Dirt Desk consists of the three states of matter most common to everyday life: solid, liquid, and gas. These are represented by dirt, water, and air. The perimeter of the dirt was defined by using a person's body as a compass, with the head at the center point and the hand marking the outer edge. When sitting at the desk the dirt extends as far as arms reach. Rubber sheets are used as paper, and are flexible, erasable, and impermeable to water.