Abstract: Workers on the second level of a structure were removing overhead shoring for the third level. Employee #1 was working on the third level, removing plywood sheathing and stacking it aside for reuse. Workers on the second level had just removed shoring for an area immediately behind Employee #1 when he stepped backward onto a piece of plywood. It tilted up and exposed a 4 ft by 5 ft hole through which Employee #1 dropped. He fell 12 ft to the concrete surface of the second level, landing on his left side. He suffered a fractured left wrist, a lacerated forehead, and a concussion. Workers on the second level should have given Employee #1 adequate warning of the hazard.