As cliche as it sounds, just imagine the audience aren't there. Trust me, most likely no ones listening other than your teacher. They're all too worried about their turns. Just make sure you practice, so you'll know what to say. Rehearse your lines in front of a mirror, your dog or a friend. That's what I do.
We do Socratic seminars every lesson unit and that's worst than presentations. You don't know what questions are going to be asked and you have to formulate your answer on the spot. I am not here for that at all. I always try to think about what can I say, and once I do it wont make sense 'cause the discussion already moved on to another topic...
I hate public speaking.