Have a subject stand one foot away from a wall in a dark room. Have an assistant stand 10' back from the wall and shine the light at the friend's head. Observe the shadow's darkest (umbra) and lightest area around the edges of the shadow (penumbra). Measure the width of the penumbra. Measure the umbra. Record your data. Have the assistant with the light move 3 feet closer to the subject and shine the light on the subject's head. Measure the penumbra and umbra at this distance. Record your data. Have the assistant move another 3' closer. Repeat the measurements and record the data in a table like below.