rainbowWith all this wacky spring weather you never know if it will be sunny or raining or both when you look out the window. Lucky for us that means plenty of rainbows. And THAT means plenty of inspiration for science projects.

Why do rainbows happen anyway? Sunlight is made up of white light. But white light is made up of other colors. When it shines through the air we see white light, but when it hits something like water, or glass, it slows down and kind of takes a right turn. Colors that have longer wavelengths don’t turn as much and colors that have shorter wavelengths turn more–so the colors get fanned out into a rainbow.  The water or glass that slows the light down and fans it out is called a prism.

It’s ALWAYS the same order Red, Orange, Yellow, Green, Blue, Indigo,  Violet (ROY G. BIV)

One experiment I love is to make a Spectroscope so kids can actually see the different colors that make up sunlight AND see the pattern.


Make a Spectroscope

All you need is an old CD and a paper towel tube to make this cool machine.


What you need


  • Empty paper towel roll
  • Craft knife and/or scissors
  • Blank or old CD
  • Pencil
  • Small piece of cardboard or cardstock
  • Tape

What You Do

  1. Stand your tube on the counter. Near the bottom, use a craft knife (an adult should do this) to cut a frown-shape slit.spectroscope





2. Directly across from the slit, make a small peephole or viewing hole using your craft knife (another step for an adult).sepctroscope slit


3. Trace one end of your paper towel roll onto your small scrap of cardboard or cardstock. Cut it out.

4. Cut a straight slit right across the center of your cardboard circle.

5. Tape the circle to the top of your spectroscope.

6.Insert the CD into your 45° angled slit with the shiny side facing up.



7. Take your spectroscope outside. Point the top slit up at the sky (NOT directly at the sun). Look through the peephole. What do you see?Now try your spectroscope with other light sources like fluorescent light, neon light and candle light. Compare what you see.


What’s going on?

A CD’s surface is mirrored with spiral tracks scratched into it. The mirror part reflects light to your eye and the tiny ridges diffract light and separate the colors of white light.