Language learning is a magical thing, but parents who want to focus on building their child's vocabulary would do well to keep J.K. Rowling and Lemony Snicket in rotation. As it turns out, kids' books use more rare words than adult TV shows, which means that — duh — literature is a fantastic vehicle for language.
But just what are rare words?
Researchers use a "standard frequency count of English" to rank words according to their rarity. The 10 most common words on the American Heritage Word List are: the, be, and, of a, in, to, have, to, it. As you move down the line, the words remain familiar, for native and fluent speakers, but you can feel yourself begin to drift away from the norm with words like "vibrate" (No. 5,000), "shrimp" (No. 9,000), and "amplifier" (No. 16,0000). Researchers define a rare word "as one with a rank lower than 10,000; roughly a word that is outside the vocabulary of a fourth to sixth grader."
So just how many rare words do children's books contain? Out of every 1,000 words in a work of kidlit, 30.9 will be rare. Although that number is lower than comic books (53.5), adult books (52.7), and newspapers (68.3), children's books contain more rare words than prime-time shows for adults (22.7) and children (20.2) alike, and even more than college graduates' conversational speech (17.3).
In fact, children's books have about the same concentration of rare words as cartoons (30.8) and expert witness testimony (28.4). It's also interesting to note that the average rank of words in kidlit is 627, which is higher than all forms of TV entertainment and college grads' conversations.
Parents don't necessarily need to cram a bunch of too-difficult books down their children's necks, but it's probably a good idea to keep this information in mind when you're deciding what your child should and should not read. Researchers Anne E. Cunningham and Keith E. Stanovich write:
For vocabulary growth to occur after the middle grades, children must be exposed to words that are rare by this definition. Again, it is print that provides many more such word-learning opportunities. Children’s books have 50 percent more rare words in them than does adult prime-time television and the conversation of college graduates. Popular magazines have roughly three times as many opportunities for new word learning as does prime time television and adult conversation.
The two go on to note that, although children may well pick up new words from TV and conversation, printed materials are the real wellsprings of vocabulary information.