This exercise helps students learn about poetic style by challenging them to write poetry in different styles. To make stylistic differences most obvious, students write about the same topic in four different ways (casual, formal, depressing, whimsical). Students write poems of 4-10 lines in groups, and then they share their writings with each other. Nearly any topic may be chosen, but the topic should be a bit unusual; I like to use the tragic tale of Millie, a fictional family dog that dies suddenly by falling down an open well, to generate interest. The exercise is a fun activity that challenges students to think about many aspects of poetry (diction, line breaks, metaphor, punctuation) as they write their versions of the poem.
Gleason, Dan, "Millie Dies in Style: Crafting Poems in Four Poetic Styles" (2012). Understanding Poetry. 2.