Continuing the discussion from Books for Kids: Grade 1 & 2:
Books receive a Lexile text measure from a software tool called the Lexile Analyzer - it describes the book's reading demand or difficulty. It uses quantitative methods, based on individual words and sentence lengths to arrive at the score. Typical Lexile score ranges by grades (class or standards) are:
Lexile score is a valuable piece of information about the difficulty of a text. It is an excellent starting point for a student’s book selection. But it is important to note that book’s Lexile measure does not consider factors such as age-appropriateness, interest, and prior knowledge.
So parents need to use this score in conjunction with their own parameters for books selection.
Refer to http://www.lexile.com/ & http://en.wikipedia.org/wiki/Lexile for any more information regarding the same.
In sites like amazon.com for many books lexile measure in mentioned in Product Details section.
Lexile score is widely used in U.S. both for books and understanding kid’s ability. I hope we also have some scientific and informed ways of books selection in schools and outside in India.