This article presents an instructional approach to constructing discovery-oriented activities. The cornerstone of the approach is a systematically asked question "If a mathematical statement under consideration is plausible, but wrong anyway, how can one fix it?" or, in brief, "If not, what yes?" The approach is illustrated with examples from…

Prediction is a great skill to have in any walk of life: it can, in fact, save lives at times. While the two investigations posed in this column may not be that dramatic, they might just increase one's appreciation of some important connections between grids and rectangles and the divisors of numbers that appear in the dimensions of those…

With a standard geoboard, five pegs by five pegs, how many different triangles can be formed using a single rubber band with the pegs serving as vertices? Discusses ways to solve this problem and offers related problems and some pedagogical considerations (particularly for the teaching of geometry and problem solving). (JN)

Presents three teaching ideas: (1) investigating patterns in the sum of four numbers in a square array, no two from the same column or row; (2) using three-dimensional coordinates to generate models of three tetrahedra; and (3) applying the K=rs area formula for a triangle to other polygons. (MDH)

A special summer course for mathematically gifted eighth graders used a problem-centered approach to develop abilities to hypothesize and carry out informal deductive proofs. Students responded well to challenging problems and worked best independently rather than in groups. (Author/CL)

Article gives a brief history and suggestions for the proof of the theorem that of all plane figures with a common perimeter, the circle has the maximum area. (RS)

These materials are intended to provide meaningful mathematical experiences for pre-algebra students. These experiences emphasize the development of computational skills, mathematical concepts, and problem-solving techniques. This bulletin may be used as the basis for the second term of a one-year course, or for the second year of a two-year…

A mult tile is a set of polygons each of which can be dissected into smaller polygons similar to the original set of polygons. Using a recursive LOGO method that requires solutions to various geometry and trigonometry problems, dissections of mult tiles are carried out repeatedly to produce tile patterns. (MDH)

Described is a theorem which is generally not present in most high school geometry textbooks. Presented are two proofs and two cases which illustrate the use of the SSA theorem. (CW)

This article explores how different proofs of a solution to the Surfer Problem provide answers to the question "Why"?

From the equality of the ratios of the surface areas and volumes of a sphere and its circumscribed cylinder, the exploration of theorems relating the ratios of surface areas and volumes of a sphere and other circumscribed solids in three dimensions, and analogous questions relating two-dimensional concepts of perimeter and area is recounted. (MDH)

Discusses the problem of finding the amount of fence it would require for the outfield fence of a baseball field of given dimensions. Presents different solution methods for each of the levels from grades 9-12. The different methods incorporate geometry, trigonometry, analytic geometry, and calculus. (MDH)

The proof that the area of a quadrilateral is one-ninth the area of another quadrilateral is presented. The proof is designed to give geometry students insight into techniques that can be used in other problems. (FL)

Describes how modifying familiar classroom formats in a college geometry class helped encourage student problem solving. Demonstrates these modified formats in the context of problems students explored, which resemble the problem-solving settings of mathematicians. (KHR)

Presents student methods for finding out the number of different squares on a chessboard. Includes extensions of the activity. (MKR)