The purpose of this lesson is to model for students gravitational waves and how they are created. Students will build a simple "Gravitational Wave Demonstrator" using inexpensive materials (plastic wrap, plastic cups, water, food coloring, and rubber bands, marbles). Students should have a basic understanding of waves and be familiar with Einstein's theory of general relativity. The activity can be done either as a teacher demonstration or student activity. This lesson is part of the Cosmic Times teachers guide and is intended to be used in conjunction with the 1993 Cosmic Times Poster.