Consider your purpose for writing the prompt. Are you trying to meet a standard, or are you simply performing a pre-reading activity? Is the prompt for creative, narrative, expository or persuasive writing? This will help you determine exactly what kind of prompt you should write.
Brainstorm a list of life experiences, thought-provoking quotations, short story ideas, first sentences or controversial topics that students might write about to connect to your purpose. If using controversial topics, steer clear of anything highly divisive that parents or students may find objectionable, such as abortion.
Write a phrase to start the prompt. Examples include "Agree or disagree with the following statement," "Write about a time when...," "Explain how you would..." or "Write a story beginning with the following sentence." These statements can help fire your imagination if you are stuck.
Write a brief prompt. Students may be confused by wordy prompts. You should be able to summarize the main idea of your prompt in a sentence or two.
Write any supporting questions, if necessary, to make sure your students write enough. For instance, if your prompt is, "Write about a time when you felt like an outsider," a student may give a one-sentence reply: "I felt like an outsider on the first day of school." To avoid this, you may wish to write questions such as, "What happened? Why did this make you feel excluded? Did you ever stop feeling like an outsider?"
Write at least one more prompt so students who do not understand or cannot relate to the first prompt have another option.
Review your prompts to make sure they are age-appropriate, respectful of students' privacy and inclusive. Your prompt should not rely on students having a certain level of income, shared religious beliefs or a specific life experience.
Search for potential first sentences for a short story or novel and write around them. Possibilities include open-ended statements, like "On my tenth birthday, my mother told me . . ." or lines of dialogue, such as "Where were you last night?" It's fine if the sentence you use is cliched; if you have a good idea based on it, you can retool the first sentence later.
Brainstorm a list of major life events, such as "birth," "first day of school," "first date," "graduation," "marriage" and "divorce." Choose your favorite event from the list and brainstorm a number of ways that this event could go wrong, or a list of obstacles a character might face trying to obtain that event. Use your favorite obstacle as the basis for a story.
Write a mash-up of two of your favorite stories or genres. Fantasy author Naomi Novik has confessed that the protagonist of her "Temeraire" novels, Will Laurence, was loosely based on Jack Aubrey, the protagonist of "Master and Commander," but adding dragons to the novels made them into something more than a Patrick O'Brian pastiche. You may find it helpful to re-imagine your favorite novel or short story as a science fiction novel, a fantasy or a romance.
Answer a prompt as a fictional character. This may lead to you creating a new character, or may give you a new perspective on one of your current characters.
Look at magazine or newspaper photographs as an inspiration for a prompt. You may wish to write the story of what is happening in the picture, or a biography of one of the people in the photograph.