Here's why:
* Target Audience: The book is primarily aimed at readers aged 10-14, which aligns with the middle-grade and young adult demographics.
* Themes and Content: The story deals with common themes of middle school life, such as fitting in, bullying, navigating friendships, and finding your place. The content is appropriate for younger readers, without being overly simplistic.
* Writing Style: The book is written in a clear, engaging style that is easy for younger readers to follow, but still holds enough depth to appeal to older readers.
While it's mainly classified as middle-grade, some consider it to fall under the young adult category due to its slightly more mature themes and characters than some middle-grade books. Ultimately, the genre is a matter of perspective and individual preference.