Henna Tattoos 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...
"latj", what are you taking about?

i understand u. if i was u though, i would have my parents come to school and talk to her.