From the title ("Introduction to Poetry") to the speaker (a teacher) this poem screams education. The speaker is bummed that his students seem to be unable to approach poems the way he wants them to. While the title and initial setting seem to fit with this theme of education, other aspects, word choice for example, and action (waterskiing? torture?), seem to contradict this theme. What's up Billy? Do you want to teach us something or not? Would you rather we learn about poetry or should we just chase rodents and waterski our lives away? In "Introduction to Poetry," the theme of education boils down to this: what is the difference between studying the arts (poetry specifically) in a traditional, book learnin' sense, and true understanding and appreciation of the arts?
Studying art and literature is a waste of students' time because the knowledge and understanding gained is not applicable in the "real world."
The whole point here is that poetry can't be understood. It's a mystery. So there's no real way to learn it in the first place.