Magicfreak667-
I have come to a very accurate conclusion over the last week looking at your posts that you, are an extremly arrogant, un-educated, full of yourself, little human-being who can only offer cinicism to people who actually know what they are talking about (which I am sure you will do to this post as well).
Anyone who believes they know what they are talking about when they tell someone to, "ignore your school rules and do what you please," is a truly misguided soul. If the school doesn't allow cards, than abide by those rules. Why put up the front that you are someone who goes against the rules. School is for LEARNING. For developing your brain, learning how to think, learning how to FOLLOW RULES, not for you to disrespect authority. Yes it is ok to sometimes question the rules that govern you, but in an educated way. It is NOT ok for you to disrespect the people and institution that is in charge of your education.
It is ok that you want to believe this crap, but when you tell people these misguided opinions, you could be putting their futures in jeapordy. Put down the cards, go to class, stop trying to tell people to be like you, because we don't need anymore McDonalds night managers.
Now for real advice to the OP. Hone your card skills at home. Perform for your family until your routines are flawless (well, close-to at least), and perform your card routines at school fucntions (games etc... off campus). While at school carry around some money. Keep a 50cent piece in classic palm for an entire class. Keep it palmed in your writing hand and see if you can take notes while still palming. Work on your retention vanish etc...
Think of this as a blessing. One of the biggest mistakes school magicians make, is that they show TOO much magic, ignoring the most important thing a performer should keep in mind to "always leave your audience wanting more." You will have a higher success rate of this if you do a lot less magic, and make the magic you do perform, more hard-hitting. Which of course means, more practice, less random performances.