Children are more inclined to like poetry than to dislike it--unless we cram it down their throats or try to teach them the "parts" (imagery, rhyme scheme, meter, etc.). So, until students are in junior high, they should be exposed to poetry--even a lot of it--but not force-fed it.
One way that works is to read them poems occasionally. They should be encouraged to verbalize whether they like or dislike what they've heard, and possibly why (although with poetry this is difficult--even for me, some poetry speaks to my soul and other poetry makes no sense whatsoever). Don't push the issue or try to change the child's mind or open their eyes to something they've missed if it discourages their viewpoint though. After all, more understanding can but often doesn't beget more enjoyment when you're dealing with children and poetry.
Don't spend a lot of time on poetry that doesn't rhyme or doesn't have a clear rhythm. To children, the rhyme and the rhythm ARE poetry, not the beautiful words or images or the brevity or any of those other things that can make words into poems for adults. When children develop the ability to abstract (about junior high age), they have a much easier time grasping and enjoying the beauty and complexity of all kinds of poetry--but they still like the fun stuff.
Don't
force them to write poetry. You don't have to be able to write verse to be able to write well. However, if they do show interest in writing poetry, encourage it. One fun way to get kids writing poetry is by having them read a simple poem (Mother Goose rhymes are great for this) or sing a children's song and then write a parody of it (change some or all of the words, but keep the general 'feel' the same). It doesn't have to be a humorous parody, although that is fun. For small children, play games with rhyming words.
I recommend using the works of these poets when teaching K-8 students: Shel Silverstein, Dr. Seuss, and Robert Frost. Everything I've read of X.J. Kennedy is also fantastic, but I haven't read as much of his (so, for example, I don't know if he writes anything that isn't appropriate for children).
You really only need two books to teach poetry to kids:
X.J. and Dorothy Kennedy's "Knock at a Star" (great poems for kids by the great poets, and lessons about poetry, too), and the anthology, edited by Scott Elledge,
"Wider than the Sky: Poems to Grow Up With." Both of these are filled with poems that happen to appeal to children, written by truly great poets (Shakespeare, W.H. Auden, Emily Dickinson, Christina Rossetti, the Brownings, etc.). Neither contain questionable material by my standards (your standards might be different, so always pre-read things you give your children).
The only caveat in choosing children's poetry is the same as choosing any materials for your children: read it before you give it.
Some poetry anthologies (like the "Kids Pick the Funniest Poems" series, edited by Bruce Lansky) are full of poems that are fine structurally but are morally ambiguous at best, focusing on bodily functions, making your family disappear, fighting with siblings (and tricking them or winning in other ways), belittling parents and other adults, whining about education (which kids don't find bothersome until someone tells them it's supposed to be), etc. While it may be normal for kids to laugh about potty humor, that doesn't make it appropriate subject matter for school. (And I NEVER like my children to read things that, even in jest, are anti-family. Just because we have fights with our siblings doesn't mean we should glorify it!). The trouble with this in poetry is that poetry is "sticky"--it is an extremely effective way of getting a message into your mind for a long time (which is why advertisers use jingles). You want to be aware of what message you're planting in your children's heads. "Fun" does not necessarily equate with "good," morally or artistically.
(Some parents dislike Shel Silverstein, feeling he has crossed these lines, but I enjoy his work and find it strikes a nice balance between acknowledging children's experiences and feelings (yes, they ARE sometimes mad at their parents) without glorifying it.)
Mostly, poetry is supposed to be joyful and fun--don't make it tedious and dreadful by the way you teach it (which is, unfortunately, what usually happens in public schools!).
