I like to use the students' own work as the material to teach revising.  It's easy to do so if there is access to a multimedia projection system and/or a computer workstation at the teacher's desk. 

At the beginning of class, I ask for volunteers to submit one paragraph of their essay-in-progress for the class to view and use in a group revision exercise.  My students type their work on a computer, so I either hand out computer disks for them to copy their work, or they hand me their disks on which they have saved their essay.  Using the computer at the teacher's workstation,  I open the essay on a student disk in our word processing program.  Then, I turn on the overhead projection equipment connected to the computer and project the student's paragraph on the screen.  From the teacher's computer, I can demonstrate revision techniques using the student's work.  A few of the techniques I like to show include:

	How to identify the topic sentence; [Isolate the first sentence and ask the students if it summarizes the main idea. If not, ask students to suggest ways to improve it.]
	How to place each sentence on one line to determine unity in ideas; [Just hit the Enter key at the end of each sentence; these extra line returns are easily removed when editing is done, and they help students to view each sentence as a separate unit.  Together, we determine if the sentence contributes to the main idea of the paragraph.]
	How to categorize or group ideas in a paragraph;
	How to determine if there is sufficient support for the main idea; [After grouping the ideas in the paragraph, ask students if these ideas fully explain the topic sentence. Ask them what they might add to further clarify.]
	How to use the spell and grammar checker utility and how to set the options.

After we have revised the paragraph on the screen, I usually ask the student writer if he/she would like me to save our revised work on the disk.  They are sometimes surprised, but invariably say "yes, please."  I assure them that they may use the revised paragraph in their essay.  While volunteers might be few and reluctant at the beginning of a semester, I usually have many eager volunteers after students see the results of this activity!