You will take a long sea voyage with the inventor of the sextant in Jean Lee Latham's Carry On, Mr. Bowditch. The list of good stories of the American frontier is long. The compelling story of a child alone in the wilderness in Milly Howard's Captive Treasure provides insight into that period of history from the Indians' point of view, while books like the well-known Laura Ingalls Wilder books show the settler's life on the frontier. Dawn Watkin's Zoli series and A Father's Promise by Donna Hess will help your children acquire a sense of history that gives meaning to the World War II names, dates, and places from your Heritage Studies books. The list of historical fiction books is long and varied.
Fanciful tales offer another part of the reading menu.
A universal truth lies under the metaphor of a good fantasy story. When the story is well written, the truth teaches itself. E. B. White's Charlotte's Web teaches more about the meaning of friendship than an explicit realistic story could ever do. In Jeri Massi's Bracken Trilogy, right always triumphs over wrong and leaves the reader with a sense of how good right is. Modern realism can support Christian values directly or indirectly.