Used Flashcards,” has studied use of e-books and other electronics by parents and children and said the lesson of all the studies is that what really matters is the back-and-forth relationship.

“Look for something that’s active, engaging, meaningful and interactive,” she said. “The bad news and the good news is, you can’t outsource learning to an app, but the good news is there’s really room for us, two minutes of time, five minutes of time, look into our children’s eyes, have the conversation.”

Perri Klass