yeh the whole event is all about tradition. the girls are 'presented' to society, and are called debutants, and the whole thing was originally call the Debut (deb for short) and wear white, which is meant to symbolise purity, innocence, etc etc. although the school tried to make out that it wasnt entirely just following tradition, so they called it "foundation ball".
every year there are girls who are totally against it, ie degrading to girls, etc etc. but everyone ends up being super excited and it was an awesome night.