This small group activity or lecture is designed to help students understand how to construct infinitesimal volume elements in cylindrical and spherical coordinates.
Students determine how a pineapple (for cylindrical) or a pumpkin (for spherical) should be cut to construct a volume element in the corresponding coordinate system.
The whole class discussion focuses on integration in curvilinear coordinates.
This activity emphasizes geometry of volume elements which provides students with a concrete three dimensional example of how to construct volume elements in curvilinear coordinates.