Common Core Standards
Grade 4
Reading RL.4.10
By the end of the year, read and comprehend literature, including stories, dramas, and poetry, in the grades 4-5 text complexity band proficiently, with scaffolding as needed at the high end of the range.
The difference between fourth and fifth graders is the support fourth graders will need when reading a book that is potentially difficult for them but not for a fifth grader. Other than that, if the student hits all the other standards, they should be good.