This program illustrates how spirals can be mathematically modeled by examining their fundamental features. Both two- and three-dimensional spirals are examined, including an amusement park slide, a Nautilus shell, and a DNA double helix. Features considered include angle, radius, pitch, rotation, and circle and wave patterns. Computer animation and mathematical formulas illustrate how shapes can be altered by manipulating their features. The mathematical relationship between radius and rotation is derived by tracking the movement of a moth. Produced by the Open University. (25 minutes)