Percy Jackson and the Olympians: The Lightning Thief
This is one of my favorite books! Although I didn't discover this book until the ninth grade, it is a grade book for younger children. It is about a boy who discovers he is the son of Poseidon and the adventures he goes through to find Zeus' lightning bolt.
Percy is a great kid for students to read about. He has dyslexia and ADHD, which I think a lot of children can relate to. This book is great for relectuant readers, not only because of how amazing it is, but also because it is the first book in a series. Get a child hooked on a series and you've created a reader! Afterwards, you can watch the movie (even though it's not the best).