Here's one of our favorite writing worksheets. Why does this one work so well? Because we give students the framework/guideline for them to start writing.
If you've ever asked students, of just about any age, to simply "write a story," the standard reply you'll receive is, "I don't know what to write about."
This worksheet hopefully will take care of that problem! By using WH questions to guide the student, it might give them some ideas to start writing.