(This post is part of my "What Age are you Writing For?" series. You can find the introduction and list of age ranges here.)
When you are writing children's books, it is very important to keep in mind the reading level of the audience. Young kids are just learning how to read and may still have books read to them or need very, very simple vocabulary in order to understand a book on their own. Older children will want to be treated like adults and will be bored by books that dumb down the writing. The length of the book is also a factor. Because of how quickly reading level changes at this age, children’s books are often sorted by very narrow age ranges.
board books: 0-2
picture books: 0-5
early reader/learning-to-read: 3-5
early reader/beginner chapter books: 6-9
Picture Books
These are your typical bedtime stories. The language used can have a wide vocabulary and complex sentences, since adults will be reading these books aloud to children. However, the word count is usually about 400-900 words, so the plots and simple and fast paced. Any subplots that exist tend to be restricted to the illustrations.
A picture book will tend to be 32 pages long. Picture books should usually have a page count that can be divided by 8, to prepare them for an offset printer. (Their paper and machines are designed to print and fold and bind books in groups of 8 pages.) The full color, high cost illustrated pages mean that other printing methods are usually impractical. Hence the 32 pages, but the flexible word counts.
Picture books will obviously include images, but they can also include pop ups or other interactive elements. Sometimes picture books are illustrated by the author, but sometimes the publisher will hire an illustrator.
Board Books
Board books are similar to picture books, but are printed on cardboard rather than paper. They are intended to be something the child interacts with directly, turning durable pages, touching textures, or counting objects.
Page counts for board books tend to be even shorter than picture books, since the pages themselves are so thick. 10-15 pages is typical. (Because they aren't paper pages, the dividing by 8 rule doesn't apply.)
There may be a single word on the page in a board book, something simple enough for the child to memorize after being read the book a few times.
Topics for board books may be things like colors or numbers or animals, rather than a plotline.
Learn-to-Read books
A book meant for children still learning to read often has 30-60 pages and a word count of 300-1500. Similar to picture books, they may have 1-2 simple sentences per page, but, unlike picture books, the sentences will often be very repetitive and similar lengths (a major no-no in other forms of writing, but a definite plus in this one). The vocabulary will often be sight words or phonetically-spelled words with 1-2 syllables. The words used should be repeated often to allow children practice recognizing common words quickly.
The few characters present in these simple tales will often be different genders to allow for the range of pronouns. Character names will all be phonetic like Sam or Pat, not Charlotte or John.
There often isn't much of a story in these books. The focus instead should be putting together words of similar difficulties and creating logical sentences to help kids understand and use the words they are reading. Each character may perform the same action as the child practices those words. There also may be simple (black-and-white) illustrations to provide context clues.
Chapter Books
Chapter books can be much longer than the other children's books I've mentioned so far. These books will tend to have 50-100 pages. They are meant for children to read completely on their own, without any adult assistance. Due to the varied reading levels of the children these books are aimed at (ages 6-9), chapter books can range from 4,000-30,000 words. These books will often be labeled by strict grade levels, ages, and even reading level standards to help parents, kids, and librarians find the right book for the right child.
Due to the higher word counts and reduce number of illustrations, chapter books will have a complete plotline and may even introduce subplots. They should have conflict and a clear resolution. The characters will range in age from about 8-12 years old.
These books are about showing children what books can be like now that they can read, and include things like dialogue, idioms, metaphors. The vocabulary in a chapter book can be more complex, though it is best to avoid too many difficult or unusual words on a single page. The sentences can also be more complex now, with multiple clauses, varied structures and lengths. Fiction or nonfiction, they should be enjoyable, exciting, funny, or cool.
Not the age range you're writing for? Check out Middle Grade.