At our school (private) we have two school captains, two vices and usually about 8 other Prefects. We have quite big roles in comparison to many other schools and have the power to give out detentions and have a roster patrolling the CBD etc etc.
I am Boys Vice Captain and here are my interview tips (I will be an interviewer this year):
1. BE YOURSELF. They smell a faker or someone who is telling them what they want to hear a mile away. E.g. the Vice-Headmaster asked me about my lack of involvement in compulsory sport and I answered honestly and sort of constructed a reasonable case and they laughed and said I was really good at avoiding them.
2. This may be bad advice, but don't be that prepared, it helps if you look like you're thinking about your questions properly.
3. Have lots of new, original ideas for stuff to do around the school (I didn't and it was really awkward)
4. Be realistic. They might give situations like 'you come to realise one of your classmates has been sneaking out at lunch, what do you do?'. Don't be like 'immediately tell the Headmaster and call for an expulsion', cos that's just ridiculous.
5. Smile and look relaxed, it shows you can talk to important people under pressure.
6. Yeah, Aerath is right, it's all well and good to say in Y11 that you can deal with all the sacrifices, but it's actually hard. Like having to attend every little grade seven music concert, participating in everything, organising socials, fairs, meetings, activities as well as upholding all the school uniform rules. And seriously, if you haven't had very much experience in leadership type stuff, don't go for School Captain. The girl this year was a totally random choice (the school likes to surprise) and she has no idea how to delegate and just has nervous breakdowns every week.
Bye bye.