Discusses a conjecture of a ninth-grade student that extended a geometry theorem about trisecting sides of a triangle. Presents a proof and extensions. (MKR)

Discusses assumptions implicit in any system of measurement. Describes a three-rectangle problem designed to help children explore additivity of areas and relationships between area and shape. Suggests ideas for action research. (FDR)

Investigated here are some of the results which can be obtained using the double-sided straight edge. Seventeen possible constructions are presented with solutions or partial solutions given to most. (MP)

Described is a method of teaching geometric constructions. The method relates five basic constructions to the properties of a rhombus. (RH)

This paper describes aspects of 13 year-olds activity in mathematics as emerged during the implementation of proportional geometric tasks in the classroom. Pupils were working in pairs using a piece of software specially designed for multiple representation (symbolic and graphical) of the variation in parametric procedures with dynamic…

This essay contains some reflections and questions arising from encounters with the text of Euclid's Elements. The reflections arise out of the teaching of a course in Euclidean and non-Euclidean geometry to undergraduates. It is concluded that teachers of such courses should read Euclid and ask questions, then teach a course on Euclid and later…

The Shepherd's Principle (to count the number of sheep in a field, count the number of legs and divide by four) is applied to the problem of finding the number of different rectangles on an N by N checkerboard. (MM)

Describes some unsolved problems in geometry, as well as some recently solved ones. Indicates that each advance generates more problems than it solves, thus ensuring a constant growth in unsolved problems. (GA)

Cooperative groups were given transparencies of eight regular inscribed polygons and overlays of corresponding circumscribed polygons and were asked to find the perimeters and ratios of perimeter to diameter. Transparencies give students a graphic illustration of limits. Includes reproducible worksheet. (NI)

Using sequential chains of regular n-gons in a row with one side touching, as for example, one triangle, two triangles, three triangles, and so on, students graph the length of the perimeter versus the number of n-gons and determine the functional relationship for different values of n. (MKR)

Presents results from research aimed to design and experiment with a set of units for teaching plane isometries in grades 3 through 12 and applies the van Hiele model of geometric reasoning to isometries. Includes a table of characteristics of teaching objectives for the van Hiele Levels in Isometries. (MKR)

Analyzes the functions of semiotic mediation in a long-term teaching experiment, Mathematical Discussion, on the plane representations of three-dimensional space by means of perspective drawing in grade two to five classrooms. (Author/MKR)

Teachers assume that by the end of primary school, students should know the essentials regarding shape. For example, the NSW Mathematics K-6 syllabus states by year six students should be able manipulate, classify and draw two-dimensional shapes and describe side and angle properties. The reality is, that due to the pressure for students to…