Provide a prism for every three to four students in an elementary school class. Expose the prisms to sunlight and manipulate them until the light splits into the colors of the rainbow. Point out how the colors flow from one to another. Pour water into a bowl and shift it until you produce a rainbow with the water. Alternatively, mist water with a water hose, shifting the mist in the full sun until the class can find the rainbow reflecting off the water droplets.
Spectroscopes split light from an individual star and determine the composition, temperature and distance of the star based on how the colors split. Dark lines in each color identify specific elements, such as iron, hydrogen, helium and oxygen. Provide the spectra for common elements and project them on a whiteboard or smartboard. Using spectral data available on the Internet, have junior high or high school students compare the identified elements with the spectra of various stars and identify the elements contained in each star.
Gratings break light up into its spectral colors. A common CD will break up light into its various spectral colors, and the colors will change if you change the kind of light you aim across the face of the CD. Angle the CD so that it reflects the light inside the room. Note the colors and patterns of the lightwave. Now turn off the light in the room and use a different kind of bulb or light source. An incandescent light bulb provides a different spectrum than the light from sunlight, a fluorescent bulb, a halogen light, candlelight or laser light. Have middle school students compare the different patterns. Compare results using a DVD.
The colors you see in the rainbow provide only a small portion of the light emitted by our sun. Gamma rays, X-rays and ultraviolet rays make up the left side of the visible spectrum, and infrared and radio waves exist on the right side. Each of these types of lightwave has a different length, with the radio waves being longer and wider than gamma or X-rays. Demonstrate using a rope tied to a door that more energy is required to create shorter wavelengths. Have an elementary or middle school student grab the other end of the rope and lift his arm up and down to create waves in the rope. Explain that the short X-rays produce damage because they have more energy behind them and can therefore probe deeper into solids than radio waves.