Lesson Plan Cuisenaire Rods

This lesson uses Cuisenaire Rods to create triangles.

Objective: Students will explore the relationships of the lengths of the sides of triangles.

Procedure: The lesson opens with the teacher showing students how a triangle can be formed using three different rods. The rods are arranged so that one corner of a rod touches each other.(The example highlighted in the CD used orange, yellow and dark green). The teacher then selects a combination of three rods (for example orange, yellow, and red) that do not come together to form a triangle. Students are encouraged to try 10 different combinations and determine whether each specific combination leads to the creation of a triangle with the three rods touching corners. Students are instructed to write the list of combinations down (length of rod and color) and indicate whether a triangle was found. In doing so, students are to look for a pattern why some combinations will and some will not result in a triangle. (In the activity, students will find that the sum of any two sides of a triangle ust be greater than the third side. If the sum of the 2 shorter sides does not exceed that of the third side, a triangle is not formed).

**In total, the CD specifies that 125 total combinations can be created (10 equilateral--all rods equal, 65 isosceles--two rods equal, and 50 scalene--all three rods of a different length)

Activity Extension--The primary focus of the activity is to see that in order for a triangle to be formed, the sum of any two sides must be greater than the third (The Triangle Inequality Theorem). The lesson can lead to a further discussion in geometry focusing on scalene, equilateral, and isosceles triangles.