- A ruler
- Aluminium foil
- A permanent marker (or similar fat pen)
- One or more long cardboard tubes (the tubes inside aluminium foil or cling film rolls work well)
- Sticky tape
- One-quarter of a cup of dry uncooked rice
- One-quarter of a cup of sesame seeds
- One-quarter of a cup of dry uncooked lentils
What to do
- Gather your materials on a flat surface.
- Tear off a piece of aluminium foil 60 cm long. You should have a piece of foil roughly 30 cm wide and 60 cm long.
- Loosely scrunch the foil lengthways, to make a 60 cm foil ‘snake’.
- Coil the snake of foil around the permanent marker to form a tight spiral shape (like a slinky).
- Insert the foil spiral into a cardboard tube and tape each end to the inside of the tube.
- Cut a piece of foil large enough to cover one of the open ends of the tube. Tape it over one end of the tube to form a tight seal.
- Pour the rice into the tube through the open end.
- Cut another piece of foil large enough to cover the open end of the tube. Tape it over the end of the tube to form a tight seal.
- Tip the tube upside down and listen to the sound it makes.
- Remove one of the foil end caps and pour out the rice. Pour in the sesame seeds and replace the foil end cap. Use new sticky tape and foil if needed.
- Tip the tube upside down and listen to the sound it makes. How is it different from the sound with the rice?
- If you have several tubes, you can make more than one. Try using lentils or other dried seeds and grains.
Questions to ask
Try using a longer tube (like one from a roll of wrapping paper). Does the sound change?
Try using a longer or shorter piece of aluminium foil to make the coil. Does that make a difference?
Instead of using a foil spiral, try pushing toothpicks through the cardboard tube in a spiral pattern. (If the cardboard is too thick to push toothpicks through, try a toilet roll instead.)
Which of these changes affects the sound the most?
When you tip the tube, the rice, seeds or lentils fall downwards and hit the aluminium foil spiral on their way. When lots of seeds fall at once, they make a repetitive sound a bit like the rain. The sound stops when all the seeds have reached the bottom of the tube.
When a seed hits the aluminium foil it causes a vibration that we can hear. Different sizes and weights of seeds make different vibrations when they hit the foil. The different vibrations make different sounds.
Did you know
A rain stick is a kind of percussion instrument, which is an instrument that produces sound by striking it or scraping something on it. Instead of hitting the rain stick directly to make the sound, the person playing the instrument does an action that causes something else to produce the sound. They turn the instrument upside down, which makes the filling, such as rice grains, fall and strike pins that are placed inside the tube so they point towards the middle. This kind of indirectly hit instrument is called a shaken idiophone. Your rain stick is also a shaken idiophone.