Education Technology

Exploring the Orthocenter of a Triangle

Published on 06/09/2008

Activity Overview

In this activity, students use the Cabri™ Jr. tools to draw altitudes in a triangle. They construct a line perpendicular to a given line and through a given point. NCTM Geometry Standard covered: Analyze characteristics and properties of 2- and 3-dimensional geometric shapes and develop mathematical arguments about geometric relationships.

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
  • Set up the TI-Navigator™ system
  • See the attached PDF file for detailed instructions for this activity
  • Print pages 19-20 from the attached PDF file for your class
  • During the Activity

    Distribute the pages to your class.

    Follow the Activity procedures:

    • Draw a triangle
    • Draw the altitudes of the triangle
    • Locate the orthocenter
    • Explore properties of the orthocenter

      TI-Navigator activity:
    • Use Screen Capture to observe and assess individual progress in drawing and exploring

    After the Activity

    Review student results:

  • As a class, discuss questions that appeared to be more challenging
  • Re-teach concepts as necessary