Every photograph needs light, but sometimes it doesn't need much. Painting with light is the process of creating an image using a tiny amount of light and a long time. For the self-portrait I set the camera on a tripod and used the self-timer and a long exposure (30" f8.0) to capture me painting with a tiny flashlight.
My photography students thoroughly enjoyed their painting with light assignment and experimented with various light sources and subjects. To introduce the concept I had them view a tutorial about painting with light.