As Gardner mentioned, Getting the Knack by Stephen Dunning and William Stafford is a really good resource with lesson plans and ideas for poetry writing assignments. I have used their found poem exercise many times, always to great success. I don’t care how old students are, they always enjoy using scissors and glue. These poems can be surprisingly good and surprisingly challenging to write, too. What I like about the book is that it presents poetry as a craft, and the exercises enable all students to become poets. This book has been in my professional development collection for years. It is a good addition to a middle grades or secondary high school English teacher’s teaching and writing toolbox.
Gardner didn’t mention this book, probably because it is out of print, but Joseph I. Tsujimoto’s Teaching Poetry Writing to Adolescents is another handy book to have in your collection, and you can find it through used book sellers at Amazon (follow the book link). It’s a shame this resource was allowed to go out of print! The strength of Tsujimoto’s work is in the variety of poetry writing assignments (18) and the student models. In this NCTE article from Classroom Notes Plus (October 2002), Rosemary Laughlin writes glowingly of Tsujimoto’s models, and this article written by Betsey Coleman in VOYA (PDF) also praises his work highly, and both say pretty much what I would say.
I have also used Inside Out: Strategies for Teaching Writing by Dan Kirby and Tom Liner (in an earlier edition not including third author Dawn Latta Kirby, but instead with writer Ruth Vinz). The focus in this book is not strictly on poetry, but on teaching writing in general, including research writing and expository writing.
Lisa Huff has a a new series of posts on teaching poetry at her blog, and the Reflective Teacher’s Literature Pocket Mod could easily be focused on just poetry. Finally, I posted my poetry unit idea to the UbD Educators wiki, and I would love feedback.