The flight instructor reported that the student pilot had an tablet computer in her lap. During the landing flare, the tablet interfered with the student pilot’s control input. In an attempt to assist the student, the flight instructor briefly diverted her attention from the landing, to shift the tablet away from the control yoke. When the flight instructor looked back outside, she realized that the airplane had floated more than halfway down the runway and had not touched down. She took control of the airplane but decided not to attempt a go-around due to trees at the runway end. The flight instructor applied full braking, but when she realized that the airplane was not going to stop on the runway, she steered left down a small embankment, rather than risk a larger embankment at the end of the runway. The nose landing gear partially collapsed, and the airplane came to rest upright off the left side end of the runway. The forward portion of the airplane’s fuselage was substantially damaged during the accident sequence. The flight instructor added that there were no preimpact mechanical malfunctions with the airplane.