A definition is given for curves parallel to a closed curve. Equations for inner and out elliptic parallels are derived and explained. (RS)

Offers an excerpt from a paper written by Nicolay Lobachevsky (1792-1856) on the topic of the then new non-Euclidean geometry in tribute to this scientist as his 200th birthday approaches. Lobachevsky discusses his ideas about parallel lines in the context of his new geometry. (MDH)

This study focuses on the constructions in terms of area and perimeter in equivalent triangles developed by students aged 12-15 years-old, using the tools provided by Cabri-Geometry II [Labore (1990). "Cabri-Geometry (software)," Universite de Grenoble]. Twenty-five students participated in a learning experiment where they were asked to construct:…

This booklet explains the historical background and construction techniques for various sets of uniform polyhedra. The author indicates that the practical significance of the constructions arises in illustrations for the ideas of symmetry, reflection, rotation, translation, group theory and topology. Details for constructing hollow paper models…

Designs and arrangements of pentominoes are examined. (SD)

An enrichment activity used in sixth and seventh grade mathematics classes to develop geometric concepts is presented. (JG)

The material attempts to find the maximum number of non-congruent figures that can be generated from a nine-pin geoboard, and considers the maximum number of figures possible on boards of any size. The exploration starts by grouping sets of pin patterns into groups of equivalent classes. (MP)

Illustrated is the use of isometric graph paper in the discovery of nonstandard area formulas. The use of definitions, geometric construction, record keeping, and conjectures about triangles, rhombuses, hexagons, parallelograms, isosceles trapezoids, rectangles, and trapezoids are described. (YP)

A series of problems concerning a geoboard with "holes" is suggested. (SD)

A new approach to classifying quadrilaterals is presented that tries to classify all possible combinations of shapes and angles by removing the traditional Euclidean viewpoints. The document concludes with a brief look at other types of polygons. (MP)