Activity Overview
The centroid, circumcenter, orthocenter, and incenter are the four classic centers of a triangle that are studied in geometry. In this activity, you will construct these center points and discover their properties.
Before the Activity
Install the Cabri Jr. App on the students' graphing calculators using TI-Connect™, a TI Connectivity Cable and the Unit-to-Unit Link Cable
Use the TI-Navigator™ to transfer the attached Cabri Jr. AppVar files to each calculator
See the attached PDF file for detailed instructions for this activity
Print pages 117 - 120 from the attached PDF file for your class
During the Activity
Distribute the pages to your class.
Follow the Activity procedures:
Use the AppVar to go directly to the exploration section
Construct a triangle and its centroid
Construct a triangle and its circumcenter Construct a triangle and its orthocenter Construct a triangle and its incenter
Investigate the properties of the figures drawn
Drag the vertices and sides of the triangle and observe the changes that the figures undergo
After the Activity
Review student results:
As a class, discuss questions that appeared to be more challenging
Re-teach concepts as necessary