One creative writing idea that students seem to enjoy a lot is to tell them to think of a story or a tale they know well and write a different version of it. They usually come up with crazy, unexpected endings!
Another creative writing activity that is fun to do is a chain story. Students sit in a circle and are given an initial sentence: If I cheat on an exam…, for instance, and they must write a story. After one minute they exchange papers with the person on their right. And continue the story. The activity finishes until everyone gets back their own paper. Students then volunteer to read their stories.