Abstract: At approximately 11:53 a.m. on January 22, 2007, Employee #1 was working at the jobsite in San Mateo, California. He was using a circular saw to cut and trim the wood around a patio door. Employee #1 was neither trained to use the circular saw nor had experience in using any circular saw. He was hired as a window installer just two months earlier. A foreman handed the circular saw to Employee #1 and just showed him the On and Off buttons on the saw and expected him to cut the wood. Employee #1 was not cutting the wood straight, however, the foreman left him unsupervised, saying that continuing working is a way of learning. After cutting the wood from both sides of the patio door, Employee #1 was trying to cut the wood from the top of the patio door. Apparently, it was too hard for him to perform the job because of the angle of cutting and height while standing on the ladder. As a result, Employee #1 partially amputated his middle finger on his left hand. He was taken to the hospital, where his finger was completely amputated.