Rising 6th graders:
Percy Jackson and the Olympians:  The Lightning Thief by Rick Riordan, available everywhere

Rising 7th graders:
Tom Sawyer, by Mark Twain, available everywhere

Rising 8th graders:
Any one of the first 4 books in the Sackett series by Louis L.Amour:

     Sackett's Land,

      To the Far Blue Mountains,

     *The Warrior's Path (*preferred), or

     Jubal Sackett. 

All tell of early settlers in America.  Available at The Book Knack in Rock Hill in limited supplies or online at Barnes & Noble (www.bn.com) in paperback or ebook format.  Several copies available through public library by request. Students who read The Warrior's Path will take a test.