Light and Sound: Grade 1 Study Guide
Sound and light are ways energy travels to our ears and eyes.
Sound is made when something vibrates, which means it moves back and forth very quickly. Touch your throat while you hum and you can feel the vibration. A drum, a guitar string and a ruler twanged on a desk all make sound this way. The vibration moves through the air to our ears.
Light comes from a source such as the Sun, a lamp or a flame. We see things when light bounces off them and reaches our eyes. In total darkness, we see nothing because there is no light.
Sound
Sounds can be loud or quiet (volume) and high or low (pitch). A big drum makes a low sound and a small one makes a high sound. A longer, looser string vibrates slower and makes a lower sound. Sound travels through air, water and solids. If something stops vibrating, the sound stops.
| Object | How it makes sound | High or low? |
|---|---|---|
| Drum | Skin vibrates when hit | Larger drum is lower |
| Guitar string | String vibrates when plucked | Shorter string is higher |
| Voice | Vocal cords vibrate | Children's are usually higher |
Light and shadows
Some materials let light pass through: transparent (clear glass), translucent (wax paper, lets some light through) and opaque (wood, blocks all light). When an opaque object blocks light, a shadow forms. Shadows are longer when the light is low (early morning or evening) and shorter when the Sun is high (noon).
Shine it at a wall in a dim room.
Try glass, wax paper and cardboard.
Which makes a shadow?
How does the shadow change?
Communicating with sound and light
People use sound and light to send messages over a distance. A bell, a whistle, a traffic light and a lighthouse all use sound or light to signal. A flashlight in Morse code or a car horn warns others. Never shine bright lights into someone's eyes or look straight at the Sun.
Worked examples and common mistakes
Example: Why can't you see anything in a closet with the door shut and the light off? There is no light to bounce off objects into your eyes. Common mistakes: thinking we see because our eyes send out light (it comes to our eyes), or that a shadow is a thing rather than the shape of blocked light. A hand shadow disappears when the lamp goes off.
Check your understanding: model answers
1. The skin vibrates. You can feel it with a finger, or see a few grains of rice jump on top. 2. Transparent: clear glass. Opaque: wood. 3. The Sun is lower in the sky in the afternoon, so the shadow is stretched out.
✨ Key Takeaways
- Vibrations make sound.
- Light helps us see.
- Opaque objects block light and make shadows.
- We use light and sound to send messages.
💬 Questions for Discussion & Reflection
- How do you know a drum is making sound when it is hit?
- Name one transparent and one opaque material.
- Why is your shadow longer in the afternoon than at noon?
Print a science observation log →