Materials
- Rope
- Emergency vehicle with siren
- Tape recorder
- Cassette tape
What to do
1. Arrange for an emergency vehicle to come to your center at a specific time with the siren on. If you invite the same emergency vehicle and person to come prior to this activity to discuss community helpers, the excitement of the visit will not be such a distraction from the discussion of sound.
2. Listen for the emergency siren. As it comes closer, the sound will change. Record this sound on the tape recorder. Listen to the siren standing still nearby. You can listen to it and record it as it goes away again.
3. How was the sound different coming and going? How did movement affect it? Refer to the cassette to check the children's answers.
4. Talk to the children about sound. Explain that we hear high pitches and low pitches and that sound is vibrations or waves moving invisibly though the air from the object that made the sound to our ear.
5. Make sounds with your voice both high and low, then feel your throat and how it vibrates. Let the children try it.
6. Use a rope to demonstrate waves. Let a child hold one end of the rope while you or another child holds the other end. Ask the children to raise and lower their hands alternating and increasing in speed.
7. Observe how the rope makes waves. The faster the children go, the more waves, the slower they go, the fewer waves.
8. Explain that the fast waves are like the high pitches and the slow waves are like the lower pitches. This is the way sound waves travel in the air to your ear. You can also explain that when a noisy object moves, the sound (or pitch) changes.
More to do
- More science: Talk about sound whenever you hear sounds during the day. Are they high pitches or low pitches? Are they moving or still?
-Joyce Dowling, Clinton, MD
