Volume of a Sphere

The Volume of a

Sphere

Lesson # 20

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2019 Open Up Resources |

Let’s explore
spheres and their
volume.

Today’s Goals

❏ I can find the volume of a sphere when I know the radius.

A Sphere in a Cylinder

Activity 20.2

● Notice & Wonder

● MLR7: Compare & Connect

Comprehend/ Apply: Activity
20.2

●Which is bigger, the volume of the
sphere or the volume of the
cylinder?

●

What do you notice? What do you wonder?

​Let's answer Questions 2 - 3 as a class.

Spheres in Cylinders

Activity 20.3

● MLR5: Co-Craft Questions &

Problems

Comprehend/ Apply:
Activity 20.3

​Now, let's focus on all questions
as a class.

Organize- Lesson 20 Synthesis

● A quick estimate for volume of a sphere is V≈ 4/3r3

● How good of an approximation is this? Can you

think of a better one?

● Calculate the volume of a sphere with a radius of

10 inches using:
○ The actual volume formula
○ The approximation formula
○ Your own approximation formula

Volume of Spheres

Practice Problems

Apply/ Summarize:
Activity 20.4

​I will explain how to complete this problem.

Practice Problems

Volume of a Sphere

Apply/ Summarize:
Activity 20.4

Multiple Choice

What is the volume of the sphere?

• 8π cm³

• 36π cm³

• 144π cm³

• 288π cm³

Multiple Choice

A soccer ball has a radius of 11 cm. Using π ~ 3.14, what is the approximate volume of the soccer ball in cubic centimeters?

• 1520

• 3135

• 4772

• 5572

Multiple Choice

A large sphere at an amusement park is 165 feet in diameter. Which of the following is closet to the volume, in cubic feet, of the sphere?

• 261,000

• 2,351,000

• 18,810,000

• 41,210,000

Multiple Choice

Which three dimensional figure is associated with the volume formula, $$V=\frac{4}{3}\pi r^3$$ ?

• cylinder

• sphere

• prism

• cone

Today’s Goals

❏ I can find the volume of a sphere when I know the radius.