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STEM Activity: Exploring Shadows on Groundhog Day

Did you know that on Groundhog Day, people across the country watch for the prediction of winter’s length based on whether a groundhog sees its shadow? Groundhog Day originates from an old superstition that if a groundhog emerges from its burrow on this day and sees its shadow, it will return to its den, signifying that winter will continue for an additional six weeks. If the groundhog does not see his shadow, it indicates spring is on the way!

While the predictions made from Groundhog Day are not based on scientific evidence, there is science behind the sunshine and shade involved in this classic holiday. With this hands-on activity, you can explore light and shadows to understand how this fun tradition is observed.


Materials Needed:

  • Flashlight
  • Markers
  • Paper towel or toilet paper tube
  • Scissors (optional)
  • Scrap paper (optional)
  • Small object (like a toy or figurine)
  • Tape (optional)


Step-by-Step Instructions:

  1. Choose a dark room or area to conduct your experiment.
  2. Place your small object inside and at the end of your paper tube.

    Helpful hint: If you do not have an object small enough to fit inside the tube, you can draw something on scrap paper, cut it out and tape it to the end.
  3. In a darkened space, hold your flashlight against the open end of the tube, opposite from the object. Turn on the flashlight and watch as the light travels through the tube.

    You’ll notice the object is illuminated and casts a shadow on the wall or surface in front of you.
  4. Try moving your tube with the object inside closer or farther away from the wall or surface, then try moving the flashlight closer or farther away from the tube.
  5. Experiment using toys or figurines of different shapes and sizes or create more objects using scrap paper.


What Are We Discovering?

Lights and shadows occur all around us. When light is cast onto an object, it blocks the light, creating a shadow in the shape of the object. This occurrence relates to the groundhog and whether it sees its shadow due to the presence or absence of sunlight.

Different sources of light like flashlights, light bulbs, candles and the sun play a crucial role in our everyday lives! The evolution of light technology has been greatly influenced by National Inventors Hall of Fame® Inductees Lewis Latimer, who invented the durable carbon filament for electric light bulbs, and Thomas Alva Edison, inventor of the electric lamp. Both experimented with light, making it possible for us to safely enjoy illumination in our homes.


Keep the Fun and Learning Going!

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