The flight instructor reported that she was teaching her student to hover as part of a flight lesson. She transferred the flight controls to her student but continued to monitor the cyclic, collective, and tail rotor controls. The helicopter drifted aft and to the right while pitching nose up, as the student increased aft cyclic. The flight instructor attempted to correct by increasing forward cyclic but the tail struck the ground. The flight instructor stated that the helicopter began to violently vibrate, and she heard a grinding noise. As she lowered the collective, the helicopter impacted the ground, and the right skid broke off. The helicopter rolled over and came to rest on its right side, sustaining substantial damage to the main rotor system, tail boom, and tail rotor system. The flight instructor reported that there were no preimpact mechanical failures or malfunctions that would have precluded normal operations.