Interesting...I generally use Classic; did not realize you couldn't get to a public journal from 2.0. I spent a couple minutes trying to see how, but couldn't find it in 2.0...maybe I'm missing it.
At any rate, the above is correct. Go to Profile, then down to Preferred Theme, change it to Classic, then click save. On the screen it takes you to next, look at the third entry from the bottom; you should be able to click on a link that takes you through making your journal public. When you do that, copy the link that it gives you toward the top and give it to your teacher.
"If you drop an egg, you don't say, 'Oh, shoot' and drop the other 11, do you?"
-Source unknown, but obviously brilliant
Reached goal 4/16/2010...but kind of afraid to look these days