The book Holes by Louis Sachar is generally considered to be appropriate for middle school students, typically around grades 5 to 8. Its reading level is often assessed to be around a 4th to 6th grade level, making it accessible to younger readers while still engaging for older teens.
The use of straightforward language, coupled with a gripping plot, helps to maintain the attention of a varied audience. Additionally, the themes of friendship, perseverance, and redemption resonate well with readers of this age group, allowing it to be both enjoyable and thought-provoking.