Using the overhead projector, or overlays on an original pattern, a variety of tessellations can be generated. Several illustrations are included. (SD)

Arguing that operations research is not as difficult and forbidding as its reputation implies, and that many problems lend themselves to analysis using common sense, the author provides examples which might be used in a secondary school classroom. (SD)

The validity of the formula for the sum of the measures of the interior angles of polygon is explored using non-convex polygons. (SD)

A review lesson based on a sports car rally is described and illustrated. It teaches detailed map reading as well as providing drill on any subject desired. Pairing students is beneficial for several stated reasons. Some students may design their own rally for presentation to the class. (Author/KM)

This article extends number bases to negative integers, then to positive rationals and finally to negative rationals. Methods and rules for operations in positive and negative rational bases greater than one or less than negative one are summarized in tables. Sample problems are explained and illustrated. (KM)

Using a set of worksheets, students will discover and apply Euler's formula regarding connected planar graphs and play and analyze the game of Sprouts. One sheet leads to the discovery of Euler's formula; another concerns traversability of a graph; another gives an example and a game involving these ideas. (Author/KM)

Rules for determining the number of initial zeros and the period of a repeating decimal are stated and proved. (SD)

The author describes several physical problems whose solutions involve a helix. He argues that students remember "offbeat" approaches to important mathematical concepts. (SD)

Three games played with regular bridge decks of cards are described. By playing the games students gain practice in use of basic operations on integers and in the development of strategies. (SD)

A total of 450 seventh and eighth graders responded to six tasks requiring proportional reasoning and representing different degrees of concreteness. Results showed that more students answered questions correctly when concrete aspects existed, and that about one-fourth of the group was unpredictable in applying proportional reasoning at the formal…