This SAC will probably be the hardest for me all year, I absolutely loathe speaking in front of the class.
Do all schools do an oral SAC ?
I think all schools do unless you do vcal or IB etc.
Yeah I used to hate speaking in front of the class, but then with the conglomeration of a few tactics I managed to overcome it and now it doesn't bother me at all.
The most important aspects
for me were:
Confidence, confidence, confidence. Just convince yourself that you are going to do well. If you've picked a topic that you like or can speak passionately about, then convincing yourself should be easy.
Convincing yourself is really the key there, if you panic now and say that you don't like speaking in front of the class then that mindframe will rub off on you when you actually present. Even what you just typed has the power to impact on the way you feel about presenting. If this sounds like crap... I used to hate maths in about year 8-9, I thought it was a useless, boring subject. Then I conducted a thought experiment on myself... I kept telling myself that maths is interesting, useful and enjoyable until that became reality. I know it seems a bit weird but, well... look at the subjects I am doing this year

Also, your depth of knowledge is paramount... don't just learn what you are going to talk about, get some insight into further/related issues/topics. It will help you formulate your speech and make it flow nicely.