At the outset, I need to be clear about two things. (1) I don't know much about poetry, and even less about the poetic literature. Of the great 18th and 19th century English poets I am almost completely ignorant; and (2) I don't care.
I have always approached teaching English as a discipline of skills (which is why I prefer the name "Language Arts.") I have no special brief for literature over all the other modes of writing. I want my students to build their toolkits as readers and writers, and I don't care much where and how they acquire their tools, so long as they work well. For instance, if you want to borrow from math and use a Venn diagram to teach metaphors, why not?
So from poetry, I'm not as interested in the sheer art of poetry as the craft elements which can contribute to the student's general literacy. To begin with, one of the greatest values poetry brings to writing in general is precision and economy. In a short piece of writing, such as ultra-short story, a song lyric or a poem, every word must be working hard to perform its task and contribute to the entire effect of the piece. Hence the challenge and fun of Hemingway's six word novels, for example:
For sale: Baby shoes, never wornSo one approach might be to pack and unpack some especially pithy poems or portions thereof.
Playing pool was just an excuse.
I finally realized he loved guacamole.
Said I'd never marry again. Damn.
My secret discovered. Plane ticket purchased.
Two lives, one day. Never again.
He woke to an empty house.
Lost her sweater. Kept his jacket.
Heaven can't. Hell won't. Now what?
Wrong day for the scenic route.
Found true love, married someone else.
Hey Stranger, coffee's on, sit awhile.
"So much depends/upon a red wheelbarrow"
"Do not go gentle into that good night"
"I took the one less traveled by/And that has made all the difference"
"I have measured my life out with coffee spoons"
"I held a Jewel in my fingers--/And went to sleep"
"yes is a pleasant country"
(Note - Shakespeare is not useful for this exercise, because he generally seems to unpack his own metaphors and images. As the experienced reader and playgoer will testify, Shakespeare always strives for utmost clarity, and eschews enigma.)
So for example, the "unpacked" version "I have measured my life out with coffee spoons" might be, "My life has become so dull and routine, that each day is like another as each mound of coffee in the spoon is like another." Or, "Another day, another pot of coffee, nothing happening but drinking cups of coffee, day after day." Or, "I keep spooning out my days like coffee until they will all be gone, like the coffee in the jar." Or some combination of all of these. None of these interpretations are all right or all wrong, but they are all contained, all "packed" into those few words, like a huge database packed into a Zip file.
The final exercise might be to take a short story or passage and condense it down into stages. First an abridged version of itself, then perhaps a list of salient points or events, then a poem, then a critical line or two of the poem. This task is best done collaboratively. What you end up with might be banal: Hamlet condensed might be: "Revenge is folly." But that's not important--what matters is what the student experiences or learns in the process of winnowing down the large to the small.
And that, ultimately, is the lesson of poetry -- that which is large contained, encompassed, suggested in that which is small.