How to Make a Rainbow in a Classroom

One of the most beautiful phenomena in nature is a rainbow. A rainbow is created when sunlight is refracted through water in the atmosphere. This is why a rainbow is visible after rain. Sunlight appears white but consists of different wavelengths of light that we see as colours. The colours of the rainbow are red, orange, yellow, green, blue, indigo and violet. Create a rainbow in a classroom using water, a mirror and light.

Place a mirror inside the beaker. Make sure the mirror is clean and does not have fingerprints, etching or stickers. Rest the mirror against the side of the glass at a 45-degree angle. Secure it with waterproof tape.

Fill a clear glass beaker with water. Markings may interfere with the light refraction and prevent a rainbow from being visible. Substitute a clear glass jar if necessary.

Place the beaker on a table. Have a student hold white poster board or cardboard in front of the beaker facing the mirror.

Turn on your light source. Close curtains and draw blinds. Ask a second student to shine light on the mirror. The light reflects off the mirror through the water and onto the cardboard. The water molecules bend the light and create a rainbow on the paper.


Sunlight works best as the light source. If the rainbow is faint or does not appear, adjust the angle of the mirror until the rainbow is visible. Try different types of lights (florescent, incandescent and LED) and compare the results. Which type of light creates the brightest rainbow?

Things You'll Need

  • Source of light
  • Glass beaker
  • Mirror
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About the Author

Robin Reichert is a certified nutrition consultant, certified personal trainer and professional writer. She has been studying health and fitness issues for more than 10 years. She holds a Bachelor of Arts in psychology from the University of San Francisco and a Master of Science in natural health from Clayton College.