Summary
Introduction
Have you ever played with your own shadow? It is fascinating how it follows your every move. But why do you not see your shadow every day? Why is your shadow very long sometimes, and other times very short? In this activity, you will make your own shadow puppet and explore how you can change the shape or size of its shadow. If you like, you can even create your own shadow play!
Materials
- Flashlight
- Table
- Light-colored wall
- Cardstock paper
- Box
- Pencil
- Scissors
- Wooden skewers or popsicle sticks
- Scotch® tape
- Optional: frosted plastic sheet
- Optional: clear plastic sheet
- Optional: stickers or markers for decoration
Prep Work
- Place a table right next to a light-colored wall.
- Put the flashlight on a box on a table so it faces the wall. It should be located about 50 cm (about 20 inches) away from the wall.
- Cut a circle (about 2-inch diameter) from the cardstock.
- Dim the lights in the room so it is dark enough to see clear shadows on the wall.
Instructions
- Switch on the flashlight and point it at the wall.
What do you see on the wall once you switch on the light? How does the appearance of the wall change when you switch the light on? - Hold the cardstock circle up halfway between the flashlight and the wall, just outside the light shining on the wall.
What do you see on the wall? Does the circle cast a shadow? Why or why not?
- Next, hold the circle directly in front of the flashlight, halfway to the wall.
What do you see on the wall this time? What shape does the shadow have?
- Cut two more 2-inch circles from the frosted and clear plastic sheets. One at a time, hold each of the circles halfway between the flashlight and the wall.
Which material makes the darkest shadow: the frosted plastic, the clear plastic, or the cardstock circle? Can you explain your observations?
- Cut a figure or puppet out of the cardstock.
- Tape a wooden skewer or popsicle stick to the cardstock puppet.
- Cast a shadow of the puppet onto the wall.
How does the shadow look? How big is it and what shape does it have?
- Decorate your cardstock puppet with stickers or markers. Cast a shadow of the puppet again as you did before.
Do the decorations change the appearance of the shadow? Why or why not?
- Try changing the distance between the flashlight and your puppet. Hold the puppet halfway between the flashlight and the wall, then move the flashlight back and forth (farther from and closer to the puppet).
What happens to the puppet's shadow as you move the flashlight?
- Try changing the distance between the puppet and the wall. Put the flashlight back in its original position, then move the puppet back and forth (closer to and farther from the wall).
How does the shadow change as you move the puppet?
- Hold the puppet halfway between the flashlight and the wall. Try moving the flashlight around and shining it at the puppet from different angles.
What happens to the puppet's shadow when you change the angle of the flashlight? How does the shadow change?
- Now that you know how you can change the shape or size of your puppet's shadow, try making long, short, small, and big shadows.
What do you have to do to achieve these different shadows?
- Turn your knowledge about light and shadow into a shadow play. Make more shadow puppets and tell a story with them! You can also create scenes on the wall by making trees, buildings, or other figures from the cardstock.
Cleanup
What Happened?
Were you able to change the size and shape of your puppet's shadow? First you had to make the shadow by placing the puppet directly in front of the flashlight. You probably did not see a shadow when you placed the circle off to the side instead of directly in front of the flashlight. This happens because light travels in straight lines. In order to block the light, the circle needs to be in front of the flashlight. This created a shadow on the wall that was the same shape as the circle.
You probably noticed that the cardstock circle made the darkest shadow. This happens because cardstock blocks all the light that shines on it. The frosted plastic lets some light through, so it did not make a very good shadow. The clear plastic lets almost all the light through, so it barely casts any shadow at all.
You should have noticed that you could make the puppet's shadow bigger by moving it closer to the flashlight, and smaller by moving it farther away from the flashlight. When you move the puppet closer to the flashlight, you block more of the light, resulting in a bigger shadow. When you change the angle of the flashlight, you can change the shape of the shadow and even make it distorted and stretched out. A steeper angle will result in a longer shadow.
Digging Deeper
The saying "where there is a shadow there must be light" tells us that you need some kind of light source to generate a shadow. For example, your own shadow that constantly follows you around on a sunny day is generated by the sun. But shadows do not necessarily disappear with the sun. Other light sources like the headlights of a car, a table lamp, or a simple flashlight can cast shadows too. The brighter the light source, the sharper your shadows will be. All light sources emit light that travels away in a straight line called a ray.
To cast a shadow, you need an object that can block the light rays. Materials that are opaque, like the cardstock, block all light and make good shadows. Materials that are translucent, like the frosted plastic, let some light through, and might make blurry or lighter shadows. Materials that are transparent, like the clear plastic sheet, let almost all light through and barely cast any shadow at all. You also need a surface, like the wall in this activity, on which to cast the shadow and make it visible.
But how can you vary the size and shape of a shadow? This can be done by either moving the light source or moving the shadow puppet. The closer an object is to a light source, the more light it blocks, resulting in a larger shadow. Changing the angle of the light source can change the length and shape of the shadow. A steeper angle will result in a longer shadow. This is why your shadow is very long if you go outside near sunrise or sunset, but very short when the sun is directly overhead at noon.
Ask an Expert
For Further Exploration
- Make more shadow puppets! Cut out different shapes or other figures from the cardstock and see how their shadows look. Can you make a puppet with moving parts?
- What happens to your shadow if you use multiple light sources? Test it by using two or three light sources at the same time. Place them all at different positions and observe how your shadow(s) change.
- Can you find a way to make colored shadows? Look at this "Colored Shadows" activity to find out how it works.
Related Resources
Project Ideas
Activities
Lesson Plans
- MS-PS4-2. Develop and use a model to describe that waves are reflected, absorbed, or transmitted through various materials.
Links
- Toppr: Light and Shadows
- University of Leicester, UK: Light does appear to travel in straight lines
- Kennedy Center: Playing with Shadows
