Volume of Prisms and Cylinders

Any solid shaped like a column has its volume found by multiplying the base area by the height. Practice varies the base across rectangular prisms and cubes, triangular prisms, trapezoidal prisms and hexagonal prisms, then moves to cylinders and half cylinders, and on to composite solids such as concentric pipes and two stacked cylinders, split apart or hollowed out.

With a cylinder lying down, children take the rectangular face resting on the floor as the base and multiply length, width and height. If 3.14 never appears in the answer, this is the pattern. For a prism with an irregular base, the indented part goes unsubtracted and the outer rectangle is used as it stands.

What surface gets calculated shifts from a flat figure to the base of a solid. The pi-based calculation fixed in Area of a Circle is used as a base area, and multiplied by height to find volume. The unit that follows, Surface Area of Solids, deals with the same solids but asks for the surface covering the outside, not the volume inside.