Education Technology

Circles in the Plane

Activity Overview

In this activity, students will use the Cabri™ Jr. application to explore circles in a plane. They will investigate the relationship between the equation of a circle, the length of its radius, and the coordinates of its center.

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 65 - 71 from the attached PDF file for your class
  • During the Activity

    Distribute the pages to your class.

    Follow the Activity procedures:

  • Show the coordinate axes and create a circle
  • Measure the radius of the circle, display the equation of the circle, and the coordinates of the center
  • Drag the circle, the center, and the radius point and observe the changes
  • Construct a point on the circle, and measure its distance to the center
  • Construct a point not on the circle, and measure its distance to the center
  • Examine the relationship between the coordinates of the center, the length of the radius, and the equation of the circle
  • 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