Kings Fifth, Brendan Voyage, Stowaway, Commodore Perry in the Land of the Shogun, Endurance is good though it takes some getting into (my husband watched the movie with the boys and enjoyed it, as well), have you tried Googlelittrips.org or combed through the book finder? Also Ambleside Online has some suggestions. Material World is a good book, though maybe more for research than reading independently. Missionay biographies are good resources for learning about cultures. Taking an interest that the student has and expounding on it can yield some fascinating geographical research and findings. Just ask me anything about the Gobi Desert and it all came from my 7yo getting a Chinese Dwarf hamster last week! I’ll keep thinking!