A bonus: examples of problematic thesis or purpose statements for the natural sciences, the social sciences, and the humanities
I've collected these from professor/friends in Chemistry, History, and Literature. Go over these: you've a lot to learn from them about what NOT to do when writing a thesis. These examples of thesis or purpose statements are taken from actual student papers / lab reports (though some have been slightly modified). Read in combination with the document above.
Click examples of strong vs weak thesis statements for SCIENCES AND HUMANITIES.docx link to view the file.