Sometimes you just have to talk to your child. What a novel idea.
See if you can set aside one half hour a week to try this. Say it's going to be Thursdays just before dinner. One of you shuffles your child off to a quiet room to discuss... nothing.
First your child will be suspicious. Did I do something wrong? Am I being punished? Of course not. Just for a chat, and if you like it, we'll do it again.
Once there, stay away from the weather and what each of you did today. That will get boring real soon. Instead focus on how the week went or how one feels about the day. Who is your most interesting teacher? What school activities would you like to take part in? Like that.
Notice that these questions do not ask for yes or no answers. These are called open-ended questions. They are designed to make someone say more than Uh huh or Nope. They will get your child to open up a little. The worst thing you can do is let he or she get away with yup or nah.
Having your child open up is vital for their protection too. I recently found a valuable site called PBS Parents that discusses talking with your child, and deals with youths of different ages. You should really have a look.
If you can get a little twinkle in the eye then the next step is to have them set a half hour aside to write about their week, or whatever they like.
If all that works, they're almost ready to write short stories.