What are great books for a 10th grader to read?

It depends to a large extent on the student. Students have a wide range of interests and of reading skills. Students often enjoy stories featuring people of their own age, and thus Lord of the Flies, To Kill a Mockingbird, or The Catcher in the Rye are often included on reading lists.
Students interested in science can enjoy H. G. Wells, Jules Verne, and works such as 1984 or Brave New World. For students in the United States, reading works set in other cultures such as the Arabian Nights, Things Fall Apart, or even the travel and animal-collecting stories of Gerald Durrell can open up new worlds. Traditional epics, such as the Homeric poems and Beowulf, seem also to be popular, though they work best for the more advanced readers in this age group. Many collections of myth, legends, and fairy tales can also be of interest; the Norse sagas will appeal to those students who have enjoyed recent movies and comics based on them. Shorter fables and fairy tales might work well for less advanced students.
History books, especially local histories or stories of Native American culture, can also spark interesting discussions.