A method is given for the analysis of geodesic domes involving plane geometry. The method shows how to calculate all necessary angles and chords, given the length of one side. (MP)

Relationships among the sides are developed for right triangles whose sides are in the ratios 1:3, 1:4, and 1:5. The golden ratio appears in the results which can be used in secondary mathematics. (DC)

Discusses six examples that discover supplementary geometry theorems by using three elementary theorems about the relationships between angles and intercepted arcs in circles. Topics in the examples include angles formed by parallel lines and the sum of the interior angles of triangles, convex quadrilaterals, star polygons, and hexagons. (MDH)

Several activities that can be used to give children more experience with triangles are submitted. By handling triangular shapes and building triangles with strips, pupils can experience a diversity of triangles in a very concrete way. Examination of triangles and nontriangles can help develop understandings of some inequalities. (MP)

The 1989 document, "Curriculum and Evaluation Standards for School Mathematics" provides a vision and a framework for revising and strengthening the K-12 mathematics curriculum in North American schools and for evaluating both the mathematics curriculum and students' progress. When completed, it is expected that the Addenda Series will…

Equations or systems of equations can be associated with letters of the alphabet printed in the coordinate plane. Messages can be coded and decoded with a computer or by hand. (SD)

Presents 5 activities for the K-1, 2-3, 4-5, 6-8 grade levels and for in the home in which students explore the concept of triangle through cooperative open-ended investigations. Provides related reproducible worksheets. (MDH)

A series of maps is presented for coloring with the fewest possible colors. (SD)

This monthly column contains teaching suggestions on: using codes to convey information, flow proofs in geometry, and volleyball and probability. (MP)

Explores applications of the Fibonacci series in the areas of probability, geometry, measurement, architecture, matrix algebra, and nature. (MDH)

Explorations of Pascal's triangle through computer programming are described. Programming offers different methods and techniques that enrich the topic. (MNS)

Discusses flexible polyhedrons, called flexors, that can be bent so that the faces stay rigid while the angles between them seem to change. Presents models representing flexors and directions on how examples can be constructed. (MDH)

Presented are activities concerning the method of graphing the equation y=kx in the Cartesian and other coordinate systems. Students progress from the graph of a straight line to the investigation of conceptually related geometric loci in non-Cartesian coordinate systems. (MDH)

Some geometric activities are described that teachers can use to give their students experiences that will influence their spatial abilities. It is noted that the goal is to improve spatial abilities, not to increase knowledge, so individual pupil responses should not be used to judge student achievement. (MP)