I would suggest practicing a lot. Something that helped me was putting periods on my notes so I knew a firm spot to take a breath and not trip over my words. If you want you can also mention your stutter to the teacher and they might make special consideration in the marking. A few of my later high school teachers did this and it really helped not being marked down because of my stutter. The teachers shouldn't get annoyed at you because it is a legitimate medical condition and if they belittle you for it you can take the issue over their heads (it very rarely comes to this) Good luck, just don't put pressure on yourself. You're just there to talk like everyone else. I would also suggest practicing in front of other people because I know I rarely stutter on my own but I stutter all the time with people in the room.