There is no set form and meter in this poem, but there's definitely a science to the way it's structured—even if that science is to make the poem seem as if it has no structure.
Let's back up: The poem is supposed to be fulfilling an assignment for a college English class. But it includes the assignment in the poem, so right away we know this is no average assignment, and no lazy college student. This poem is set up to be more.
Yet throughout the poem, we get hints that the poem is written in a stream of consciousness style. "Stream of consciousness" means writing down the first thing that comes to mind, and just rolling with it. Things like asking questions (line 6) and describing the journey home from class in detail (11-14), support this style. It's casual, and seems as if it's flowing straight from the speaker's head.
Whether or not the poem was actually written in stream of consciousness, or just made to seem that way, the casual style instantly allows the reader to connect with the speaker. This isn't a hoity-toity poem with lots of difficult metaphors and parts that are hard to get through. It's more like we're given a glimpse into the speaker's mind.
We get so far inside his mind, in fact, that sometimes we nearly get lost. Take, for example:
I feel and see and hear, Harlem, I hear you:
hear you, hear me--we two--you, me, talk on this page.
(I hear New York, too.) Me—who? (18-20)
Who did what with the when now? These lines are kind of confusing to read, but that's because they're supposed to be. In a poem that grapples with identity—what it means to be black, white, or human—the speaker uses form to communicate the confusion that can result from such a line of questioning. This is not a speaker who has everything figured out. He's someone who is searching for answers. The stream of consciousness of lines like these helps to get that idea across.
As a result, they also make our speaker more relatable. As he attempts to make a connection across the page with his instructor, he makes a connection with the reader. Lucky for us, that's pretty appropriate for this poem, which is all about engagement and all not about separation—like the kind of distance you might feel when trudging through a super-tough, complex poem. Nope. This speaker wants us to know that, "As I learn from you, / I guess you learn from me—" (37-38). For that to happen, there must be a personal connection at work, which is made through the poem's conversational, open form.
How does the form accomplish this? Well, it's mainly with word choice. Take, for example, the phrase: "I guess." This isn't a long poem, but we see that phrase three times: in lines 17, 21, and 38. What's up with that? Was Hughes really just guessing? Likely not. Instead, this phrase is like a verbal tic (like, "you know?" or "anyways") that gets repeated in spoken conversation. So, reading this poem is a lot like being in a personal convo.
That's not to say that poetic form just gets chucked out the window, though. Oh, no. Like any good conversation, this poem keeps us at the edge of our seat, waiting to hear what comes next. One way it does that is through enjambment. By ending lines mid-sentence, the reader is brought along with some inertia into the next line. For example, take those same lines:
As I learn from you,
I guess you learn from me— (37-38)
After line 37, we're left hanging. "As I learn from you…" What? Tell us! Ah, the suspense is killing! So, we head to line 38 with a question in the back of our mind, much like the speaker has burning questions—about race and society—in the back of his mind, and in the lines of this poem!