Describes a theorem for finding an area of simple lattice polygons. Includes proof and Java applet simulation.

Three-dimensional objects constructed by slotting together a series of planar cross sections made from card. Downloadable templates in PDF, PS and Word formats.

Educational toys used to teach geometry and model building to create squares, spheres, stars and other regular shapes with sticks and connecting pieces. Products include kits and lesson plans.

Derivation of volume equations for regular polygons, polyhedra, and polytopes, with images.

Vertex figures, filling, faceting diagrams, stellation, defining polytopes through generators, trimethoric and trisynaptic polyhedra, space-filling polyhedra, lost stellations of the icosahedron, and links.

Enumeration, cartesian coordinates of vertices, naming, and counting the shapes.

Polytopes and optimal packing of p points in n dimensional spheres. Contains a java applet based on a model which allows for generation of multidimensional regular and semi-regular polytopes.

Definitions, pictures, templates, and coordinates of the regular 3d and 4d polytopes. Also includes waterman polyhedra, polar and star spheres, and the time star.

Regular, rectified, and truncated polytopes with normal and hidden-detail-removed projections. Images, animations, and links.

Comprehensive list of links to sites on geometric properties of the shapes.