In an interview with Cynthia Dewi Oka back in 2013, poet Andrea Walls talked about the soap epitaphs she started seeing on the backs of car windows around Camden, New Jersey. They struck her as poems that illustrated "the way that we vanish and the way we say we were here vanishes too." This week, write something using an impermanent medium, paying particular consideration to the medium itself. Write a poem about the ocean on a sandy beach, or about your childhood in chalk on the sidewalk. Write a poem for your partner in the condensation on the bathroom mirror. But most importantly, don't write it on paper. It will vanish, but that doesn't mean you have to forget it.