# 6th Grade - Find The Circle's Area And Circumference

 Grade Level: 6th Skill: Geometry Topic: Find the Circle's Area and Circumference Goal: Understand the concept of a constant such as pi; know the formulas for the circumference and area of a circle. Skill Description: Understand that pi is the ratio of the circumference of any circle to its diameter. Pi can be written using the symbol . Since pi is the ratio of c to d, it is always worth the same value. Sixth graders are required to round pi to the value of 3.14 in decimal form or 22/7 in fraction form. However, the value of pi is an approximation because pi is an infinite decimal. In fact, using a computer to get a closer estimation of pi, you’d get 3.14159265358979323846.

## Building Blocks/Prerequisites

### Sample Problems

 (1) A hat has a diameter of 6 inches. Which formula could be used to find the area of the hat? (a) A = 6 (b) A = 12 (c) A = 36 (c) (2) Which is the correct algebraic representation for the area of a circle? (a) A = d (b) A = rr (c) A =  r2 (b) (3) A can lid has a diameter of 12 cm. Write the formula that should be used to find the circumference of the can lid. (C   x 12) (4) A Frisbee has a radius of 4 in. Express algebraically the formula that should be used to solve for circumference. Express algebraically the formula that should be used to solve for circumference. (C   (r x 2) or C  (4 x 2)) (5) A car tire has radius of 12 inches. What is its diameter? (24)

### Online Resources

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