Education Technology

# Activities

9-12

60 Minutes

• ##### Device
• TI-83 Plus Family
• TI-84 Plus
• TI-84 Plus Silver Edition
• ##### Software

Cabri Geometry™
TI Connect™

• ##### Accessories

TI Connectivity Cable

• ##### Other Materials
This is Activity 11 from the EXPLORATIONS Book:
Exploring The Basics Of Geometry With Cabri

## Midsegment of a Trapezoid

#### 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.

• 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