Circumference and Diameter of Circles

This lesson by Mr. Richards covers the concept of circumference, focusing on understanding and calculating the circumference of circles. Key terms such as radius, diameter, and center are explained. Real-world examples are provided to illustrate the relationships between these terms. The lesson includes formulas for calculating radius and diameter, as well as the circumference using Pi. Practice problems are included to reinforce learning, and the lesson concludes with a summary of key points.

What is the main objective of today's lesson?

• To find the circumference of circles

• To find the area of squares

• To calculate the volume of cylinders

• To measure the perimeter of triangles

Which term describes the distance around a circle?

• Diameter

• Center

• Circumference

• Radius

How is the diameter related to the radius of a circle?

• Diameter is three times the radius

• Diameter is equal to the radius

• Diameter is twice the radius

• Diameter is half the radius

If the diameter of a circle is 14 inches, what is the radius?

• 28 inches

• 7 inches

• 21 inches

• 14 inches

What formula is used to find the circumference of a circle using its diameter?

• Circumference = 2 * Pi * radius

• Circumference = Pi * radius

• Circumference = diameter / 2

• Circumference = Pi * diameter

What is the approximate value of Pi often used in calculations?

• 3.14

• 4.13

• 2.71

• 1.62

If a circle has a radius of 21 inches, which approximation of Pi should be used?

• 3.14

• 22/7

• 3.15

• 3.1415

What is the circumference of a circle with a diameter of 70 inches using 22/7 for Pi?

• 240 inches

• 210 inches

• 230 inches

• 220 inches

What is the circumference of Big Ben's clock face if its diameter is 23 feet?

• 74.3 feet

• 70.5 feet

• 72.2 feet

• 71.8 feet

How much fencing is needed for a circular fence with a diameter of 4 feet using 3.14 for Pi?

• 11.56 feet

• 12.56 feet

• 13.56 feet

• 14.56 feet