Sounds are determined by how an object vibrates. Volume is dependent on how hard the air is pushed through. Sound travels more slowly than light. Sound waves travel at the same speed, but vibrate in different ways. Some vibrate quickly and have a high frequency or pitch, while others vibrate slowly and give a lower pitch.
Use this clip to illustrate how pitch is determined. Related activities could include experimenting with different instruments to explore pitch in relation to the size and method of creating a sound. How does the thickness of the type of string contribute to the pitch of piano strings? Make instruments using different materials and test them against other instruments. What else contributes to a sound apart from vibration?