The Volume of a Sphere

5 min

Teacher Prep
Setup
1–2 minutes of quiet work time followed by a whole-class discussion.

Narrative

The purpose of this activity is for students to practice sketching spheres and labeling the radius and diameter of the sphere.

Launch

Give students 1–2 minutes of quiet work time, and follow with a whole-class discussion.

Student Task

Here is a method for quickly sketching a sphere:

  • Draw a circle.
  • Draw an oval in the middle whose edges touch the sphere.

<p>Two images.  First, a circle.  Second, a circle drawn with an oval in the middle whose edges tough the sphere. Half of the oval is dotted to indicate that it would be on the back of the sphere.</p>

  1. Practice sketching some spheres. Sketch a few different sizes.
  2. For each sketch, draw a radius and label it rr.

Sample Response

  1. Answers vary.
  2. Answers vary.
Activity Synthesis (Teacher Notes)

Invite students to share their sketches. Ask students to share what the diameter would look like if they did not already draw one in. Remind students that sketches can be used to help visualize a problem where an image might not be provided. In today’s lesson, they will be working with activities that may or may not have images provided, and they should sketch images or label any images provided to use as a tool to help understand the problem thoroughly.

Standards
Addressing
  • 8.G.C·Solve real-world and mathematical problems involving volume of cylinders, cones, and spheres.
  • 8.G.C·Solve real-world and mathematical problems involving volume of cylinders, cones, and spheres.

20 min

10 min