Light and shadows surround us throughout most of the day—and even through the night, except in the darkest places. When we walk around outside on a bright sunny day, our shadows follow us wherever we go, changing in shape and size, and sometimes providing some very funny representations of our true selves. Whoever heard of a 12-foot-tall second grader? Trees and flowers and fences and pets cast shadows, too. These representations generally mimic the shape and movements of the objects and creatures that create them, but sometimes they play tricks on our eyes.

Although it's not possible to perform shadow tricks just anywhere, the requirements for creating shadows are simple. First, you need a source of light, preferably a strong one like the Sun. Next, you need a surface on which to cast a shadow. Lastly, you need an object between the light source and the surface that will block light and keep it from continuing on its path.

Light is a form of energy that radiates from its source in all directions in much the same way that waves travel away from a splash caused by a stone tossed into a pond. No matter where light originates—from the Sun or from a light bulb—it travels in straight lines as it passes through space until it encounters an object. Objects that are made of materials through which light passes uninterrupted are called transparent. Materials that completely block light are called opaque; those that let some light pass, but through which you cannot see clearly, are called translucent.

Performing shadow tricks is a fun way to explore how light behaves when it encounters various materials and objects. In this video segment, the children use the Sun as their light source and a sheet as the surface on which to project their shadows. They use their bodies and other opaque objects such as balls to block the light and cast shadows onto the sheet. Because the children use a translucent sheet as their screen, the audience sees only the shadows that the actors cast, while details of their activities remain hidden from view.

Print Background Essay