I use this in my College Composition class, but it can be used for middle school, high school, home-school, adult education, etc.
The start of the presentation explains free-writing. It also discusses Peter Elbow, the benefits of free-writing, and the expectations.
Following that are 56 Free-writing topics.
I suggest five minutes timed for each topic at the start of the class.
These include images, engaging prompts, songs, quotes, descriptive writing, etc.
At the end of the 40 days, I find my students are more comfortable with writing and write more efficiently when generating ideas.