The helicopter experienced dynamic rollover and came to rest on its left side while attempting to take off. The 423-hour helicopter flight instructor reported in the NTSB Form 6120.1 (Pilot/Operator Aircraft Accident/Incident Report) that the instructional flight comprised of practice autorotations and rapid decelerations or quick-stops. The practice area where these maneuvers were performed was reported by the flight instructor as "a grassy, dirt area with occasional dirt mounds raising approximately 1 and 1/2 feet above the ground." The ground was also wet and muddy due to thunderstorms having passed through the area prior to the flight. While executing the third quick-stop maneuver, the student pilot receiving instruction performed a normal take off from a 3-foot hover. The helicopter assumed a pronounced nose low attitude while accelerating during takeoff and the toe of the right landing gear skid simultaneously contacted a dirt mound. The student attempted to correct the right yawing condition by over-controlling to the left, while the flight instructor compensated by raising the collective and applying right cyclic. The flight instructor concluded that "by the time the inputs were felt the helicopter had reached its critical angle and rolled [to the] left side." The helicopter sustained structural damage to the main rotor, fuselage, tail boom, and tail rotor. The flight instructor and student pilot were able to exit the helicopter unassisted and neither was injured. At the time of the accident the flight instructor reported having accumulated 116 hours as a flight instructor and the student had accumulated a total of 24 hours in helicopters. The weather at the accident site was reported as calm winds, 10 miles visibility, a broken ceiling at 2,100 feet AGL, and a temperature of 26 degrees Celsius.