When teaching Argumentative Essays it could be very useful for students to focus on frequently used words and phrases that are specific to argumentative essays. Here are the links to a websites that contain these lexical items.http://owl.english.purdue.edu/handouts/general/gl_argpers.html
When dealing with persuasive writing, it will be helpful for you to outline the argument by premises and conclusions. By looking at the structure of the argument, it is easy to spot logical error.
"Universities are full of knowledge. The freshmen bring a little in, and the seniors take none away, and knowledge accumulates."
--Harvard President A. L. Lowell
Premise 1: Freshmen bring a little (knowledge) in
Premise 2:Seniors take none away
Premise 3:Knowledge accumulates
Conclusion: Universities are full of knowledge
(Here, the conclusion of one argument is used as a premise in another. This is very common.)
"Even though there may be a deceiver of some sort, very powerful and very tricky, who bends all his efforts to keep me perpetually deceived, there can be no slightest doubt that I exist, since he deceives me; and let him deceive me as much as he will, he can never make me be nothing as long as I think I am something. Thus, after having thought well on this matter, and after examining all things with care, I must finally conclude and maintain that this proposition: I am, I exist, is necessarily true every time that I pronounce it or conceive it in my mind."
-- Ren? Descartes, Meditations
Argument 1 Premise 1: To be deceived ... I must exist
Conclusion of Argument 1 When I think that I exist I cannot be
Argument 2 Premise 1: deceived about that
Conclusion:I am, I exist, is necessarily true ...