Write a story about time travel;
You're going to do the following:
Create a character;
Go back to a time period of your choosing;
They're allowed to bring their phone with 1 app, which one will they bring?
Write about the consequences of bringing their phone and app to the past.
Done?
It's unlikely you're actually done with your story. Check it for grammatical mistakes or nuances. Try to expand your story as well.