Bioluminecence: Light produced by living organism.

light ray: a straight-line beam of light as it travels outwards of it source.

Law of Reflection: the angle of an incomming light ray equals the angel of the reflected ray.

Concave mirror: a mirror that curves in on the shiny side.

Convex mirror: a mirror that curves out on the shiny side.

Opaque: completely blocking light from passing through.

Transparent: letting all light through, so that objects on the other side can be seen clearly.

Translucent: letting only some light through, so that objects on the other side appear blurry.

Polarization: allowing light vibrations to pass through in only one direction.

Refraction: the bending of light rays as they pass from one substance into another.

Convex lens: a lens that curves outward (is thicker at the middle than at the edges) and brings light rays together.

Concave lens: a lens that curves inward (is thicker at the edges than at the middle) and spreads light rays apart.

Prism: a cut piece of clear glass (or plastic) with two opposite sides in the shape os a triangle or other geometric shape.

Spectrum: a band of colors produced when light goes through a prism.

Primary color: red, green, or blue; mixing these colors can produce all the colors of the spectrum.

Primary pigment: magenta, cyan, yellow; material with any of these colors absorbs one primary color of light and reflects the other two.