The flight instructor of a tailwheel-equipped airplane reported that he attempted a three-point, full stall landing, with a right-quartering crosswind of about 4 knots. During the touchdown there was a small bounce which the flight instructor described as minor and controllable. The airplane touched down again, and he applied further aft yoke which resulted in another small bounce and final touchdown. Once the airplane was on the runway, he applied full aft yoke, and the airplane immediately veered to the right and exited the runway. The flight instructor attempted to correct with full left rudder, but the airplane exited the right side of the runway and contacted terrain with the left wingtip and nose. The airplane came to rest upright. The airplane sustained substantial damage to the left wing and left aileron. Examination of the airplane revealed no preaccident mechanical failures or malfunctions that would have precluded normal operation.