Lesson 18

In this lesson students learn that the volume of a cylinder is the area of the base times the height, just like a prism. This is accomplished by considering 1-unit-tall layers of a rectangular prism side by side with 1-unit-tall layers of a cylinder. After thinking about how to compute the volume of specific cylinders, students learn the general formulas \(V=Bh\) and \(V=\pi r^2 h\).

In the warm-up, students recall that a circle’s area can be determined given its radius or diameter. Students also become familiar with what is meant by radius and height as those terms apply to cylinders. Next, students compute the volume of a cylinder by multiplying the area of its base by its height. Finally, students compute volumes given radius and height, and find radius or height given a cylinder’s volume and the other dimension by reasoning about the structure of the volume formula.