Education Technology

Investigating Segments in a Quadrilateral

Activity Overview

In this activity, students use the tools of Cabri™ Jr to test their knowledge of geometry. They investigate the properties of the shape formed by connecting the midpoints of adjacent sides of a quadrilateral. 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
  • See the attached PDF file for detailed instructions for this activity
  • Print pages 34 - 35 from the attached PDF file for your class
  • During the Activity

    Distribute the pages to your class.

    Follow the Activity procedures:

  • Draw a quadrilateral
  • Find the midpoints of the sides of the quadrilateral
  • Draw segments to join the midpoints of adjacent sides of the quadrilateral
  • Explore characteristics of the shape formed
  • Show that one pair of opposite sides is parallel and congruent
  • Test this conjecture on other quadrilaterals by moving to a vertex
  • After the Activity

    Review student results:

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