Children’s literature can be categorized in a number of ways. One way would be according to the genre. Another way would be, according to the intended age of the reader.
In general, it is easy to distinguish between books written for younger and those for older children. Books for younger children use large print, simple language and very many illustrations. Books for older children have more complex language and plot, smaller print and fewer illustrations.
Age Category #1: Picture books (0-5 years)
Books created for pre-readers, where illustrations play a critical role in narration of the story. Many of these books are lullabies and nursery rhymes. Stories are simple, print is large and a variety of interesting formats are often used like board books, pop-ups, audio books, lift-the-flaps etc. (More complex, advanced versions of picture books are available for children up to 10years.)
Age Category #2: Early reader books (5–7 years)
These easy-to-read books are designed to help children just starting to read on their own. These books are 32-64 pages long and have 2-5 sentences per page. Sometimes the story is divided into short chapters. They have eye-catching illustration on almost every page and plenty of dialogue and action. Amelia Bedelia books by Peggy Parish and Frog and Toad books by Arnold Lobel.
Age Category #3: Transition books (7– 9 years)
Sometimes called “early chapter books”, these books begin where early reader books end. With smaller trim size, 2-3 page chapters, fewer illustration these books are ideal to prepare children for chapter books. Encyclopedia Brown by Donald J Sobol.
Age Category #4: Short chapter books (7–10 years)
Although the plot is more complex than transition books, there is still a lot of dialogue and action. Short paragraphs, 3-4 page chapters, 45-60 page length – keeps it simple for young readers who are ready to move on from transition books.
Age Category #5: Longer chapter books (9-12 years)
This is the age at which many children turn into confident, avid readers who are ready and willing to be challenged by more advanced writing. There are many wildly popular book series targeted specifically at this age group like “The wimpy Kid” and “Magic Tree House”. The length of the books is 100-150 pages and the stories are more complex with sub-plots and secondary characters.
Age Category #6: Young-adult books (12–18 years)
The books in this genre focus mainly on the worries and conflicts faced by the modern teenager. They are usually 150-200 pages long, although some very successful books like Eragon and Harry Potter have twice the length. The books have several major characters, although there is almost always one main protagonist.
It has to be kept in mind the dividing line between age categories is hardly watertight and books near the borderline may fall into either category. And in the end, everything depends on the readers, their readiness and their reading abilities.