# Surf for More Math

## CHAPTER 5: MEASUREMENT

**Lesson 6: Calculating the Area of a Circle **

Use these interactive activities to encourage students to have fun on the Web while learning about measurement. Students can try these activities on their own or in pairs.

**Goal**

Develop and apply the formula for the area of a circle.

**Builds Upon**

Student book pages 216–219

**Instructions for Use**

**Interactive Area of a Circle** allows students to explore the relationship between area, radius, and circumference of a circle.

Click and drag a point on the circle. Note how the calculation for area changes when the radius of the circle changes. Recall that the raised 2 after the r means that r is multiplied by itself (r2 = r × r).

**Calculating Areas** is an online quiz that allows students to practice calculating the area of a variety of shapes, including circles.

Take this online quiz to show how you are able calculate the area of a variety of shapes. Find the solution to each problem using a paper, pencil and a calculator. Then select your answer from the options given (A, B, C or D). Click the “Check It” button at the end of the quiz to check your answers.