Is it long or short? You could be asking about a distance. You could be asking about time. You could be asking about a story.
Whether something is long or short depends on the context and on a person’s perspective.
Today, search your surroundings, your memory and your imagination for things that you–or someone–could consider to be both long and short. Write about one of them, or several.
When you have finished writing, give your work a title and write the date on it. Illustrate the page if you like.