I'm very glad you decided to stay in the class! I have an issue particularly with blocking in classroom settings. I have always avoided taking classes that require a lot of speaking in front of the whole class. I took a 400 level economics class that was structured similar to a graduate business or law course. It was reliant on the old cold-calling, forum style. There were 75 or so people in it. This kind of thing used to be my worst nightmare. However, the biggest thing is confidence. I dressed well, sat in the front, and took anything that came at me, sometimes with success, sometimes not. Take it from a guy who used to let stuttering control his life. Don't let it influence your decisions.