Education Technology

Dilations in the Plane (Transformations)

Published on 06/09/2008

Activity Overview

In this activity, students will explore the properties of dilations and the relationships between the original and image figures.

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 cables
  • See the attached PDF file for detailed instructions for this activity
  • Print pages 31 - 40 from the attached PDF file for your class
  • During the Activity

    Distribute the pages to your class.

    Follow the Activity procedures:

  • Construct a slider tool to generate a number in the range of approximately -4.5 to 4.5 units
  • Draw a small scalene triangle on the left half of the screen and mark a point in the center of the screen
  • Dilate the triangle
  • Investigate the relationship between the original triangle (the pre-image) and the new triangle (the image)
  • Drag a vertex of the pre-image and the center of dilations
  • Observe what happens to the image
  • Measure the lengths of corresponding sides, angles, and areas of the pre-image and image
  • Explore different dilation factors
  • After the Activity

    Students will fill in the Data Collection and Analysis sheet.

    Review student results:

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