If I Were Teaching a Course...

...in Creative Writing, I would give (at least) these four assignments:

1) Write a sonnet with complete meter and a traditional rhyme scheme. Try to use some sonnet conventions.
2) Write a free-verse poem, with no rhyme, which is to some degree about a physical, existing location.
3) Write a short prose piece (at least three pages) including dialogue between 4+ characters.
4) Write a short prose piece that does not contain any dialogue or adverbs, and contains no more than one adjective per paragraph (average). Use perfectly formal language: no contractions, no fragments, no comma splices or run-on sentences.

I would also offer as an optional 'challenge' the writing of a sestina or a villianelle. Haiku sequences would also be a good idea.

I was thinking about this last night. Now, why would I assign these particular tasks?

Well...
I truly think that learning to write at least half-decent poetry is a major step toward writing excellent prose. You can write good prose without being able to write poetry, and you can likely get toward excellent without it, but I can assure you that being able to write poetry hugely improves your ability in prose. Hence two poetry assignments.
However, being able to write decent free-verse poetry (which most poets these days choose to write) requires, in my opinion, a stronger sense of form poetry. Sonnets are a good place to learn form, but I think haikus might give you certain skills as well. If you only write free-verse, I think you have a harder time learning rhythm. If you have something which forces a rhythm upon you (ie. metre), you get a sense of that rhythm better. It's a similar idea to learning the rules before you break them. So in order to write good free-verse, you need to be able to write at least half-decent form poetry. Or, at least, it helps.
Oh, and if free verse gets too abstract, it sucks majorly. So that's why it's about something concrete.
OK, the dialogue piece. Why? Well, most people struggle with dialogue. This will help with that. Also, you'll eventually need to learn how to manage multi-person conversations (as Jon can attest to), and this challenge should equip you for it.
Finally, the last prose. Why the ban on modifiers? Because modifiers are cheap ways of communicating. Verbs and nouns are more powerful, so use these whenever possible. Use adverbs when only an adverb can convey what you want to say. This is a rule most modern "literary" authors use. It does improve the elegance of your prose...and if you want to break this rule, you still have to know it. So write without adverbs and with few adjectives for a while, and once your communication skills have improved, you can let the modifiers back in.
Why the formal language? Again, you want to get a grip on structure and perfect communication. Once you've mastered this, then you can venture into breaking the rules.

Now, the caveats.

This is my own career. If you look at some of the stuff I was writing free-verse in my earlier university career, it lacks the structure, the pacing, and the design that the later free-verse has. This is because I hadn't sufficiently learned how to use this. Some of my improvement came from writing more formed verse. The thing is, though, that's not all that helped. Reading my peers' free-verse and reading 'professional' free verse. Also, Wayde Compton's 49th Parallel Psalm. That uses awesome line-breaks, which are crucial to writing poetry that doesn't suck badly. If you have a copy of Lake Effect 4, I'd say you should look at the free verse in that, and I'll particularly direct you to "south-end headphone seraphim" by Adam Wray, "black dog on repeat" by Anna Maxymiw, and "without consent" by Angela Hickman. Any will do, though. Look at their line breaks and rhythms. That is how one can write good free verse. I have also written some newer free verse of which I might be more inclined to brag; the earlier stuff is mediocre, as I said.

Other people, however, learned differently. Some started with free verse and have never ventured seriously into form, unless required to for an assignment. I think Anna Maxymiw took this course. Some began with prose and worked into poetry by force...and a good thing, too, because their poetry rocks (Sean Seal, in the anthology). But I still maintain that my assignments are good, because they work different muscle groups, and regardless of the order you prefer, I don't think anyone will argue that these skills don't reinforce each other.

That is all for now.