The Lion, the Witch, and the Wardrobe is an incredible novel by C.S. Lewis. I read this book in 5th grade with my class. It is about four children who make their way to a far away land called Narnia; there they become prisoners to an evil witch who calls herself the Queen of Narnia; huge sacrifices are made and war is brought up between the four children and the witch.
This story can be read in a 5th grade classroom; I would use this to have discussions on sacrifice, character analysis, and theme during the reading. You could also use this to do a compare and contrast between the four siblings, and describe the relationship between the four and how they work together. You can also have the students write about what it means to be a hero and what makes Aslan a hero.