Grade: Middle
Subject: Mathematics

#1425. What is it...a triangle?

Mathematics, level: Middle
Posted Wed Dec 1 07:59:32 PST 1999 by Mark Blackburn (
Betsy Layne High School, Betsy Layne, USA
Materials Required: Tangrams, computer, Geometer's Sketchpad, a performance event
Concepts Taught: Geometry/measurement

Core Content Are:
Stufdents will:
*Develop a definition of a triangle
*Identify the parts of a triangle
*Claify triangles by their parts
Embedded Core Content:
Mathematical structure
Opening Activity
In your own words, what is a triangle? What relationship does a triangle have with a square? A hexagon? An octagon?
Teacher directions
This leson can be taught in groups or individually. The major limitation to the lesson is the amount of computers and tangrams are avilable for class.
Student directions
Students will use the tangrams to build or choose the appropriate triangle being discussed. The ywill use the definitions to find the triangle in question. In groups, the students will construct triangles on Geometer's Sketchpad and other students will classify the triangles an identify the parts of the constructed triangles.
Closing activity
Students will review the main ideas discussed in the lesson.
In your environment, find twenty triangles, draw the triangles as you seethem and classify the triangles according to their attributes (SIDE AND ANGLE).