Lesson Plan - Get It!
- Why does sunlight pass through a window, but not through a brick wall?
- Have you ever noticed that light travels through some objects, but not through others?
Unlike sound waves, light waves pass through objects based on the object's atomic structure, not its state of matter. (For more information about sound, check out Aditional Resources in the right-hand sidebar.)
When talking about the way light reacts to objects, you first need to group all objects into one of three categories:
Transparent objects are those that allow light to pass through.
They most commonly transmit light. Sometimes, the light can be refracted as it shines through the transparent object.
Usually when you think of transparent objects, you assume that they are clear, yet this is not always the case. Examples of transparent objects include glass, certain plastics, and diamonds and other gem stones.
Find an object you think is transparent. Shine a flashlight at the object.
- Does the light go through the object?
If so, the object is transparent.
Translucent objects both transmit and reflect light.
The light that does shine through translucent objects is scattered. When the light is scattered, it appears to only partially shine through the object and will not allow you to see objects on the other side clearly. Examples of translucent objects include tinted windows, frosted glass, and your finger!
Find an object that you think is translucent. Shine a flashlight at the object.
- Does the light only partially shine through the object?
If so, the object is translucent.
Opaque objects either reflect light or absorb light.
Opaque objects do not allow any light to shine through. Examples of opaque objects include brick, wood, steel, and bone.
Find an object that you think is opaque. Shine a flashlight at the object.
- Does the object allow any light to shine through?
If not, the object is opaque.
Now, grab a piece of paper and either fold both sides vertically toward the center, or draw two, evenly-spaced lines down the center to create three equal columns. Label the first column "Transparent," the middle column "Translucent," and the last column "Opaque."
As you watch the following ADLC - Elementary Science: Translucent, Transparent, Opaque (ADLC Educational Media) video, you will see a scientist experiment with different objects to determine which are transparent, translucent, and opaque. As the scientist experiments with each object, write the name of the object in the correct column:
After the video, share your chart with your teacher or parent.
- Were you surprised by which category any of the objects fell into?
Discuss your response with your teacher or parent.
Some of the objects you should have written in the opaque category include wood, aluminum foil, and cardboard. Some objects you should have written in the translucent category include tissue paper, plastic bag, and sunglasses. The transparent category should include objects such as the clear plastic bag and glass.
When you are finished reviewing your answers, move on to the next section to perform your own experiment.