This experiment designed for beginning physics students, is related to postal regulations restricting the size of envelopes. A graph is constructed that allows for testing the mailability of envelopes. (MP)

Activities involving set union and intersection, graphing solutions of open sentences, and negation are described. These activities afford students with opportunities for computational practice as well as instruction on equations and inequalities. (SD)

Rational points in the plane were defined as points having both coordinated rational. Students solved several problems linking rational points with lines, circles, and other geometric figures. (SD)

The issue of division by zero is discussed. Activities that cover the topics of measurement division, partition division, relationship to fractions, confusion with dividing into zero, dividing zero by zero, and relation to more formal numbers are presented. (KR)

Using the methods described, pattern representation of operations in modular systems can be developed. (SD)

The design of a "percent computer" that uses the concept of similar triangles is presented. The device can be easily made by elementary and secondary pupils out of graph paper and string. Sample student problems are included. (MP)

The Triple Representation Model of problem solving is presented. The use of microcomputers in this problem-solving environment is discussed, and examples are provided. The integration of this method into the mathematics curriculum is described. (CW)

A list of potential writing ideas and general guidelines to be used in integrating writing into the mathematics classroom are provided. Ideas under the headings of narrative, descriptive, and expository writing are included. (KR)