Breakfast... hmm, usually one of porridge, cereal, a crumpet with peanut butter, piece of toast or one of those Fruity Bix bars. The last three were invariably eaten in the car on the way to school, or during early morning Maths Ext classes.
I did pretty well in the HSC, but it probably would have helped if I'd eaten breakfast a) properly and b) not on the move... maybe I wouldn't have zonked out at around 9:30am every morning.
During the HSC, all my exams except for German were in the morning. If it was a 3 hr exam, I had 3 Weetbix for breakfast (so I didn't get hungry during the exam). If it was 2 hrs I had 2- 2 1/2, coz I could eat sooner.