I'm pretty sure you can't teach turtles or tortoises tricks... As well, corn is a bad choice of "treat," or food at all. Tortoises have been known to play with balls (i.e. tennis balls), so maybe he'd be interested in that, but I highly doubt you'd be able to teach the turtle a trick. Remember, reptiles aren't dogs... They don't have the intelligence, motivation, or desire to please that make dogs so easy to train. Very different animals...
I highly recommend reading through this Box turtle care website: http://boxturtlesite.info/
and posting on this forum: http://tortoiseforum.org
... You can ask about your "training" theory on the forum to see if anyone has any input for you.
Taylor, slave to...
Beardieless.. RIP, Man Ray (10-13-12)
Plus 0.2 Corn snakes, 1.1.8 Kisatchie Corn snakes, 1.0 Gopher snake, 1.1 Boa Constrictors, 0.1 Rosy boa, 1.0 Woma python, 0.1 Taiwan Beauty snake, 0.0.1 Leopard tortoise, 0.0.1 Schneider's skink, lots of roaches, and 2 dogs