Light is a form of energy. It interacts with matter, or the material that makes up an object, in different ways based upon the qualities of that material. Light passes through objects that are transparent. These items appear to be clear. Materials that are translucent let some light pass through, but this light is scattered. These items look milky or fuzzy. Some materials are reflective, or bounce light back. Reflective items are shiny. And objects that are opaque block the light.

As Barkley and Ted learned in this video, shadows are created when light is blocked by an object. A shadow takes the shape of the object that is blocked. Depending on how close the object is to the light source and the nature of the light source, the shadow may be the same size as the item, smaller than the item, or larger (like Barkley's frightening bug) than the actual item. The closer an object to the light source, the larger and fuzzier the shadow. It’s fun to “play” with creating shadows and changing their shapes.

Nature has some special events based upon shadows. During a solar eclipse, the Earth’s moon passes between the Earth and sun, blocking the sun and casting a shadow on the Earth. The moon is nearly 400 times smaller than the sun, but it can block the sun's light because the sun is so much farther away.

During a lunar eclipse, the Earth is directly between the sun and the moon, blocking the sun’s light and casting a shadow on the moon. Usually, the moon looks bright due to the sun’s light reflecting off of its surface.

Since the moon relies on light from the sun, only half of the moon is bright. You can demonstrate this by using a small ball (to represent the moon) and a flashlight (to represent the light from the sun). In a darkened room, shine the flashlight on the ball and you’ll notice that only half of the ball is lit. Because the ball (moon) is opaque, the light of the flashlight (sun) is blocked. Only half of the moon is lit at anytime. And … when the Earth lines up just right, it can sometimes block the sun’s light from reaching the moon at all. Luckily, this doesn’t happen often and when it does, it lasts for only a few minutes.