Henna Tattoos For Kids

henna dilemma! (mehndi and school dress code?)?

First I got in trouble for drawing traditional mehndi designs on my hand with a pen. My teach says it's against the rules because the kids who want tattoos and cant will whine if I am allowed to have henna.
Right now my arms are covered in (gorgeous) mehndi and I've been wearing long sleeves but summer is coming... how can I have henna without appearing rebellious? I though of putting tape over it but will my teach think I'm just trying to be a brat about it?
There's a night at the school coming up where I'm going to help out with the kids and there will be no dress code... if I wear short sleeves and my teach sees is that rude to him?
I am a really obedient kid as much as I can, always labeled as 'the good kid' , and want to keep my rep...
sorry "carla m", this is about as much of my life you're gonna get

I'd just talk to them about it. If you go in respectfully and present your point calmly and intelligently, that could really help. It doesn't sound like you're the type to have problems with doing this! You might also explain what mehndi *is*; they may not be aware of its cultural background.