Light and Shadows
Grade 2 · Science · Study Guide
Light helps us see the world — and when it is blocked, it makes shadows! Discover the science of light and shadows.
Light is a form of energy that lets us see. The Sun is Earth's most important source of natural light. Other sources of light include lamps, fire, and even some animals like fireflies! Light travels in straight lines and moves incredibly fast — about 186,000 miles per second!
When light hits an object, three things can happen. Light can pass through transparent objects like clear glass and windows. Light can be blocked by opaque objects like walls and books. When light is blocked, a shadow forms on the other side of the object. Light can also pass partway through translucent objects like frosted glass — you can see light through them but not clearly.
Shadows change depending on where the light source is. In the morning, shadows are long because the Sun is low in the sky. At noon, when the Sun is high overhead, shadows are very short. This is how people used shadows to tell time before clocks were invented! You can make shadows with a flashlight and your hands in a dark room.
| Type | What Happens to Light | Examples |
|---|---|---|
| Transparent | Light passes through clearly | Clear glass, window, water |
| Translucent | Light passes through but blurry | Frosted glass, wax paper, tissue |
| Opaque | Light is blocked; shadow forms | Wood, brick, your hand, book |
Key terms
- light
- A form of energy that allows us to see
- shadow
- A dark area formed when an object blocks light
- transparent
- Lets light pass through clearly (like clear glass)
- opaque
- Blocks light completely and creates shadows (like a brick wall)
- translucent
- Lets some light through but not clearly (like frosted glass)
- reflect
- When light bounces off a surface
Flashcards
- Light
- A form of energy that lets us see; travels in straight lines
- Shadow
- A dark shape formed when an opaque object blocks light
- Transparent
- Lets light pass through clearly — like a clear window
- Opaque
- Blocks all light — like a wood door or brick wall
- Translucent
- Lets some light through but not clearly — like frosted glass
- Reflect
- When light bounces off a surface (mirrors reflect light very well)
Practice questions
What is a shadow?
- A type of light energy
- A dark area formed when an object blocks light
- A rainbow made of colors
- A reflection in a mirror
Show answer
Answer: A dark area formed when an object blocks light
Shadows form when an opaque object blocks light from passing through, leaving a darker area behind it.
Light travels in straight lines.
Show answer
Answer: True
Light always travels in straight lines — this is why shadows have clear edges.
An object that blocks light completely is called ___.
Show answer
Answer: opaque
Opaque materials block all light from passing through them, which is why they create shadows.
When are outdoor shadows shortest?
- Early morning
- Late afternoon
- Around noon
- At sunset
Show answer
Answer: Around noon
At noon the Sun is directly overhead, so shadows are directly underneath objects and very short.
Clear glass is transparent because it lets light pass through.
Show answer
Answer: True
Transparent materials like clear glass allow light rays to pass through without blocking them.
Fun facts
- Light from the Sun takes about 8 minutes to travel 93 million miles to reach Earth!
- A mirror is so smooth that it reflects light perfectly, creating a clear image!
- Rainbows form when light passes through water droplets and separates into all its colors!
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