I don't know if you stammer/stutter whn you are alone, I know I sometimes do and sometimes don't...so I do. What I do to combat this is focus less on the exact words I'm going to say and instead think of brief thoughts in little sections, these brief thoughts may be the main idea of your presentation and instead focus on your breathing, easy and even and DO NOT FOCUS on the people who are listening/watching you. It's like when someone else gives a presentation, you don't give your utmost attention and diligence, you kind of listen, you're in and out. Keep that in mind, no one is examining your every move or every sound you make, people are more inclined to themselves and so just act like you're practicing the presentations. Sometimes i use my stuttering as sort of a quirky kind of thing, long pauses may lead to laughter, stumbling over your words is no different. Dont get too serious, keep it light and kind hearted. Good luck mah manz, but I'm sure you're gonna do great. Also what I love to think about is what is will be like once the presentation is over, pure bliss! Once again good luck and mainly, fuck everyone else, the only one actually grading your shit is the teacher and it may be helpful to make them aware of your speech disfluencies.