Read examples of persuasive writing. Political speeches, letters to the editor and pamphlets are all excellent examples of this type of writing. If you can find a point-counterpoint article, this would be an ideal example.
Divide the examples into important parts of a persuasive essay: the argument, the facts used to support the argument and the refutations of the opposite viewpoints. These are all important aspects that will help students to write convincing and effective persuasive essays.
Analyze each of the examples: ask students why some are more effective than others and ask them to evaluate which authors back up their statements with facts and reports and which make unsubstantiated claims.
Ask students to each pick a topic that can produce differences in opinion. These should be topics that can be debated with factual support, such as "Violent video games lead to an increase in violence" or "Schools should not use standardized tests to evaluate student progress." Give students the option to support a stance or oppose it.
Have the students conduct research, either at home or by arranging a trip to the library during class. Require them to find at least three sources to use in a short piece of persuasive writing, either in newspapers, magazines or online.
Set a due date, and on that day, have the students present their persuasive essays to the class. You can also require them to turn a copy in at the end of class.