Dunno if anyone cares, but thought I'd share how it works down here. Our school year starts in February and ends in November, whereas you guys start a new grade midway through the year....I guess it is so that you are on vacation during the summer season. Depending on what type of school you goto, depends on the arrangement.
Private Schools: For the most part, they have their "Formal" (prom) about mid way through 12th grade. Don't ask me why....I think its ridiculous. They have this big event then show up at school 3 days later. Crazy.
They then have their graduation at the end of the year. I guess followed by a party.
Public School: This is me. Most public schools have their graduation on the Thursday of their last week. They then go straight from the graduation to their "Formal", followed by the post-party which is usually huge and on somebody's property who owns acreage. One person from our grade volunteered to host all 200 of us. Was great.
The next day (Friday) is mostly to recover, and then Saturday you travel to a place called "Surfers Paradise" to engage in a week of celebrations called "Schoolies Week". Basically thousands of drunk 17 year olds running amuck (legal drinking age here is 18).
It was a great time, although I would have loved to experience it the way the movies depict the US final days of high school.