The flight instructor reported that, while demonstrating a soft field takeoff for a student pilot, he maintained full back pressure with the control yoke, put in 10° of flaps, lined up on the wet, grass, 1,900 ft runway, and added full power. He further noted that the airplane was not accelerating as anticipated due to the runway conditions. The airplane lifted off about two-thirds of the way down the runway and he decided that the airspeed of 65 mph was "not adequate." Additionally, he saw tall trees at the end of the runway, so he decided to abort the takeoff and land on the remaining runway. He reduced power, the airplane touched down, and he applied the brakes. The airplane overran the runway, went down an embankment, and the right landing gear struck a rock hidden by the tall grass. The airplane continued across a gravel road and came to rest in a yard.

The airplane sustained substantial damage to the left wing and fuselage.

The flight instructor reported that there were no preaccident mechanical failures or malfunctions with the airplane that would have precluded normal operation.