This is based on factors like:
* Vocabulary: The books use a fairly simple vocabulary, suitable for children in this age range.
* Sentence structure: Sentences are generally straightforward and easy to understand.
* Themes and content: While the books have fantasy elements, they are generally age-appropriate and deal with themes that resonate with children in this age group.
* Length and complexity: The books are generally of a length and complexity suitable for this age range, although some of the later books may be slightly more challenging.
However, it's important to note that reading age is a general guideline.
* Individual children will vary in their reading abilities. Some children may be ready for Charlie Bone books earlier, while others may need a bit more time.
* The specific book within the series can also influence reading age. Earlier books in the series are generally easier than later ones.
Ultimately, the best way to determine if a Charlie Bone book is suitable for a child is to read a sample chapter or two. This will give you a good sense of the vocabulary, sentence structure, and overall complexity of the book.