Thesis Statement
Topic + Theme + Impact = Thesis
http://historydayexpert.blogspot.com/2011/01/writing-successful-thesis-statement.html
http://www.chicagohistoryfair.org/images/stories/pdfs/2_how_to_write_a_thesis_statement_easy.pdf
http://www.washingtonhistory.org/files/library/history-day-thesis.pdf
http://nhddelaware.wordpress.com/2010/03/03/thesis-statements/