You will need:
• 3 different size plastic cups (yoghurt cups work perfectly)
• 20 cm length of string
• 3 toothpicks
WHAT TO DO
Pierce a hole in the base of each of the cups.
Thread a piece of string through the hole in the cup and fasten the end to a toothpick to prevent the string from coming out.
Wet the string and run your thumb and forefinger along the length of the string.
SO HOW DOES IT WORK?
When rubbed the wet string vibrates and these vibrations are transferred to the empty cup. The sound is then amplified to the empty cup. The different size cups produce different pitch sound.