This is one of my favorite "reworking content" activities, but it's the sort which can go awry quickly if students get off target. I highly recommend a required "rough draft" / mini-conference step should you choose to use this one. That being said, I really like the final products most of the time.
Here's the general idea - students will use a famous American poem as their template, rewriting it with new content as specified by you. The primary goal is to force the sort of "manipulation of knowledge" stuff discussed in the Post-Reading Intro; the process of reworking information into a very specific new format promotes understanding and retention (although it sounds so boring when you put it that way!) Students must not only think through the information far more than theyd like in order to do this decently, they must also identify main ideas and relevant supporting details, etc. so as to fit them into the new format effectively. The secondary goal is to have students wrestling with word choice, meter, pacing, structure, etc. - critical ELA / Communication skills.
Why not just have them write poems or (gods forbid!) "raps" of their own to explain the content? That's up to you, of course, but I personally loathe letting them write content-driven poetry from scratch. Mostly this is because it usually sucks, but I also find that the "limits" imposed by modeling the work after existing pieces promote a wider variety of skills, as well as forcing some element of quality control. Bonus: they become familiar with at least one classic American poem along the way.
You should prepare a few examples using content you've already covered - something you just can't review often enough. If that's just not gonna happen, at least save good ones from year to year. You might also look at the master of this, Weird Al Yankovic - although he has limited content goals, whereas we're all about the substance, baby.
In case you have no idea what a "Weird Al" is, he does parody music and videos of hit songs. I'm too old to keep up with the new stuff, but here's a Nirvana music video that was popular in the early 1990's. Obviously you're welcome to watch the whole thing, but at least give it through the first chorus (that's about 90 seconds in for you old timers.) before going on to Weird Al's reworking of it:
And here's the Weird Al version. Note how he maintains the basic format, feel, structure, and rhyme scheme of the original work while changing the content and thus the message:
This is a great assignment - but lay the groundwork well, teacher-type, or you'll be reading some serious doo-doo, I assure you. And don't forget that mandatory "rough draft" / mini-conference stage.