It's a 15 marker, so you're aiming for about 900 words in 40 minutes thereabouts. Usually contains an orientation, complication, climax (sometimes) and a resolution. Although, you can start off your story with a complication. Try and stick to one setting, maybe two if you really have to. Avoid several characters. Preferably 1 or 2, 3 at maximum. Steer clear of obvious cliched story lines (I woke up and I realised I belonged, girl at high school mean girls style). Ask or email your teacher for a list of really common cliched story lines. Obviously, make sure it relates somehow to belonging (or not belonging). Don't throw the word belonging in every sentence, once or twice is acceptable. Use paragraphs, the usual. Don't forget to practice too, get some past papers and try linking the stimuli in with your chosen story line.