PBS in the Classroom

What Makes a Shadow? Engaging Activities with Nature Cat

  • SHARE:

January, February, March—will winter ever end? When you look outside, the earth is either buried under snow and ice or largely colorless, odorless, and dormant or dead. Everything seems to be holding its breath! Even a walk through Daisy’s garden shows no change—just the same brown, bent over stalks and frozen ground. You know there is life hidden all around you (see All a ‘Hush’ in Daisy’s Garden), but you are looking for an inspired, teachable, tangible moment for today. 

So let’s get your students excited about heading outside for a little nature exploration. How about some shadow play and some observations about a particular shadow over time? 

It’s a fact: Since the winter solstice (see episode 123B, Winter Dance Party), the days have been getting longer and the nights shorter. It’s hardly noticeable at first. Tomorrow will only be about one minute and 25 seconds longer than today. But as those minutes add up, you become increasingly aware of the extra daylight. It’s no longer so dark when you return home from school!

This return of the light is something to celebrate, and, indeed, cultures have honored and feted the winter solstice for thousands of years—often in conjunction with their hopes for a productive growing season. The ancient Romans held a weeklong celebration called Saturnalia to honor Saturn, the god of agriculture. Farther north, the ancient Norse celebrated Yule by lighting logs and feasting. For each spark of fire, the Norse believed a new piglet or calf would be born in the coming spring. In Japan, the winter solstice is especially important to farmers, who rejoice that the Sun has ‘returned’ to support the crops they will plant.

So much for the Sun, but what does that mean for our shadows? The Sun “moves” from roughly east to roughly west across the sky each day. The Sun’s height above the horizon also changes each day. The Sun reaches highest above the horizon in the summer, and stays closest to the horizon in the winter. When the Sun is at its highest, shadows are at their shortest; when it’s at its lowest, shadows are at their longest. But in between, the shadow lengths are changing.

During winter, shadows are longer because the Sun appears lower in the sky (closer to the horizon) than it does during the spring, summer and fall. But each day since the winter solstice, winter-length shadows are getting a little bit shorter. You can track this change in the shadows around us. In fact, tracking the length of a shadow at the same time and place over time is one way ancient cultures marked the passage of the different seasons.

To demonstrate the interplay between shadows and the position of a light source, stick a pencil vertically into a lump of clay on a table or desk. Dim the lights in your classroom and use a flashlight to make a shadow. Ask students to tell you what you have to do to change the length of the shadow. [Raise the flashlight higher or lower than where it was at the start.] Have them make guesses about how the shadow will change as you raise or lower it. Then move the flashlight higher and lower to show what happens.

Explain that you are going to observe similar shadow changes outdoors, as the sun moves higher and higher above the horizon each day. To connect with the natural world, you can point out that the changing amount of the Sun’s light and warmth triggers a plant or animal’s response to what it can and should do at various points throughout the year. For birds, for example, it triggers when to mate and build a nest, or when to migrate; for butterflies and their caterpillars, it triggers when to lay eggs, and when to hibernate or migrate; for humans, it triggers when to till the earth for spring planting, or when to insulate against the cold.

Ready to head outside? Find an open area that receives sunlight (a garden, a playground, a field) and that you can return to from time to time with your students over a period of three to four weeks. Here we will track the length of shadows, and make the connection between the height of the Sun in the sky and the amount of heat and daylight we experience.

Materials:

  • Vertical object (garden stake, playground slide, tree stump—anything upright that casts a shadow you can measure)
  • Measuring tape
  • Clock
  • Sunny day

Whichever object you use should be in a place where the shadows of other objects won’t interfere with your measurements. For the activity to be successful, your object needs to stay in the same place and position during the period you are taking your measurements.    

Decide on a time of day to take your measurements. You are going to measure the length of your object’s shadow every few days, at the same time, depending on available sunshine. Once a week over a longer period of time also works. To measure, start at the base of the object and measure to the farthest tip of the shadow. Note on a chart (see below) how long it is each time you measure. Over time, help children notice that the shadow is growing shorter.

You can then draw the connection between warmth and height of the Sun above the horizon. For example, as the Sun moves across the sky, higher and higher above the horizon, the warmer the Sun feels. This is exciting news for those who dislike the cold—though your shadow may be shrinking, the Sun is feeling stronger by the day.

Example of simple chart: 

Date/time (at the same time each day)

Length of shadow



 


Bonus Activity: Have students close their eyes and turn their faces toward the Sun each time you go outside to soak up some of the Sun’s warmth for a few minutes. (Wind chill can interfere with this, so it won’t work on blustery days unless you can find a place out of the wind.) By March, your students should be able to feel that the warmth is greater on their faces.

These kinds of activities give young children tangible ways to observe that the quality of daylight is changing and what that means for them and other living things. You are helping them develop specific sensitivities to seasonal shifts as we move from winter towards spring—a sensitivity that can help shoo away the winter blues. Now doesn’t the sunshine feel grand on your face?

Frances Nankin and Jesse McMahon Content Producers and Writers

Frances Nankin is an award-winning editor, writer and television/Web producer with more than 35 years experience developing content for children’s educational media. Prior to her current role as Content Producer for NATURE CAT with Spiffy Entertainment, she was Executive Producer/Editorial Director for the CYBERCHASE series with Thirteen/WNET, New York. Before that, she was Co-director of Science Content for THE MAGIC SCHOOL BUS TV series with Scholastic Productions. Nankin, a self-taught naturalist who grew up in the Ramapo Mountains of New York, is the author of several science-related books for children, and was the founding editor of a number of children’s magazines, including COBBLESTONE, a history magazine now in its 39th year of publication. 

Jesse McMahon, Content Producer for Nature Cat, holds a master’s degree in journalism, and brings to the team more than a decade of experience in research and writing in print media and educational publishing. She  telecommutes from Maine, where she lives with her husband, two dogs and numerous chickens. McMahon's other TV credits include Content Brief Writer for Cyberchase and Science Consultant for Magic School Bus Rides AgainMcMahon's byline has also appeared in numerous publications, including The Boston Globe, ProPublica and the Investigative Reporting Initiative at Northeastern University. Her commitment to volunteer work in environmental advocacy and deep respect for the natural world is a passion she is delighted to transfer to young viewers.

Join the PBS Teachers Community

Stay up to date on the latest blog posts, content, tools, and more from PBS Education!

InfoQuotex