u said u performed a centavo wat is that?
It is a mexican coin used in a few magic effects
Personally, it's my advice to absolutely never perform anything beyond pet tricks in school. The fact of the matter is, people, particularly in school, tend to look at magic as a challenge. I'd advise avoiding it.
Anyway, in your situation, you handled it wrong. If he was certain that he figured it out, he wouldn't have asked you. He still had doubt. You led on to the Bat. Any time I mess up (and I have completely revealed a trick), I go into some incredibly long explanation that the trick is slight of hand.
¿Also if some of us "kids" who are still in school don't do magic in school then what venue do we have? Adults either go "Oh, how cute" or "Wait a minute I should be able to do this too " because they hate being fooled by kids. I meen adults my mom knows and that I know have given up by know, but still it is hard to work on showmanship you have been working on for a while if school is one of your only venues.