Alf Coles and Barry Orr reflect on what it looked like when Alf taught a year 7 lesson. In this article, Alf was asked by Barry (student) if he would take a lesson with the Y7 class that he had taken over from another teacher in the department in order to see what someone else might do with his lesson plans. Alf describes what some moments with…

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)

Several times a week I walk by a metal chair that is fastened to a flat concrete slab at an outdoor bus stop here in Boulder. One day I noticed on the concrete a nice shadow image of the woven metal seat of the chair (Fig. 1). The seat and back of the chair are formed from 3.8-cm wide strips of metal spaced 3.8 cm apart. The seat is about 39 cm…

The author re-enacted the "Meno's" discussion between Plato and the slave about doubling the size of the square, and found that a six-year-old's answers paralleled those of the slave; neither had formal knowledge of geometry. Plato stated that learning is recollection of knowledge held before birth. (CHK)