Improving education - one lesson at a time - Mini Sagas

I am teaching high school students writing. I try to facilitate learning rather than prescribe activities, but it has some difficulties. I think the problems persist for many reasons and I do not judge them for treating my classes as an interlude. However, I think I would be doing them an injustice by not exerting a little pressure. We do a lot of collaborative writing and there are three girls who work well together. One girl is not very good at English, but she is writing very good stories. Tonight, the story they wrote together needed some work. When I gave it back, they tore it up. I wasn't angry, but I said I was disappointed because I thought they wanted to improve. I hope that making the class less bound by rules and tasks that need to be complete, I can help open up the class and the students imagination and allow them to develop some intrinsic motivation to improve. I must show that I am interested, but I cannot let them 'get away' with less than an improvement in their work.