Education Technology

# Activities

• ##### Subject Area

• Math: Geometry: Triangles

9-12

20 Minutes

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

TI Connect™

• ##### Accessories

TI Connectivity Cable

## Investigating Lengths of Segments in a Triangle

#### Activity Overview

In this activity, students connect the midpoints of two sides of a triangle, to draw the midsegment of the triangle. They investigate how the length of this segment relates to the third side of the triangle. 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 28-29 from the attached PDF file for your class
• #### During the Activity

Distribute the pages to your class.

• Draw a triangle
• Find the midpoints of two sides of the triangle
• Draw and measure the segment joining the midpoints of these two sides
• Compare the length of this segment to the length of the third side of the triangle

• 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