FORTUNE — So, Mom and Dad, you don’t like your kids demanding to know “why” after every answer? And, teachers, do those relentless questions from the front row drive you crazy as you attempt to cover today’s state-mandated lesson plan? You’ll hate Paul Harris’ controversial new book, Trusting What You’re Told. In it, the Harvard professor of education challenges entrenched notions of cognitive development. Rather than seeing children as “scientists in the crib” who learn through observation, Harris argues that they’re nascent anthropologists who learn best from the “testimony” of “informants.” That’s how we find out the world is round, for example. Harris’ research cuts against much of what happens in today’s classrooms; instead, it demands verbally acute teachers — one might imagine Mister Rogers as the paragon — as well as patient parents. Fortune contributor David A. Kaplan recently spoke to Harris about how listening to others can be more important than hands-on learning.
I thought a key part of education is getting children to read — to get them to be little researchers.
The portrait of cognitive development I’m trying to undermine is not that of the child as a kind of scholar or bibliophile, but the image you get from people like Rousseau or Piaget or Montessori, where the child is a hands-on experimenter. That vision is too narrow.
Most early grades prize the hands-on, right?
If you think about the Montessori classroom, the child is given some bricks to assemble, and the child sees the bricks can be placed in some kind of serial order from shortest to tallest. While that strategy may well work for observable regularities in the world, it’s not a strategy when evidence isn’t readily available.
Where do children get their information?
Teachers, parents, experts. They’ll learn to trust some more than others. But I’m not just offering a portrait of young children. We’re all stuck with the fact that the amount of knowledge we can gather for ourselves is minuscule compared with the amount we gain by listening to experts, whether it’s how to invest or what to do if we have a cancer.
Why is it important to distinguish how children learn?
In preschool there’s not very much emphasis on choosing teachers who are good at having a dialogue with children. At school, you see a sharp decline in the quality of dialogue. At home, children ask more questions. They have more sustained exchanges with a parent.
Isn’t that out of necessity — at home it’s a lower “student-teacher” ratio?
Of course in some sense it’s dictated by practicalities. But teachers are mostly selected for their ability to be “nurturers” rather than for verbal or intellectual abilities.
Does questioning become less important?
No. It extends to elementary school and even high school. I don’t know about your children, but mine complain that often when they’ve asked questions in school, there’s not been time to deal with them. It’s the curriculum that dictates the pace of learning.
This story is from the July 12, 2012 issue of Fortune.