I used this poem for an interview when asked to teach a twenty minute lesson because it engages readers. The poem's topic--overcoming a personal problem--is interesting to students and observers alike. The poem's simple style and accessible metaphor make for easy and open discussions. Students feel little pressure of "failing" while talking about this poem.
This download includes the poem by Portia Nelson, and includes the instructions/questions for using this with students. If not using it for an interview, the poem works as an excellent supplement to any unit on identity or facing personal struggles.
I always have success with this short poem--students really like it.
Please check out my lesson plans for "Five Ways to Kill a Man"; because of the similarities in style, the poems make great companion pieces.