I call this the "Reverse Purpose" chart. Instead of asking students to think of a writing purpose and then begin their writing task, I give them the opportunity to get inspired by a question that leads them to a writing purpose. This is matched with 4th grade social studies topics in NYC, but can easily adapt to your social studies or nonfiction focus.
This PPT includes questions related to immigration, U.S. Government, and the founding of America. This is also a great way to embed choice when you have a limited number of texts or resources to offer your students but still want them to have some say over their research and writing.