Students will measure the circumference and diameter of round objects. They will send in their measurements through TI-Navigator™ and discover the relationship between the circumference and diameter.
Students will note why all points do not lie exactly on the line y=PIx. Then students will use Cabri™ Jr. to measure the circumference and diameter of a circle. Once they send their second set of measurements, students will note why all points created from Cabri Jr. lie exactly on the line y=PIx.

Students should have access to either the TI-83 or TI-84 family of calculators and the attached document.

Detailed directions for the student and teacher are in the attached document. An application variable that is a constructed circle with diameter is also attached.
I. Have students complete the handout (see attached document). II. Have students send in their data through the TI-Navigator™. III. Plot the students' data in the Activity Center, discuss the relationship between the circumference and diameter, and then plot the line y=PIx. IV. Have students collect data for a constructed circle in Cabri™ Jr. and send in their data through the TI-Navigator. V. Plot the students' data and discuss why the computer-generated data lies exactly on the line.

Review student answers: