The following is an effective exercise from page 39 of Noah Lukeman's The First Five Pages which I put into practice recently. It can be done individually, in small groups, with original pieces, or even with a variety of passages from any literature. However, I personally like it with original writing--it demonstrates to the students another meaningful way to edit their work beyond scanning for obvious spelling or punctuation errors.
These can be done the progression shown or you will still gain something from doing any one of them. I think they can be particularly effective with the middle school student as this audience is painfully aware of the parts of the speech and often question why do we have to study them? These types of exercises demonstrate that each piece of language (an adjective, an adverb) can enable as well as disable our writing. Lukeman notes that just because you know how to use a particular brush stroke doesn't mean you'd necessarily smear it on a particular painting...or just because we can add parts and accessories to a car doesn't mean that we do.
Step 1. Remove every adjective and adverb from the first page of your manuscript and list them separately. How man are there? Now read the first page aloud (without the adjectives or adverbs). How does it read? Faster? Are your major ideas still conveyed without them?
Step 2. Look at your list of removed adjectives and adverbs. How many are commonplace or cliche? Cross out each one and beside it write down a less expected replacement. Now go back to your first page and insert your replacements. Read it aloud. How does it read now?
Step 3. Remove every noun and verb from the first page of your manuscript and list them separately. How many are commonplace or cliche? Cross out each one and beside it write down a less expected replacement. Now go back to your first page and insert your replacements. Read it aloud. How does it read now?
Step 4. Finally rewrite the first page completely, abiding by the rule that you cannot use any adjectives or adverbs. Watch how this forces you to come up with nouns and verbs that have to stand on their own, without any support from adjectives and adverbs. What are the differences? Can any of these be incorporated?