Poetry / How to really determine the theme of a poem? [2]

Can someone help me figure out how to determine the theme of a poem? I have to write on the theme of three different poems. I know what I think they are about, but that is never what my instructor thinks they are about.

How can I figure this out? Thank you.

Poetry / I have to write a poem for our midterm exam... [6]

Evidently, I just don't "get it." My professor wants us to write three poems for our midterm exam. I have never written a poem in my life and would not have the first clue as to what to write about, how long the poems should be, or how to make them rhyme.