I'm in Hong Kong. Well, we have supervision, i.e we have to stay at school until 7:30pm at night without mobiles, watched by teachers. But it's quite easy to get round that, like don't hand in our mobiles, sms in the toilet...
So when I finish, I coullddd just sms someone in england =P It doesn't have to be exact, it's helpful even if for say bio for example 'Stdy Heart, Dig.Sys.ileum.strctre.sperm.' As exams only test you on a proportion of the stuff, you can easily cram the 4 or 5 really revelant pages in a few hours. It's even better for essay exams, like eng lit, giving u a question like 'Frankenstein essntially gd man, jst make mistakes, discuss' That'd help , cuz it'd give u a few hours to plan your essay, think through, find sources etc. vs...10 minutes in the exam room. And less stress=P