Mind-boggling! Display the colors of the rainbow by rotating a black-and-white disk! Spin the disk in the opposite direction and the color order reverses. How is this possible? It is the result of the brain's perception of flashing white light. A fun and unusual hands-on activity that allows students to explore the mysteries of the brain, learn about color, as well as the persistence of vision. Dry erase marker is provided so students can easily erase marks and experiment with line thickness and length to determine the best pattern for the Benham's disk. Enough laminated Benham's disks are provided for sixteen groups of students. Instructions and background information are also included.