Teaching adolescents Writing to Inform and Persuade

I am going to be teaching a course on writing to inform and persuade. (basically an expository writing class with some specific focus)

What lessons have you found particularly useful. Which have been a waste of time and energy? What, if any, books or articles on writing have you found meaningful?

What is the most persuasive thing you have read? What is the best description you have read?

What is the worst thing a teacher can do to you in a class like that?

What advice would you give me?

Below, in parentheses, are responses to questions/comments received elsewhere.

(some details: either 10 or 13 students in the class (my choice on if the last three don't get in), one hour per week in the evening, 14 sessions over 17 weeks, broad mix of 12-17 year olds, all home schoolers)

(By persuasive I mean things that try to convince you of a particular point of view or belief, whether political, ethical, religious, or opinion.

A review of a movie, book, or piece of software can do that. An advertisement can do that.

Sometimes a book might persuade one to care more or something of that sort. I think of a book that 'persuades' me to stay up reading as a different sor of issue.)

(Mostly, they know each other and have been in a classroom environment before. Several of them have had me in one sort of class or another, though not really in this framework.

I am not giving out grades, but I will be giving out evaluations, based on their growth as writers and on their writing rather than comparative to each other.

I suspect that getting them to speak up will be harder, initially, than making them wait would be!)