The author explores relationships among the lengths of sides of a triangle, one of whose angles measures 60 degrees. A computer program designed to search for special triangles is included. (SD)

Students use a series of isosceles right triangles constructed on a geoboard to discover patterns and form generalizations. (MP)

Presented are practical activities relevant to teaching mathematics in the American Indian culture that can be used in the non-Indian classroom. Discussed are tessellations, exercises that allow for artistic creativity and geometric exploration. The use of Pascal's triangle is included. (KR)

Relationships between the linear dimensions, surface area, and volume of parallelepipeds are examined. (SD)

Activities involving estimation of the number of objects in a configuration can motivate students to consider parametric models. (SD)

Having students find and cut out of graph paper the 12 pentominoes can provide an enjoyable exercise in perception, discovery, and double checking. The pentominoes can then be used to illustrate informally several geometric concepts. (SD)

This pamphlet introduces the student to the basic ideas and procedures of transformational geometry through a series of worksheets. After developing intuitively the idea of rigid motion, vector diagrams are introduced, and translations are discussed in some detail. (SD)

A series of lessons in which the concept of symmetry is informally developed is described. Rotational and reflection symmetries are examined. Pictures and sample worksheets illustrate the article. (SD)

A learning activity relating modular arithmetic to patterns of figures determined by points equally spaced around a circle is described. (SD)

Geometric concepts and theorems can be discovered by high school students using the materials described. Among the topics explored are Platonic solids and Euler's formula. (SD)

Helping students notice the geometric shapes and symbols around them and in the world's cultures is a fascinating way to make mathematics meaningful. (Editor/SJL)

Describes an activity that utilizes four pattern blocks to help students understand and explain perimeter. Engages students in making and supporting conjectures about a scenario that involves trains composed of various shapes with different perimeters. (DDR)

Beginning with a set of design cards and a rectangular grid, students can generate interesting and colorful designs using rotations, reflections, and translations. (SD)

Five activities involving an array of numbers called an even triangle are given. Properties of the triangle are listed and some generalizations are proven. (MP)