Maryanne Wolf is more cautious. “By no means do we know fully whether or not [tablets] are the best medium for children’s learning at all,” she says. “But we’re in a digital age, and what is imperative is that we learn what works best for different children, in what amounts, at what ages.” Students need to develop what are called “deep reading” skills—inference, analogical and deductive thinking—and that requires time and focus. She worries that a medium that insists on rapid-fire processing and partial attention may not be ideal. At the same time, she believes that well-designed learning apps can bridge that gap. “I think our 21st-century brain is going to need both kinds of cognitive processes: a biliterate brain with faster processing, but that knows when to think and read and focus deeply,” she says.