Beads made from UV sensitive materials change color when exposed to the Sun, but remain colorless when indoors away from sources of UV light. How do they work? This experiment can really gets kids asking some great questions that will ultimately lead to some deep understanding of electromagnetic radiation.

Purchase some Solar beads from a science store to perform this experiment. I made some bracelets with my daughter and sent her outside at the local school. She was so excited because the beads changed color. Before I knew it, more kids were requesting these bracelets. Although she is only 4, we started by asking here questions:

• Why do they change color?
• When you are indoors do they still change color when you are next to a closed window?
• Can we stop them from changing color by putting them in plastic bags?
• What about a glass jar? What happens if we put sun screen cream on the inside of the jar?

Before we knew it she was trying to find all sorts of material to test. Does a tee shirt work?

A few years from now we will re-visit this with her to explain some science in more detail. Using a "black light" you can make the beads turn colors even though there is no visible light coming from the lamp. This can help to demonstrate the spectrum of light: your eyes are only sensitive to a certain part of the spectrum, which we perceive as going from red, though orange, yellow, green, blue, indigo and violet. But other parts of our body are clearly sensitive to more of spectrum, because spending too much time in the sun will definitely have an affect.

In fact you might ask you child how far this goes. What happens if you make the wavelength of light shorter and shorter ... does it stop? Surely if there is light with shorter wavelength than we can see with our eyes, there has to be more out there? This can very rapidly lead to a discussion of x-rays, and gamma rays. Now that's real radiation, and if you think UV light is harmful to your skin, what do think those wavelengths will do?

What about longer wavelengths? If you make the light wave length longer what do you get? You can ask them about the antenna on your car. Does the length of the antenna tell you anything about the wavelength of the radio waves it is receiving?

As you can see, these beads can be the starting point for a lot of "scientific discussion" with your kid. Challenge them, and make then answer questions. You'll be surprised. at just how much they can "get" at an early age.

Other questions:

• Short wavelength UV light used to kill bacteria. How does that work?
• UV light harmful to a lot of things, including the human body. What happens when you get a tan or sunburn?
• Some people are born more sensitive to UV light, a condition called Xeroderma Pigmentosum.
• Short wavelengths of UV light are blocked by glass. Can you test the effectiveness of this using you beads?