What Can You See Through It?

SECTION 1

What's Happening?

🔍 LOOK AT THIS!

Now think about this: What about wax paper or a frosted cup? You can see some light, but everything looks blurry. Why does that happen?

Three children looking through different materials: clear glass, wax paper, and cardboard

💭 Think About It

Why can you see through some things but not others?
What does the material do to the light?

SECTION 2

Big Ideas About Light and Materials

Light is all around us! It comes from the sun, from lamps, and from flashlights. When light hits something, different things can happen. The material — that means what the thing is made of — changes what the light does.

1

Some Materials Let All the Light Through

Some materials are transparent. That means light goes right through them. You can see clearly through them! Clear glass and clean water are transparent.

2

Some Materials Let Only Some Light Through

Some materials are translucent. That means only some light gets through. Things look blurry and fuzzy! Wax paper and frosted glass are like this.

3

Some Materials Block All the Light

Some materials are opaque. That means no light gets through at all. You cannot see anything on the other side! Cardboard and wood are opaque.

✦ KEY TAKEAWAY

KEY TAKEAWAY

SECTION 3

Let's Try It!

Scientists look closely at things to learn about them. That is called observing. Let's be scientists and observe what light does with different materials!

🔬 LET'S TRY THIS!

1

Step 1Put a small toy on a table. Shine the flashlight at it. Can you see the toy? Yes! There is nothing in the way.

2

Step 2Now hold clear plastic wrap between the flashlight and the toy. Look through the wrap. What do you see?

3

Step 3Next, hold wax paper between the flashlight and the toy. Look through it. What do you see now?

4

Step 4Last, hold cardboard between the flashlight and the toy. Can you see the toy? What happened?

After each try, think about this: Did the light get through? Could you see the toy?

Diagram showing a flashlight shining through three different materials toward a toy bear

SECTION 4

What We Found Out

When we tried the investigation, we saw something really cool! The material between the light and the toy changed what we could see.

Through the clear plastic wrap, we could see the toy perfectly. That is because the light went straight through. Clear wrap is transparent.

Through the wax paper, the toy looked blurry. We could see some light, but not a clear picture. That is because the wax paper mixed up the light. Wax paper is translucent.

Through the cardboard, we could not see the toy at all! The light could not get through. Cardboard is opaque.

Material	What Happened to the Light?	What Did We See?
Clear plastic wrap	Light went through ☀️	Saw the toy clearly ✓
Wax paper	Some light got through 🌤️	Toy looked blurry 〰️
Cardboard	Light was blocked 🚫	Could not see the toy ✗

This is our evidence! Evidence means the things we saw and noticed. We can use our evidence to explain: different materials change the light in different ways, and that changes what we can see on the other side.

SECTION 5

Do You See the Pattern?

Scientists love to find patterns. A pattern is when something happens the same way again and again. Let's look for a pattern!

When something lets light through, we can see through it. When something blocks light, we cannot see through it. That is a cause and effect pattern! The material causes the light to change. The effect is what we see.

Cause and effect diagram showing how materials cause different effects on light

This pattern is everywhere! It is not just about flashlights and paper. Think about these examples:

Example	What Happens?
Looking through a fish tank 🐟	The glass is transparent — you see the fish clearly!
Shower door 🚿	Frosted glass is translucent — you see shapes but not details.
A wooden door 🚪	Wood is opaque — you cannot see the other room!

✦ KEY TAKEAWAY

KEY TAKEAWAY

SECTION 6

Light and Materials in the Real World

People use what they know about light and materials to make things every day! Let's look at some examples.

1

🪟 Windows

Windows are made of transparent glass so you can see outside. You can watch the rain, see the trees, and let sunlight in!

2

🕶️ Sunglasses

Sunglasses are translucent. They let some light through so you can still see. But they block some light to keep your eyes safe on sunny days!

Can you think of a time you would want to block the light? What about when you are sleeping? Thick, opaque curtains block the light so your room stays dark. People chose that material on purpose!

🛠️ Design Challenge

SECTION 7

Words to Know

📖 KEY VOCABULARY

Light — Light is what lets us see things. It comes from the sun, lamps, and flashlights.
Material — What something is made of. Glass, paper, and wood are all different materials.
Transparent — A material that lets all the light through. You can see clearly through it. Example: clear glass.
Translucent — A material that lets some light through. Things look blurry through it. Example: wax paper.
Opaque — A material that blocks all the light. You cannot see through it at all. Example: cardboard.

SECTION 8

Practice: Show What You Know!

1

Maya holds a clear glass of water up to a sunny window. What will she most likely see on the other side of the glass?

2

James puts a piece of wax paper over the end of a flashlight and turns it on. He looks at the wax paper. What evidence would show that wax paper only lets some light through?

3

Sofia shines a lamp at a thick wooden board. She looks at the side of the board facing away from the lamp. It is dark on that side. What does this evidence tell us about how the wooden board changes the light?

4

Liam tests three materials by holding each one in front of a flashlight: a clear plastic bag, a sheet of tissue paper, and a thick book. He writes down what he sees on the other side of each material. Which set of observations is the best evidence for how each material changes the light?

SECTION 9

What's Next?

🔮 WHAT'S NEXT?