In Chapter Three in Concepts in Composition we are introduced to two revision approaches: internal and external(80). Donald Murray encourages the internal approach to revision. Which would you teach in your classroom? Which is taught in most composition classrooms? Are there benefits or drawbacks in emphasizing both?
In most of my experiences of school prior to college (and even in college at times) external revision is the style of revision that was predominantly taught. The downfall of teaching only this style of revision is obvious in its onesidedness; it's limited and functions only as a mechanical focus lacking completely in any sort of content adjustment. Seeing as though either taught solely as the only means of revision would not allow for a complete method of revision, a hybrid blend of the two would be a better choice for a composition course. However, the one adjustment I would make would be to focus a little bit more on the internal revision (as I believe content is more valuable then stylistic errors) which tends to be the harder of the two styles to impart on students. The benefits of having a duel approach comes down to the fact that a balanced methodology typically is, well... balanced. Students are able to learn multiple avenues of revision in which they get to focus on the portions that they find they are lacking in the most. Not all students will be poor mechanically for instance and the hybridity would allow for them to move on to other potential erroneous aspects within their drafts. The only possible issue to come from teaching both would be in that students may gravitate to the easier of the two (external) and completely disregard content revision.