Energy all around us
Energy is what makes things happen. It makes things move, light up, get warm and make sounds. Today we’ll learn about three kinds of energy: light, sound and heat.
Light
Light lets us see. Without light, everything would be dark.
Where does light come from?
Some things give off their own light:
- the Sun (our biggest light source!)
- a lamp or flashlight
- a candle flame
- fireflies
- a TV or tablet screen
The Moon looks bright, but it doesn’t make its own light. It reflects light from the Sun, like a mirror.
Light travels in straight lines
Light moves very fast in straight lines. That’s why you can’t see around corners.
Shadows
When something blocks light, it makes a shadow. A shadow is the dark shape behind the object.
- Your shadow is long in the morning and evening, when the Sun is low.
- Your shadow is short at lunchtime, when the Sun is high.
- If you move closer to a flashlight, your shadow gets bigger.
What can light pass through?
| Lets all light through | Lets some light through | Blocks light |
|---|---|---|
| Clear glass, water | Wax paper, frosted glass | Wood, a book, your hand |
Sound
Sound is energy we hear. Sound happens when something vibrates, or moves back and forth very fast.
- Pluck a guitar string. You can see it vibrate!
- Put your hand on your throat and hum. Feel the buzz?
- Tap a drum. The top shakes and makes a sound.
The vibrations travel through the air to your ears.
Loud and soft
A loud sound has a lot of energy. A soft sound has a little.
- Hit a drum hard → loud sound.
- Tap it gently → soft sound.
Very loud sounds can hurt your ears. Cover your ears near fire trucks or fireworks.
High and low
- A small bird chirps with a high sound.
- A big dog growls with a low sound.
- Short, thin strings make high sounds. Long, thick strings make low sounds.
Heat
Heat is energy that makes things warmer.
| Things that give heat | What heat does |
|---|---|
| The Sun | Warms the land, water and you |
| A stove or oven | Cooks food |
| A campfire | Keeps us warm |
| Rubbing your hands | Makes them warm |
Heat can melt ice, melt chocolate, and dry wet clothes. Always ask an adult before touching anything hot.
Energy changes
Energy can change from one kind to another.
- A lamp changes electricity into light and a bit of heat.
- A drum changes your tap into sound.
- A campfire makes light and heat.
Common mistakes
- Thinking the Moon makes light. It reflects the Sun’s light.
- Thinking sound just appears. Something must vibrate.
Try it yourself
- Shine a flashlight on a wall. Make shadow animals with your hands.
- Stretch a rubber band over a box and pluck it. Can you see and hear the vibration?
- Put a piece of chocolate in the sun and one in the shade. Which melts first?
Quick recap
- Energy makes things move, light up, warm up and make sound.
- Light lets us see; shadows form when light is blocked.
- Sound is made by vibrations; it can be loud or soft, high or low.
- Heat makes things warmer.
- Energy can change from one kind to another.