If we ask a vague question, such as, 'What is poetry?' we expect a vague answer, such as, 'Poetry is the music of words,' or 'Poetry is the linguistic correction of disorder.'
That's a wonderful change that's taken place, and so most poetry today is published, if not directly by the person, certainly by the enterprise of the poet himself, working with his friends.
I am grateful for - though I can't keep up with - the flood of articles, theses, and textbooks that mean to share insight concerning the nature of poetry.
Besides the actual reading in class of many poems, I would suggest you do two things: first, while teaching everything you can and keeping free of it, teach that poetry is a mode of discourse that differs from logical exposition.
Even if you walk exactly the same route each time - as with a sonnet - the events along the route cannot be imagined to be the same from day to day, as the poet's health, sight, his anticipations, moods, fears, thoughts cannot be the same.