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Spherical Sketchpad: A dynamic java program modeling spherical
geometry

David Austin

William C. Dickinson
Geometers' Sketchpad has been used in the classroom for many years to help
students explore the geometry of the Euclidean plane. This software enables
students to create arrangements of lines, circles and other objects,
dynamically move them and then make precise conjectures concerning their
arrangement. In more recent years, dedicated software, such as NonEuclid, has
been created to do the same type of dynamic constructions only in the
hyperbolic plane. Over the summer of 2002, we wrote a java program, Spherical
Sketchpad, which models the geometry of the sphere. This is a dynamic program
that has a very similar functionality to Geometers' Sketchpad and allows
students to visualize, explore and form conjectures about spherical geometry.
We will speak about Spherical Sketchpad and its uses in our Euclidean and
non-Euclidean Geometry courses. We will give a short demonstration of the
program and then discuss how we used it in our classrooms. Sample labs and
assignments will be discussed as well as student reactions. It should be noted
that our program can made to stand-alone or be used as applet. At the end of
the talk we will distribute a web address for the applet so that all
participates can explore the program.