For most students, the hardest part about finding the volume of a solid of revolution is identifying whether to use disks or washers* and what the radius/radii are. This set of 24 problems lets students focus on those two important aspects, with four sets of six related problems. Students are not asked to complete the (sometimes tedious) calculations to find the volume; instead, they are asked only to focus on identifying whether to use disks or washers and giving expressions for r (and R, for washers).
An answer key is included.
*This file does not include any problems that need to be solved by the shell method.