One from waaay back in the archives this time.

Write a story where the moon is falling out of its orbit (your reasons may vary).  What will the people of Earth do to solve the problem?

(My answer to this was “prop it up on really long stilts and build a city below it because in its shadow is the only safe place to hide from the radiation now that the atmosphere has been destroyed by the entry process”.  I think I was 12 or 13 at the time.)