Choose a story starter, then discuss and share your ideas with someone else.
You can write it in any style - a poem, cartoon strip, play, dialogue and story, something else, .. or completely freestyle.
You can spread this task over two days by having one day to discuss and write (a short piece), followed by the second day being sharing your story or part of it with the class or someone at home.
Or, you can do two mini writing challenges, one on each day - choose, discuss, write and share (these can be short pieces).
You could give yourself a 10/15/20 minute writing limit! Or challenge yourself to include pictures too!
The fun here is being free to write, create and share your own imaginative story!