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.