This is a rough grade level/classification of books. However, if you are looking for specific grade/age level this guide may be helpful.

{Preschool and Under}
Books geared for Newborns on up to five years-old.

{Kindergarten}
Books geared for six year-olds.

{First Grade}
Books geared for seven year-olds.

{Second Grade}
Books geared for eight year-olds.

{Third Grade}
Books geared for nine year-olds.

{Middle School}
Books geared for ten to twelve year-olds.

{Junior high}
Books geared for thirteen to fourteen year-olds.