Education Technology

Midsegment of a Trapezoid

Published on 06/09/2008

Activity Overview

Students study the Midsegment Theorem for Trapezoids.

Before the Activity

Install the Cabri™: Jr. App on the students' graphing calculators using one of these two methods:

  • TI-Connect™,  a TI Connectivity Cable, and the Unit-to-Unit Link Cable
  • TI-Navigator™  "send to class" feature
  • See the attached PDF file for detailed instructions for this activity
  • Print pages 45 - 47 from the attached PDF file for your class
  • During the Activity

    Distribute the pages to the class.

    Follow the Activity procedures:

  • Construct a segment AB
  • Construct a segment CD parallel to AB (not of the same measure)
  • Construct segments AD and BC to form a trapezoid ABCD
  • Drag point A so that AD is not parallel to BC
  • Construct a midsegment by joining the midpoints of segments AD and BC
  • Alter the trapezoid and check whether the midsegment is parallel to segments AB and CD
  • The midsegment is parallel to the two parallel sides of the trapezoid
  • Measure the lengths of AB, CD, and the midsegment
  • Observe that the length of the midsegment is half the sum of the lengths of AB and CD
  • Alter the trapezoid
  • Observe that for all trapezoids, the length of the midsegment is half the lengths of the two parallel sides
  • After the Activity

    Review student results:

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