Gold bars for the instructors -minimum of three for even the newest grade 3 and five gold bars and a star for the CFI. This really pulls in the young students who see the gold bars like teenagers see Ronaldo's jazzy front hair buzz.
Promise each student two gold bars when he completes his/her first solo. Better still give the TIF student a fancy looking voucher for a set of gold bars at the local pilot shop. Add the cost to the TIF of course - students will never twig. Keeps the pilot shop in business, too. Works every time.
