When You Reach Me's is made up of tantalizingly brief chapters with clever titles. They're a treat for any level reader – especially those with short attention spans.
The larger concepts in the book, though, take a while to digest. The book's discussion of time travel in Chapter 31, for example, might require an afternoon of head scratching to really comprehend. While you may read this one pretty quickly, you'll be thinking about When You Reach Me long after you put the book down.
Further note: this book is heavily "intertextual." That means When You Reach Me often refers to other books and depends upon those other books to help it make meaning. A familiarity with Madeline L'Engle's A Wrinkle in Time, the book Miranda carries around with her, will help you better understand When You Reach Me. We think A Wrinkle in Time would be a great buddy book to read alongside this one.