Introduction

At least in part, geometry is an exploration of shapes, and the triangle, the simplest of polygons, provides a surprising variety of explorations for the middle school learner. As a geometric figure, it offers opportunities to study fundamental concepts of congruence and similarity as well as that critical discovery of ancient mathematicians, the Pythagorean theorem. As a source of problems for classroom practice, triangles appear at work in the context of measurement and construction. And triangles are featured in famous roles, such as the Sierpinski triangle and Pascal’s triangle.

Each set of resources in this publication opens to one of these distinct views of the triangle. We begin with background information for the teacher, followed by online resources on triangles as geometric figures, as workers in solving real-world application problems, and as well-known geometric objects. We hope your classes will enjoy all three sides of the triangle!

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Copyright January 2007 — The Ohio State University. This material is based upon work supported by the National Science Foundation under Grant No. 0424671. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

This work is licensed under a Creative Commons License.