Lénárt sphere

The Lénárt sphere and accessories are produced by the company Lénárt Educational Research and Technology. The basic set includes: • An eight-inch transparent plastic sphere • A torus-shaped support to place under the sphere • Hemispherical transparencies that fit over the sphere for students to draw on with marker pens or cut out shapes with scissors • A spherical ruler with two scaled edges for drawing great-circle arcs and measuring spherical angles and great-circle distances • A spherical compass and center locator for drawing small circles • A set of wet-wipe markers for writing and drawing on the sphere and transparencies • A hanger for displaying spherical constructions and designs • A 16-page booklet of suggested activities, "Getting Started on the Lenart Sphere" • A four-color polyconic projection of the earth that one can cut out and transform into a globe The company also sells replacement parts, extra transparency sheets, wet-wipe markers, and Lénárt's book Non-Euclidean Adventures on the Lenart Sphere, which describes more activities for students. == Related tools ==

Spherical Easel is an interactive geometry software tool for exploring spherical geometry (see ). Other interactive geometry software is typically limited to the flat plane. == History ==

Spherical trigonometry is fundamental to ancient astronomy and astrology, celestial navigation, and geodesy and cartography, and it used to be a standard part of undergraduate mathematics education. In recent decades hand computations have been replaced by electronic computers and spherical trigonometry has been pushed out of the typical mathematics curriculum by other topics. The Lénárt sphere is widely used throughout Europe in university courses on non-Euclidean geometry and geographic information systems (GIS). == See also ==