Globally, 77,000 students from 400 schools in 148 countries take the transnational certificate that is an alternative to the HSC. "A bit of banter between the groups," says Alexandria Smith, left, with Annabelle McMahon. Credit:Janie Barrett The worldwide nature of the examinations means that students must wait 24 hours before discussing the tests with anyone. It is a longer wait than most for Australian pupils, who are some of the first in the world to hear the examiner call "pens down" at 11:30am. "It gives me time to make peace with myself," said 17-year-old Annabelle McMahon. "It's better for me because I get really nervous when I ask people about the exam."

Annabelle's St Paul's classmate, Alexandria Smith, echoed her sentiments. "I'm more happy not knowing anything. We can't improve it now. It is just more stress." Along with 60 of their classmates and more than 350 other NSW students, the pair will sit up to 12 exams between now and November 24, almost twice as many as their HSC counterparts. Overall, there are more than 80 IB exams in subjects as diverse as global politics, philosophy, English and maths, with a curriculum that focuses more on breadth than specialisation and has a compulsory community service component. The IB diploma goes for two years compared to the HSC's one.

"You can be tested on day one of year 11," said Alexandria. The teenagers said that finishing their IB almost a month after the majority of the rest of state's year 12 students was worth the wait. The last of the state's 77,000 HSC students will finish their HSC exams when the Visual Arts exam concludes at 3:30pm on Wednesday. "There is always a bit of banter between the groups," said Alexandria. "We have had six weeks to prepare and be better equipped for our exams." "For our HSC friends we are a bit jealous that they do get to go on to holidays now, but my HSC friends said I'm going to be jealous of your ATAR'."

Last year Australian students dominated the International Baccalaureate exams, performing well above the global average and claiming a high proportion of the top marks despite the relatively small cohort. Overall they made up 10 per cent of the top scores, despite accounting for less than 3 per cent of all students. The national average of 34.22, which equals an ATAR of more than 90, was well above the global average of 29.95. Antony Mayrhofer, the Director of Learning Services at St Paul's, said that the IB was becoming increasingly popular as an accreditation for Australian universities.

"But there is not a huge jump into the IB diploma in NSW," he said. "One reason is because the HSC is such a strong credential". The IB continues on Wednesday with Economics, English and Classical languages. The HSC finishes with Visual Arts, Food Technology, French Extension and Modern Greek Extension.