Surface Area And Volume

Once shapes leave the flat page and become solid, two new measurements matter: how much space a solid takes up, and how much surface it has. Volume tells you the capacity of a box, a tank or a tin; surface area tells you how much material wraps it or how much paint covers it. A small family of formulas handles cuboids, prisms, cylinders, spheres, cones and pyramids.

In this lesson you will calculate the volume and surface area of the standard solids, learning how prisms all share one idea (cross-section times length) and how the curved surfaces of cylinders, cones and spheres are found. The key habit is keeping track of units: volume is always cubic and surface area always square, and confusing them is the classic mistake this lesson trains you to avoid.