Purpose and Thesis
Writers choose from a variety of purposes for writing. They may write to expresstheir thoughts in a personal letter, to explain concepts in a physics class, to explore ideas in a philosophy class, or to argue a point in a political science class.
Once they have their purpose in mind (and an audience for whom they are writing), writers may more clearly formulate their thesis. The thesis, claim, or main idea of an essay is related to the purpose. It is the sentence or sentences that fulfill the purpose and that state the exact point of the essay.
For example, if a writer wants to argue that high schools should strengthen foreign language training, her thesis sentence might be as follows:
"Because Americans are so culturally isolated, we need a national policy that supports increased foreign language instruction in elementary and secondary schools."