Education Technology

Dilations in the Plane (Transformations)

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