Early books have simple plots and some repetition. Some books use repeating episodes or complex plots organized chronologically. As books become more challenging, more interpretation will be needed. Easier books provide pictures to support the reader in gaining meaning and solving words. Picture support gradually decreases as you move up the gradient of difficulty.
More challenging texts use multisyllable words and a wider range vocabulary to express meaning.
The gradient begins with very simple sentences and goes on to include longer, more complex sentences with embedded clauses. Literary features such as flashbacks or metaphors may introduce a challenge. Complexity gradually increases to ideas and topics that children would not experience in everyday lives. Some sophisticated themes require maturity for understanding and may mean that a book is more challenging, even if other factors make it seem easy. An experienced primary teacher, Gay Su Pinnell is a Professor in the School of Teaching and Learning of The Ohio State University College of Education.