To learn more
about the Columbian Exchange, check out these sites and sources:
http://daphne.palomar.edu/scrout/colexc.htm
http://en.wikipedia.org/wiki/Columbian_Exchange
http://www.calstatela.edu/faculty/jtomask/471/colexchng.htm
http://weuropeanhistory.suite101.com/article.cfm/ColumbianExchange