An investigation using pieces of string to produce sounds with different pitches. A string has been attached to a weight. When the string is plucked, it is easy to see the vibrations producing the sound. When extra weights are added, the pitch becomes higher as the string becomes tighter and vibrates faster. The pitch of the string can be affected by its length and thickness.

This clip is from:
Science Clips, Changing Sounds
First broadcast:
12 October 2007

The clip could be used at the end of a lesson on sound, after pupils have carried out a carousel of activities investigating factors that affect pitch, like blowing across bottles filled with different amounts of water, plucking thick and thin strings and twanging different lengths of a ruler over the end of the table. What do they notice about the pitch of the note? Do they notice any patterns emerging (such as thicker strings, larger amounts of air or water produce lower notes)? These findings should be explained and linked to the speed of the vibrating material, demonstrating how slower vibrations produce lower sounds. The clip could be paused before each mini experiment for the pupils to predict results. Playing the remainder of the clip should enable them to check the accuracy of their predictions as well as assess their understanding of the concept.