Building with Triangles

Each geometric investigation in this unit begins with an open-ended question that engages students in a study of triangles and their properties. This lesson was adapted from "IDEAS" by Marea W. Channel, which appeared in the November, 1993 Arithmetic Teacher (Teaching Children Mathematics), Vol. 41, No. 3.

Math Content

Students will:

• explore ways of building different basic shapes from triangles
• investigate basic properties of triangles
• investigate the relationships among basic geometrical shapes
• discover that it is not possible to construct some triangles from given lengths
• discover that the lengths of any two sides must be greater than the length of the third side
• build a foundation for the understanding of fractals

Individual Lessons

Lesson 1 - What's So Special About Triangles, Anyway?

Students explore ways of building different basic shapes from triangles. They also investigate the basic properties of triangles, as well as relationships among other basic geometric shapes.

Lesson 2 - What Does it Take to Construct a Triangle?

Students explore the importance of the side lengths of a triangle and when triangles can or cannot be constructed on the basis of these lengths.

Lesson 3 - How Many Triangles Can You Construct?

Students identify patterns in a geometrical figure (based on triangles) and build a foundation for the understanding of fractals.