This Instructional Activity is a part of the Lesson 20, Unit 5, Grade 8. The purpose of this activity is to build from the concrete version in the previous activity to a generalized formula of a sphere with an unknown radius. The previous activity prepared students with strategies to work through this task where they must manipulate the variables in the volume equations. Students first calculate the volume of the cylinder and cone in the activity and use what they learned in the previous activity to calculate the volume of the sphere. Finally, they are asked about the relationship between the volume of the cylinder and sphere, which connects back to the discussion of the previous activity.