In high school we had to submit a weekly paper. Some weeks we were given prompts or a subject and others just the style of writing required. This is a format I use with our oldest to help introduce and improve his writing. This set of high school writing prompts from Language Arts Classroom over at Teachers Pay Teachers, includes over 30 prompts. You can use them as bell ringers, inclusion in journals, or as a way to end class. The topics are divided into argumentative, expository, and narrative prompts.