What Can Light Go Through?

SECTION 1

🔍 What's Happening?

🔍 Anchoring Phenomenon

Now try holding up a book. Can you see through it? No! The light stops. What about a thin sheet of paper? You can see a little bit of light, but everything looks fuzzy.

A child holds three objects in front of a flashlight: clear glass, wax paper, and a book. Each one lets through a different amount of light.

💭 Thinking Questions

SECTION 2

💡 What Scientists Know

Different things do different things to light. Some let all the light through. Some let a little light through. Some stop the light completely!

Scientists sort materials into three groups based on what they do to light.

1

Transparent

That means light goes all the way through. You can see clearly through it. A window is transparent!

2

Translucent

That means some light goes through, but it looks blurry. Wax paper is translucent!

3

Opaque

That means no light goes through. You cannot see through it at all. A book is opaque!

✦ KEY TAKEAWAY

Key Takeaway

SECTION 3

🔬 Let's Try It!

🔬 Let's Investigate!

Get a flashlight (or use a bright lamp).
Gather things from around your home: a clear cup, a piece of tissue paper, a piece of cardboard, a plastic bag, and anything else you want to test.
Hold each thing in front of the flashlight. Look at the other side. How much light do you see?
Sort each thing into a group: transparent, translucent, or opaque.

You are thinking like a scientist! Scientists test things and then sort them into groups. That is called classifying.

The Flashlight Test: Shine a flashlight through a clear cup, tissue paper, and cardboard to see how much light passes through each.

SECTION 4

🧪 What We Found Out

When we test materials with light, we can compare what happens. Then we can sort them into groups!

Here is what we found when we tested different things:

Material	What Happened to Light	Group
Clear glass cup	All the light went through	Transparent
Clear plastic bag	All the light went through	Transparent
Tissue paper	Some light went through (blurry)	Translucent
Wax paper	Some light went through (blurry)	Translucent
Cardboard	No light went through	Opaque
Book	No light went through	Opaque

Look at the table. Materials that did the same thing to light go in the same group. That is how we classify them!

When something is transparent, light passes through and you can see clearly. When something is translucent, only some light passes through. Things look fuzzy. When something is opaque, no light passes through. You cannot see the other side at all.

SECTION 5

🔎 Do You See the Pattern?

Scientists love to find patterns. A pattern is when something happens the same way again and again.

Here is a pattern we found: Thick, heavy things usually block more light. Thin, see-through things usually let more light through.

This pattern works for many things in your life!

Where You Are	What Lets Light Through?	What Blocks Light?
At home 🏠	Windows (transparent)	Walls (opaque)
At school 🏫	Glass door (transparent)	Wooden door (opaque)
Outside 🌳	Clear water (transparent)	Rocks (opaque)
In the kitchen 🍳	Plastic wrap (transparent)	Aluminum foil (opaque)

✦ KEY TAKEAWAY

Key Takeaway

SECTION 6

🌍 People Use This Science!

People use what they know about light and materials every day to solve problems!

1

🏠 Windows in Houses

Windows are made of transparent glass so sunshine can come in. That helps people see inside!

2

🕶️ Sunglasses

Sunglasses are translucent. They let some light through to help you see, but they block some light to keep your eyes safe.

3

🎪 Curtains

Curtains can be thick and opaque to block light when you want to sleep. Or thin and translucent to let soft light in.

4

☂️ Umbrellas

Umbrellas are opaque. They block sunlight to keep you cool on a hot day!

🛠️ Design Challenge!

SECTION 7

📖 Words to Know

Transparent — Light goes ALL the way through. You can see clearly. (Example: a glass window)
Translucent — SOME light goes through, but things look blurry. (Example: wax paper)
Opaque — NO light goes through. You cannot see the other side. (Example: a book)
Classify — To sort things into groups based on what they are like.
Material — What something is made of. (Example: glass, paper, wood)

SECTION 8

✏️ Show What You Know!

1

Mia shines a flashlight at a piece of clear plastic wrap. She can see her toy dinosaur on the other side. What kind of material is the plastic wrap?

2

Leo holds a thick piece of cardboard in front of a lamp. No light comes through the cardboard. How should Leo classify the cardboard?

3

Sara tests three materials by shining a flashlight behind each one. She writes down her results in a chart. A frosted shower curtain lets some light through, but Sara cannot clearly see objects behind it. How should she classify the shower curtain?

4

Jayden's class tested a window, wax paper, and a wooden block by shining light on each one. They found the window let all light through clearly, the wax paper let only some light through, and the wooden block let no light through. Which list correctly classifies all three materials?

SECTION 9

🔮 What's Next?