Give kids freedom to exercise their wildest imaginary thoughts by asking them to write the most exciting adventure they can come up with. Have each creative middle schooler put himself in the story as the main character. Invite them to be as inventive as possible. Don't restrict students with any rules or requirements to give them complete creative freedom.
For a writing project with a tangible outcome, have your students create their own books. Each kid can tailor the book to their own interests and skills; they can include photos or original artwork to support the story. When the books are finished, bind them for a collectible. At the end of the project, have a showcase or create a class library so the students can show off their creations.
Middle school kids can get tired of ordinary, boring writing assignments because they are not entertaining. For a project that will fool them into having fun, have them create their own stories but leave a few words out. Each student can write a story, leaving empty spaces for some verbs, nouns, adverbs and adjectives. The project is a fun way to help them learn the parts of speech. When they are all finished, photocopy each form, pass them around and have other students fill them out. Kids can also read them aloud so everyone can laugh at the results.
Use creative writing prompts to get your students going. Choose open-ended ones, like, "I believe..." or less traditional prompts, like, "The asteroid was about to hit the earth and..." By providing an unexpectedly informal subject to write about, you can give students a fun way to express their creative sides and practice writing. You can do a whole list of prompts for short responses or have them pick one and write a more lengthy response. If your students are up for it, they can even write their own prompts and trade them with other classmates for a more interactive project.