Light
Lesson #2: Transparent, Translucent, Opaque
Time frame: 60 minutes
Please write the vocabulary words on the board before the lesson
Vocabulary
Transmit- to cause light, heat, sound, etc. to pass through a medium
Transparent material- a material that transmits light without scattering it
Translucent material- a material that scatters light as it passes through
Opaque material- a material that reflects or absorbs all of the light that strikes it
Absorb- to take in and retain light
Reflect- to throw or bend back light (for example) from a surface
Objectives
Students will be able to
1. Understand the terms transparent, translucent and opaque
2. Be able to categorize objects as transparent, translucent and opaque
3. Understand how the thickness of an object can change whether it is transparent,
translucent or opaque
Introduction
While studying the science of light, students must understand the difference between
transparent (light can travel through), translucent (some light can travel through) and
opaque (no light can travel through). Discuss what these terms mean and give an
example in the room for each. Ask whether the ball they used last week was
transparent, translucent or opaque? How do they know?
Focus Activity #1: Sorting Transparent, Translucent, Opaque
Give students table and ask them to sort out the materials into transparent, translucent
and opaque.
Materials:
Translucent items:
● Tissue paper
● Waxed paper
● Paper towel
● Frosted light bulb
● Eyelids
● Piece of white paper
Transparent items:
● Plastic wrap
●
●
●
●
●
Clear glass
Bubble wrap
Laminating material
Clear plastic lids
Water
Opaque:
● Construction paper
● Cardboard
● Felt
● Styrofoam
● Tin foil
● Wood
● Cloth
● Hand
● Stack of white paper
After completing the sorting activity, ask if there are any "set" of rules that determine
whether something is translucent, transparent or opaque. Plastic is an interesting
material to discuss as the students discover that it can be all three.
Absorption
In which category was light absorbed the most? How do you know?
Opaque objects absorb or reflect all of the light that strikes them. You can’t see through
opaque materials because light cannot pass through them.
Draw the following diagram on the board and follow the arrows.
Explain how if all light either reflects off a surface or gets absorbed, then no light makes
it through to the other side – this scenario would make an object opaque. But if some
light is transmitted, then light does get through, which would make the substance
translucent. If most of the light is transmitted and not absorbed or reflected, the
substance is transparent.
Pass out worksheet that shows how light absorbed and transmitted in opaque,
transparent and translucent materials.
Explain to students that colors absorb different amounts of light. EX: black absorbs
more light than white does – that is why you get much hotter when you wear black on a
summer day.
Activity #2: Application to the Ocean
Ask kids why one sheet of paper is translucent but a stack of papers is opaque.
(Each sheet absorbs - soaks up - some light. When light has to pass through many
sheets, all the light is absorbed.)
Deep-sea divers know it is dark deep below the ocean’s surface. Just as a paper
absorbs some light, so does water. As light passes through a lot of water, a little bit of
light is absorbed at a time. After a while, very little light is left. In the ocean, sunlight
passes only through the top layers of water. It is very dark deep in the ocean.
For this reason, many kinds of sea creatures that live deep down in the ocean have to
create their own light as opposed to depending on the light of the sun. This light that
they make is called bioluminescent light.
Read and explore about these fish using the iPad app Creatures of Light and going to
The Deep Ocean.
Conclusion/Assessment
Go over vocabulary