That's why I like free verse. I leave the meter to the high school teachers. Our state standards do require knowledge of sound devices by 8th grade though. Consonance, assonance, alliteration, repetition...all those little tricks to appeal to the Dr. Seuss "in a box with a fox" part of your brain.
Now, before you start thinking that I am a rap superstar masquerading as a middle school teacher, let me assure you that I am not. My knowledge of rap is old school and the Legendary Roots Crew. My Adidas spend most of their time on a closet shelf. But my English teacher ears intuitively know the difference between someone with flow and a suckah M.C. I think.
Let rap help you teach sound devices. Please make sure that you check out the lyrics first. If you don't have time for that, may I recommend "Run's House"? Try it for free here: http://www.youtube.com/watch?v=0xMJZHrG_94
Many teens are familiar with at least Rev. Run of rap pioneers Run-DMC as he recently had a successful MTV reality series that showcased his family life. You can check that out here: http://www.mtv.com/shows/runs_house/season_6/series.jhtml
I have created a worksheet that includes the lyrics of "Run's House" as well as definitions of the sound devices and instructions for identifying them on the handout. It can get a little messy, and fascinating. Whatever your feelings about rap, it gets the job done when you need to teach sound devices, and the poems in your literature book leave you hanging.