On October 3, 2000, about 1041 hours Pacific daylight time, a Robinson R22 Beta, N8340N, operated by Helistream, Inc., Costa Mesa, California, rolled over during landing at the Long Beach Airport, Long Beach, California. Visual meteorological conditions prevailed during the instructional flight that was performed under 14 CFR Part 91. No flight plan was filed for the local area flight. The helicopter was substantially damaged. The certified flight instructor (CFI) who possessed a commercial pilot certificate received a minor injury. The student pilot was not injured. The flight originated from Santa Ana, California, about 0950. The CFI reported to the National Transportation Safety Board investigator that he was providing dual instruction to his student. When the accident occurred both he and his student were handling the flight controls. The CFI directed that the student enter an autorotation while hovering between 2 and 3 feet above the dirt field. The student responded by rapidly lowering the collective, and the helicopter descended. Before the CFI could regain control, the helicopter's left skid touched down and "dug in." Thereafter, the main rotor blades impacted the ground, and the helicopter rolled over onto its side. The CFI did not report having experienced any mechanical malfunction with the helicopter during the accident flight. The CFI indicated that during the previous 5-minute period, he had practiced this same maneuver with the student and had not experienced any unusual problems with the student's performance. Regarding the CFI's experience providing flight instruction to students, the CFI reported having given a total of 2,000 hours of dual instruction, of which 1,800 hours were given in Robinson helicopters. During the preceding 90-day period, the CFI gave 180 hours of instruction in the Robinson.