Sundials

Lesson Objective

Using a sundial, the children will explore the Sun as a source of light causing shadows and will learn that the Sun travels, causing shadows to change.

Science

What You'll Need

Sundial with a gnomon (or a broom in a bucket)
Playground or flat surface
Butcher paper
Chalk or markers – 3 different colors
Tape – 1 roll

What To Do

Note: This lesson will require taking the children outside several times throughout the day. It is important to stand in exactly the same spot when you draw the shadows, so your record is reliable.

Tell the children they are going to talk about shadows today and will be going outside three times during the day to do an activity with the Sun.
Early in the day, tape the butcher paper on the playground or a flat surface so that it does not move.
Place the sundial (or broom in a bucket) on the butcher paper. Tape the bucket and the broom in place so they do not move.
Mark where you are standing in relation to the sundial with an “X” and draw the gnomon (or broomstick) shadow on the butcher paper.
Encourage the children to observe their own shadows and compare their shadows with the shadow from the sundial.
After an hour or more, go back outside and stand on the “X” you marked on the butcher paper. Draw the gnomon (or broomstick) shadow on the butcher paper using a different color marker.
Have the children compare the shadow tracings on the butcher paper (see Guiding Student Inquiry).
After another hour or more, stand on the “X” and draw the gnomon (or broomstick) shadow on the butcher paper using a third color marker.
Have the children compare the shadow tracings on the butcher paper (there should be three).

Guiding Student Inquiry

Describe what you see.
Describe what is making the shadow.
Make a prediction about what might happen to the shadow when we come back later.
Describe what happened to the shadow since the first time we traced it.
Explain what is making the shadow change.

Explore, Extend & Integrate

You could use a camera (instead of butcher paper) to document the shadows.
You can do this activity several times throughout a month or a season, or do it seasonally. The children will be able to see the changes in the shadows if the shadows are documented using the same position for the sundial (or broomstick) and if the children are standing in the same spot every time they document this.
Keep the butcher paper, labeled with the date and time of day from one season to the next, to compare the shadows. Discuss why the shadows are longer or shorter depending on the season.
Make a gnomon out of clay and a pencil. Use flashlights to create shadows.

Check for Children’s Understanding

Could children explain what created the shadow?
Could children explain why shadows changed during the day?
Could children explain that the Sun or another light source is needed to make shadows?

Resources

Did You Know?

Shadows are created by the Sun or another light source shining on an object. Any object that can block light will create a shadow. A good example is your body. Since light cannot pass through your body, your body creates a dark area where it blocks the sunlight. The patch where the light cannot reach is called a “shadow.” Shadows change in length over the course of the day. Longer shadows are cast early in the morning and late in the afternoon. The shortest shadow is at noon when the Sun is directly overhead. Because the Earth is moving, the Sun, which is the source of light, is in a continually changing position in the sky, creating the change in shadows.

A long time ago, people began to notice how much of the day was over by looking at their shadows. Eventually, this led to the invention of the sundial. A simple sundial is a stick, or “gnomon,” set in the center of a round, flat surface that stays in the same place during the course of the day. The sundial works by casting a shadow from the gnomon in different positions at different times of the day.

Vocabulary: Child-Friendly Definitions

Sun – the star that is nearest to the Earth; the Earth receives heat and light from the Sun and travels around it.
light – the form of energy that makes it possible for the eye to see. The Sun produces light.
shadow – the dark image on a surface caused by something that blocks light from the Sun.
change – to become different.
sundial – a device that stands in a garden or on a lawn to show the time of day. A sundial has a flat, round disk with numbers and a pointer that casts a shadow. As the shadow moves across the numbers, the sundial shows what time it is.
gnomon – the column on a sundial that casts a shadow and thus indicates the time of day.

Lesson Tips

Be sure to do this activity on a sunny day.
Be certain that the sundial/broom in a bucket and you are in exactly the same spot each time you trace the shadow of the sundial.
Some children might be tempted to look at the Sun once they realize the Sun is creating the shadows. Explain to them that it is very important not to look directly at the Sun because it will damage their eyes.
If a sundial is not available, you can use a flagpole or a stationary pole from the playground equipment as a substitute. Make sure that the pole is stationary and will not move over time.

Books

Moonbear’s Shadow by Frank Asch
Shadow by Suzy Lee
Guess Whose Shadow? by Stephen R. Swinburne
What Makes a Shadow? by Clyde Robert Bulla

Home School Resources

Home educators: use these printable lesson PDFs to teach this lesson to your home schoolers. They're available in English and Spanish.

Home/School Connections

Las Conexiones a la Casa

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Content Provided By

Visit The National Air & Space Museum website

Common Core State Standards Initiative – These lessons are aligned with the Common Core State Standards ("CCSS"). The CCSS provide a consistent, clear understanding of the concepts and skills children are expected to learn and guide teachers to provide their students with opportunities to gain these important skills and foundational knowledge^[1]. Visit the CCSS

There are currently no Common Core Standards for pre-k, but these lessons are aligned as closely as possible to capture the requirements and meet the goals of Common Core Standards. However, these lessons were neither reviewed or approved by the National Governors Association Center for Best Practices or the Council of Chief State School Officers, which together are the owners and developers of the Common Core State Standards.

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