# Activities

• • • ##### Subject Area

• Math: Middle Grades Math: Algebraic Thinking
• Math: Middle Grades Math: Geometry
• Math: Middle Grades Math: Measurement
• Math: Middle Grades Math: Number Sense
• Math: Middle Grades Math: Statistics and Probability

• ##### Author 6-8
9-12

75 Minutes

• ##### Device
• TI-83 Plus Family
• TI-84 Plus
• TI-84 Plus Silver Edition
• TI-Navigator™
• ##### Other Materials
Teacher Notes Student Handout

## Function of a Circle

#### Activity Overview

Students use Cabri,Jr. to construct a circle and its radius, measure both the circumference and the radius, and then collect data showing the relationship between the two. Using the TI-Navigator students input their data into lists and see the scatterplot of the collected data displayed on a coordinate system. They discover that the relationship is linear, a direct variation, and that the constant of variation is a very special irrational number (but NOT pi!).

#### Before the Activity

Teacher's Notes Activity Overview

#### During the Activity

*Activator (a pretest using Learn Check with Quick Poll) *Find attached a word document file for detailed instructions for the Cabri,Jr. construction. *Also attached is a similar word document to use if students do not have time to create this construction. An AppVars is attached with construction complete.

#### After the Activity

Administer LearnCheck B and review results using Class Analysis. Use the formula C = pi * d to show development of 6.28 using the commutative and associative properties. If students did not input the correct equation this helps them see the relationship between the formula and the equation.