Prism-shaped objects you'll see in everyday life include ice cubes, barns and candy bars. The regular geometry of the prism makes it useful for designing buildings and simple products. You'll also find prisms in the natural world, such as mineral crystals.

## Prisms: Geometric Objects

Prisms are mathematically defined as solid objects with flat sides, identical ends and the same cross section throughout the entire length of the object. Cones, cylinders and spheres aren't prisms because some or all of their sides aren't flat. There are several types of prisms, such as:

- rectangular prisms
- cubes
- triangular prisms
- pyramids
- pentagonal prisms
- hexagonal prisms

## Cubes: Useful and Decorative

Cubes are often the easiest and most common prism to locate in everyday life. **A cube has equal-length sides and same-size faces, giving it a three-dimensional square shape. ** Examples of common cubes include: dice, square ice cubes, Rubik's cubes, square tissue boxes, sugar cubes, solid square tables and square pieces of cake, casserole, fudge or cornbread. Children's toys, such as solid wood, plastic and fabric blocks, are available in cube shapes. Some outdoor planter stands and decorative seating, such as ottomans, come in a variety of cube sizes.

## Rectangular Prisms: Boxes and Tanks

Rectangular prisms are similar to cubes, but the **cross sections are rectangular with unequal adjacent sides,** giving them a 3-D rectangular shape. Some examples in everyday life include: rectangular tissue boxes, juice boxes, laptop computers, school notebooks and binders, standard birthday presents -- such as shirt boxes -- cereal boxes and aquariums. Larger structures, such as cargo containers, storage sheds, houses and skyscrapers are also rectangular prisms.

## Pentagonal Prisms: Sometimes Irregular

Even though you don't see too many examples of pentagonal prisms in daily life, one is quite common -- the barn. **Many pentagonal prisms, such as barns, are irregular because the sides don't have equal edge lengths or equal angles. ** However, all of the cross sections are the same and they have flat sides and matching ends. The Pentagon, which is the headquarters of the U.S. Defense Department, is another example of a pentagonal prism.

## Triangular Prisms: Trestles and Bars

A triangular prism has **two triangular bases and three rectangular sides** and is a pentahedron because it has five faces. Camping tents, triangular roofs and "Toblerone" wrappers -- chocolate candy bars -- are examples of triangular prisms.

## Pyramids as Prisms

**A pyramid is also a pentahedron, but it only has one rectangular side and the four triangle-shaped sides meet at a single vertex or point**. Pyramids aren't easy to find in everyday life. However, they have symbolic meaning in Egyptian culture, so some artists and designers incorporate pyramids into their artwork, sculpture, interior design or architecture. The Great Pyramid of Giza in Egypt and the Great American Pyramid in Memphis, Tennessee are prime examples of pyramids.

## Hexagonal Prisms: Nuts and Bolts

**Hexagonal prisms have eight faces and are considered octahedrons. ** They have two hexagonal bases and six rectangular sides. You don't usually find large-scale examples of hexagonal prisms, but there are several small-scale examples, such as unsharpened pencils, bolt heads and hardware nuts.

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About the Author

As curriculum developer and educator, Kristine Tucker has enjoyed the plethora of English assignments she's read (and graded!) over the years. Her experiences as vice-president of an energy consulting firm have given her the opportunity to explore business writing and HR. Tucker has a BA and holds Ohio teaching credentials.