The size of a child’s vocabulary upon entering kindergarten is one of the strongest predictors of how successful that student will be in reading comprehension several years later, says Anne Fernald, a professor of human biology and director of the Language Learning Lab at Stanford. An expert on infant language development, she joined Stanford Graduate School of Education Dean Dan Schwartz and Senior Lecturer Denise Pope on this episode of School’s In to discuss how children learn vocabulary and what parents can do to help their children succeed.

Listen to the full episode at the link below and find more episodes at Stanford Radio. School’s In airs weekends on SiriusXM Insight channel 121.

Interview Highlights

Watching TV isn’t enough

TV doesn't care about you out there; it's indifferent to the viewer. Talking with a child involves adjusting to a very immature learner who's starting at zero, basically, and rapidly changing from month to month. You’re making your speech appropriate to what you know that child is interested in. You're following the gaze of the child and seeing what he or she is looking at, and talking, naming that…. And then upping the ante as the child starts talking back. They’re pulling, and if you're there and open to that and ready to feed them brain nutrition – language ­– then it's a wonderful duo. But it's interesting that it's not common at all in many cultures.

How vocabulary predicts reading comprehension

Babies can only learn to understand and speak language through interactions with caregivers and others at home. For the first four or five years of life, the school is not involved. And yet, the size of their vocabulary when they show up at school at four or five is tested. They haven't set foot in school yet at all, but the size of their vocabulary is one of the strongest predictors of how successful they will be in reading comprehension four years later when they get to the fourth grade.

How to build vocabulary

You can spend those first few years with your child building that foundation because you are the source of that: You can only learn words that you are hearing from other people. And by the way, in our studies and others, we look at what is the effect of overheard speech, and [whether] just hearing lots of language going on is helpful…. There are those who say, “Well, look, on the playground, all the time, he's hearing all this stimulating speech from other children.” The problem is other children aren't taking that child’s perspective, aren't using the words they know he knows, aren't following his interests; they're on their own trajectory. So speech from other kids is also not related to vocabulary growth.