The EJS Phases of Moon JS model displays the appearance of the Moon and how it changes depending on the position of the Moon relative to Earth and Sun. The right window shows Earth (at the center) and Moon, as well as a circle tracing out Moon's orbit. The Sun is far to the right in this picture and therefore the right side of Earth and Moon are bright while the left sides are dark. By using the options, the Moon View window (left) shows the appearance of the Moon as seen from Earth when the Moon is in the position shown in the main window. The EJS Phases of the Moon JS model includes supplemental documents (see below) that include a middle school lesson plan.