A spectroscope is a device that lets us find out what things are made of. It works by taking light and splitting it up into its component colors. Different elements make different colors when they glow. We can make objects and gasses glow by heating them up in a flame, or by passing electricity through them. The spectroscope spreads out the colors of the light, and we can identify the elements by the bright lines we see in the spectroscope.
I begin this lesson telling students that today they will build instrument that splits light into its different wavelengths, which humans see as different colors. Students have spent several prior lessons learning about light and the electromagnetic spectrum. Violet has the shortest wavelength that people can see and red the longest. This instrument can also identify wavelengths that humans cannot see, such as infrared and ultraviolet radiation. Light usually contains a mixture of different wavelengths; by studying these, scientists can find out useful information, such as the chemical elements present at the source of the light. Spectroscopes are widely used in astronomy, chemistry, and other areas.
For the majority of this lesson, students build spectroscopes with paper, cd, and black crayons. I pass out all the supplies prior to students entering the classroom. Each student receives: a clear CD-R, a marker for tracing, heavy construction paper, scissors, ruler, and masking tape.
I display the directions for all students. Making Simple Spectroscopes I go over the directions and show students how to fold the tabs. Next, I direct students to construct and build their spectroscope.
As students build their spectroscopes, I circulate around the room and assist as necessary.
You can see in these photographs students cutting and folding in order to create a spectroscope.
One challenge I had for this lesson was videoing students constructing their spectroscope. I ended up helping many students with the folding, gluing, and taping. Watch the video below to see some finished spectroscopes and hear my thoughts about changing the spectroscope design.