A discussion of the so-called rose curves defined by simple trigonometric functions in polar coordinates. (MM)

This article presents some easily stated but unsolved geometric problems. The three sections are entitled: Housemoving, Manholes and Fermi Surfaces" (convex figures of constant width), Angels, Pollen Grains and Misanthropes" (packing problems), and The Four-Color Conjecture and Organic Chemistry." (MM)

Conditions for congruency of triangles are investigated. (DT)

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)

Describes how a 3-inch by 5-inch card can be used to develop properties of similar triangles and prove the Pythagorean theorem. (MKR)

Presents interesting investigations and activities for inscribed and escribed circles of right-angled triangles. (ASK)

Around 300 BC, Euclid wrote "The Elements", a major treatise on the geometry of the time, and what would be considered "geometry" for many years after. Arguably "The Elements" is the second most read book of the western world, falling short only to The Bible. In his book, Euclid states five postulates of geometry which he uses as the foundation…

This paper reports a case study which involved 32 secondary school students participating in an online collaborative learning (OCL) activity known as Diary of Discovering Geometry. This activity aimed to explore the real contents in the learners' surrounding for discovering the spatial concepts and the applications of geometry. The purpose of the…

In this article we describe our experiences using picture books to provide young children (five- to six-year-olds) with a learning environment where they can explore and extend preliminary notions of mathematics-related concepts, without being taught these concepts explicitly. We gained these experiences in the PICO-ma project, which aimed to…

Adam, an 11th grader, was identified as gifted and accepted into a two week summer enrichment program. He signed up for "Geometry with Flash Programming." He had no prior programming experience but had a strong and healthy self-image as mathematics student. Although Adam had a positive attitude toward mathematics and saw himself as a successful…

This article reports on an investigation of how teachers of geometry perceived an episode of instruction presented to them as a case of engaging students in proving. Confirming what was hypothesized, participants found it remarkable that a teacher would allow a student to make an assumption while proving. But they perceived this episode in various…

Students enter the geometry classroom with a strong concept of fairness and a sense of what it means to "play by the rules," yet many students have difficulty understanding the postulates, or rules, of geometry and their implications. Although they may never have articulated the properties of an axiomatic system, they have gained a practical…